Abstract

A low-cost adsorbent (Detarium senegalense stem bark extract coated shale (DSMS)) comprising pristine shale (PSH) coated with D. senegalense stem bark extract was prepared and utilized for the adsorption of Cr(VI). The DSMS and PSH were characterized by the SEM, XRD, FTIR, EDX, TGA, and BET. The batch adsorption experiment results showed that DSMS exhibited an excellent ability to adsorb chromium with a maximum removal occurring at pH 2, dosage of 0.05 g and 180 min contact time. The adsorption process was best described by the pseudo-second-order for DSMS and Elovich model for PSH which depicts chemisorption as the major mechanism responsible for the uptake of Cr(VI) onto the adsorbents. Langmuir model provided the best fit to the isotherm analysis on both materials. The maximum adsorption capacity of DSMS and PSH were 64.98 mg g⁻¹ and 29.97 mg g⁻¹ respectively. The thermodynamics revealed that the adsorption of Cr(VI) was feasible, endothermic and entropy driven. Furthermore, after five cycles of reuse, both DSMS and PSH demonstrated effective regeneration and reusability for Cr(VI) uptake. The structural properties, reusability, and high adsorption capabilities of DSMS indicate that they could be used as low-cost adsorbents in large-scale Cr(VI) wastewater treatment.

Novelty statement Plant extracts are packed with a variety of polyphenolic compounds, such as aldehydes, alcohols, carboxylics, ethers, ketones, and phenols which contains several functionalities useful in the adsorption of toxic metals. Despite this, research on the use of plant extracts in the modification of adsorbent materials for enhanced adsorption is rare. This study reports for the first time the use of Detarium senegalense stem bark extract coated shale adsorbent for the efficient uptake of Cr(VI) ion.

摘要

一种低成本吸附剂（Detarium senegalense茎皮提取物涂层页岩（DSMS）），包含涂有D. senegalense的原始页岩（PSH）制备茎皮提取物并用于吸附 Cr(VI)。DSMS和PSH通过SEM、XRD、FTIR、EDX、TGA和BET表征。批量吸附实验结果表明，DSMS 表现出优异的铬吸附能力，在 pH 2、0.05 g 用量和 180 分钟接触时间时去除率最大。吸附过程最好用 DSMS 的准二级模型和 PSH 的 Elovich 模型来描述，该模型将化学吸附描述为负责将 Cr(VI) 吸收到吸附剂上的主要机制。Langmuir 模型为两种材料的等温线分析提供了最佳拟合。DSMS和PSH的最大吸附量分别为64.98 mg g ^-1和29.97 mg g ^-1分别。热力学表明Cr(VI)的吸附是可行的、吸热和熵驱动的。此外，经过五次重复使用后，DSMS 和 PSH 都表现出有效的再生和可重复使用 Cr(VI) 吸收。DSMS 的结构特性、可重复使用性和高吸附能力表明它们可以用作大规模 Cr(VI) 废水处理中的低成本吸附剂。

新颖性声明植物提取物富含多种多酚化合物，例如醛、醇、羧酸、醚、酮和酚，它们含有多种可用于吸附有毒金属的功能。尽管如此，关于使用植物提取物改性吸附材料以增强吸附的研究很少。本研究首次报道了使用Detarium senegalense茎皮提取物包覆的页岩吸附剂来有效吸收 Cr(VI) 离子。