活性炭纤维吸附石化废水中苯酚的吸附平衡及动力学

以活性炭纤维(ACF)为吸附剂,研究了ACF对石化废水中苯酚的吸附平衡及动力学。在25、40、55及65℃下测定了吸附平衡等温线,采用Langmuir、Freundlich和Redlich-Peterson等温方程对吸附平衡数据进行了拟合,结果表明吸附平衡数据更符合Langmuir与Redlich-Peterson方程。体系温度从25、40、55升高到65℃时,ACF对模拟废水中苯酚的吸附能力随温度升高而降低,而ACF对石化废水中苯酚的吸附能力并不完全随温度升高而降低。ACF对石化废水与模拟废水中苯酚的吸附过程均符合拟二级动力学方程。颗粒内扩散模型对吸附动力学实验数据的拟合结果表明,吸附初期吸附速率主要受颗粒内扩散控制且石化废水中苯酚吸附的k_id随温度升高而增大,吸附中后期吸附速率除了受颗粒内扩散控制外还受到外扩散的影响。热力学分析表明,石化废水中ACF吸附苯酚过程的ΔG<0,由于石油类物质对苯酚吸附的影响,温度升高ΔG的数值变化不大。

Equilibrium and kinetics of phenol adsorption from petrochemical wastewater with activated carbon fiber

Activated carbon fiber (ACF) was used for the adsorption of phenol in petrochemical wastewater. Adsorption isotherms at 25, 40, 55 and 65℃ were determined and fitted with Langmuir, Freundlich and Redlich-Peterson equations. The results show that the adsorption equilibrium data fit Langmuir and Redlich- Peterson equations better than the Freundlich equation. The phenol adsorption ability of ACF from simulated wastewater decreases with the increase of temperature, while the situation is somewhat different with petrochemical wastewater. The adsorption kinetic data fit the pseudo-second-order kinetic model well in petrochemical wastewater and simulated wastewater. The intra-particle diffusion is the main rate-controlling step in the initial period and k_id of phenol adsorption increases with temperature in petrochemical wastewater. The adsorption rate is influenced by intra-particle diffusion and external diffusion in the middle and later period. Thermodynamic analysis shows that the ΔG value is negative, indicating that the adsorption of phenol in petrochemical wastewater by ACF is spontaneous. However, ΔG does not change obviously with temperature owing to the influence of oil on phenol adsorption in petrochemical wastewater.