改性粉煤灰与H_2O_2联用去除亚甲基蓝的动力学分析

Study on Decomposition Kinetics of Methylene Blue by Modified Fly Ash Combined with Hydrogen Peroxide

采用改性粉煤灰与H_2O_2联用形成类Fenton系统,对亚甲基蓝进行去除分析,考察了反应温度、pH值对去除效果的影响,并分别采用一级反应动力学、二级反应动力学和颗粒内扩散模型对反应过程进行拟合。结果表明,当亚甲基蓝初始质量浓度为40 mg/L,pH值为10,H_2O_2质量浓度为3.3 g/L,温度为90℃,投加0.2 g/200 mL改性粉煤灰,反应10 min亚甲基蓝去除率达96%以上。亚甲基蓝的降解采用二级反应动力学模型拟合效果更佳,对于高质量浓度的亚甲基蓝溶液,随H_2O_2质量浓度的增大去除率相应增加,然而,当H_2O_2质量浓度继续增加时,k2的值反而呈下降趋势。改性粉煤灰吸附亚甲基蓝时,吸附速率受颗粒外扩散过程的控制。

Fenton like system was formed by modified fly ash and H2O2, the removal of methylene blue were analyzed. The effects of reaction temperature, pH value on adsorption were investigated, and the reaction kinetics was described by first-order kinetic model, second-order kinetic model and intra-particle diffusion model. It was found that the removal rate of methylene blue was over 96% after 10 min under the conditions of initial concentration of 40 mg/L, pH value of 10, H2O2 concentration of 3.3 g/L, temperature of 90 ℃ and modified fly ash of 0.2 g/200 mL. The second-order kinetic model was effective, the removal rate of methylene blue increased accordingly with the increase of H2O2 concentration when the methylene blue concentration was high. While H2O2 concentration further increased, coefficient k2 decreased. The adsorption rate should be controlled by the external diffusion process.