Department of Chemistry, Michael Okpara University of Agriculture, Umudike, Nigeria.
Chemical Sciences Department, Olabisi Onabanjo University, Ago-Iwoye, Nigeria.
Int J Phytoremediation. 2021;23(14):1486-1496. doi: 10.1080/15226514.2021.1913991. Epub 2021 May 8.
A low-cost adsorbent ( stem bark extract coated shale (DSMS)) comprising pristine shale (PSH) coated with 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 and 29.97 mg g 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. 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 stem bark extract coated shale adsorbent for the efficient uptake of Cr(VI) ion.
一种低成本吸附剂（原页岩涂覆有茎树皮提取物）由原页岩（PSH）和涂覆有茎树皮提取物组成，用于吸附六价铬。DSMS 和 PSH 采用 SEM、XRD、FTIR、EDX、TGA 和 BET 进行了表征。批处理吸附实验结果表明，DSMS 对铬的吸附能力极强，最大去除率发生在 pH 值为 2、用量为 0.05 g 和 180 min 接触时间。吸附过程最适合描述 DSMS 的准二级动力学和 PSH 的 Elovich 模型，这表明化学吸附是 Cr(VI) 被吸附剂吸收的主要机制。Langmuir 模型对两种材料的等温线分析提供了最佳拟合。DSMS 和 PSH 的最大吸附容量分别为 64.98mg/g 和 29.97mg/g。热力学表明，Cr(VI)的吸附是可行的、吸热的和熵驱动的。此外，经过五次循环重复使用后，DSMS 和 PSH 都表现出对 Cr(VI)吸收的有效再生和再利用能力。DSMS 的结构特性、可重复使用性和高吸附能力表明，它们可用作大规模 Cr(VI)废水处理中的低成本吸附剂。植物提取物中含有多种多酚类化合物，如醛类、醇类、羧酸类、醚类、酮类和酚类，其中包含几种对有毒金属吸附有用的官能团。尽管如此，关于植物提取物在增强吸附用吸附剂材料改性中的应用的研究却很少。本研究首次报道了使用茎树皮提取物涂覆的页岩吸附剂来有效吸附六价铬离子。
