聚乙烯醇-海藻酸钠固定香菇废弃物吸附Pb和Cd的最佳配方  

Optimal Condition of PVA-SA Immobilizing Lentinus edodes Residue for Absorbing Lead and Cadmium

作　　者：马培[1,2] 张丹[1] 何海江[1,2] 

机构地区：[1]中国科学院水利部成都山地灾害与环境研究所,成都610041 [2]中国科学院研究生院,北京100049

出　　处：《应用与环境生物学报》2009年第5期724-729,共6页Chinese Journal of Applied and Environmental Biology

基　　金：国家自然科学基金项目(No.40871111)资助~~

摘　　要：选用香菇废弃物作为生物吸附剂,用聚乙烯醇(PVA)-海藻酸钠(SA)固定香菇粉制成PVA-SA固定香菇,以吸附溶液中铅(Pb)和镉(Cd)的能力为主要评价指标,结合成球性、机械强度和耐酸性等,通过正交试验确定出吸附Pb的PVA-SA固定香菇最佳配方是8%PVA+1%SA+3%香菇粉+2%CaCl2的饱和H3BO3,对Pb的吸附率为95.4%,吸附Cd的PVA-SA固定香菇的最佳配方是5%PVA+1%SA+3%香菇粉+2%CaCl2的饱和H3BO3,对Cd的吸附率为63.7%.二小球的成球性、机械强度和耐酸性都较好.Langmuir等温吸附模型能最好地拟合香菇吸附Pb的热力学过程,相关系数R2达0.9939;Freundlich模型能更好地描述香菇吸附Cd的热力学过程,R2为0.9993.Freundlich等温吸附模型适合描述PVA-SA固定香菇吸附Pb和Cd的热力学过程,R2分别为0.9587和0.9823.自由香菇对Cd的理论最大吸附量qm-Langmuir(2.8321mgg-1)小于PVA-SA固定香菇的理论最大吸附量qm-Langmuir(6.4475mgg-1),自由香菇吸附Pb的Freundlich模型参数k(0.3127)小于PVA-SA固定香菇吸附Pb的k(0.4310),香菇固定后吸附Cd和Pb的能力有所提高.PVA-SA固定香菇吸附Pb和Cd的吸附平衡时间分别为3h和7h,比自由香菇吸附Pb和Cd的平衡时间(1h)长.伪二级动力学模型能很好地拟合固定香菇吸附Pb和Cd的动力学过程,R2分别为0.9999和0.9946,由该模型计算出的对Pb和Cd的平衡吸附量理论值分别为0.4536mgg-1和0.2060mgCdg-1.伪二级动力学模型能很好地拟合固定香菇吸附Pb和Cd的动力学过程,由该模型计算出的固定香菇对Pb和Cd的平衡吸附量理论值分别为0.4536mgg-1和0.2060mgg-1,自由香菇对Pb和Cd的平衡吸附量理论值分别为1.8172mgg-1和0.8425mgg-1.PVA-SA固定香菇吸附Pb/Cd的伪二级动力学反应速率常数k2为1.3241/1.2531,自由香菇吸附Pb/Cd的k2为0.7805/0.2130,自由香菇吸附Pb/Cd的k2大于固定香菇的k2,表明固定香菇吸附Pb/Cd达到平衡所需要的时间比自由香菇所需要的时间长.In this study,Lentinus edodes residue was immobilized by polyvinyl alcohol-Na-alginate（PVA-SA） for lead and cadmium biosorption.Based on the ability of absorbing lead and cadmium from aqueous solution,the mechanical strength and balling property,an orthogonal experiment was done to confirm the optimal condition of PVA-SA immobilizing L.edodes.The optimal immobilization condition for absorbing lead was 8%（m/V） PVA ＋ 1% sodium alginate ＋ 3% L.edodes ＋ 2% CaCl2 saturated boric acid solution,with biosorption rate of 95.4%, while that for absorbing cadmium were 5% PVA ＋ 1% SA ＋ 3% L. edodes ＋ 2% CaCI2, with biosorption rate of 63.7%. Langmuir model best described free L. edodes Pb2＋ biosorption isotherm, with R2 0.993 9. Freundlich model best fitted free L.edodes Cd2＋ biosorption isotherm, with R2 0.999 3. Freundlich model best fitted Pb2~ and Cdz＋ isotherm biosorption process by PVA-SA immobilizing L. edodes, with R2 0.958 7 and 0.982 3,respectively. The theoretic maximum biosorption quantities qm-Langmuir^2.8321mgg-1〈qm-Langmuir^6.4475mgg-1 indicated after immobilizing treatment, capacity of L. edodes for Cd2＋ biosorption increased.K（Pb-Freundlich,free）^0.3127〈K（Pb-Freundlich,immobilization）^0.4310 showed after immobilizing treatment, capacity ofL. edodes for Pb^2＋ biosorption also increased. Cd^2＋ and Pb^2＋ biosorped by L. edodes reached equilibrium within 60 min with equilibrium quantities qe of 1.812 mg/g and 0.844 mg/g, respectively, while that by PVA- SA immobilizing L. edodes reached within 3 h and 7 h separately with qe of 0.200 8 mg/g and 0.492 5 mg/g, respectively. Pseudo-second-order model well fitted Pb^2＋ and Cd^2＋ biosorption kinetics by immobilizing L. edodes and free L.edodes. The rate constant of Pseudo-second-order model for free L. edodes was k2pb 1.324 1/k2cd 1.253 1, and that for PVA-SA immobilizing L. edodes was k2pb 0.780 5 and k2Cd 0.213 0. Fig 3, Tab 6, Ref 16

关 键 词：PVA-SA 固定 香菇废弃物 热力学 

分 类 号：X703[环境科学与工程—环境工程] X171