香菇废弃物固定化方法的改进及其对Cd2+的吸附研究

The improvement on immobilization of Lentinus edodes residue and its adsorption of Cd2+

聚乙烯醇(PVA)、海藻酸钠(SA)、香菇废弃物粉末以7∶3∶3的质量比混合,水浴加热溶解后,用CaCl2饱和硼酸溶液固定化。以2%CaCl2饱和硼酸的固定化时间、磷酸盐浓度以及磷酸盐的固定化时间为因子进行正交实验,以成球性、机械强度、Cd^2+吸附平衡时间和吸附率为指标,确定最佳固定化方法,并研究了固定化香菇对Cd2+的吸附机理。结果表明,香菇废弃物的最佳固定化方法为:将质量比为7∶3∶3的PVA、SA、香菇废弃物粉末混合,水浴加热溶解,用注射器将混合液滴入2%CaCl2饱和硼酸固定化24 h后,移至浓度5 g/L的磷酸盐进行二次固定化反应6 h。改良后的固定化香菇小球吸附Cd2+的平衡时间大大缩短,由7 h缩短至1 h,准二级动力学方程能够很好地模拟改良固定化香菇对Cd^2+的动力学吸附过程,R2=0.999 8。改良固定化香菇对Cd2+的热力学吸附过程符合Langmuir模型与Frendlich模型,相关系数R2分别为0.939 5和0.998 3,对Cd^2+的理论最大吸附量为11.99 mg/g,最大吸附量较改良前大大提高。

The blend ratio of polyvinyl alcohol,sodium alginate,and Lentinus edodes residue powder was 7∶3∶3,after being heated and dissolved in water bath,CaCl2 saturated boric acid solution is used for immobilization.Considering the balling property,the mechanical strength,the Cd^2+equilibrium adsorption time and ratio,this study carried out an orthogonal experiment to find the best way to immobilize Lentinus edodes residue.To reveal the adsorption mechanism were carried out.Results showed that the best way to get a better adsorbent was to drop the dissolved PVA+SA+Lentinus edodes residue mixture by needle in the 2% CaCl2 saturated boric acid solution for 24 h,then transfer the adsorbent into 5 g/L phosphate,and let the mixture stand for 6 h.The Cd2+adsorption equilibrium time by the improved immobilized Lentinus edodes residue was shortened from 7 h to 1 h.Pseudo-second-order model well fitted the Cd^2+ adsorption kinetics,with R2= 0.999 8.Langmuir model and Frendlich model both fitted the Cd^2+ adsorption thermodynamics well,with R2=0.939 5 and 0.998 3,respectively.The theoretical maximum adsorption quantity increased to 11.99 mg/g.