Miretzky P, Cirelli A Fernandez
Centro de Geociencias-Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla 3001, Queretaro, Mexico.
J Hazard Mater. 2009 Aug 15;167(1-3):10-23. doi: 10.1016/j.jhazmat.2009.01.060. Epub 2009 Jan 23.
Mercury (Hg) is one of the most toxic heavy metals commonly found in the global environment. Its toxicity is related to the capacity of its compounds to bioconcentrate in organisms and to biomagnify through food chain. A wide range of adsorbents has been used for removing Hg(II) from contaminated water. Chitosan is obtained by alkaline deacetylation of chitin. The adsorption capacity of chitosan depends on the origin of the polysaccharide, and on the experimental conditions in the preparation, that determine the degree of deacetylation. A great number of chitosan derivatives have been obtained by crosslinking with glutaraldehyde or epichlorohydrin among others or by grafting new functional groups on the chitosan backbone with the aim of adsorbing Hg(II). The new functional groups are incorporated to change the pH range for Hg(II) sorption and/or to change the sorption sites in order to increase sorption selectivity. The chemical modification affords a wide range of derivatives with modified properties for specific applications. Hg(II) adsorption on chitosan or chitosan derivatives is now assumed to occur through several single or mixed interactions: chelation or coordination on amino groups in a pendant fashion or in combination with vicinal hydroxyl groups, electrostatic attraction in acidic media or ion exchange with protonated amino groups. This review reports the recent developments in the Hg(II) removal in waste water treatment, using chitosan and its derivatives in order to provide useful information about the different technologies. When possibly the adsorption capacity of chitosan and chitosan derivatives under different experimental conditions is reported to help to compare the efficacy of the Hg(II) removal process. A comparison with the adsorption capacity of other low-cost adsorbents is also tabled.
汞（Hg）是全球环境中常见的毒性最强的重金属之一。其毒性与其化合物在生物体中生物富集以及通过食物链生物放大的能力有关。多种吸附剂已被用于从受污染水中去除Hg(II)。壳聚糖是通过甲壳素的碱性脱乙酰作用获得的。壳聚糖的吸附能力取决于多糖的来源以及制备过程中的实验条件，这些条件决定了脱乙酰度。通过与戊二醛或环氧氯丙烷等交联，或在壳聚糖主链上接枝新的官能团以吸附Hg(II)，已获得了大量壳聚糖衍生物。引入新的官能团是为了改变Hg(II)吸附的pH范围和/或改变吸附位点，以提高吸附选择性。化学改性提供了一系列具有特定应用改性性能的衍生物。现在认为，壳聚糖或壳聚糖衍生物对Hg(II)的吸附是通过几种单一或混合相互作用发生的：以悬垂方式或与邻位羟基结合在氨基上进行螯合或配位，在酸性介质中的静电吸引或与质子化氨基进行离子交换。本综述报告了在废水处理中使用壳聚糖及其衍生物去除Hg(II)的最新进展，以便提供有关不同技术的有用信息。如有可能，报告壳聚糖和壳聚糖衍生物在不同实验条件下的吸附容量，以帮助比较Hg(II)去除过程的效果。还列出了与其他低成本吸附剂吸附容量的比较。
