地球科学进展  2018 , 33 (6): 578-589 https://doi.org/10.11867/j.issn.1001-8166.2018.06.0578

综述与评述

黏土矿物在富营养化水体和底泥磷污染控制中的应用研究进展

邹银洪12, 张润宇1*, 陈敬安1, 王立英1, 陆顶盘12

1.中国科学院地球化学研究所,环境地球化学国家重点实验室,贵州 贵阳 550081
2.中国科学院大学,北京 100049

Research Advance in the Application of Clay Minerals to Phosphorus Pollution Control in Eutrophic Water Bodies and Sediments

Zou Yinhong12, Zhang Runyu1*, Chen Jing’an1, Wang Liying1, Lu Dingpan12

1.State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
2.University of Chinese Academy of Sciences, Beijing 100049, China

中图分类号:  P57;X52

文献标识码:  A

文章编号:  1001-8166(2018)06-0578-12

通讯作者:  *通信作者:张润宇(1979-),男,内蒙古乌兰察布人,研究员,主要从事环境地球化学研究.E-mail:zhangrunyu@vip.gyig.ac.cn

收稿日期: 2017-11-15

修回日期:  2018-05-5

网络出版日期:  2018-06-20

版权声明:  2018 地球科学进展 编辑部 

基金资助:  *国家自然科学基金项目“黏土矿物对富营养化湖泊内源磷的钝化机制及其有机质的复合影响”(编号:41573133)贵州省应用基础研究计划重大项目“贵州典型深水型湖库水环境健康风险及综合调控理论与技术”(编号:[2015]2001)资助.

作者简介:

First author:Zou Yinhong(1987-),male,Zunyi City,Guizhou Province,Master student. Research areas include water pollution control. E-mail:zouyinhong@vip.gyig.ac.cn

作者简介:邹银洪(1987-),男,贵州遵义人,硕士研究生,主要从事水污染控制研究.E-mail:zouyinhong@vip.gyig.ac.cn

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摘要

水体富营养化已成为当今全球亟待解决的重大环境问题之一。磷是造成淡水湖库富营养化的主要限制因子,其过量输入不仅导致浮游藻类的异常增殖及湖水溶解氧和透明度的显著降低,而且衍生的藻毒素、嗅味物质对生态系统和人类健康造成严重危害。当湖库外源磷输入得到有效遏制后,水体与底泥中内负荷磷的污染控制直接决定着富营养化的治理成效。黏土矿物是一类在自然界中广泛分布的非金属矿藏资源,具备孔隙多、比表面积大、优良的表面吸附和离子交换等性能,近年来在生态环境修复与治理领域备受关注。简述黏土矿物的主要类型及其理化特性,归纳了典型黏土矿物的不同改性方法及其优缺点,概括了黏土矿物应用在富营养化水体和底泥磷污染控制中的最新研究成果,重点探讨了黏土矿物的除磷机理、关键影响因子以及潜在的生态环境影响,在此基础上对未来的研究方向予以展望。

关键词: 富营养化 ; ; 化学钝化 ; 黏土矿物 ; 改性

Abstract

Eutrophication has become a major global environmental concern. As the main factor responsible for freshwater lakes and reservoirs eutrophication, the excessive input of phosphorus (P) initiates phytoplankton blooms as well as the significant reduction in dissolved oxygen and transparency in lake, thus secreting algae toxins and derived odor substances which seriously threaten the ecosystem and human life. When the external inputs are effectively curbed, the control of internal-P loading including eutrophic water and sediment directly determines the effectiveness of eutrophication. Clay minerals are a kind of nonmetallic mineral resources widely distributed in nature. It has been extensively applied in ecological environment restoration and management in recent years, ascribing to its large specific surface area, porosity and the excellent surface adsorption and ion exchange performance. This paper introduced the main types of clay minerals and their physicochemical characteristics, summarized the advantages and disadvantages of different modification methods on typical clay minerals, presented the latest research results of its application in P control of eutrophic water and sediment, discussed the factors influencing the mechanism of P removal and their potential ecological environment impact, and pointed out the future research direction.

Keywords: Eutrophication ; Phosphorus ; Chemical inactivation ; Clay minerals ; Modification.

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邹银洪, 张润宇, 陈敬安, 王立英, 陆顶盘. 黏土矿物在富营养化水体和底泥磷污染控制中的应用研究进展[J]. 地球科学进展, 2018, 33(6): 578-589 https://doi.org/10.11867/j.issn.1001-8166.2018.06.0578

Zou Yinhong, Zhang Runyu, Chen Jing’an, Wang Liying, Lu Dingpan. Research Advance in the Application of Clay Minerals to Phosphorus Pollution Control in Eutrophic Water Bodies and Sediments[J]. Advances in Earth Science, 2018, 33(6): 578-589 https://doi.org/10.11867/j.issn.1001-8166.2018.06.0578

自工业活动以来,世界经济呈现持续快速发展,人类和各种生物活动不断将营养物质从地下向地表、由流域向湖库水体迁移和富集,造成全球性的水体富营养化问题[1]。磷(P)是导致水体富营养化最主要的限制因子之一[2],其过量输入不仅导致湖库浮游藻类的异常增殖及水体溶解氧和透明度的显著降低,而且衍生的藻毒素、嗅味物质等对生态系统和人类健康产生严重危害[3]。最新研究表明,在过去的4个世纪里,经由外源磷流失进入中国淡水的总磷量增加了3倍,其中人为活动的贡献率从16世纪的20%剧增到2012年的83%[4],且磷在淡水生态系统中的积累远比氮快[5]。因此,当湖库水体外源磷输入逐渐得到有效遏制后,对富营养化水体与底泥中内负荷磷的污染控制已成为水环境领域的研究热点和难点[6,7]

迄今为止,对于富营养化水体磷的控制技术包括吸附法[8]、膜分离法[9]、离子交换法[10]和混凝法[11]等。其中,吸附法具有高效、经济、易操作及无二次污染等优点,常用吸附剂主要有粉煤灰、硅藻土、铁铝氧化物和稀土氧化物等[6,8,11]。目前,针对底泥磷的污染控制主要有曝气复氧、水力冲刷、环保疏浚、物理覆盖、化学钝化和生物修复等技术[6,7]。其中,化学钝化通过向水—底泥系统投加所优选的钝化剂,经絮凝、吸附、沉淀等共同作用,有效抑制内源磷的释放,被认为是一种原位经济的治理技术[2,6,7,12]。常用钝化剂有铝盐、铁盐和钙盐,但往往受到pH、氧化还原电位等因素不同程度的限制[2,12,13]

黏土矿物(clay minerals)是一类重要的非金属矿藏资源,广泛分布于天然土壤和沉积物中,由于其比表面积大、孔隙多、极性强,具备优良的表面吸附和离子交换性能,常应用于重金属污染、有机污染及水体富营养化等领域,其去污性强、环境友好、成本低廉,尤其是改性处理后的黏土矿物应用效果更好[7,14,15]。由于黏土矿物种类和组成繁杂,其在富营养化水体和底泥磷的控制研究虽有诸多文献报道,尚缺乏较为全面系统的比较研究与科学总结,特别是对一些新兴的黏土矿物改性材料的除磷机制及其影响因子的认知还不清楚。鉴于此,本文简述黏土矿物的主要类型及其理化特性,归纳了几种典型黏土矿物的不同改性方法和优缺点,概括了典型黏土矿物在富营养化水体和底泥磷污染控制的最新研究成果,重点探讨了黏土矿物的除磷机理、关键影响因子及其对水生生态环境的影响,并指出了未来可能拓展的研究方向。

1 黏土矿物

黏土矿物是天然产出的具有无序过渡结构的微粒质点(<2 μm)的晶质硅酸盐矿物和非晶质硅酸盐矿物的总称,其成因主要有3种方式:①经土壤风化和淋滤作用形成;②经成岩和沉积作用形成;③经交代与充填作用形成。我国分布有上述各种成因产状的黏土矿物[16]。根据结晶学特征可将黏土矿物分为硅酸盐黏土矿物和非硅酸盐黏土矿物。

1.1 硅酸盐黏土矿物

硅酸盐矿物的基本结构单元是硅氧四面体和铝(镁)氧(氢氧)八面体。硅氧四面体是由1个硅离子(Si4+)和4个氧离子(O2-)构成,进而聚合形成带负电荷的硅片,表示为n(Si4O10)4-;铝氧八面体的基本结构是由一个铝离子(Al3+)和6个氧离子或氢氧离子构成,各自聚合为带负电荷的铝片,表示为n(Al4O12)12-。硅片与铝片的结合可以是2∶ 1型或1∶ 1型。除凹凸棒石、海泡石等为层链状外,其他硅酸盐黏土矿物均为层状结构,其层间包含可交换的无机阳离子,并有一部分氧原子电子暴露在晶体表面。这种特有分子结构及不规则的晶体缺陷,使其对水体中的污染物具有良好的吸附性能。相比于1∶ 1型矿物晶体结构,2∶ 1型硅酸盐黏土矿物常存在同晶置换,一般带有永久负电荷,阳离子交换容量较高,例如蒙脱石、凹凸棒石、蛭石和累托石等[16],目前用于富营养化水体中磷的净化材料主要为前2种。

1.1.1 蒙脱石

蒙脱石(Montmorillonite)是一类具有天然纳米特征的无机超高分子量硅(铝、镁)酸盐聚合物,一般结构式为:

Ex(H2O)4{(Al2-x,Mgx)2[(Si,Al)4O10](OH)2},

其中E为层间可交换阳离子,主要为Na+和Ca2+,其次有K+和Li+等。蒙脱石主要由基性火成岩在碱性环境中风化而成,也存在海底沉积的火山灰分解后的产物。自然界分布广泛,美国、俄罗斯、意大利等国都有丰富的资源产出,我国主要分布在内蒙古、浙江、河北、辽宁、新疆等地。

蒙脱石是膨润土(又称斑脱岩)的主要成分,根据层间主要阳离子的种类,可分为钠基蒙脱石、钙基蒙脱石、锂基蒙脱石等变种。蒙脱石属于2∶ 1型单斜晶系结构,表面积为600~800 m2/g,且在晶体结构内部存在着如Fe,Al和Mn阳离子类质同象置换,阳离子交换容量(Cationic Exchange Capacity,CEC)为70~130 mmol/100g[16]。当置换阳离子比中心离子化合价低时,使结构增加等量的负电荷,由晶体表面吸附的阳离子补偿,这一构造特性决定了蒙脱石的一系列重要性质,如阳离子交换性、膨胀性、吸附性等特性,且因价廉易得、无毒无害,用其作为水环境修复与治理材料的前景很好。

1.1.2 凹凸棒石

凹凸棒石(Attapulgite)又称为坡缕石,是一种具有特殊纤维状晶体结构的含水富镁铝硅酸盐矿物,其理想的化学分子式为:Mg6Si8O20(OH)2(OH2)44·4H2O。凹凸棒石呈土状和致密块状,多产于沉积岩和风化壳中,几乎遍布世界各地,我国主要集中分布于甘肃、江苏、内蒙、贵州、四川等地区。

凹凸棒石为层链状2∶ 1型黏土矿物,每个晶体结构单元内含有8个水分子,其中4个水分子与Mg2+形成配位结晶水,另外4个水分子则以游离态形式束缚于结构的孔道内。晶体中部分Si4+被Fe3+和Al3+替代,而Mg2+又可被Fe2+,Fe3+和Al3+替代,导致凹凸棒石表面的电荷不平衡,以及因结晶边缘断键形成Si—OH和Al—OH,这些—OH可以与被吸附的物质形成共价结合。相比于蒙脱石,凹凸棒石的CEC较低,通常在50 mmol/100g以下[16]。但由于凹凸棒石具有发达的孔道,具有特殊的胶体性能和晶体结构,且结构中含有B、L酸位点,使其具有优越的载体性、吸附性、离子交换性和悬浮性等,可作为一种廉价且环境友好型的水处理吸附材料[14,17]

1.2 非硅酸盐黏土矿物

非硅酸盐黏土矿物是一类在矿物结构和化学成分上与硅酸盐黏土矿物存在显著差异的黏土矿物,主要包括铁、铝、锰的氧化物,其结构既可呈结晶质状态存在,也可以非晶质状态存在[16]。这类黏土矿物通过质子化和表面羟基H+的离解产生正、负电荷,且表面活性官能团多,对磷的吸持和迁移有着特殊的作用。

1.2.1 氧化铁矿物

自然环境中氧化铁矿物常以细小的纳米晶体形式存在,通过Fe(III)盐溶液在各种温度和pH条件下水解、金属螯合物的热解、固相在干燥或溶液状态下热转化以及溶解—再沉淀反应等不同途径形成,常以针铁矿(α-FeOOH)、纤铁矿(γ-FeOOH)、赤铁矿(α-Fe2O3)、磁赤铁矿(γ-Fe2O3)、磁铁矿(Fe3O4)和无定形铁(Fe(OH)3)等形式存在于岩石土壤、沉积物和水体中。α-FeOOH普遍存在Al同晶替代,最高可达33%。由于Al3+半径比Fe3+半径小,Al替代Fe后,针铁矿的结晶度变差,晶胞变小,颗粒变小,比表面积、吸磷能力和磁化率均随Al替代量的增大而增加[18]。实验室研究已表明氧化铁矿物材料表面积大,容易合成或改性,对磷酸盐具有强吸附性[19]。因此,在富营养化水体中磷的控制方面得到了诸多的研究和应用。

1.2.2 氧化铝矿物

氧化铝矿物是由氢氧化铝在不同的受热条件下,经脱水热转型而成,具有不同型态(如α-Al2O3,γ-Al2O3和η-Al2O3等)。α-Al2O3比表面积小,但热稳定性好;γ-Al2O3和η-Al2O3的比表面较大、孔隙率高、耐热性强、成型性好,具有较强的表面酸性和一定的表面碱性[20]。此外,氧化铝矿物可以制成球、片、条、蜂窝、微球等多种形状和尺寸的颗粒,常作为载体负载活性组分,并可以与其发生相互作用,提高吸附性、催化活性和选择性。因此,氧化铝矿物被认为是一种多孔、高分散度的材料,也是一种常应用于污水处理的优良吸附剂[21,22]

2 黏土矿物的改性

自然条件下的黏土矿物往往存在一些缺陷,对水中污染物的去除效果欠佳,去除时间也较长。若要提高黏土矿物对富营养化水体磷的去除效果,则需要对其进行改性处理。目前,这方面的相关研究报道很多,概括起来主要有以下3种方法:①物理改性,即通过物理方法改变其结构,热处理是常用的方法;②化学改性,常利用无机酸碱与有机试剂改性;③复合改性,通过添加一些辅助剂,以及添加酸、碱、盐或有机物与黏土矿物按比例混合,然后在适当的温度下进行改性得到新的合成物,或者先通过高温对黏土矿物进行处理,然后再与一些物质进行复合处理[11,14,17,21]

2.1 蒙脱石的改性

天然蒙脱石的阳离子交换容量和层间距均较小,可接触的内表面小以及表面亲水性使其应用受到很大程度的限制。因此,为了扩大蒙脱石的应用领域,通常需要对蒙脱石进行改性,主要改性方法及其优缺点见表1

表1   蒙脱石的改性方法及其优缺点

Table 1   Modification methods of montmorillonite and their advantages and disadvantages

改性方法改性机理优点缺点参考文献
酸改性通过加酸浸泡,蒙脱石层间的金属阳离子溶出,使得其孔道得到疏通,有利于吸附质分子的扩散,电离出来的H+还可以置换出层间的金属阳离子,从而减弱层间作用力,永久性负电荷增多增大了内部孔结构容积,提高吸附性能吸附效果受酸的浓度控制[23]
盐改性利用蒙脱石的膨胀性和层间阳离子可交换性的特点,通过使无机金属阳离子水解产生的金属羟基阳离子进入蒙脱石层间来置换出可交换阳离子增大比表面积、稳定性增强,吸附性增强,有效、可回收重复利用过量使用会引起水体pH值过高,对生物体造成严重危害[7,24~28]
热改性蒙脱石在高温煅烧下依次失去表面水、骨架结构中的结合水孔隙率增加,结构更为疏松,吸附性能得到一定改善不详[29]
有机改性如有机长链烷基季铵盐对蒙脱石表面改性或有机硅烷偶联剂对蒙脱石表面羟基进行嫁接改性增强蒙脱石亲有机性、比表面积、稳定性和吸附能力,且吸附剂具有一定的再生性稳定性差,会造成水体二次污染[30,31]
复合改性将有机组分(如长链烷基季铵盐、有机硅烷偶联剂)与无机阳离子(如铁、铝)通过化学方法嫁接负载在蒙脱石表面复合改性后的蒙脱石具有亲有机性且更稳定,更加环保在实际应用中可能受其他污染物干扰,影响其吸附率[31,32]

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2.2 凹凸棒石的改性

针对凹凸棒石黏土的改性有热处理法,酸、碱、盐处理法及有机改性等方法,其优缺点见表2

表2   凹凸棒石的改性方法及其优缺点

Table 2   Modification methods of attapulgite and their advantages and disadvantages

改性方法改性机理优点缺点参考文献
热改性通过高温焙烧可以蒸发凹凸棒土中的几种形态
水(孔道吸附水、结晶水和表面吸附水)
增大比表面积,提高吸附效果加热需要消耗较多
的热量,成本高
[14,33,34]
酸改性经酸浸泡后的凹凸棒土内部四面体与八面体结构部分溶解。同时,半径较小的H+会置换出层间的 K+,Na+,Mg2+和 Fe3+改变凹凸棒土胶体的带电性和吸附活性,提高吸附性能酸浓度过高易破坏
凹凸棒土的结构
[17,35,36]
碱改性在碱液条件下,凹凸棒土末端的Si液中四面体溶解速度大于Mg2+,Al3+和Fe3+的溶解速度,形成无定形态的MgO和FeOx的聚集比表面积增大,吸附性能增强除磷效率低,吸附
时间较长
[36,37]
盐改性通过离子交换置换凹凸棒土层间直径较大的离子来扩大孔径比表面积增大,吸附性能增强不详[38,39]
有机改性通过以大分子量的有机基团取代凹凸棒土表面存在的可交换阳离子以及晶格内的部分结晶水和吸附水,从而在凹凸棒土表面接枝含氨基或羧基的大分子有机物吸附性能好、选择性好、时间短、除磷效率高改性方法过程复杂,
成本较高
[40,41]

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2.3 氧化铁矿物改性

氧化铁矿物在水体环境中主要以各种铁盐的形式存在,极易受到水体氧化还原条件和pH值变化的影响,对水体磷的吸附有效时间较短,且易造成水体二次污染。为了提高其对水体磷的去除效果,许多研究者将其进行改性处理,主要的处理方法及其优缺点见表3

表3   氧化铁矿物的改性方法及其优缺点

Table 3   Modification methods of iron oxide minerals and their advantages and disadvantages

吸附剂制备过程优点缺点参考文献
石英砂负
载氧化铁
筛取粒度较小的石英砂滤料,先用浓盐酸溶液浸泡后,洗净烘干。按一定比例将Fe(NO3)·9H2O溶于双蒸水,与洗净后的石英砂均匀混合,烘干,冷却后,用双蒸水洗去未负载的氧化铁颗粒,直至中性,烘干备用对磷的吸附效果好,并解决粉末吸附剂难以回收的问题不详[42,43]
水合氧
化铁
将氨水溶液与三氯化铁溶液均匀混合,所得沉淀用去离子水反复洗涤至中性,再将沉淀物烘干至质量恒定,碾成粉末状,得到固体水合氧化铁吸附剂样品对磷酸根有较强的吸附能力,并且制备方法简单、材料价格低廉、且无生态毒性pH值及反应时间影响其吸附性能[44,45]
羟基氧
化铁
将三价铁盐与羟基混合,形成原位水解生成的羟基氧化铁比表面积大,有利于磷的吸附吸附剂多为粉末状,固液分离难,不利于磷的回收及吸附剂的再生[46~48]
沸石负载
氧化铁
用稀盐酸浸泡沸石,冲洗至中性,烘干。按一定比例将Fe(NO3)3溶解于超纯水中,并与预处理的沸石混合均匀,烘干。再将负载后的沸石清洗至中性,烘干备用除磷性能好、容易再生和价格低廉等优点pH值影响其吸附
性能
[49]
铁锰复合
氧化物
将铁盐与高锰酸钾在碱性条件下混合,便可获得铁
锰复合氧化物
比表面积增大,对磷的吸附性能较好吸附效果受共存离子及pH值的影响[50,51]

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2.4 氧化铝矿物改性

氧化铝矿物中通常含有较多杂质(如硅、钛等),且在水体pH过酸或过碱时,对磷的吸附效果偏低。通过提纯辅以活性、磁改性、负载铁和负载铁锰复合处理,可以提高氧化铝矿物对磷的去除率(表4)。

表4   氧化铝矿物的改性方法及其优缺点

Table 4   Modification methods of alumina mineral and their advantages and disadvantages

吸附剂制备过程优点缺点参考文献
活性氧化铝将铝矾土原料经化学处理除杂而制得氧化铝原料,Al2O3含量达到高纯级别,将活性氧化铝粉碎,放入烘箱中,烘干后,放入干燥器中冷却至室温备用比表面积大、吸附性能佳,且高温和酸性条件有利于对磷的去除在碱性和低温条件,不利于对磷的去除,且运行成本高[52~54]
盐改性活
性氧化铝
向质量浓度为10%的Al2(SO4)3或Na2SO4溶液中加入粉末状γ-Al2O3,在常温下振荡、静置后,用纯水冲洗,烘干备用吸附除磷效果比未经改性的更佳受吸附剂用量和温度的影响[22,55]
磁改性
氧化铝
将AlCl3溶液倒入硅包被磁铁矿中,以NaOH溶液调节pH至弱碱性(磁分离)后,清洗风干,研磨备用比表面积增大,有利于磷的吸附,吸附剂可反复利用受离子竞争和表面水和氧化铝影响[56,57]
铁铝氧化
物复合剂
凝胶蒸发法:将Fe(NO3)·9H2O和Al(NO3)·9H2O与乙二醇以1∶ 3的比例混合溶解,用磁力搅拌加热器以90 ℃蒸发溶剂,硝酸乙二醇自燃产生泡沫,最后得到松散的粉末,焙烧后备用吸附性能优,不受水体共存离子的影响铝延缓了合成化合物的晶度[58,59]

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3 不同黏土矿物对水体和底泥中磷的控制效果

3.1 蒙脱石

天然蒙脱石对水体磷具备一定的吸附净化能力,尤其是经改性处理后的蒙脱石除磷效果更佳。例如,Tanyol等[29]考察了酸和热改性膨润土对磷酸溶液的去除效果。经处理后吸附剂的表面面积增加,对初始磷酸盐浓度为150 mg/L的最大吸附量可达21.1 mg/g,对磷的去除效果显著高于原状膨润土。Kasama等[26]研究表明,在磷初始浓度为3.2 mmol/L,pH值为3~7时,羟基铝柱撑膨润土的磷吸附容量可达0.66 mmol/g,比原状膨润土高出2个数量级。Yan等[27]研究表明,无机柱撑膨润土是去除水中磷酸盐的优良吸附剂,其吸附效率可达90%以上。此外,经无机有机复合改性后的蒙脱石对水体磷酸盐的吸附效果更优,如Zhu等[32]采用AlCl3和溴化十六烷基三甲基铵(Cetyltrimethyl Ammonium Bromide,CTMAB)共同改性制得无机—有机复合蒙脱石吸附剂,该吸附剂对磷吸附容量显著高于AlCl3柱撑蒙脱石,对P O43-的去除率可达到99%,沉降性能也优于CTMAB改性蒙脱石,比单一的有机蒙脱石或无机柱撑蒙脱石更适合处理含磷废水[31]

锁磷剂(Phoslock)最早是由澳大利亚水河协会(Water River Confraternity,WRC)及联邦科学与工业研究组织(Commonwealth Scientific and Industrial Research Organization,CSIRO)研制的治理富营养化水体中磷及底泥磷释放的专利产品,主要成分为镧改性膨润土,该产品首先对西澳洲沿海平原的2个夏季水华频繁的河口(Canning河和Vasse河)进行了性能测试。结果表明,在将锁磷剂浆液撒入的几个小时内,水体磷含量低于检测下限,并且镧改性膨润土对以浮游藻类占主导的Vasse河控磷效果较为明显,但对以水草占主导的Canning河治理效果不明显[60]。Lürling等[61]在2008年使用锁磷剂和聚氯化铝协同治理荷兰Rauwbraken湖爆发性的蓝藻。结果显示,水体总磷(Total Phosphorus,TP)平均浓度从169 μg/L降到了14 μg/L,并且该湖直到2013年均表现为寡营养湖,水体TP浓度降低近90%。Mrquez-Pacheco等[62]将锁磷剂应用于一个旅游、渔业和供水为一体的富营养化水库,结果显示2周时间内水体磷含量下降近75%。Gunn等[63]将锁磷剂应用于英国Loch Flemington湖,发现夏季水体透明度增加,TP浓度显著降低;Meis等[7]利用锁磷剂对Loch Flemington湖进行修复发现,底泥中惰性磷含量增加,而还原态可溶性磷和有机磷等活性态比例降低。国内也有相关的研究报道,朱广伟等[64]通过室内泥柱培养实验表明,锁磷剂对西湖底泥内源磷释放有明显的控制效果,可将上覆水溶解性活性磷浓度控制在0.01 mg/L以下,春季、夏季和冬季的底泥磷释放控制率分别为76%,98%和62%,说明锁磷剂在控制湖库内源磷释放方面能发挥积极的作用。

3.2 凹凸棒石

Gan等[33]研究表明热活化凹凸棒石对磷酸盐的吸附效果显著高于原状凹凸棒石,并发现该改性工艺在酸性介质中更有效。同时探讨了不同浓度酸改性凹凸棒石对磷的吸附净化性能,其中以3%的酸改性处理效果最佳,在1%投加量下,除磷率较原土提高了95%,水体残留磷浓度均小于0.02 mg/L,水体磷浓度达到我国地表水Ⅰ类标准[35]。Yin等[14,65]发现富钙黏土材料—海泡石与凹凸棒石能以Ca2-P和Ca8-P的钙磷结合态持久控磷,并通过传统的物理及化学改性,确立了热处理(温度在1 000 ℃范围内)可显著增强富钙黏土固磷容量的方法,从原始的约10 mg/g增加至约40 mg/g。韩梅香等[34]进一步研究指出,添加5%~20%热改性(700 ℃)凹凸棒石不仅可以增强底泥对磷的固持能力,而且会增加底泥的磷最大吸附量1.5~2.0倍,且吸附速率增加1.7~3.7倍。

3.3 氧化铁矿物

由于不同种类的铁氧化物具特殊的理化性质,对水体磷污染的控制效果存在显著差异。Kang等[66]在实验室比较了水铁矿、针铁矿、赤铁矿等处理生化二级含磷废水效果。结果表明,水铁矿除磷效果远好于针铁矿和赤铁矿,其原因是水铁矿结构的无定形使其比表面积远大于针铁矿和赤铁矿。莫德清等[45]研究了水合氧化铁对含磷废水的吸附特性。研究表明,在酸性条件下吸附性能较好,当溶液pH值为2时,对磷的去除率达92.5%;而在碱性条件下去除率为35%。齐晓璐等[48]将三价铁盐与一定摩尔比的OH-混合,通过原位水解生成的羟基氧化铁(原位FeOxHy)并将其用于控磷。结果发现:不同摩尔比条件下原位FeOxHy对磷的去除率均随铁投量增大而升高,且在中性pH范围内具有最佳效果;在相同铁投量条件下,磷去除率随着OH-与Fe3+摩尔比的升高而降低。对于碱度较低的体系,通过投加一定量OH-可促进Fe3+水解,进而使其更易与水中的H2P O4-与HP O42-结合,生成具有多核羟基的磷酸铁络合物。李海宁等[51]研究表明,包覆海砂能够充分发挥铁锰复合氧化物对磷的吸附性能,最大磷吸附容量达1.2 mg/g,且对磷的吸附速率较快。陆燕勤等[49]发现磷的去除率随着沸石负载氧化铁吸附剂投加量和铁负载含量的增加而升高,吸附效果在中性条件下最佳,沸石负载氧化铁具有控磷性能好、容易再生和价格低廉等特点,在实际水处理应用中具有广泛的前景。

3.4 氧化铝矿物

活性氧化铝是一种多孔、高分散度的材料,有很大的比表面积,其微孔表面具有较强吸附能力,是一种有效的除磷吸附剂,可应用于提高自来水的生物稳定性和水体磷污染控制[52,54]。磁性氧化铝在pH值为5~9的范围内吸附磷效果最好,最大磷吸附量为12.9 mg/g,且去除较快速,温度的升高对其最大吸附量略有提升作用。在实际污水处理中,其最佳投量为1.25 kg/t,且使用1 mol/L NaOH可以成功地对吸附后的磁性氧化铝进行解吸,磁性氧化铝显示出良好的磷回收和反复利用的性质[57]。Tofik等[59]制备了铁铝二元氧化物纳米材料并将该吸附材料应用于水体磷吸附研究,发现铁铝二元氧化物纳米材料对磷具有强吸附性,最大的吸附率为16.4 mg/g,吸附效率可达99.9%,是治理水体磷污染的新型材料。

4 黏土矿物的除磷机理及其主要影响因子

4.1 黏土矿物的除磷机理

4.1.1 硅酸盐黏土矿物的除磷机理

硅酸盐黏土矿物对磷的去除机理主要包括静电吸附、离子配位交换和共沉淀等。静电吸附表现为黏土矿物对极性物质的优先选择性吸附作用,而磷酸根离子带有负电荷,容易被吸附。离子配位交换是指黏土矿物中的金属离子在水体中以氢氧化物形式存在,水体中HP O42-可与OH-进行离子配位交换。共沉淀作用为黏土矿物中的Ca,Fe和Al等化学成分与水体和底泥中的活性磷转化为Ca-P,Fe-P和Al-P等难溶的磷酸盐,从而将磷固化与沉积。Zhu等[32]研究了无机—有机复合改性蒙脱石对磷酸盐的吸附机理,发现吸附剂表面的Al—OH官能团被P O43-替代,为离子配位交换。王虹[67]研究表明锆改性膨润土主要是以配位体交换和内层络合形式吸附磷,并以金属氧化物结合态磷和残渣态磷的形式存在,在低溶解氧条件下难以释放出来。锁磷剂的控磷机制主要有吸附与共沉淀2种作用(图1),即由锁磷剂中的化学活性成分镧与水体中的磷酸根反应,生成溶解度极低的磷酸镧沉淀,并附着在悬浮颗粒载体上,进一步吸附磷酸盐而后随颗粒缓慢沉降到水体底部[28,63]

Yin等[14]研究表明,在700 ℃下热处理的天然富钙凹凸棒石(NCAP700)中的活性钙对磷具有极强的固定能力,不仅其下沉过程中会吸附水体中的磷酸盐,而且在底泥表面还可形成一层薄的覆盖层,能有效抑制底泥中活性磷向上覆水体中的释放(图2)。显然,该钝化剂兼有化学沉淀与物理覆盖2种功能。

图1   锁磷剂的除磷机理示意图

Fig.1   Schematic diagram of P control mechanism of Phoslock

图2   凹凸棒石的除磷机理示意图[14]

Fig.2   Schematic diagram of P control mechanism of NCAP700[14]

4.1.2 金属氧化物的除磷机理

除上述几种作用外,金属氧化物除磷还有表层沉淀、路易斯酸碱作用等,均与水体的pH有关,适宜pH值范围为2~10[50](图3)。表层沉淀通常快速而难以逆转,当水体中沉淀组分的浓度超过了沉淀的溶度积时,磷与金属离子的沉淀就会发生[68]。路易斯酸碱作用表现在低pH时,溶液中存在过量的H+,金属活性位点被质子化成弱酸,充当电子受体;磷酸根离子成为一个弱碱,作为电子供体。在碱性环境下,金属活性位点变成弱碱,磷酸根离子变成弱酸。这意味着在金属活性位点和P O43-之间存在着电子受体和路易斯酸碱作用,且金属活性位点可能与磷酸盐中的氧阴离子发生反应,形成M—O配位键。当一个磷酸盐分子靠近金属中心时,聚类表面会释放一个H2O群,通过酸碱性的路易斯相互作用,可能形成一个单配位基复合物。这种单配位基复合物会继续攻击未反应的邻水或羟基物种,形成一个双配位基复合体[69]

图3   金属氧化物除磷机理示意图[50]

Fig.3   Schematic diagram of P control mechanism of metal oxides[50]

氧化铁表面的氧原子在水中会发生水化作用生成表面羟基及Fe(OH)3,能强烈吸附水中的磷酸盐;同时也能与磷酸盐反应生成以FeOOH-PO4形态存在的络合物[18]。Kim等[47]采用磷核磁共振技术揭示了铁氧(氢氧)化物与水体中磷酸盐的作用机理,发现主要以Fe—O—P共价键结合。而铝氧(氢氧)化物可以对磷酸盐通过配位交换作用方式在(氢)氧化铝表面形成(如NaAl3(OH)4(PO4)2,Al3(OH)3(PO4)2和AlPO4·2H2O等)内层络合物[70]

4.2 黏土矿物除磷的热力学与动力学机制及其主要影响因子

4.2.1 黏土矿物吸附磷的热力学与动力学机制

不少学者研究了黏土矿物对磷的吸附热力学与动力学过程。改性黏土矿物对磷的等温吸附过程通常符合Linear,Langmuir或Freundlish吸附模型,动力学过程可用Elovich 模型、准一级动力学模型或准二级动力学模型进行描述[50]。例如,Tanyol等[29]研究发现热活化膨润土的对磷的吸附更符合Langmuir等温线模型,吸附过程受外部传质和内扩散的控制,在早期阶段是外部传质,而后阶段是内部扩散;吸附动力学符合准二级模型,说明二者之间具有高亲和性,且吸附为自发的吸热过程。Yan等[27]发现,羟基铝、铁等柱撑膨润土对水溶液中磷酸盐的吸附均符合准二级模型,实验数据与Freundlich和Langmuir吸附等温线模型吻合得很好。对于热改性凹凸棒石,在溶液磷浓度低于0.5 mg/L时,Linear模型可以很好地描述磷的吸附过程,而在较高磷浓度下(>1 mg/L),更符合Langmuir等温吸附模型[34]。铁氧化物吸附磷属于快速吸附(15 s内)且吸附动力学符合准二级动力学模型,吸附过程主要受化学吸附机理的控制;Freundlich模型可很好地描述磷在氧化铁表面的吸附行为[48]。铝氧化物吸附磷的动力学过程一般符合Elovich 模型[50,70]

4.2.2 黏土矿物除磷的主要影响因子

黏土矿物对磷的控制效果与其自身物化性质、投加量、反应时间和水体环境状况密切相关,如pH值、水温、DO、水体磷浓度、有机质、光照、水动力和水生生物组成等。黏土矿物组成中的钙素含量、胶体氧化铁和胶体氧化铝等活性化学成分的比例,是决定其去除磷能力的重要前提[14]。Huang等[25]研究发现锆铝柱撑蒙脱石对磷酸盐的吸附容量随pH值的降低而增加;共存阴离子的存在(如S O42-,Cl-,N O3-)对吸附容量具有一定的影响。低光照强度下,溶液中各种离子的活性增加,导致膨润土对磷的吸附效果较好,而当光照强度过大时,整个溶液中的熵值过高,导致溶液系统不稳定,不利于对磷的控制[71]。最新研究表明,锁磷剂的应用受水体溶解氧和pH值的影响较小[72],但受水体碱度及溶解有机质的干扰较大[73]。水体中腐殖质可以与锁磷剂中的镧结合,使钝化磷的效果大大减弱。金属氧化物除磷方面主要受水体pH和氧化还原电位的影响。此外,黏土矿物投加量的增加有利于对磷的控制。例如,Mrquez-Pacheco等[62]发现当锁磷剂投加比例(锁磷剂与水体总磷量比)为15∶ 1时,15天后水库溶解性磷酸盐浓度下降25%~50%,将投加比例提高为40∶ 1时,2周时间内水体磷含量下降约75%。

5 黏土矿物的“二次释放”对水生生态环境的影响

近年来,随着铁盐、铝盐、钙盐及黏土矿物等不同类型钝化剂的逐渐应用,其对水生生态环境的潜在影响也开始引发关注。例如,铝改性钝化剂的应用可导致水体溶解铝含量升高,从而降低生物多样性,并引起鱼类腮畸形甚至死亡。一些研究表明,胶状Al(OH)3絮凝体可长期在动物细胞表面凝聚引起生物腮肥大,从而导致无脊椎动物的种类和数量减少,以及鱼类的死亡,导致水生生态环境恶化[74,75]。一些富钙黏土矿物钝化剂的投放会使水体pH值及水体碱度升高,进而引起金属氧化物结合态磷的释放,并危害水生生物[2]。湖泊中施加锁磷剂后立即可以检测到镧的浓度,并对浮游动物(如大型溞和网纹溞)产生短期的负面效应,而对于人类健康风险可以忽略不计[15]。此外,黏土矿物沉降到水体底部,会在沉积物表面形成一层薄的覆盖层,进而改变水体溶解氧的扩散度,影响底栖生物的生境与摄食活动[76,77]。因此,黏土矿物的使用不仅关系到水体和底泥磷污染控制的效果,还关系到对水生生态环境的潜在影响。在黏土矿物的使用过程中应加强对水质和水生生物的实时监测,对除磷效果与潜在生态风险进行客观评价。

6 展 望

综上所述,黏土矿物本身无臭、无味、无毒,且比表面积大、孔隙多、吸附性能强、化学稳定性好,可作为富营养化水体中内负荷磷控制的新材料,具有广阔的应用前景。今后还需着重加强以下几个方面的研究:

(1)根据不同湖库的水文地质特征,特别是水深、水动力条件、底泥性质与生物种群等特征,弄清水体及底泥中磷的来源、污染程度和迁移活化通量,确定适宜的黏土矿物类型、用量与改性方法,建立科学的应用技术方案。

(2)运用梯度扩散薄膜技术(Diffusive Gradients in Thin films,DGT)等原位微界面高分辨率手段和31P NMR、X射线吸收精细结构光谱等现代表征技术,深入阐明黏土矿物在不同环境介质中微观控磷机制及其主要影响因子。

(3)改性黏土的使用量和频率不仅关系到富营养化水体磷的控制效果,也关系到水生生物体的安全。例如,铝改性黏土可能因铝盐的溶解或水解作用而导致生物慢性铝中毒。锁磷剂中的改性物镧在一定剂量范围内也会对生物体产生毒理学效应。因此,在改性黏土矿物的施用过程中,除加强对控磷效果的长期评估外,也要对水质和水生生物进行实时监测。

(4)探索黏土矿物与其他材料或技术的联合应用。不同黏土矿物具有各自的优缺点和适宜应用条件,因此其单一应用在某些湖库中可能难以取得理想效果,应加强与其他材料或技术联合应用的试验与示范研究。如利用壳聚糖改性黏土,既能高效吸附水体中的磷,也能促进藻华的絮凝沉降。黏土矿物也可与生态浮床配合使用,生态浮床可以消减风浪等水动力扰动对黏土矿物控磷效果的影响,进一步吸纳富营养化水体中的磷酸盐,增加透明度和溶解氧,从而更好地改善水质。

The authors have declared that no competing interests exist.


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[黄肖容, 李雪辉.

γ-氧化铝膜的表面酸碱性

[J].分子催化, 2001, 15(1):6-10.]

[本文引用: 1]     

[21] Tanada S, Kabayama M, Kawasaki N, et al.

Removal of phosphate by aluminum oxide hydroxide

[J]. Journal of Colloid & Interface Science, 2003, 257(1):135-140.

DOI      URL      PMID      [本文引用: 2]      摘要

The development and manufacture of an adsorbent to remove phosphate ion for the prevention of eutrophication in lakes are very important. The characteristics of phosphate adsorption onto aluminum oxide hydroxide were investigated to estimate the adsorption isotherms, the rate of adsorption, and the selectivity of adsorption. Phosphate was easily adsorbed onto aluminum oxide hydroxide, because of the hydroxyl groups. The adsorption of phosphate onto aluminum oxide hydroxide was influenced by pH in solution: the amount adsorbed was greatest at pH4, ranging with pH from 2 to9. The optimum pH for phosphate removal by aluminum oxide hydroxide is 4. The selectivity of phosphate adsorption onto aluminum oxide hydroxide was evaluated based on the amount of phosphate ion adsorbed onto aluminum oxide hydroxide from several anion complex solutions. It is phosphate that aluminum oxide hydroxide can selectively adsorb. The selectivity of phosphate onto aluminum oxide hydroxide was about 7000 times that of chloride. This result indicated that the hydroxyl groups on aluminum oxide hydroxide have selective adsorptivity for phosphate and could be used for the removal of phosphate from seawater.
[22] Li Xing,Fan Qian,Yang Yanling,et al.

Adsorption performance of trace phosphorus removal by modified active aluminum oxide

[J]. Journal of Beijing University of Technology,2009,35(6):825-829.

[本文引用: 1]     

[李星,范茜,杨艳玲,.

改性活性氧化铝吸附去除水中痕量磷的性能

[J]. 北京工业大学学报,2009,35(6):825-829.]

URL      [本文引用: 1]      摘要

为了获得更为高效的去除水中痕量磷的方法,通过静态吸附试验考察了经Al2(SO4)3或Na2SO4改性的活性氧化铝(γ-Al2O3)吸附除磷性能,观察了吸附剂投量、pH值及水温变化对PO4^3-P去除效果的影响及改性前后的γ-Al2O3对模拟水样中不同形态磷的去除效果.结果表明:γ-Al2O3经Al2(SO4)3或Na2SO4改性后对PO4^3-P的去除效果比改性前有显著提高,对PO4^3- -P的去除率分别提高了18.53%和14.34%;改性γ-Al2O3对PO4^3- -P的去除率在-定的投量范围内随投量的增加明显提高;改性γ-Al2O3对PO4^3- -P的吸附作用以物理吸附为主,随着温度和pH值的升高,除磷效果均呈下降趋势;经Al2(SO4)3改性的γ-Al2O3表现出更好的除磷效果和较强的水质适应性;水中浊质对吸附除磷效果影响较大,因此γ-Al2O3更适合滤后水的深度除磷.
[23] Pawar R R, Gupta P,

Lalhmunsiama, et al. Al-intercalated acid activated bentonite beads for the removal of aqueous phosphate

[J]. Science of the Total Environment,2016,572:1 222-1 230.

DOI      URL      PMID      摘要

The separation of fine spent sorbents from treated water after remediation is a major difficulty associated with phosphate wastewater treatment technology. In this study, a novel aluminium-pillared acid activated bentonite powder (Al-ABn) and alginate immobilized aluminium-pillared acid activated bentonite beads (Al-ABn-AB) were synthesized and used for the removal of aqueous phosphate. The phosphate removal behaviour of adsorbents were evaluated by batch experiments as a function of various parameters such as pH, initial concentration, contact time, temperature, adsorbent dose and presence of coexisting ions. The sorption isotherm studies by Langmuir model showed 12.87 and 11.11 mgP/g maximum phosphate uptake capacity for Al-ABn and Al-ABn-AB, respectively. The kinetic studies confirm that the adsorption of phosphate by Al-ABn and Al-ABn-AB follows a pseudo-second-order model. The feasibility of Al-ABn-AB was also assessed in continuous mode in fixed bed column and the loading capacity obtained was 4.55聽mg/g. The adsorption capacity of Al-ABn-AB beads remained at relatively high even after four regeneration cycles. Furthermore, the applicability of the synthesized adsorbents towards real municipal wastewater confirmed that novel synthesized Al-ABn and Al-ABn-AB are the promising adsorbents for the removal of phosphate from contaminated water.
[24] Borgnino L, Avena M J, Pauli C P D.

Synthesis and characterization of Fe(III)-montmori-llonites for phosphate adsorption

[J]. Colloids & Surfaces A: Physicochemical & Engineering Aspects, 2009, 341(1/3):46-52.

[25] Huang W,Chen J,He F,et al.

Effective phosphate adsorption by Zr/Al-pillared montmorillonite: Insight into equilibrium, kinetics and thermodynamics

[J]. Applied Clay Science, 2015, 104:252-260.

DOI      URL      [本文引用: 1]     

[26] Kasama T,Watanabe Y,Yamada H,et al.

Sorption of phosphates on Al-pillared smectites and mica at acidic to neutral pH

[J]. Applied Clay Science,2004,25(3/4): 167-177.

DOI      URL      [本文引用: 1]      摘要

To investigate sorption behaviors and mechanisms of phosphates, phosphate sorption (hereafter, P sorption) experiments were carried out for synthetic montmorillonite, beidellite, saponite, and fluor-tetrasilicic expandable mica pillared with cationic, Keggin ion-like, Al clusters (Al clst). The P sorption experiments were done in the final pH range of 3 to 7 at room temperature and at an initial concentration of 3.2 mmol/l P. The P sorption maxima for the Al clst samples were 0.66鈥0.87 mmol/g, which are higher by about 2 orders of magnitude than those for smectites without Al clst pillars. The sorption ability of the Al clst samples is nearly as high as that of Al-bearing minerals and materials such as boehmite and amorphous Al hydroxide, which are regarded as effective absorbents to remove P from water. Examinations by X-ray diffraction analysis, infrared spectroscopy, scanning electron microscopy, and analytical transmission electron microscopy indicated that the P sorption is mostly related to the OH functional groups of the Al clst pillars, but little to the P species in solution, the reactive sites on the edge surface of smectites and mica, or possible precipitates. The P sorption maxima increased with increasing an amount of Al clst pillars in the Al clst samples, suggesting that the P sorption maximum is determined by the number of the OH functional groups of the Al clst pillars and is independent of the structures and chemical compositions of the host phases.
[27] Yan L G,Xu Y Y,Yu H Q,et al.

Adsorption of phosphate from aqueous solution by hydroxy-aluminum, hydroxy-iron and hydroxy-iron-aluminum pillared bentonites

[J]. Journal of Hazardous Materials, 2010, 179(1/3):244.

DOI      URL      [本文引用: 2]     

[28] Haghseresht F, Wang S B, Do D D.

A novel lanthanum-modified bentonite, Phoslock, for phosphate removal from wastewaters

[J]. Applied Clay Science, 2009, 46(4):369-375.

DOI      URL      [本文引用: 1]      摘要

Phoslock 03, a lanthanum-modified bentonite, has been investigated for phosphate uptake from synthetic and real wastewaters in laboratory and field. In laboratory tests, equilibrium and kinetics were studied at various temperatures, ionic strength, and pHs. The investigation indicated that phosphate adsorption occurs through a chemisorption process. The activation energy of the adsorption process was calculated based on pseudo-second order rate constant. The maximum adsorption capacity of Phoslock was unaffected at pH 5–7, but decreased at higher pHs. The monovalent phosphate anion, H 2PO 4 61, had the greatest affinity for the adsorbent surface. Furthermore, it was also shown that the activation energy was lower at a higher solution pH attributed to the loss of adsorption sites at the higher pHs while it remained unaffected by the ionic strength of the solution. A field test also demonstrated that the Phoslock works well for phosphate uptake in polluted waters.
[29] Tanyol M,Yonten V,Demir V.

Removal of phosphate from aqueous solutions by chemical-and thermal-modified bentonite clay

[J]. Water Air & Soil Pollution,2015,226(8): 1-12.

DOI      URL      [本文引用: 2]      摘要

The study investigated phosphate adsorption from aqueous solutions using chemical- and thermal-modified bentonite in batch system. The adsorbent was characterized by SEM, BET, and FTIR spectroscopy. Contact time, beginning phosphate concentration, pH of the solution, and the effects of the temperature on phosphate adsorption capacity were determined by a series of experimental studies. In a wide pH range (3–10), high phosphate removal yields were obtained (between 94.23 and 92.26%), and with the increase in temperature (from 25 to 45°C), phosphate removal increased. Langmuir and Freundlich isotherms were used to determine the sorption equilibrium, and the results demonstrated that equilibrium data displayed better adjustment to Langmuir isotherm than the Freundlich isotherm. Phosphate sorption capacity, calculated using Langmuir equation, is 20.37mgg 611 at 45°C temperature and pH3. Mass transfer and kinetic models were applied to empirical findings to determine the mechanism of adsorption and the potential steps that control the reaction rate. Both external mass transfer and intra-particle diffusion played a significant role on the adsorption mechanism of phosphate, and adsorption kinetics followed the pseudo-second-order-type kinetic. Furthermore, thermodynamic parameters (Δ H °, Δ G °, Δ S °) which reveal that phosphate adsorption occur spontaneously and in endothermic nature were determined. The results of this study support that bentonite, which is found abundant in nature and modified as an inexpensive and effective adsorbent, could be used for phosphate removal from aqueous solutions.
[30] Wang J,Ma H,Yuan W,et al.

Synthesis and characterization of an inorganic/organic Modi-fied bentonite and its application in methyl orange water treatment

[J]. Desalination & Water Treatment,2014,52(40/42): 7 660-7 672.

[31] Ma J,Zhu L.

Simultaneous sorption of phosphate and phenanthrene to inorgano-organo-bentonite from water

[J]. Journal of Hazardous Materials,2006,136(3): 982-988.

DOI      URL      [本文引用: 1]     

[32] Zhu R,Zhu L,Zhu J,et al.

Sorption of naphthalene and phosphate to the CTMAB-Al13 intercalated bentonites

[J]. Journal of Hazardous Materials,2009,168(2/3): 1 590-1 594.

DOI      URL      PMID      [本文引用: 2]      摘要

This work aimed to develop novel bentonite based sorbents that could simultaneously remove hydrophobic organic compounds (HOCs) and phosphate from water. Cetyltrimethyl ammonium bromide (CTMAB) and hydroxy-aluminum (Al 13 ) were used to intercalate bentonite simultaneously or sequentially to prepare series of inorganic–organic bentonites (IOBs). Structures of the prepared IOBs were characterized, and their sorptive characteristics towards naphthalene and phosphate were investigated. Results showed that both CTMAB and Al 13 could intercalate into bentonite's interlayers if they were simultaneously used or if CTMAB was first used for the intercalation. The resulting IOBs were as effective as the CTMAB modified bentonites in sorption of naphthalene from water, and they were shown to be more effective in sorption of phosphate from water than the Al 13 pillared bentonite. However, if Al 13 was first used for the intercalation, the interlayers of the bentonites would be “locked” by the intercalated Al 13 , and thus CTMAB could hardly further intercalate bentonite. As a result, the obtained IOBs showed weak sorption efficiency towards naphthalene, and its sorption capacity towards phosphate was also lower than the corresponding Al 13 pillared bentonites. Results of this work showed that IOBs prepared with proper processes could be efficient sorbents towards both HOCs and phosphate.
[33] Gan F, Zhou J, Wang H, et al.

Removal of phosphate from aqueous solution by thermally treated natural palygorskite

[J]. Water Research, 2009, 43(11):2 907-2 915.

DOI      URL      PMID      [本文引用: 1]      摘要

Abstract The potential of activated palygorskite was assessed for sorption of phosphate from aqueous solution. The natural palygorskite used was treated by thermal activation over 100-1000 degrees C for 2h. The thermal activation increased the phosphate sorption capacity and the highest phosphate sorption capacity occurred at 700 degrees C. H700 (palygorskite heated at 700 degrees C) showed higher sorption rate than natural palygorskite (NPAL), and the removal was favorable in acidic media. The sorption data were described using Freundlich isotherm equation over the concentration range (5-1000mg/L) (25 degrees C). Calcium bound phosphorus was the main fraction of the adsorbed phosphorus, about 98.0% in NPAL and 58.2% in H700, but the extractive Ca-P species varied greatly, Ca(2)-P was 87.7% in NPAL and 3.0% in H700, Ca(8)-P was 10.1% in NPAL and 54.5% in H700, and metal bound phosphorus was less than 2% in NPAL but more than 41.4% in H700, respectively. The dependence of the phosphate sorption capacity in the heating samples on thermal activation appears to be related to major changes in the crystal structure of palygorskite, and more calcium, iron and aluminum were released from the crystal matrix at 700 degrees C, which promoted phosphorus sorption.
[34] Han Meixiang,Yin Hongbin,Tang Wanying.

Phosphorus sorption from aqueous solution by the thermally-treated attapulgite amended sediment

[J]. China Environmental Science,2016,36(1):100-108.

[本文引用: 2]     

[韩梅香,尹洪斌,唐婉莹.

热改性凹土钝化底泥对水体磷的吸附特征研究

[J].中国环境科学,2016,36(1):100-108.]

DOI      URL      [本文引用: 2]      摘要

基于前期选择的廉价热处理富钙凹土为依据,通过向底泥中添加不同比例的热处理富钙凹土,研究材料添加后底泥对磷的吸附及对底泥磷的转化特征.结果表明,添加材料后会显著增强底泥对磷的固持能力和吸附速率,其中5%~20%的材料添加会增加底泥的磷最大吸附量1.5~2.0倍,吸附速率增加1.7~3.7倍.材料添加后的底泥具有较强的抗干扰能力,其中pH值、NO3-以及HCO3-对磷吸附的干扰作用明显减弱,而SO42-和SiO32-依然会对添加材料底泥产生较大的影响.磷形态分析表明,材料添加可以将可移动磷转化为Al-P和Ca-P,增加了底泥中惰性磷的比例,由此会显著降低底泥磷向上覆水体的释放.以上研究结果表明,热处理富钙凹土是湖泊富营养化控制的一种有效材料,可以用于底泥磷释放的控制.
[35] Gan Fangqun,Zhou Jianmin,Wang Huoyan,et al.

Effect of acid concentration on phosphate adsorption capacity of acid modified palygorskites

[J]. Acta Pedologica Sinica,2010,47(2):319-324.

[本文引用: 1]     

[干方群,周健民,王火焰,.

不同浓度酸改性对凹凸棒石粘土磷吸附性能的影响

[J].土壤学报,2010,47(2):319-324.]

[本文引用: 1]     

[36] Jozefaciuk G, Matykasarzynska D.

Effect of acid treatment and alkali treatment on nanopore properties of selected minerals

[J]. Clays & Clay Minerals, 2006, 54(2):220-229.

DOI      URL      摘要

Bentonite, biotite, illite, kaolin, muscovite, vermiculite and zeolite were acidified or alkalized with HCl or NaOH of concentrations 0.0, 0.1, 1.0 and 5.0 mole dmat room temperature for 2 weeks and converted into Ca homoionic forms. Low-temperature nitrogen and room-temperature water-vapor adsorption-desorption isotherms were used to characterize the mineral pores of radii between 1 and 30 nm. Nanopore volumes, size distributions, average radii and fractal dimensions were calculated. Values calculated from the nitrogen isotherms differed from those derived from water-vapor data. With an increase of the acid-treatment concentration, the pore volumes measured using both adsorption techniques increased markedly for all minerals. The pore radii measured from nitrogen isotherms appeared to decrease for all minerals except zeolite, while the pore radius calculated from water-vapor data increased in most cases. The fractal dimension measured from water vapor isotherms decreased in all cases indicating smoothing of the mineral surfaces and decrease in pore complexity. No well defined trends in any of the pore parameters listed above were noted under alkaline treatment. In the reaction of each mineral with acid and alkali treatments, the individual character of the mineral and the presence of impurities seems important.
[37] Zhang Jianmin,Zhou Lei,Liu Yutao,et al.

Modification of paiygorskites by alkali-acid and the effect of the phousphorus removal

[J]. Journal of Xian Polytechnic University,2013,27(6):760-763.

[张建民, 周磊, 刘玉涛,.

凹凸棒石的碱酸改性及除磷效果探究

[J].西安工程大学学报, 2013,27(6):760-763.]

DOI      URL      摘要

比较分析了不同酸、碱及酸碱复合改性凹凸棒石对模拟含磷废水的吸附净化性能,并探讨了不同改性对凹凸棒石磷吸附性能的影响.结果显示,当凹凸棒石与质量分数为9%的盐酸在固液比为1:2条件下改性,磷吸附效率达53.59%.NaOH先与凹凸棒石1:1混合均匀后焙烧改性,再将碱改性后的凹凸棒石与质量浓度为9%的盐酸在固液比为1:2再进行改性,吸附效率高达99%以上即碱酸复合改性的凹凸棒石极大地提高了其对磷的吸附效率.
[38] Pan M,Lin X,Xie J,et al.

Kinetic,equilibrium and thermodynamic studies for phosphate adsorption on aluminum hydroxide modified palygorskite nano-composites

[J]. RSC Advances,2017,7(8):4 492-4 500.

DOI      URL     

[39] Zhang Y,Lv X J,Kou X Y.

Kinetics and thermodynamic investigation of phosphate adsorption on AlCl3 modified palygorskite

[J]. Advanced Materials Research, 2013, 683:530-533.

DOI      URL     

[40] Chen H, Zhang J P.

Study on preparation of organo-attapulgite clays and properties of superabsorbent composites

[J]. Chinese Journal of Applied Chemistry, 2006, 23(1):69-73.

DOI      URL      摘要

Organo-attapulgite clays were prepared by means of mechanical stirring and ultrasonic treatment in a hexadecyltrimethylammonium bromide ( HTAB) and attapulgite clay mixture solution. The attapulgite clay and organo-attapulgite clays were characterized by using XRD, FTIR, SEM and TEM techniques. The results show that the HTAB cations were adsorbed on the surface of attapulgite needles, and dispersion of the organo-attapulgite clays showed nano-dimension. Organic contents of the two organo-attapulgite clays prepared by either mechanical stirring or ultrasonic treatment under the same conditions were 5. 12% and 2. 98% , respectively. The two organo-attapulgite clays were used for the preparation of organic-inorganic hybrid superabsor-bents. When the clay content was 10% , the water absorbencies of the two resulting superabsorbent composites reached 3 820 g/g and 3 323 g/g , respectively, which are higher than that of superabsorbent composite prepared with untreated attapulgite clay(2 872 g/g).
[41] Zhang J M, Zhang Q, Meng L G, et al.

Influence of graft modification process on organic grafted attapulgite adsorbing phosphorus

[J]. Industrial Water & Wastewater, 2014,45(3):47-51.

URL      摘要

Organic grafting can reduce the loss of attapulgite powder during the phosphorus adsorption process, however, grafting influence the adsorption performance of attapulgite on phosphorus also. For the purpose of reducing the said negative influence, a test on the grafte of modified attapulgite was carried out, and the influences of different grafting processes on grafted product adsorbing phosphorus were discussed. The results showed that, when the dosage of acrylamide, N,N鈥-methylene bisacrylamide, sodium bicarbonate and modified attapulgite were 0.7, 0.04, 1 and 1 g respectively, the application amount of absolute ethyl alcohol, 5% potassium persulfate solution and water were 5, 1 and 7 mL respectively, the removal rate of phosphorus by organic grafted attapulgite could reach 92%, which was 93.8% of the ungrafted one, and the adsorption capacity reached 4.6mg/g.
[42] Bailey R P, Bennett T, Benjamin M M.

Sorption onto and recovery of Cr(VI) using iron-oxide-coated sand

[J]. Water Science & Technology, 1992, 26(5/6):1 239-1 244.

DOI      URL      摘要

No abstract available.
[43] Xu Guangmei,Shi Zhou,Deng Jun.

Characterization of adsorption of antimony and phosphate by using IOCS with XRD,FTIR and XPS

[J]. Acta Scientiae Circumstantiae,2007,27(3):402-407.

Magsci     

[许光眉,施周,邓军.

石英砂负载氧化铁吸附除锑、磷的XRD、FTIR以及XPS研究

[J].环境科学学报,2007,27(3):402-407.]

DOI      URL      Magsci      摘要

通过XRD、FTIR以及XPS方法研究了石英砂负载氧化铁(IOCS)吸附锑、磷的机理.研究结果表明,IOCS表面氧化铁的晶型为α-Fe<sub>2</sub>O<sub>3</sub>;OH-及Fe—O键可以在FTIR谱图上检测到.XPS测定结果表明,IOCS吸附锑过程中氧原子及铁原子发生了电子转移,而IOCS吸附磷的过程几乎没有发生电子转移.XPS的价带谱研究表明,IOCS与锑的结合强度大于IOCS与磷的结合强度.由于锑、磷的吸附,导致IOCS表面铁原子的浓度有所降低;XPS溅射结果表明,锑较磷更能与深层的氧化铁发生反应.
[44] Xiang Xuemin,Liu Ying,Zhou Jiti,et al.

Sorption-desorption of phosphate in wastewater by hydrous iron oxide

[J]. Environmental Science,2008,29(11):3 059-3 063.

[项学敏,刘颖,周集体,.

水合氧化铁对废水中磷酸根的吸附—解吸性能研究

[J].环境科学, 2008,29(11):3 059-3 063.]

[45] Mo Deqing,Duan Junyuan,Wang Xijing.

Studyon phosphate contained waste water adsorption byhydrous iron oxide

[J]. Environmental Science &Technology,2012,35(Suppl.2): 66-69.

[本文引用: 1]     

[莫德清,段钧元,王曦兢.

水合氧化铁对含磷废水的吸附特性研究

[J].环境科学与技术,2012,35(增刊2):66-69.]

[本文引用: 1]     

[46] Genz A, Kornmüller A, Jekel M.

Advanced phosphorus removal from membrane filtrates by adsorption on activated aluminium oxide and granulated ferric hydroxide

[J]. Water Research, 2004, 38(16):3 523-3 530.

DOI      URL     

[47] Kim J,Li W, Phillips B L,et al.

Phosphate adsorption on the iron oxyhydroxides goethite (α-FeOOH), akaganeite (β-FeOOH), and lepidocrocite (γ-FeOOH): A31P NMR study

[J]. Energy & Environmental Science,2011,4(10):4 298-4 305.

[本文引用: 1]     

[48] Qi Xiaolu,Sun Lihua,Zhang Yajun,et al.

Effectiveness and mechanism of the in situ formed iron hydroxide (FeOxHy) towards the removal of phosphate by coagulation and adsorption

[J]. Chinese Journal of Environmental Engineering,2014,8(2): 505-512.

[本文引用: 2]     

[齐晓璐,孙丽华,张雅君,.

原位水解生成的羟基氧化铁凝聚吸附除磷效能与机制

[J].环境工程学报,2014,8(2): 505-512.]

[本文引用: 2]     

[49] Lu Yanqin,Zhu Li,He Zhaoju,et al.

Phosphate adsorption from waste water byiron-oxide coated-zeolite

[J]. Environmental Engineering,2015,(4):48-52.

[本文引用: 1]     

[陆燕勤,朱丽,何昭菊,.

沸石负载氧化铁吸附剂吸附除磷研究

[J].环境工程,2015,(4):48-52.]

DOI      URL      [本文引用: 1]      摘要

采用铁盐溶液蒸发法制备沸石负载氧化铁吸附剂,探讨其对磷的吸附 性能.结果表明:随着沸石负载氧化铁吸附剂投加量的增加,单位质量吸附剂对磷的吸附量先升高后降低;磷的去除率随负载铁含量的增加而升高;pH =7时,去除率高达92.6%;吸附剂对磷的去除率受共存离子的影响较小;吸附数值可采用Freundlich等温模型拟合,相关性显著;吸附过程很好地 遵循准二级动力学模型;采用NaOH为再生剂效果较好,再生率随着NaOH溶液浓度的提高而提高.
[50] Li M,Liu J,Xu F,et al.

Phosphate adsorption on metal oxides and metal hydroxides: A comparative review

[J]. Environmental Reviews,2016,24(3): 319-332.

DOI      URL      [本文引用: 5]      摘要

Abstract Phosphorus removal from wastewater is important for eutrophication control of water bodies. Metal oxides and metal hydroxides have always been developed and investigated for phosphorus removal, because of their abundance, low cost, environmental friendliness, and chemically stability. This paper presents a comparative review of the literature on the preparation methods, adsorption behaviors, adsorption mechanisms, and the regeneration of metal (hydr)oxides (e.g., Fe, Zn, Al, etc.) with regard to phosphate removal. The contrasting results showed that metal hydroxides could offer an effective and economic alternative to metal oxides, because of their cost-benefit synthesis methods, higher adsorption capacities, and shorter adsorption equilibrium times. However, the specific surface area of metal oxides is larger than that of metal hydroxides because of the calcination process. Metal oxides with a higher pH at the zero point of charge have wider optimal adsorption pH ranges than metal hydroxides because of their surface precipitation in alkaline solutions. The regeneration of metal oxides using acids, bases, and salts and that of metal hydroxides using acids and bases has been critically examined. Further research on uniform metal (hydr)oxides with small particle size, high stabilities, low cost, and that are easily regenerated with promising desorbents are proposed. In addition, quantitative mechanism study and application in continuous-mode column trials are also suggested.
[51] Li Haining,Chen Jing,Li Qiumei,et al.

Adsorptive removal of phosphate from water using Fe-Mn binary oxide coated sea sand

[J]. Acta Scientiae Circumstantiae,2016,36(3): 880-886.

Magsci      [本文引用: 1]     

[李海宁,陈静,李秋梅,.

铁锰复合氧化物包覆海砂的吸附除磷研究

[J].环境科学学报,2016,36(3):880-886.]

DOI      URL      Magsci      [本文引用: 1]      摘要

利用铁锰复合氧化物包覆海砂制备了一种用于污水除磷的新型颗粒状吸附剂, 并对其表面特性与磷吸附行为进行了研究. 扫描电镜(SEM)分析结果表明, 包覆后海砂颗粒表面凹凸不平且多孔, BET比表面积由0.06增至2.52 m<sup>2</sup>&#183;g<sup>-1</sup>. 磷吸附实验结果表明, 包覆后海砂对磷的吸附能力显著提高, 最大吸附容量为1.01~1.23 mg&#183;g<sup>-1</sup>, 优于多数文献报道的负载改性砂颗粒吸附剂; 吸附动力学更符合准二级动力学方程, 推测磷在包覆海砂表面发生了化学吸附; 溶液pH对磷吸附有一定影响, 离子强度则影响不大; 共存阴离子对磷吸附影响的大小顺序为SiO<sub>3</sub><sup>2-</sup>> CO<sub>3</sub><sup>2-</sup>> F<sup>-</sup>> SO<sub>4</sub><sup>2-</sup>> Cl<sup>-</sup>.
[52] Ku Y, Chiou H M.

The Adsorption of fluoride ion from aqueous solution by activated alumina

[J]. Water Air & Soil Pollution, 2002, 133(1/4):349-361.

DOI      URL      [本文引用: 1]      摘要

The adsorption of fluoride ion in aqueous solution by using alumina was studied in this research. The experimental resultsindicated that the removal efficiency was influenced significantly by solution pH and the optimum operating pH wasfound to be in the range of 5 to 7. For neutral and acidic solutions, the adsorption capacities of fluoride by alumina wasinterfered by the presence of sulfate. The Langmuir and Freundlich isotherms can well describe the equilibrium behaviorsof the adsorption processes. The experimentally determined lowvalues of activation energy indicate nonspecific adsorption isthe predominant mechanism. The surface reaction-limiting batchkinetic model can adequately describe the removal behaviors offluoride ion by alumina adsorption in the batch system.
[53] Wang J L, Zhang Y J, Feng C M, et al.

Adsorption capacity for phosphorus comparison among activated alumina, silica sand and anthracite coal

[J]. Journal of Water Resource & Protection, 2009, 1(4):260-264.

[54] Meng Wenna,Xie Jie,Wu Deyi, et al.

Study on phosphate removal and recovery by activated alumina

[J]. Environmental Science,2013,34(1):231-236.

[本文引用: 1]     

[孟文娜,谢杰,吴德意,.

活性氧化铝对水中磷的去除与回收研究

[J].环境科学,2013,34(1):231-236.]

URL      [本文引用: 1]      摘要

使用活性氧化铝作为吸附剂研究其对磷的吸附特性,并对不同提取剂对磷的回收效果进行了讨论.结果表明,活性氧化铝对使用蒸馏水、自来水及洱海入湖河流罗时江水配制的磷溶液有不同的磷吸附效果,其对3种不同磷溶液的吸附等温线模型均符合Langmuir模型,经计算得到理论最大吸附量分别为20.88、32.15和29.85 mg·g-1.通过吸附试验表明,电解质的存在对吸附效果有促进作用.pH值越低,活性氧化铝表面的Zeta电位越高,越有利于磷吸附.对比使用4种不同提取剂的试验结果表明,使用0.1 mol·L-1NaOH基本可以完全提取活性氧化铝吸附的磷.
[55] Chubar N I,Kanibolotskyy V A,Strelko V V, et al.

Adsorption of phosphate ions on novel inorganic ion exchangers

[J]. Colloids & Surfaces A Physicochemical & Engineering Aspects,2005,255(1/3):55-63.

DOI      URL      摘要

The demand for cost effective adsorbents is widespread recognition through drinking water–liquid wastes treatment technologies. The novel ion exchangers based on individual and mixed hydrous oxides (ZrO 2 · x H 2 O, Fe 2 O 3 ·Al 2 O 3 · x H 2 O and Fe 2 O 3 ·2Al 2 O 3 · x H 2 O) have been obtained by sol–gel method from easily available and cheap raw materials and employed for adsorption of H 2 PO 4 61 from aqueous systems. High specific surface area of the materials was found: 404, 396 and 38802m 2 02g 611 for ZrO 2 · x H 2 O, Fe 2 O 3 ·Al 2 O 3 · x H 2 O and Fe 2 O 3 ·2Al 2 O 3 · x H 2 O correspondingly. Adsorbents were characterized by potentiometric titration (anion exchange and cation exchange capacities (on H and OH 61 ions)), zeta-potential and pore volume studies. pH effect of phosphate ions sorption on the double hydroxides of Fe and Al was stronger than on the hydrated zirconium dioxide, however, all investigated sorbents are capable to work in the pH range from 3 to 10 having sufficient sorption capacity. Increasing the ionic strength of the solutions with adding electrolyte NaCl increased sorption of phosphate ions on ZrO 2 · x H 2 O. The presence of Ca 2+ in the solution increased sorption capacity at the higher equilibrium concentration of phosphate ions >4002mg02P02l 611 . Isotherms of the phosphate ions sorption on Fe 2 O 3 ·Al 2 O 3 · x H 2 O and Fe 2 O 3 ·2Al 2 O 3 · x H 2 O were obtained at the pHs 3, 6 and 9. Isotherms fitted the Langmuir model. Data on the kinetics of phosphate sorption fit well to the pseudo-second-order model. It is supposed that mechanism of phosphate ions adsorption onto individual oxides hydrated is not only ion exchange between P(V) ions and hydroxide groups, present on the surface, but it is also a result of nucleophylic S N 2-i-replacement of OH groups via formation of intermediate six-centered complex with the release of water molecules.
[56] Bozorgpour F, Ramandi H F, Jafari P, et al.

Removal of nitrate and phosphate using chitosan/Al2O3/Fe3O4 composite nanofibrous adsorbent: Comparison with chitosan/Al2O3/Fe3O4 beads

[J]. International Journal of Biological Macromolecules,2016,93(Pt A):557-565.

DOI      URL     

[57] Lai Li,Xie Qiang,Fang Wenkan,et al.

Removal and recycle of phosphor from water using magnetic core/shell structured Fe3O4@SiO2 nanoparticles functionalized with hydrous aluminum oxide

[J]. Environmental Science,2016,37(4):1 444-1 450.

[本文引用: 1]     

[赖立,谢强,方文侃,.

水合氧化铝负载的磁性核/壳结构Fe3O4@SiO2纳米颗粒对水中磷的去除及再利用

[J].环境科学,2016,37(4):1 444-1 450.]

[本文引用: 1]     

[58] Jeong Y, Fan M, Singh S, et al.

Evaluation of iron oxide and aluminum oxide as potential arsenic(V) adsorbents

[J]. Chemical Engineering & Processing Process Intensification, 2007, 46(10):1 030-1 039.

DOI      URL      摘要

Iron (Fe 2O 3) and aluminum oxide (Al 2O 3) were found to be good and inexpensive adsorbents for As(V) removal in drinking water despite their relatively small surface area. The experimental results for this study suggest that by careful selection of the relative concentration of arsenic, pH, and dosages of Fe 2O 3 and Al 2O 3, As(V) removal efficiency as high as 99% can be achieved. At lower pH (<7), and also depending on the dosages of Fe 2O 3 and Al 2O 3 and the initial concentration of As(V), over 95% of As(V) adsorption was observed within a contact time of 20–60 min. The adsorption of As(V) on Fe 2O 3 and Al 2O 3, like that on other nonporous adsorbents, is mainly controlled by the surface area. The adsorption of As(V) on Fe 2O 3 and Al 2O 3 was found to follow the Langmuir isotherm between the pH values of 5 and 9. The maximum As(V) uptake values at pH 6 – the optimal pH value for adsorption – using Fe 2O 3 and Al 2O 3, were calculated as 0.66 mg/g and 0.17 mg/g, respectively. No significant variation in the uptake of As(V) on Fe 2O 3 as compared with Al 2O 3 was observed at different pH values. The initial sorption rate of Fe 2O 3 is higher than that of Al 2O 3. All these factors make Fe 2O 3 a better adsorbent than Al 2O 3. Fe 2O 3 is a useful and effective adsorbent for POE (pint of entry) and POU (point of use) water treatment systems, such as small-scale commercial or individual home water treatment systems. Even though the adsorption capacities of Fe 2O 3 and Al 2O 3 for As(V) are quite low compared with those of other absorbents, their low cost makes them useful adsorbents. They may be very useful in arsenic removal from water in endemic areas such as China, India, and Bangladesh.
[59] Tofik A S,Taddesse A M,Tesfahun K T,et al.

Fe-Al binary oxide nanosorbent: Synthesis,characterization and phosphate sorption property

[J]. Journal of Environmental Chemical Engineering,2016,4(2): 2 458-2 468.

DOI      URL      [本文引用: 1]      摘要

Phosphorous removal using efficient treatment approach such as adsorption is vital for the control of eutrophication. In this study, nanosized Fe-Al binary oxide sorbent was synthesized through a modified gel evaporation method and employed for adsorption of phosphate from aqueous system. The nanosorbent was characterized by x-ray diffraction (XRD), scanning electron microscope coupled with energy dispersive x-ray spectroscopy (SEM/EDX), tunneling electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and flame atomic absorption spectroscopy (FAAS). Langmuir model showed the best fit to the experimental data with a maximum adsorption efficiency of 16.4mg/g. Having all parameters optimized, it has been found that the nanosorbent exhibited 99.86% phosphate adsorption efficiency. The effect of co-existing anions on the adsorption of phosphate was also studied and no significant effect on the efficiency of the nanosorbent was observed due to competing ions such as fluoride. Desorbabilty of phosphate was investigated and found to be increased with increasing pH. The results of thermodynamic studies indicated that the process is spontaneous and endothermic. Both macroscopic and microscopic approaches were employed to predict the mechanism of phosphate adsorption on the Fe-Al binary oxide nanosorbent. Accordingly, the phosphate adsorption is presumed to occur via the replacement of surface hydroxyl groups by the phosphate species and formation of inner-sphere surface complexes at the water/oxide interface.
[60] Robb M,Greenop B,Goss Z,et al.

Application of Phoslock TM,an innovative phosphorus binding clay,to two Western Australian waterways: Preliminary findings

[J]. Hydrobiologia,2003,494(1/3): 237-243.

DOI      URL      [本文引用: 1]     

[61] Lürling M,Van O F.

Controlling eutrophication by combined bloom precipitation and sediment phosphorus inactivation

[J]. Water Research,2013,47(17): 6 527.

DOI      URL      PMID      [本文引用: 1]      摘要

Abstract The hypothesis that the combination of the flocculent polyaluminium chloride (PAC) with the lanthanum-modified bentonite Phoslock(03) (Flock & Lock) could sink effectively a water bloom of cyanobacteria and could shift a turbid, cyanobacteria infested lake to a clear water lake was tested in a controlled laboratory experiment and a whole lake experiment. In the laboratory, a relatively low dose of the flocculent PAC (2.2 and 4.4 mg Al l(-1)) was insufficient to sediment positively buoyant cyanobacteria (Microcystis aeruginosa). Similarly, the lanthanum modified clay (dosed at 390 mg l(-1)) was insufficient to sediment the positively buoyant cyanobacteria. However, the combination of PAC and Phoslock(03) effectively sedimented cyanobacteria flocks. Likewise, a combined treatment of 2 tons PAC and 18 tons Phoslock(03) in Lake Rauwbraken in April 2008 effectively sedimented a developing cyanobacteria bloom of Aphanizomenon flos-aquae. The average chlorophyll-a concentration in the two years prior to this Flock & Lock treatment was 19.5 (±36.5) μg l(-1), while it was as low as 3.7 (±4.5) μg l(-1) in the years following the treatment. The combined treatment effectively reduced the amount of total phosphorus (TP) in the water column from on average 169 (±126) μg P l(-1) before the application to 14 (±15) μg P l(-1) after the treatment. Based on mean summer chlorophyll-a and TP concentrations, the lake was shifted from a eutrophic/hypertrophic state to an oligo/mesotrophic state. From directly after treatment in April 2008 until and including 2013, Lake Rauwbraken remained in an oligo-mesotrophic clear water state with TP reduced to less than 10% of the pre-treatment. This result shows that eutrophication in relatively small, isolated, stratifying lakes can be restored by targeting both water column and sediment P using a combination of flocculent and solid phase P-sorbent. Copyright 08 2013 Elsevier Ltd. All rights reserved.
[62] Mrquez-Pacheco H,Hansen A M,

Falcón-RojasA. Phosphorous control in a eutrophied reservoir

[J]. Environmental Science & Pollution Research,2013,20(12): 8 446-8 456.

[本文引用: 2]     

[63] Gunn I D M,Meis S,Maberly S C,et al.

Assessing the responses of aquatic macrophytes to the application of a lanthanum modified bentonite clay,at Loch Flemington,Scotland,UK

[J]. Hydrobiologia,2014,737(1): 309-320.

DOI      URL      [本文引用: 2]     

[64] Zhu Guangwei,Li Jing,Zhu Mengyuan,et al.

Efficacy of phoslock on the reductionof sediment phosphrus release in West Lake,Hangzhou,China

[J]. Environmental Science,2017,(4):1 451-1 459.

[本文引用: 1]     

[朱广伟,李静,朱梦圆,.

锁磷剂对杭州西湖底泥磷释放的控制效果

[J].环境科学,2017,(4):1 451-1 459.]

[本文引用: 1]     

[65] Yin H,Kong M,Fan C.

Batch investigations on P immobilization from wastewaters and sediment using natural calcium rich sepiolite as a reactive material

[J]. Water Research,2013,47(13): 4 247-4 258.

DOI      URL      [本文引用: 1]     

[66] Kang S K,Choo K H,Lim K H .

Use of iron oxide particles as adsorbents to enhance phosp horus removal from secondary wastewater effluent

[J]. Separation Science & Technology,2003,38(15): 3 853-3 874.

[本文引用: 1]     

[67] Wang Hong.

Study on the Adsorption of Phosphorus in Water and Sediment by Using Zirconium-Modified Clay and Lanthanum-Modified Zeolite[D]

.Shanghai:Shanghai Ocean University, 2016.

[本文引用: 1]     

[王虹.

锆改性粘土和镧改性沸石的固磷作用研究[D]

.上海:上海海洋大学,2016.]

[本文引用: 1]     

[68] Jung Y,Alam S U,Sun Y,et al.

Removal and recovery of phosphate from water using sorption

[J]. Critical Reviews in Environmental Science & Technology,2014,44(8): 847-907.

DOI      URL      [本文引用: 1]      摘要

Sorption is an effective, reliable, and environmentally friendly treatment process for the removal of phosphorus from wastewater sources which otherwise can cause eutrophication of receiving waters. Phosphorus in wastewater, if economically recovered, can partly overcome the future scarcity of phosphorus resulting from exhaustion of natural phosphate rock reserves. The authors present a comprehensive and critical review of the literature on the effectiveness of a number of sorbents, especially some novel ones that have recently emerged, in removing and recovering phosphate. Mechanisms and thermodynamics of sorption, as well as regeneration of sorbents for reuse using acids, bases, and salts, are critically examined.
[69] Acelas N Y,Martin B D,López D,et al.

Selective removal of phosphate from wastewater using hydrated metal oxides dispersed within anionic exchange media

[J]. Chemosphere,2015,119: 1 353-1 360.

DOI      URL      [本文引用: 1]     

[70] Li W,Feng X,Yan Y,et al.

Solid state NMR spectroscopic study of phosphate sorption mechanisms on aluminum (hydr)oxides

[J]. Environmental Science & Technology,2013,47:8 308-8 315.

DOI      URL      PMID      [本文引用: 2]      摘要

Sorption reactions occurring at mineral/water interfaces are of fundamental importance in controlling the sequestration and bioavailability of nutrients and pollutants in aqueous environments. To advance the understanding of sorption reactions, development of new methodology is required. In this study, we applied novel (31)P solid-state nuclear magnetic resonance (NMR) spectroscopy to investigate the mechanism of phosphate sorption on aluminum hydroxides under different environmental conditions, including pH (4-10), concentration (0.1-10 mM), ionic strength (0.001-0.5 M), and reaction time (15 min-22 days). Under these conditions, the NMR results suggest formation of bidentate binuclear inner-sphere surface complexes was the dominant mechanism. However, it was found that surface wetting caused a small difference. A small amount (<3%) of monodentate mononuclear inner-sphere surface complexes was observed in addition to the majority of bidentate binuclear surface complexes on a wet paste sample prepared at pH 5, which was analyzed in situ by a double-resonance NMR technique, namely, (31)P{(27)Al} rotational echo adiabatic passage double resonance (REAPDOR). Additionally, we found that adsorbents can substantially impact phosphate sorption not only on the macroscopic sorption capacity but also on their (31)P NMR spectra. Very similar NMR peaks were observed for phosphate sorbed to gibbsite and bayerite, whereas the spectra for phosphate adsorbed to boehmite, corundum, and 纬-alumina were significantly different. All of these measurements reveal that NMR spectroscopy is a useful analytical tool for studying phosphorus chemistry at environmental interfaces.
[71] Si Jing,Lu Shaoyong,Jin Xiangcan,et al.

Effect of pH value and light on La-modified bentonite adsorption of phosphorus and nitrogen in water

[J]. China Environmental Science,2009,29(9):946-950.

Magsci      [本文引用: 1]     

[司静,卢少勇,金相灿,.

pH值和光照对镧改性膨润土吸附水中氮和磷的影响

[J].中国环境科学,2009,29(9):946-950.]

DOI      URL      Magsci      [本文引用: 1]      摘要

在不同的pH值和光照条件下考察了镧改性膨润土对模拟农田区河水中氮、磷的去除效果.结果表明,当pH值为4~8时,膨润土对氮和磷的去除效果较好,总氮去除率约82%,最高达93%;在pH值为4~6时,3d后对磷的去除率保持在95%以上,最高达99%.在光照强度为10,20μmol/(m2·s)时,镧改性膨润土的氮、磷吸附效果较好,总氮去除率在第14d前保持在72%以上,光照强度为20μmol/(m2·s),第7d时最大去除率达93%;总磷去除率保持在90%以上.
[72] Ross G,Haghseresht F,Cloete T E.

The effect of pH and anoxia on the performance of Phoslock ,a phosphorus binding clay

[J]. Harmful Algae,2008,7(4): 545-550.

DOI      URL      [本文引用: 1]      摘要

This study examined the adsorption of phosphate by Phoslock, a lanthanum modified clay, by investigating the effect of solution pH and presence of algal mass on its kinetic behavior. In addition, the effect of anoxic conditions on its ability to retain the adsorbed phosphate was studied. It was found that Phoslok 庐; was most effective at pH values between 5 and 7, and the adsorption capacity decreased above pH 9. The adsorption capacity was lower in algae-containing lake water than in prepared reverse osmosis water solutions. The phosphorus was not released from the Phoslock 庐; under anoxic conditions.
[73] Reitzel K,Balslev K A,Jensen H S.

The influence of lake water alkalinity and humic substances on particle dispersion and lanthanum desorption from a lanthanum modified bentonite

[J].Water Research,2017,125:191-200.

DOI      URL      [本文引用: 1]     

[74] Steinman A D,Ogdahl M.

Ecological effects after an alum treatment in Spring Lake,Michigan

[J]. Journal of Environmental Quality,2008,37(1): 22-29.

DOI      URL      PMID      [本文引用: 1]      摘要

Abstract A whole-lake alum treatment was applied to eutrophic Spring Lake during October and November 2005. Eight months later, an ecological assessment of the lake was performed and compared with data collected in 2003 and 2004. Field measurements showed reduced soluble reactive phosphorus (SRP) and total phosphorus (TP) concentrations in the water column the summer after the alum application, but chlorophyll levels and irradiance profiles were not significantly affected. Total macroinvertebrate density declined significantly in 2006 compared with 2004, with chaoborids and oligochaetes experiencing the greatest reductions. Internal phosphorus release rates, measured using sediment cores incubated in the laboratory, ranged from -0.052 to 0.877 mg TP m(-2) d(-1) under anaerobic conditions. These internal loading rates were significantly lower than those measured in 2003 at three out of four sites. Mean porewater SRP concentrations were lower in 2006 than in 2003, but this difference was statistically significant only under aerobic conditions. The NaOH-extractable SRP fraction in the sediment was also significantly lower in 2006 compared with 2003, whereas the HCl-extractable SRP sediment fraction showed the opposite pattern. Overall, these results indicate that the alum treatment effectively reduced internal P loading in Spring Lake. However, water column phosphorus concentrations remain high in this system, presumably due to high external loading levels, and may account for the high chlorophyll levels. An integrated watershed management approach that includes reducing internal and external inputs of P is necessary to address the cultural eutrophication of Spring Lake.
[75] Egemose S,Wauer G,Kleeberg A.

Resuspension behavior of aluminum treated lake sediments: Effects of ageing and pH

[J]. Hydrobiologia,2009,636(1): 203-217.

DOI      URL      [本文引用: 1]      摘要

Lake restoration with aluminium (Al) has been widely used in shallow lakes, but it is unknown how ageing of the Al floc affect resuspension behaviour, sediment stability and entrainment of Al and phosphorus (P). High primary production in shallow lakes can lead to high pH in the water column with a potential release of Al and P during resuspension events. A laboratory resuspension experiment at defined hydrodynamic conditions using a calibrated erosion chamber was performed with intact sediment cores (with intact vs. disturbed biofilm on the surface) from previously Al-treated shallow Lake M02llen, NE Germany. Newly applied Al reduced surface sediment stability, but ageing led to the same stability as untreated sediment within 202months with an intact biofilm and within 402months with a disturbed biofilm. Dissolved Al increased markedly at resuspension after 202days and 202weeks of ageing and with elevated pH (9–11) in the water. The Al floc were redissolved and dissolved Al increased with elevated pH and shear velocity. Dissolved P concentration was constantly low due to excess binding capacity of the Al floc. In conclusion, Al application to shallow lakes prone to resuspension and with a high production must be done in periods with less resuspension risk to allow 2–402months time for floc stabilization. Otherwise, possible resuspension and high(er) pH may lead to elevated concentrations of dissolved Al in the water column.
[76] Svatos K.

Commercial silicate phosphate sequestration and desorption leads to a gradual decline of aquatic systems

[J].Environmental Science & Pollution Research,2017,25(3):1-7.

[本文引用: 1]     

[77] Waajen G,Pauwels M,Lürling M.

Effects of combined flocculant-Lanthanum modified bentonite treatment on aquatic macroinvertebrate fauna

[J].Water Research,2017,122:183.

DOI      URL      [本文引用: 1]     

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