高吸附量纤维素膜的制备及其对Pb2+的吸附性能

Preparation of cellulose membrane with high adsorption capacity and its adsorption performance for Pb2+

以纤维素为原料,氢氧化钠、尿素、硫脲为溶剂体系制备纤维素膜,研究凝固浴的种类、H2SO4体积分数、凝固温度和凝固时间对纤维素膜吸附Pb2+的影响。采用准二级动力学模型研究吸附速率的快慢;采用SEM、比表面积和平均孔径、FTIR和XRD分析纤维素膜的结构和吸附机理;采用TG对纤维素膜的热性能进行分析。结果表明,以体积分数为7%的H2SO4为凝固浴、凝固温度为40℃、凝固时间为120min时,纤维素膜对Pb2+的吸附量达到最大,为343.0mg/g。纤维素膜吸附Pb2+符合准二级动力学模型。纤维素膜由表面致密变为含有孔洞的结构,吸附Pb2+后孔洞被填满,纤维素膜中的C=O键和N—H键与Pb2+产生螯合作用。纤维素膜中部分纤维素结晶型由Ⅰ型转变为Ⅱ型,结晶度降低;纤维素膜的热稳定性高于纤维素。

Cellulose membrane was prepared with cellulose as raw material,sodium hydroxide,urea and thiourea as solvent system.The effects of types of coagulation bath,volume fraction of H2SO4,coagulation temperature and time on the adsorption of cellulose membrane for Pb2+were investigated.The rate of adsorption was studied by pseudo second order dynamics model.The structure and adsorption mechanism of cellulose membrane was analyzed by SEM,specific surface area and average pore,FTIR and XRD.The thermal properties of cellulose membrane was analyzed by TG.The results showed that when H2SO4 was used as coagulation bath,volume fraction of H2SO4 was 7%,coagulation temperature was 40℃,and coagulation time was 120 min,the adsorption capacity of cellulose membrane to Pb2+ions reached the maximum value of 343.0 mg/g.The adsorption of Pb2+by cellulose membrane conformed to pseudosecond-order kinetic model.The cellulose membrane changed from surface densification to pore-containing structure,and the pores were filled after Pb2+adsorption,the C=O bond and N—H bond in cellulose membrane could chelate Pb2+.Crystal form of part cellulose in cellulose membrane changed from typeⅠto typeⅡ,and the crystallinity decreased.The thermal stability of cellulose membrane was higher than that of cellulose.