阴离子捕获剂及其在污染防治与环境修复领域中的应用

综述了阴离子捕获剂的结构、性能、制备与表征方法、吸附专属性及其在环境修复方面的应用。阴离子捕获剂是一种具有层状结构的阴离子粘土，由于其特殊的结构和性能，可通过层间阴离子交换、层状结构重建等机制来吸附环境中的阴离子，从而清除环境中的污染物。大量研究表明。阴离子捕获剂对环境中以络阴离子形式存在的重金属污染物有很强的吸附能力，并能有效吸附水体中的N、P、As、Se和放射性元素。此外，阴离子捕获剂还能吸附有机污染物，如农药、酚类化合物、洗涤剂和腐殖质等。从环境中除去不同类型的有毒有害组分。需使用不同类型的阴离子捕获剂。其吸附能力主要由捕获剂本身的特点和外部理化条件所决定。阴离子捕获剂的研究已成为当前环境保护工程和技术研究的一个新热点。

ANION GETTER AND ITS UTILIZATION IN POLLUTION PREVENTION AND ENVIRONMENT REMEDIATION

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:
M^Ⅱ_1-xM^Ⅲ_x(OH)₂] A^n-_x/n?mH₂O
Where M^Ⅱ=Mg²⁺,Zn²⁺,Fe²⁺, and other divalent cations; M^III= Al^3+,Fe³⁺, and other trivalent cations; A^n-= CO^2-₃, Cl^-, NO^-₃, SO^2-₄ 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.