不同组成粉煤灰吸附亚甲基蓝的性能和机理研究

Study on mechanism and properties of methylene blue adsorption on different compositions coal fly ash

从三个电厂取得三种不同组成和性质的粉煤灰,研究了粉煤灰对水溶液中亚甲基蓝的吸附性能和机理.结果表明,影响粉煤灰吸附的最重要的因素是粉煤灰粒度而不是C含量.三种粉煤灰对亚甲基蓝的吸附均符合二级吸附动力学模型,渭河、西郊和灞桥粉煤灰的二级吸附速率常数分别为5.580、4.149和2.204×10-2g.mg-1.min-1.吸附过程均由颗粒内扩散控制,渭河、西郊和灞桥粉煤灰的颗粒内扩散速率常数分别为0.067、0.109和0.160mg.g-1.min-1/2.亚甲基蓝浓度增加,粉煤灰对亚甲基蓝的吸附量增加;粉煤灰投加量增加,其对亚甲基蓝的吸附量减小;随着溶液pH值增加,粉煤灰对亚甲基蓝的吸附量先增加后略有下降.

Three kinds of coal fly ashes were collected from three thermal power plants. Kinetics, mechanism and other influencing factors of methylene blue adsorption by coal fly ashes have been studied. The results showed that the most important factor influencing adsorption is the particle size other than the C content of coal fly ash. The kinetics of methylene blue adsorption on the Weihe coal fly ash, Xijiao coal fly ash and Baqiao coal fly ash all follow the seconed-order kinetic equation, their second-order adsorption rate constants being 5. 580,4. 149 and 1. 204 × 10^-2 g · mg^-1 · min^-1 respectively. The adsorption process is controled by intra-particle diffusion. The intraparticle diffusion rate constants of methylene blue adsorption onto Weihe, Xijiao and Baqiao coal fly ashes are 0. 067, 0. 109 and 0. 160 mg · g^-1 · min^-1/2 respectively. The adsorbed amount increases with the initial concentration of methylene blue decreasing and increases with the dosage of coal fly ashes increasing. The adsorbed amount of methylene blue increases first and then decreases slightly with the initial pH increasing.