Recent progress made on anion getter was summarized in this article, including the preparation techniques, characterization methods, adsorption performance, and their applicability in the environment remediation. Hydrotalcite (HT)-like compounds and other layered double hydroxides (LDHs) with similar structure are effective anion getter. The crystal structure of HT-like compounds consists of brucite-like positively charged layers, compensated with negatively charged interlayers containing anions and water molecules. The general formula of these compounds is as follows:
[MⅡ1-xMⅢx(OH)2] An-x/n•mH2O
Where MⅡ=Mg2+,Zn2+,Fe2+, and other divalent cations; MIII= Al3+,Fe3+, and other trivalent cations; An-= CO2-3, Cl-, NO-3, SO2-4 and other anions;xvaries between 0.2 and 0.33.
One of the most important properties of the HT-like compounds is the high anionic exchange capacity, related to their lamellar structure that allows the exchange of its original anions with those present in aqueous solution. On the other hand, Mg-Al mixed oxide, obtained by calcination of HT-like compounds at about 500℃,adsorbed anions from water through the reconstruction of their layered structure. Both processes, anion exchange and layer reconstruction, may be affected by HT structural characteristics such as interlayer anion and crystallinity.
Recent research confirms that anion getter is capable to absorb heavy-metal contamination, which exists in the environment as complexing anions. Anion getter also absorbs N, P, As, Se and radioactive elements in the water, as well as organic compounds, such as pesticide, herbicide, phenolic agents, washing agents and humus.To remove different poisonous and nocuous components in the environment, we need different anion getters,which depends on the getter’s own characteristics, and the exterior physiochemical conditions. The research on the anion getter has been a hotspot for environment protection in recent years.