Gong Han, Chu Wei, Gong He, Huang Airu, Lin Jingjun, Yan Muting
Joint Laboratory of Guangdong Province and Hong Kong Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University Guangzhou China
Department of Civil and Environmental Engineering, Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong
RSC Adv. 2020 Sep 28;10(59):35646-35657. doi: 10.1039/d0ra05704e.
This study aims at systematically examining the potential of removing the emerging pollutant sulfamethoxazole (SMX) from aqueous solution under photo-assisted peroxymonosulfate (PMS) activation by Fe(ii). The residual SMX was determined by HPLC analysis. The concentration of Fe(ii) ([Fe(ii)]) was monitored during SMX degradation. Fe(ii) and PMS cooperated with each other for faster SMX photodegradation; a relatively lower or higher molar ratio between Fe(ii) and PMS led to lower SMX removal efficiency due to the insufficient radicals or scavenging effect. A fixed reaction ratio of [Fe(ii)] : [PMS] with 1.6 : 1 at the first 5 min was detected for reactions with [Fe(ii)] ≥ 0.5 mM or [PMS] ≤ 0.25 mM. The pH level of around 6.0 was recommended for optimal SMX removal under the treatment process UVA + Fe(ii) + PMS. Six transformation products were detected through UPLC/ESI-MS analysis, and four of the proposed intermediates were newly reported. Concentrations of the intermediates were proposed based on the isoxazole-ring balance and the Beer-Lambert law. Total Organic Carbon (TOC) reduction was mainly attributed to the loss of benzene ring, N-S cleavage, and isoxazole ring opening during SMX degradation. The contributions of reactive species OH˙ and SO˙ were determined based on quench tests. The acute toxicity of SMX to the rotifers was eliminated after the proposed treatment, demonstrating that the process was effective for SMX treatment and safe to the environment.
本研究旨在系统考察在铁（Ⅱ）光助过一硫酸盐（PMS）活化体系下从水溶液中去除新兴污染物磺胺甲恶唑（SMX）的潜力。通过高效液相色谱（HPLC）分析测定残留的SMX。在SMX降解过程中监测铁（Ⅱ）（[Fe（Ⅱ）]）的浓度。铁（Ⅱ）和PMS相互协同作用，实现更快的SMX光降解；铁（Ⅱ）与PMS之间相对较低或较高的摩尔比会因自由基不足或清除作用而导致较低的SMX去除效率。对于[Fe（Ⅱ）]≥0.5 mM或[PMS]≤0.25 mM的反应，在前5分钟检测到[Fe（Ⅱ）]∶[PMS]的固定反应比为1.6∶1。在UVA + Fe（Ⅱ）+ PMS处理过程中，建议pH值约为6.0以实现最佳的SMX去除效果。通过超高效液相色谱/电喷雾质谱（UPLC/ESI-MS）分析检测到六种转化产物，其中四种推测的中间体为新报道的。基于异恶唑环平衡和比尔-朗伯定律提出了中间体的浓度。总有机碳（TOC）的降低主要归因于SMX降解过程中苯环的损失、N-S键断裂和异恶唑环开环。基于猝灭试验确定了活性物种·OH和·SO的贡献。经所提出的处理后，SMX对轮虫的急性毒性消除，表明该过程对SMX处理有效且对环境安全。
