污泥基吸附剂对亚甲基蓝和环丙沙星的吸附性能研究

Adsorption of methylene blue and ciprofloxacin by activated sludge-derived adsorbent

亚甲基蓝和环丙沙星是水体中2种污染物,对生态环境有潜在危害.本文以市政剩余活性污泥为原料,氯化锌为活化剂热解制备污泥基吸附剂,研究盐酸酸洗浓度、氯化锌浓度、热解温度、热解时间等对污泥基吸附剂吸附水中亚甲基蓝和环丙沙星性能的影响.结果表明:(1)污泥基吸附剂对亚甲基蓝的吸附性能随盐酸酸洗浓度的增大而增加,对环丙沙星的吸附性能则随盐酸酸洗浓度的增大呈先降后增趋势,两者均在1.500 mol·L^(-1)盐酸浓度下取得最优值.(2)污泥基吸附剂对亚甲基蓝和环丙沙星的吸附性能随氯化锌浓度和热解温度的增加呈先升后降趋势,在氯化锌浓度为4.0 mol·L^(-1)、热解温度为500℃时有最优值;随着热解时间的延长,污泥基吸附剂对亚甲基蓝和环丙沙星的吸附性能分别在500℃热解70 min和80 min时有最优值.(3)污泥基吸附剂的最佳制备条件为:氯化锌4.0 mol·L^(-1)活化2 h、500℃热解70 min和80 min、1.500 mol·L^(-1)盐酸酸洗;以此制得的污泥基吸附剂对亚甲基蓝和环丙沙星的去除率分别为97.7%和96.4%,平衡吸附量分别为97.9 mg·g^(-1)和3.9 mg·g^(-1),且污泥基吸附剂对亚甲基蓝和环丙沙星的吸附过程均符合准二级动力学方程.

Methylene blue and ciprofloxacin are common contaminants in the aqueous environment and have great potential hazards to the environment.An adsorbent was prepared in this study using municipal waste activated sludge as raw material,zinc chloride as activator,and pyrolysis as the main treatment unit.The adsorption of methylene blue and ciprofloxacin in water by the sludge-derived adsorbent were investigated.The results show that:(1)The adsorption efficiency of methylene blue by the sludge-derived adsorbent increased with the increase of the pH level of the acid wash,while the adsorption efficiency of ciprofloxacin decreases firstly,and then increased,and the best performance of the sludge-derived adsorbent was obtained under 1.5 mol·L^(-1) hydrochloric acid wash.(2)The adsorption efficiencies of methylene blue and ciprofloxacin by the sludge-derived adsorbent both showed first elevation and then reduction trends with the increase of zinc chloride concentration and pyrolysis temperature,and were optimized at 4.0 mol·L^(-1) zinc chloride activation and 500℃ pyrolysis for 70 and 80 min(for methylene blue and ciprofloxacin,respectively).(3)The optimized preparation procedure for the sludge-derived adsorbent was as follows:activating the sludge with 4.0 mol·L^(-1) zinc chloride solution for 2 h,pyrolyzing at 500℃ for 70 min or 80 min,and washing with 1.500 mol·L^(-1) hydrochloric acid,achieving removal rates of 97.7% and 96.4% for methylene blue and ciprofloxacin,respectively,with equilibrium adsorption capacity of 97.9 mg·g^(-1) and 3.9 mg·g^(-1),respectively.The adsorption processes of methylene blue and ciprofloxacin by the sludge-derived adsorbent were well described by the pseudo-second order kinetic equation.