煤质颗粒活性炭对染料废水中苯胺的吸附性能及机理

Adsorption property and mechanism of aniline on coal activated carbon

研究煤质颗粒活性炭对苯胺的吸附性能及机理对染料废水中大量苯胺类污染物的去除具有重要的技术支撑作用。开展了炭投加量/化学需氧量(COD)、不同浓度、吸附时间及pH值的煤质颗粒活性炭对苯胺的吸附实验,绘制吸附等温线及吸附动力学曲线。结果表明在单因素条件下,随着炭投加量/COD增加,废水中苯胺污染物去除率逐渐上升,且当炭投加量/COD大于4.5时,去除率上升幅度较小,考虑运行经济成本,建议最优炭投加量/COD取4.5;苯胺初始浓度越大,单位吸附量增大,去除率降低;吸附时间越长,吸附量与去除率均上升;pH值在1~4时,去除率及吸附量逐渐上升,当pH值为5时苯胺去除效果最好,随着pH值继续上升,去除率及吸附量有下降趋势。Langmuir等温线方程拟合度高达0.99,苯胺在煤质颗粒活性炭表面发生单分子层吸附;Freundlich等温线方程特征常数小于0.5,为0.33,煤质颗粒活性炭对苯胺有较强吸附性;吸附过程符合准二级动力学特征,说明煤质颗粒活性炭对苯胺吸附作用力强,饱和煤质颗粒活性炭再生方式应采取热再生;根据Weber-Morris方程特征曲线,依次发生了表面吸附、粒子内扩散及内表面吸附3个阶段吸附过程,水中有机物去除速度在表面吸附阶段最快,说明煤质颗粒活性炭比表面积为吸附效果的主要影响因素,而微孔数量的影响较小。

The study on adsorption performance and mechanism of aniline on coal granular activated carbon is important technical support for removing a large number of aniline pollutants in dye wastewater.Through adsorption experiments of aniline on coal based granular activated carbons with different concentrations,carbon dosages/COD,adsorption times and p H values,and the adsorption isotherm and adsorption kinetics curves it is shown that the removal rate of aniline and the unit adsorption capacity of aniline are 17.28 mg/g and 98.8%,respectively when the single control variable is carbon dosage/COD of 4.5,under the premise of other conditions being unchanged.When p H value is 5,the aniline removal efficiency is the best.Aniline removal rate and unit adsorption capacity are 16.17 mg/g and 92.47%,respectively.Similarly,when other variables remain unchanged,the higher the concentration,the higher the unit adsorption capacity,but the lower the removal rate;the longer the adsorption time,the higher the adsorption capacity and removal rate.The fitting degree of Langmuir isotherm equation is 0.9929,indicating that a monomolecular layer of aniline is adsorbed on the surface of coal granular activated carbon.The Freundlich characteristic constant 1/n is 0.3363,indicating that this adsorption process is easy to occur.In addition,the adsorption process is more in line with the quasi-second-order kinetics,and the adsorption rate is controlled by internal diffusion and internal surface adsorption process.This study provides reference for improving operating efficiency and reducing treatment cost of activated carbon adsorption process.