铜离子和亚甲蓝在柠檬酸酯化麦草上的吸附行为

Adsorption behavior of copper ion and methylene blue on citric acid-esterified wheat straw

以固相酯化法制备一种具有羧基的柠檬酸改性麦草阳离子吸附剂.用批次实验法研究了不同实验条件下(pH值、吸附剂量、吸附质浓度和吸附时间)水溶液中铜离子和亚甲蓝在酯化麦草上的吸附行为.结果表明:溶液初始pH≥4.0时,铜离子和亚甲蓝达到最大吸附值.≥2.0g·L-1的酯化麦草能去除铜浓度为100mg·L-1溶液中96%的铜及亚甲蓝浓度为250mg·L-1溶液中99%的亚甲蓝.酯化麦草对铜离子和亚甲蓝的吸附符合Langmuir等温模型,其最大吸附能力分别为79.37mg·g-1和312.50mg·g-1.铜离子和亚甲蓝达到吸附平衡的时间分别为75min和5h,准一级和准二级反应动力学方程可分别描述酯化麦草对铜离子和亚甲蓝的吸附过程.

A cationic adsorbent with carboxyl groups derived from citric acidesterified wheat straw （EWS） was prepared by the method of solid phase preparation, and a batch experiment was conducted to study the adsorption behaviors of Cu （Ⅱ） and methylene blue （MB） in aqueous solution on the EWS under conditions of different initial pH, adsorbent dosage, adsorbate concentration, and contact time. The results showed that the maximum adsorption of Cu （Ⅱ） and MB was obtained when the initial solution pH was ~〉 4. 0. 96% of Cu （Ⅱ） in 100 mg ·L^-1 Cu solution and 99% of MB in 250 mg· L^-1 dye solution could be removed by ≥2.0 g· L^-1 of EWS. The adsorption of Cu （Ⅱ） and MB fitted the Langmuir sorption isothermal model. The maximum removal capacity （Qm） of EWS was 79.37 mg·g^-1 for Cu （Ⅱ） and 312. 50 mg·g^-1 for MB, and the adsorption equilibrium of Cu （Ⅱ） and MB was reached within 75 rain and 5 h, respectively. The adsorption processes of Cu （Ⅱ） and MB could be described by pseudo-first order and pseudo-second order kinetic functions, respectively.