海藻酸钠凝胶海绵体的制备及其对Pb^2+和Cu^2+的吸附

Preparation of sodium alginate gel sponge and its adsorption for Pb^(2+)and Cu^(2+)

以海藻酸钠与钙离子交联形成凝胶,采用真空冷冻干燥技术将凝胶制备成超轻海绵体,考察其对Pb^(2+)和Cu^(2+)的吸附作用。结果表明,在溶解过程,天然多糖海藻酸钠微观结构首先由丝状结构逐渐向片层结构伸展,而海藻酸钠凝胶海绵体则形成了致密的多孔结构,微观结构发生变化。当海藻酸钠与氯化钙交联比(质量比)是1∶5时,所得的凝胶海绵体的比表面积达到2.1543 m2/g。在pH=3,吸附时间50 min,海绵体质量浓度为0.5 g/L,吸附温度40℃的优化条件下,该海绵体对Cu^(2+)和Pb^(2+)的吸附量分别达到29.4和88.9 mg/g。重复使用5次后,海绵体对Cu^(2+)和Pb^(2+)的吸附量分别为18.7和77.1mg/g。吸附动力学拟合结果表明,海绵体对Cu^(2+)和Pb^(2+)的吸附以化学吸附为主。

Sodium alginate and calcium ions were cross-linked to form gel,and then the ultra-light sponge was prepared through disposing of gel by vacuum freeze-drying.The adsorption of Pb^(2+)and Cu^(2+)by the sponge was investigated.The results showed that the microstructure of natural polysaccharide sodium alginate gradually extended from filiform to lamellar during the dissolution process.However,the sponge of sodium alginate gel formed a dense porous structure.When the cross-linking ratio(mass ratio)of sodium alginate to calcium chloride was 1∶5,the specific surface area of the obtained gel sponge reached 2.1543 m2/g.The adsorption capacity of Cu^(2+)and Pb^(2+)reached 29.4 and 88.9 mg/g under the optimal conditions of pH=3,adsorption time of 50 min,mass concentration of the sponge of 0.5 g/L,and 40℃.After being reused 5 times,the adsorption capacity of Cu^(2+)and Pb^(2+)by the sponge was 18.7 and 77.1 mg/g,respectively.The fitting results of kinetics adsorption revealed that the adsorption of Cu^(2+)and Pb^(2+)by the sponge was mainly chemical adsorption.