分光光度法研究粉煤灰对亚甲基蓝的吸附及其机理研究

以龙岩雁石火电厂粉煤灰对亚甲基蓝进行吸附实验,探讨了改性粉煤灰、粉煤灰用量、吸附时间、温度对亚甲基蓝吸附的影响。当粉煤灰投加量为4g/L,亚甲基蓝浓度15mg/L,常温条件下,在60min左右,亚甲基蓝降解率达到了98%以上。结果表明,利用粉煤灰处理亚甲基蓝,具有处理效果好、简单,经济等特点。利用Freundlich等温式和Langmuir等温式对其吸附行为进行描述,表明粉煤灰易于吸附亚甲基蓝,吸附属于化学吸附;用颗粒内扩散方程和准二级吸附动力学方程对实验数据进行回归分析,更好地描述亚甲基蓝在粉煤灰上的吸附。准二级吸附动力学方程能够反映亚甲基蓝在粉煤灰上的吸附机理,准二级吸附速率常数k2=0.5758g/(mg.min)。本研究为粉煤灰处理印染废水提供了理论依据和实践依据。

Study on Adsorption Properties and Mechanism of Methylene Blue on Coal Fl y Ash by Spectrophotometry

The adsorption of methylene blue by coal fly ash collected from Yanshi thermal power plant was studied.The influences of modified coal fly ash,quantity of coal fly ash,adsorption time and temperature on the adsorption effect of methylene blue were investigated.When fly ash quantity adds to about 4g/L,methylene blue density 15mg/L,temperature 25℃,around 60 mins,the degradation rate of methylene blue reached 98%.The methylene blue in waste water is successfully absorbed with coal fly ash,and the adsorption procedure is easy,simple and efficient.The adsorption mechanism was discussed based on Freundlich isotherm and Langmuir isotherm as the chemisorption.The intra-particle diffusion model and pseudo-second-order kinetic model have been used to test experimental data,and pseudo-second-order kinetic model is provided the best fit.The kinetics of methylene blue adsorption on the coal fly ash follow the second-order kinetic equation,and the second-order adsorption rate constants is 0.5758g/（mg·min）.This provided the theoretical and practical basis for the coal fly ash to deal with pigment printing waste water.