生物质电厂飞灰吸附脱Cd性能及动力学研究

Adsorption and Kinetic Characteristics of Cd Removal by Fly Ash from Biomass Power

本文研究了生物质电厂飞灰对不同离子的吸附能力,并对Cd离子吸附动力学进行分析。结果表明:飞灰对As (III)、As (V)、Cr三种离子基本没有吸附能力;对Cd离子的吸附能力很强,随着Cd浓度由0.1 ppm升高到20 ppm,飞灰对Cd离子的脱除能力显著降低。当温度由15℃升高到35℃时,飞灰对Cd的脱除能力增大,然而当浓度超过10 ppm时,升高温度对提高飞灰脱除能力的影响有限。飞灰除镉吸附动力学过程与伪二级动力学速率方程拟合度更高,R2超过0.997。由颗粒内扩散模型分析可知,飞灰除镉的反应前期主要受粒子内扩散控制,而吸附的中后期主要受粒子内扩散和膜扩散共同控制。

This paper studied different kinds of ions adsorption ability of the fly ash from the biomass power plant and analyzed the Cd ions adsorption kinetics. The results showed that the fly ash had no adsorption capacity for As (III), As (V) and Cr ions, but had a strong adsorption capacity for Cd ions. With the increase of Cd ions concentration from 0.1 ppm to 20 ppm, the Cd ions removal ability of fly ash decreased significantly. When the temperature increased from 15˚C to 35˚C, the removal ability of fly ash increased. However, when the concentration exceeded 10 ppm, the effect of increasing the temperature on the removal ability of fly ash was limited. The kinetic process of Cd removal by adsorption with fly ash had a higher fitting degree with the pseudo-second-order kinetic rate equation, and the R2 was over 0.997. According to the analysis of intra-particle diffusion model, the removal of Cd by fly ash was mainly controlled by intra-particle diffusion in the early stage of reaction, while the adsorption was mainly controlled by both intra-particle diffusion and membrane diffusion in the middle and late stage.