Department of Civil Engineering, Schulich School of Engineering, University of Calgary, Calgary, AB T2N 1N4, Canada.
Department of Civil Engineering, Schulich School of Engineering, University of Calgary, Calgary, AB T2N 1N4, Canada.
Chemosphere. 2020 Jun;248:125911. doi: 10.1016/j.chemosphere.2020.125911. Epub 2020 Jan 16.
This paper presents an evaluation of UV/PAA process for degradation of four pharmaceuticals venlafaxine (VEN), sulfamethoxazole (SFX), fluoxetine (FLU) and carbamazepine (CBZ) with comparison to UV/HO process. The effectiveness of combining PAA and HO at various proportions while irradiating with UVC were also evaluated. UVC/PAA (λ = 254 nm) was effective in degrading all four pharmaceuticals and followed pseudo first-order kinetics. Increasing PAA dosage or UVC intensity resulted in a linear increase in pseudo-first order rate coefficient. Both PAA in dark conditions and UVA/PAA (λ = 360 nm) were marginally effective to degrade SFX and ineffective to degrade VEN, CBZ and FLU; indicating the need for UVC irradiation for activation of PAA. For similar oxidant dosages of 50 mg/L UVC/HO was found to be faster than UV/PAA for VEN, CBZ and FLU by 55%, 75% and 33%, respectively. Under similar conditions, SFX was degraded 24% faster by UV/PAA. Increase in the proportion of HO to PAA in UVC/PAA/HO improved kinetics of degradation compared to PAA alone. Tests on TOC were conducted to determine the amount of acetic acid that is released to water when treatment by UVC/PAA is conducted. Results demonstrated that 70% of PAA by mass was ultimately converted to acetic acid and remained in the treated solutions. Hydroxyl radical attack is hypothesized to be the main mechanism of degradation by UV/PAA as degradation intermediates identified for all the target pharmaceuticals coincided with by-products identified during UV/HO process.
本文评价了 UV/PAA 工艺对文拉法辛（VEN）、磺胺甲恶唑（SFX）、氟西汀（FLU）和卡马西平（CBZ）四种药物的降解效果，并与 UV/HO 工艺进行了比较。还评估了在辐照 UVC 时，以不同比例结合 PAA 和 HO 的效果。UVC/PAA（λ=254nm）能有效降解这四种药物，遵循准一级动力学。增加 PAA 用量或 UVC 强度会导致准一级速率系数呈线性增加。PAA 在黑暗条件下和 UVA/PAA（λ=360nm）对 SFX 的降解效果仅略有效果，对 VEN、CBZ 和 FLU 则无效；表明需要 UVC 辐照来激活 PAA。对于类似的氧化剂剂量 50mg/L UVC/HO 比 UV/PAA 更快地降解 VEN、CBZ 和 FLU，分别快 55%、75%和 33%。在类似条件下，SFX 经 UV/PAA 处理降解速度快 24%。在 UVC/PAA/HO 中增加 HO 与 PAA 的比例，与单独使用 PAA 相比，可提高降解动力学。通过 TOC 测试确定了用 UVC/PAA 处理时释放到水中的乙酸量。结果表明，质量的 70%的 PAA 最终转化为乙酸并留在处理溶液中。假设 UV/PAA 的主要降解机制是羟基自由基攻击，因为所有目标药物的降解中间体都与 UV/HO 工艺中鉴定的副产物一致。
