季铵型阳离子纤维素吸附水中铬和镉

Adsorption of Chromate and Cadmium Complexes by Quaternary Ammonium Cationic Cellulose

以异丙醇为分散剂,3-氯-2-羟丙基三甲基氯化铵(CHPTAC)与碱纤维反应,经醚化接枝后得季铵型阳离子纤维素(QACC)。研究了QACC对镉和铬的吸附性能:在318K、pH为5时,QACC对铬酸盐(以Cr6+计)的吸附容量为125.3mg/g;在318K、pH为3时,QACC对四氯合镉(以Cd2+计)的吸附容量为136.5mg/g;QACC对铬酸根阴离子和四氯合镉配阴离子吸附过程的表观活化能分别为48.17、69.14kJ/mol;吸附过程均符合Lagergren二级动力学方程,等温吸附模型均符合Langmuir等温式,实质是季铵盐阳离子与金属配阴离子之间通过缔合作用的化学吸附过程。QACC经8次解吸再生后,吸附容量仍保持在98%以上,说明QACC具有较好的再生性能,可循环多次利用。

Quaternary ammonium cationic cellulose （QACC） was synthesized by using 3-chloro-2- hydroxypropyltrimethyl ammonium chloride （CHPTAC） as etherifying agent and isopropyl alcohol as dispersing media. The adsorption properties of QACC was studied at 45 ℃ and pH of 5. 0 for chromate （measured by Cr^6＋）, and at 45 ℃ and pH of 3.0 for cadmium （measured by Cd^2＋） complexes. The saturation adsorption capacities of chromate and cadmium complexes are 125.3 and 136.5 mg/g, and the apparent activation energies of the adsorption are 48.17 and 69, 14 kJ/mol, respectively. Besides, hoth adsorption processes fit with pseudo-second-order kinetics model and adsorption rates increase as the temperature rises. Both adsorption patterns fit the Langmuir isotherm, which means they are both monomolecular layer adsorption. Meanwhile, the main force of chemical adsorption process is attributed to coordination bond. The adsorption capacity of QACC is up to 98% after eight times of desorption regeneration, showing that QACC is good for cyclic utilization.