• 关键词：高分子絮凝剂  壳聚糖  巯基乙酸  含镉废水

• 基金项目：甘肃省水环境科学与工程创新团队(No.2006-07)

• 张文杰
• 兰州交通大学环境与市政工程学院, 兰州 730070

• 徐敏
• 兰州交通大学环境与市政工程学院, 兰州 730070

• 常青
• 兰州交通大学环境与市政工程学院, 兰州 730070

• 王卓亚
• 兰州交通大学环境与市政工程学院, 兰州 730070

• 韦俊
• 兰州交通大学环境与市政工程学院, 兰州 730070

• 摘要：以壳聚糖、巯基乙酸为原料,通过酰胺化反应合成了一种具有重金属捕集功能的新型高分子絮凝剂——巯基乙酰壳聚糖(MAC),研究了其对含Cd²⁺废水水样的处理性能,并对影响处理性能的因素(pH、有机络合剂及浊度等)进行了探讨.结果表明,该絮凝剂对Cd²⁺有很好的捕集功能,采用不同相对分子质量、不同脱乙酰度的壳聚糖合成的MAC,其对Cd²⁺的去除效果也不同,其中,采用相对分子质量20万～40万、脱乙酰度大于90%的壳聚糖合成的MAC对Cd²⁺的去除效果较好,处理Cd²⁺浓度为10mg·L^-1的废水水样,在原水浊度为80NTU的条件下,最高去除率可达到93.10%.废水中Cd²⁺浓度与其最佳投药量存在一定的化学计量关系.pH值会影响Cd²⁺的去除,在pH为5.5～8.5的范围内,pH值升高,Cd²⁺的去除率也随之升高.腐殖酸对Cd²⁺的去除有促进作用,EDTA对Cd²⁺的去除有一定的抑制作用.Cd²⁺和致浊物质可以起到相互促进去除的作用,出水浊度可达3NTU以下.

• Abstract：Anovel water-soluble macromolecular flocculant,mercaptoacetyl chitosan (MAC) which traps heavy metals,was synthesized by reacting chitosan with mercaptoacetic acid.The flocculation performance of MACwas evaluated using cadmium-containing water samples as the target.Some factors which affect the removal of Cd²⁺ were also studied.The experimental results showed that:①MAChad strong binding capabilities for Cd²⁺.The removal efficiency of Cd²⁺ depended on the molecular weight and degree of deacetylation of chitosan.When MACwas prepared with chitosan with a molecular weight of 200000～400000 and degree of deacetylation over 90%,the highest removal rate of Cd²⁺ (93.10%) was reached in the water sample containing 10mg·L^-1 Cd²⁺ and 80 NTUturbidity.② Water samples with different concentrations of Cd²⁺ had different optimum dosages of MAC,and there was a stoichiometric relationship between the optimum dosage of MACand concentration of Cd²⁺.③ The pHhad some effect on the removal rate of Cd²⁺.When pHvalue was changed from 5.5 to 8.5,the removal rate of Cd²⁺ increased.④When humic acids were present in the cadmium-containing water sample,the removal rate of Cd²⁺ increased,but,the presence of EDTAin the water sample impeded the removal of Cd²⁺ to some extent.⑤ Cd²⁺ and turbidity-causing substances were removed synergistically,and the water turbidity of the effluent was below 3 NTU.

• Key words：macromolecule flocculant  chitosan  mercaptoacetic acid  cadmium wastewater

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