Abstract

In this study, apricot stones were modified with citric acid and used in the adsorption of methylene blue. Fourier transform infrared (FT-IR) Scanning electron microscopy (SEM), and X-Ray Diffraction (XRD) were used to characterize the adsorbent. The influence of the initial pH, temperature, contact time, and initial concentration on the adsorption process was investigated. The thermodynamic investigation showed that adsorption was spontaneous and the adsorption process was endothermic. In experimental studies, isotherm models by Langmuir, Freundlich, Temkin, and Dubinin – Radushkevich (D-R) were analyzed and experimental data showed the best agreement with the Temkin isotherm model. We found that the maximum monolayer adsorption capacity for the Langmuir isotherm model was 19.01 mg/g. Pseudo-first and second-order models were examined and, according to the results of the kinetic model analysis, the highest correlation coefficient (R²> 0.99) belongs to the pseudo-second-order kinetic model. It was concluded that the adsorption mechanism was carried out in both the intra-particle diffusion and the liquid film diffusion model.

摘要

在这项研究中，杏核用柠檬酸改性并用于亚甲蓝的吸附。傅里叶变换红外 (FT-IR) 扫描电子显微镜 (SEM) 和 X 射线衍射 (XRD) 用于表征吸附剂。研究了初始pH、温度、接触时间和初始浓度对吸附过程的影响。热力学研究表明吸附是自发的，吸附过程是吸热的。在实验研究中，分析了 Langmuir、Freundlich、Temkin 和 Dubinin – Radushkevich (DR) 的等温线模型，实验数据显示与 Temkin 等温线模型最吻合。我们发现 Langmuir 等温线模型的最大单层吸附容量为 19.01 mg/g。检查了伪一阶和二阶模型，并且，² > 0.99)属于伪二级动力学模型。得出的结论是，吸附机理在颗粒内扩散和液膜扩散模型中均有发生。