粉煤灰基沸石对亚甲基蓝和Cr(Ⅲ)的共吸附行为——Ⅰ.吸附动力学和吸附热力学

Co-adsorption behavior of methylene blue(MB) and Cr(Ⅲ) on synthesized zeolite from fly ash: Ⅰ.Adsorption kinetics and thermodynamics

以粉煤灰为原料,采用优化改进的水热晶化一步法合成沸石。借助FTIR、XRD和SEM对沸石理化特性进行表征,分析水中双组分污染物亚甲基蓝(MB)和Cr(Ⅲ)的共吸附去除特性。结果表明,合成沸石产物呈菱形或多面体形,在XRD图谱中可见NaP1型沸石特征峰。共吸附过程为准二级反应,以化学吸附为速率控制步骤。Langmuir和Freundlich等温线方程都能有效地描述反应过程,298 K条件下,沸石对MB和Cr(Ⅲ)的理论最大吸附量分别为7.8186 mg/g和8.8889 mg/g。吸附过程自发、吸热,反应后体系自由度降低,推测吸附位点的直接竞争为MB和Cr(Ⅲ)去除的主导机制之一。

Zeolite was synthesized from fly ash via a modified fusion method,the approaches of FTIR,XRD and SEM were used to reveal the characteristics of the products,and co-adsorption effects on MB and Cr（Ⅲ） were analyzed.The results show the synthesized products,NaP1 zeolite,indicated from the XRD pattern,are rhombic or polyhedral type.The pseudo-second order kinetic equation fit better the co-adsorption process,and the chemical-adsorption effect might be the key step.Langmuir and Freundlich isotherms could describe the reaction efficiently,the maximum adsorption capacity for MB and Cr（Ⅲ） are 7.8186 mg/g and 8.8889 mg/g at 298 K,respectively.The removal process is spontaneous and endothermic,and the negative value of ΔS0 reflects decreasing randomness at the reaction interface.The direct competitive adsorption mechanism on active sites of zeolite surface for MB and Cr（Ⅲ） might work in the reaction.