State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou, 310027, China.
State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou, 310027, China.
Environ Pollut. 2021 Dec 1;290:117991. doi: 10.1016/j.envpol.2021.117991. Epub 2021 Aug 18.
Porous carbons are appealing low-cost and metal-free catalysts in persulfate-based advanced oxidation processes. In this study, a family of porous biochar catalysts (ZnBC) with different porous structures and surface functionalities are synthesized using a chemical activation agent (ZnCl). The functional biochars are used to activate persulfate for sulfamethoxazole (SMX) degradation. ZnBC-3 with the highest content of ketonic group (CO, 1.25 at%) exhibits the best oxidation efficiency, attaining a rate constant (k) of 0.025 min. The correlation coefficient of the density of CO to k (R = 0.992) is much higher than the linearity of the organic adsorption capacity to k (R = 0.694), implying that CO is the intrinsic active site for persulfate activation. Moreover, the volume of mesopore (R = 0.987), and Zeta potential (R = 0.976) are also positive factors in PS adsorption and catalysis. In the mechanistic study, we identified that singlet oxygen is the primary reactive oxygen species. It can attack the -NH group aligned to the benzene ring to form dimer products which could be adsorbed on the biochar surface to reach complete removal of the SMX. The optimal pH range is 4-6 which will minimize the electrostatic repulsion between ZnBCs and the reactants. The SMX degradation in ZnBC/PS system was immune to inorganic anions but would compete with organic impurities in the real wastewater. Finally, the biochar catalysts are filled in hydrogel beads and packed in a flow-through packed-bed column. The continuous system yields a high removal efficiency of over 86% for 8 h without decline, this work provided a simple biochar-based persulfate catalyst for complete antibiotics removal in salty conditions.
多孔碳是基于过硫酸盐的高级氧化过程中一种有吸引力的低成本、无金属催化剂。在这项研究中，使用一种化学活化剂（ZnCl）合成了一系列具有不同多孔结构和表面官能团的多孔生物炭催化剂（ZnBC）。功能性生物炭被用于激活过硫酸盐以降解磺胺甲恶唑（SMX）。具有最高酮基（CO，1.25%）含量的 ZnBC-3 表现出最佳的氧化效率，达到 0.025 min 的速率常数（k）。CO 密度与 k 的相关性系数（R = 0.992）远高于有机吸附容量与 k 的线性度（R = 0.694），表明 CO 是过硫酸盐激活的固有活性位。此外，中孔体积（R = 0.987）和 Zeta 电位（R = 0.976）也是 PS 吸附和催化的积极因素。在机理研究中，我们确定了单线态氧是主要的活性氧物质。它可以攻击与苯环对齐的 -NH 基团，形成二聚体产物，这些产物可以被吸附在生物炭表面上，从而完全去除 SMX。最佳 pH 范围为 4-6，这将最小化 ZnBC 和反应物之间的静电排斥。ZnBC/PS 体系中的 SMX 降解对无机阴离子具有抗干扰性，但会与实际废水中的有机杂质竞争。最后，生物炭催化剂被填充在水凝胶珠中，并填充在流动通过的填充床柱中。连续系统在 8 小时内无需下降即可产生超过 86%的高去除效率，这项工作为在含盐条件下完全去除抗生素提供了一种简单的基于生物炭的过硫酸盐催化剂。
