王棕果壳粉吸附亚甲基蓝性能研究

研究了不同条件下王棕果壳粉对亚甲基蓝的吸附性能,得到吸附的最佳条件为王棕果壳用量10g/L,溶液pH值7,吸附时间30min,温度30℃,亚甲基蓝去除率可达98%。应用准一级动力学方程、准二级动力学方程、颗粒内扩散方程模拟了王棕果壳粉吸附亚甲基蓝的动力学过程,准二级动力学方程的R²值均大于0.9991,且平衡吸附量的计算值(q_e,cal)与实验值(q_e,exp)非常接近,说明该方程适合描述整个吸附过程。用Langmuir和Freundlich模型模拟吸附等温线,结果表明Langmuir方程(R²值均大于0.995)更适合描述此吸附过程,在303K下最大单层吸附量为17.36mg/g。计算了吉布斯自由能变(ΔG⁰)、焓变(ΔH⁰)、熵变(ΔS⁰)、吸附势(E)等热力学参数,ΔG⁰、ΔH⁰、ΔS⁰均小于0,说明此吸附过程是一个自发进行的、放热的、趋于有序的吸附过程。在相同温度下,随着亚甲基蓝初始质量浓度的增加,对应的E值逐渐降低。

Study on Adsorption of Methylene Blue on Roystonea regia Shell

The adsorption properties of Roystonea regia shell for methylene blue at different conditions were studied. The optimal adsorption conditions were the dosage of Roystonea regia shell 10g/L, PH value 7, adsorption time 30min and temperature 30℃. At this condition, the removal rate of MB was about 96.11%.The pseudo-first-order, pseudo-second-order and intraparticle diffusion models were used to fit adsorption data in the kinetic studies. And the results showed that the adsorption kinetic described by the pseudo-second-order model was more accurate with R²>0.999 1 and values of q_e.caland q_e.expwere close.The equilibrium isotherms were conducted by using Langmuir and Freundlich models. The adsorption could be well depicted by the Langmuir adsorption isotherm(R²>0.995). And the maximum monolayer adsorption capacity was 17.36mg/g at 303K estimated from the Langmuir model. The Gibbs free energy change(ΔG⁰), enthalpy change (ΔH⁰), entropy change (ΔS⁰) and adsorption potential(E) were calculated.The ΔG⁰, ΔH⁰ and ΔS⁰ were negative. This indicated that the adsorption was a spontaneous,exothermic and decreasing entropy process. At the same temperature,with the increase of concentration of methylene blue solution, the adsorption potential gradually reduced.