Performance of coffee husk biochar in sulfadiazine retention and remediation of soil water contamination: a batch and column study_Article

This research aimed to analyse the effect of biochar as a filtering layer in the transfer mechanisms of Sulfadiazine (SDZ), an antibiotic found in urban surface waters. Laboratory tests of kinetics and sorption isotherms of SDZ with biochar were conducted in batch conditions. Additionally dynamic adsorption analyse was performed on sand column experiments and breakthrough curves were established. As it is fundamental for understanding the SDZ transport dynamics, simulations of the breakthrough curves were performed using Hydrus-1D, for comparison. The results suggest that the biochar significantly improves the SDZ sorption rates. With a biochar filtering layer into the column, a rapid increase in sorption was observed throughout the first hours, reaching the equilibrium condition within 24 hours, and the experimental data were best fitted through a pseudo-second-order model. Additionally, a markable dependency was observed for the loading capacity of the biochar with the experimental condition of the sorption test, as the loading value without batch (41%) was below the obtained in the batch trials (53%). The simulations also showed that the Convection Dispersion Equation and the two site sorption models best fit the observed data, indicating no chemical equilibrium. Furthermore, the adjustments of the kinetics and sorption isotherms suggest that chemisorption in multiple layers was the predominant mechanism in sorption. Consequently, it is possible to infer that despite the risk SDZ represents to the environment and humans, the coffee husk biochar can be an effective alternative to mitigate its presence, or even more, to remove this contaminant from urban waters.

本研究旨在探究生物炭（biochar）作为过滤层对磺胺嘧啶（Sulfadiazine, SDZ）迁移机制的影响，磺胺嘧啶是一种广泛检出于城市地表水中的抗生素。本研究在批量间歇实验条件下，开展了磺胺嘧啶与生物炭的动力学及吸附等温线实验室测试。此外，通过砂柱实验开展了动态吸附分析，并绘制了穿透曲线。鉴于穿透曲线是解析磺胺嘧啶迁移动力学的核心基础，本研究采用Hydrus-1D软件对穿透曲线进行模拟以作对照。研究结果表明，生物炭可显著提升磺胺嘧啶的吸附速率。当砂柱中引入生物炭过滤层后，初始数小时内吸附量快速上升，并在24小时内达到吸附平衡，且实验数据与准二级动力学模型拟合度最优。此外，生物炭的吸附负载容量与吸附实验的操作条件存在显著相关性：无批量预处理的负载值（41%）低于批量实验所得的负载值（53%）。模拟结果同时显示，对流弥散方程（Convection Dispersion Equation）与双位点吸附模型对实验观测数据的拟合效果最佳，这表明体系未达到化学平衡。此外，动力学与吸附等温线的拟合结果表明，多层化学吸附是该吸附过程的主导机制。综上可推断，尽管磺胺嘧啶对环境与人类健康均存在潜在风险，但以咖啡壳为原料制备的生物炭可作为有效途径缓解其污染，甚至可用于从城市水体中去除该类污染物。