吸附铅、镉固定化细菌胞壁多糖小球包埋条件的优化选择

The optimization of the embedding conditions of the beads immobilized cell wall polysaccharides for the adsorption of plumbum and cadmium

细菌已广泛应用于重金属废水的处理,多糖则是细胞壁的主要成分,并通过螯合作用吸附重金属,而固定化技术具有处理效率高,生产成本低等优势。采用正交实验法,以聚乙烯醇和海藻酸钠为包埋剂,同时添加活性炭,硅藻土等对细菌胞壁多糖进行固定化,并以吸附铅、镉能力为主要考察指标,同时从机械强度、传质性、耐酸性等方面综合考虑,选择最优化的固定化小球最佳配方。结果表明,在聚乙烯醇、海藻酸钠、活性炭、硅藻土、多糖、二氧化硅和饱和硼酸中氯化钙的质量分数分别为10%、0.2%、1.5%、1.5%、0.8%、4%、3%,胶联时间为16h,己二胺浓度为0.06mol?L-1的条件下制得的固定化小球对铅、镉吸附的能力较强,并按照最佳配方进行了验证实验,对铅的吸附量达到4.4575μmol?g-1,对镉的吸附量达到4.1708μmol?g-1,机械强度、传质性和耐酸性都较好。

At present, bacteria has been extensively applied for the treatment of heavy metals wastewater. Polysaccharides is the major composition of cell wall of bacteria and can adsorb heavy metals by the chelation. The immobilization technology has a lot of advantages such as high efficiency of treatment, low cost of production, and so on. So, the immobilization of the cell wall polysaccharides of bacteria is investigated in this paper. Two materials named polyvinyl alcohol （PVA） and sodium alginate are used as embedding medium, and active carbon, diatomite are added also. By considering the adsorption ability for plumbum and cadmium as well as the properties of mechanical intensity, the transmission and acid-proof, the optimal embedding conditions are determined through orthogonal experimentation, which shows the percentage of PVA, sodium alginate, active carbon, diatomite, polysaccharides, silicon dioxide and calcium chloride should be 10%, 0.2%, 1.5%, 1.5%, 0.8%, 4%, 3% respectively, the couplet time 16 h, the concentration ofhexamethylene diamine 0.06 mol·L^-1. The beads made on conditions above get the adsorption capacity of plumbum and cadmium separately 4.457 5 μmol·g^-1 and 4.170 8 μmol·g^-1 and the better properties of mechanical strength, transmission and acid -proof are observed.