Department of Chemistry, Vaal University of Technology, Vanderbijlpark, 1911, South Africa.
Department of Chemistry, Vaal University of Technology, Vanderbijlpark, 1911, South Africa; Department of Applied Chemistry, National University of Science and Technology, Bulawayo, Zimbabwe.
Environ Res. 2022 Sep;212(Pt D):113445. doi: 10.1016/j.envres.2022.113445. Epub 2022 May 21.
Based on the premise that aqueous anions of hexavalent chromium (Cr(VI)) are capable of electrostatic interaction with cationic and polar active sites, acid-washed Madacamia nutshell biomass was sequentially treated with diethylenetriamine (DETA) and maleic anhydride (MA) to graft poly(diethylenetriamine-co-maleic anhydride). By displaying a new peak at 1685 cm ascribed to amide CO stretching vibrations, Fourier transform infrared spectroscopy highlighted the formation of amide groups through reaction of DETA with carboxyl groups on the biomass surface. Scanning electron microscopic images of the MA-modified biomass displayed polymeric growths attributed to copolymerization of DETA with MA. The polar and ionizable amide and amine groups of the grafted copolymer endowed the adsorbent with Cr(VI) removal capabilities over a wide pH range demonstrated by removal efficiencies between 70.9% and 81.7% in the pH 1.6 to pH 10.0 range for the treatment of 20 mL solutions containing 100 mg L Cr(VI) with 200 mg of adsorbent. Conformity of the adsorption isotherm data to the Freundlich model revealed the heterogeneous nature of the adsorbent surface, which comprised a variety of functional groups capable of interaction with Cr(VI) species in solution. The Sips isotherm model provided the best fit to the equilibrium experimental data, and the adsorption capacity was 779.1 mg g at pH 1.6, room temperature and an adsorbent dosage of 5.0 g L. The findings indicate that Cr(VI) adsorption onto diethylenetriamine and maleic anhydride modified Madacamia nutshell biomass is a promising option for Cr(VI) removal from aqueous solutions.
基于六价铬（Cr(VI)）的水合阴离子能够与阳离子和极性活性位点发生静电相互作用的前提，用二乙烯三胺（DETA）和马来酸酐（MA）依次处理经酸处理的澳洲坚果壳生物质，以接枝聚（二乙烯三胺-co-马来酸酐）。傅里叶变换红外光谱通过显示 1685 cm 处归因于酰胺 CO 伸缩振动的新峰，突出了通过 DETA 与生物质表面上的羧基反应形成酰胺基团。MA 改性生物质的扫描电子显微镜图像显示了聚合物的生长，归因于 DETA 与 MA 的共聚。接枝共聚物的极性和可离子化的酰胺和胺基团使吸附剂在很宽的 pH 范围内具有去除 Cr(VI)的能力，在 pH 1.6 至 10.0 范围内，用 200 mg 吸附剂处理含有 100 mg L Cr(VI)的 20 mL 溶液时，去除效率在 70.9%至 81.7%之间。吸附等温线数据符合 Freundlich 模型表明，吸附剂表面具有异质性，表面包含多种官能团，能够与溶液中的 Cr(VI)物种相互作用。Sips 等温线模型对平衡实验数据提供了最佳拟合，在 pH 1.6、室温且吸附剂用量为 5.0 g L 时，吸附容量为 779.1 mg g。研究结果表明，用二乙烯三胺和马来酸酐改性的澳洲坚果壳生物质吸附 Cr(VI)是从水溶液中去除 Cr(VI)的一种很有前途的选择。
