海藻酸钙包覆聚苯乙烯磺酸钠软胶囊去除废水中Cu^(2+)和Cd^(2+)

Removal of Cu^(2+) and Cd^(2+) from Wastwater by Calcium Alginate-coated Polystyrene Sulfonate Capsule

采用滴定-固化包裹法制备得到以海藻酸钙(Alg)为壳,内包聚苯乙烯磺酸钠溶液(PSSA)的椭球状软胶囊(PSSA@Alg软胶囊),用其吸附溶液中的Cu(Ⅱ)和Cd(Ⅱ).结果表明:PSSA@Alg软胶囊对溶液中Cu(Ⅱ)和Cd(Ⅱ)的吸附量随溶液pH升高而增大,吸附过程包括表面吸附和固态海藻酸钙壳内缓慢扩散,符合拟二级动力学模型,分别在约240,360 min时达到吸附平衡;等温吸附数据与Langmuir模型拟合良好,25℃条件下,PSSA@Alg软胶囊对Cu(Ⅱ)和Cd(Ⅱ)的最大吸附量分别为143.92,193.64 mg·g^(-1).海藻酸钙上的羧基和聚苯乙烯磺酸钠上的磺酸基团在重金属离子吸附过程中起重要作用.

Oval-shaped soft capsule( PSSA @ Alg) with sodium polystyrene sulfonate( PSSA) capped inside calcium alginate( Alg) shell was prepared by titration-curing packaging method and was used to adsorb Cu( Ⅱ) and Cd( Ⅱ) in solution. The results showed that the adsorption capacity for Cu( Ⅱ) and Cd( Ⅱ) adsorbed by PSSA @ Alg soft capsule increased with the increase of solution pH. The adsorption process included surface adsorption and slow diffusion to the solid calcium alginate shell,which was in line with the pseudo-second order kinetic model and reached equilibrium in about 240 and 360 min,respectively. The isothermal adsorption data fitted well with the Langmuir model. The maximum adsorption capacity of Cu( Ⅱ) and Cd( Ⅱ) at 25 ℃ were 143.92 and 193.64 mg·g-1 respectively. The carboxyl groups on calcium alginate and the sulfonate group on PSSA played an important role on the adsorption of heavy metal ions.