以纤维为造孔剂的粉煤灰基材料对染料的吸附研究

Adsorption Performance of Fly Ash Based Adsorbent with Fiber as Pore-Forming Agent for Dye Removal

以粉煤灰为骨料,膨润土为粘结剂,造纸废渣中的细小纤维为造孔剂,经过成型烧结后制备得到新型吸附材料(GAFF),应用于处理亚甲基蓝和龙胆紫这2种碱性阳离子染料,考察了染料溶液p H、浓度、温度等因素对吸附行为的影响。实验结果表明,吸附量随着染料p H值增大而增大,但当p H值大于5时,吸附量变化不大;升高反应温度及增大染料初始浓度,吸附量也随之增大。使用Langmuir、Freundlich和Tempkin吸附等温线拟合吸附数据,通过比较R2值可以得出Langmuir等温线更适合拟合GAFF对2种染料的吸附,且使用该模型计算得出的GAFF对亚甲基蓝和龙胆紫染料的最大吸附量分别是222.22和714.28 mg/g。使用拟一级动力学、拟二级动力学和颗粒内扩散模型拟合数据后发现该吸附过程更符合拟二级动力学方程。

A kind of new adsorbent called GAFF was produced and applied for the treatment of basic dyes including methylene blue and crystal violet. GAFF was produced by mixing fly ash, bentonite and fiber from paper sludge well, shaped and sintered at a high temperature. The adsorption experiment was conducted at different p H value, dye concentrations and temperatures to study their impacts on adsorption capacity. Results showed that as the p H value grew, the adsorption capacity also increased but not so much at p H value higher than 5. Moreover, higher temperature and dye concentration led to higher adsorption capacity. Adsorption data were modeled using Langmuir, Freundlich and Temkin adsorption isotherms and the adsorption process fitted very well to Langmuir model. In addition, the maximum adsorption capacities, which were calculated from Langmuir model, of GAFF onto methylene blue and crystal violet were 222.22 mg/g and 714.28 mg/g respectively.Adsorption kinetics were verified by pseudo-first-order, pseudo second-order and intra-particle models. The results indicated that the dye uptake process followed the pseudo second-order model.