好氧颗粒污泥细菌藻酸盐对Cu^(2+)的生物吸附和机制探讨

Cu^(2+) Biosorption by Bacterial Alginate Extracted from Aerobic Granules and Its Mechanism Investigation

以好氧颗粒污泥中提取的细菌藻酸盐为原料制备干藻酸钙吸附剂,对水溶液中的Cu2+进行了吸附研究.对比了不同pH值和吸附剂投加量对吸附性能的影响,同时对吸附过程进行了模型拟合,测定了该吸附剂的解吸性能,并用傅立叶变换红外二阶导数光谱和原子力显微镜分析对吸附机制进行了探讨.结果表明,藻酸钙对Cu2+的吸附反应是一个比较快速的过程.当Cu2+初始浓度为100 mg/L,吸附剂投加量为0.7g/L时,吸附最佳pH值为4,吸附能力为67.67 mg/g.吸附过程可用Langmuir和Freundlich模型来描述.好氧颗粒污泥藻酸钙吸附剂对Cu2+的吸附过程中有离子交换和pH值升高现象发生,溶液中的Cu2+与吸附剂上Ca2+交换的同时需要有H+的参与来维持电荷平衡.傅立叶变换红外二阶导数光谱和原子力显微镜分析表明,好氧颗粒污泥藻酸钙吸附剂中MG嵌段与Cu2+和Ca2+结合的方式不同,Cu2+能与吸附剂表面的MG嵌段发生螯合,使藻酸钙表面的结构更加有序.以100 mmol/L HCl为解吸剂,解吸效率可达到91%.

The biosorption characteristic of copper ions onto dried Ca-alginate made of bacterial alginate extracted from aerobic granules was investigated in batch system.The biosorption rate of Cu^2＋ onto the alginate,effects of pH and alginate dosage on Cu^2＋ biosorption capacity and adsorption isotherm were analyzed.The biosorption of Cu^2＋ onto the dried Ca-alginate was a rapid process.The maximum Cu^2＋ uptake was 67.67 mg/g at pH 4,initial Cu^2＋ concentration of 100 mg/L,dried Ca-alginate dosage 0.7g/L.Accumulation of Cu^2＋ followed Langmuir and Freundlich adsorption isotherm.Cu^2＋ adsorption was accompanied by Ca^2＋ releasing from the dried Ca-alginate and H＋ uptake,indicating that the ion exchange between Cu^2＋ and Ca^2＋ requires H＋ for charge balance.FT-IR secondary derivative spectra and atomic force microscopy analysis gave proof that,the reaction of MG blocks in dried Ca-alginate with Cu^2＋ and Ca^2＋ were different.Cu^2＋ may form complex with MG blocks,leading to a much more ordered structure on the surface of the dried Ca-alginate.The dried Ca-alginate bio-adsorbent was regenerated by 100 mmol/L HCl with 91% Cu^2＋ recovery.