Photocatalytic remediation technology has been shown to be a favorable approach for the removal of a range of environmental pollutants in water treatment. While this approach can often achieve complete degradation, often overlooked are reaction intermediates that are potentially as harmful as the original parent compound. In the case of photocatalytic oxidation of the herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA), we have recently shown that 4-chloro-2-methylphenol (CMP) is formed as the primary intermediate. To ensure the continued development of the technology, it is crucial to ensure the removal of both MCPA and CMP can be achieved by photocatalysis. Reported here is the enhanced photocatalytic removal and subsequent suppression of MCPA and CMP respectively, by the addition of small quantities of H₂O₂. While the addition of H₂O₂ often accelerates degradation rates (via increased OH radical production), it was found to restrict the formation of CMP in this study through competitive adsorption at the surface of TiO₂. Based on the combination of MCPA removal coupled with supressed CMP formation, 0.5% H₂O₂ was determined to be an optimal loading for the process. Under these conditions 100% MCPA removal was achieved (to the limit of HPLC detection) after 45 min irradiation at a degradation rate of ∼1 mg L⁻¹ min⁻¹ (ƞ_photon = 4.4), which also resulted in a ∼83% reduction in CMP formation when compared to a system with no H₂O₂ present.

事实证明，光催化修复技术是去除水处理中一系列环境污染物的有利方法。尽管这种方法通常可以实现完全降解，但常常忽略了可能与原始母体化合物一样有害的反应中间体。在光催化氧化除草剂2-甲基-4-氯苯氧基乙酸（MCPA）的情况下，我们最近表明，形成了4-氯-2-甲基苯酚（CMP）作为主要中间体。为确保技术的持续发展，确保通过光催化同时去除MCPA和CMP至关重要。此处报道的是通过添加少量的H ₂ O增强了光催化去除并分别抑制了MCPA和CMP₂。尽管添加H ₂ O ₂通常会加快降解速度（通过增加OH自由基的产生），但在本研究中发现通过在TiO ₂表面的竞争性吸附来限制CMP的形成。基于去除MCPA和抑制CMP形成的结合，确定0.5％H ₂ O ₂是该工艺的最佳负载量。在这些条件下，以〜1 mg L ^-1 min ^-1（ƞ_光子的降解速率）照射45分钟后，达到100％的MCPA去除率（达到HPLC检测的极限）。 = 4.4），与不存在H ₂ O ₂的系统相比，这也导致CMP形成减少约83％。