Liu Hang, Yao Runlin, Yu Mingling, Ye Zongda, Lu Yingrui, Yu Xiaolong, Tang Jin, Sun Jianteng
School of Environmental Science and Engineering, Guangdong University of Petrochemical Technology, Maoming 525000, China.
Natural Resources Ecological Restoration Center of Guangxi Zhuang Autonomous Region, Nanning 530029, China.
Toxics. 2025 May 30;13(6):458. doi: 10.3390/toxics13060458.
Hexavalent chromium (Cr(VI)) is of significant interest in the environmental field due to its high toxicity. Biochar is commonly used as an adsorbent for Cr(VI) removal from wastewater. However, its lower removal efficiency remains a persistent challenge. This study develops an iron-modified rice straw biochar through a simple precipitation and pyrolysis method and applies it for Cr(VI) removal in wastewater, which could convert waste into treasure and improve the adsorption performance of adsorbent. In the adsorption experiments, the results revealed that the adsorption efficiency of Cr(VI) reached 95.54% within 480 min (conditions: adsorbent dosage 2.67 g/L, pH 2.5, temperature 25 ± 2 °C). The Langmuir isotherm model was more suitable to describe the adsorption behavior of Cr(VI) by Fe-BC, and the fitted adsorption capacity achieved 10.03 mg/g. The experimental process was better described by the pseudo-second-order kinetic model, indicating that the adsorption process chemical adsorption was the rate-limiting step. The thermodynamic experiments revealed that the adsorption process of Cr(VI) by Fe-BC was spontaneous and endothermic. Column experiments demonstrated that a lower flow speed was beneficial to adsorption performance. Mechanistic studies highlighted the synergistic roles of electrostatic attraction, ion exchange, and reduction in Cr(VI) removal. These findings provide novel perspectives and innovative approaches for the development and application of adsorbents.
六价铬（Cr(VI)）因其高毒性而在环境领域备受关注。生物炭通常用作从废水中去除Cr(VI)的吸附剂。然而，其较低的去除效率仍然是一个长期存在的挑战。本研究通过简单的沉淀和热解方法制备了铁改性稻草生物炭，并将其应用于废水中Cr(VI)的去除，这可以变废为宝并提高吸附剂的吸附性能。在吸附实验中，结果表明在480分钟内Cr(VI)的吸附效率达到95.54%（条件：吸附剂用量2.67 g/L，pH 2.5，温度25±2°C）。Langmuir等温线模型更适合描述Fe-BC对Cr(VI)的吸附行为，拟合吸附容量达到10.03 mg/g。实验过程用准二级动力学模型能更好地描述，表明吸附过程中化学吸附是限速步骤。热力学实验表明Fe-BC对Cr(VI)的吸附过程是自发的且吸热的。柱实验表明较低的流速有利于吸附性能。机理研究强调了静电吸引、离子交换和Cr(VI)还原在去除过程中的协同作用。这些发现为吸附剂的开发和应用提供了新的视角和创新方法。
