紫外光辐射鱼腥藻产生羟基自由基的特性

为了清晰藻类光化学生态修复受污染水体中活性氧的作用机制,研究了低紫外辐射强度下鱼腥藻产生羟基自由基(·OH)的特性,并系统分析了关键因素的影响.结果表明,紫外光辐射鱼腥藻可产生大量的·OH,暗处和自然光条件下短时间内·OH产生量近似为零.鱼腥藻数量增加,可提升·OH产生量,过高藻浓度可导致光穿透性变差.鱼腥藻水溶液酸性较强或呈碱性时,不利于·OH的产生,较适宜p H值为6—7.低温不利于·OH的产生,且35℃时·OH产生量与25℃时·OH产生量相差较小.增加光照强度,可提升·OH的产生量.热预处理鱼腥藻不利于·OH的形成,但超声处理鱼腥藻可提高·OH产生量.     

Rapid dephosphorylation of glyphosate by Cu-catalyzed sulfite oxidation involving sulfate and hydroxyl radicals

Environmental Chemistry Letters - Glyphosate is a broad-spectrum toxic herbicide that has entered the environment. Advanced oxidation processes efficiently remove various persistent organic...     

Degradation of endocrine disruptor bisphenol A in drinking water by ozone oxidation

The ozone oxidation of endocrine disruptor bisphenol A in drinking water was investigated. A stainless completely mixed reactor was employed to carry out the degradation experiments by means of a batch model. With an initial concentration of 11.0 mg/L, the removal efficiencies of BPA (bisphenol A) could be measured up to 70%, 82%, and 90% when the dosages of ozone were 1, 1.5, and 2 mg/L, respectively. The impacts on BPA degradation under the conditions of different ozone dosages, water background values, BPA initial concentrations, and ozone adding time were analyzed. The results showed that ozone dosage plays a dominant role during the process of BPA degradation, while the impact of the contact time could be ignored. UV wavelength scanning was used to confirm that the by-products were produced, which could be absorbed at UV254. The value of UV254 was observed to have changed during the ozonation process. Based on the change of UV254, it could be concluded that BPA is not completely degraded at low ozone dosage, while shorter adding time of total ozone dosage, high ozone dosage, and improvement of dissolved ozone concentration greatly contribute to the extent of BPA degradation. The effects of applied H₂O₂ dose in ozone oxidation of BPA were also examined in this study. The O₃-H₂O₂ processes proved to have similar effects on the degradation of BPA by ozone oxidation.     

Decomposition of aqueous chlorinated contaminants by UV irradiation with H2O2

In the present study, the decomposition rates of carbon tetrachloride (CCl₄) and 2,4-dichlorophenol (2,4-DCP) in water by the ultraviolet (UV) light irradiation alone and H₂O₂/UV were experimentally investigated. The detailed experimental studies have been conducted for examining treatment capacities of the two different ultraviolet light sources (low and medium pressure Hg arc) in H₂O₂/UV processes. The low or medium UV lamp alone resulted in a 60%–90% decomposition of 2,4-DCP while a slight addition of H₂O₂ resulted in a drastic enhancement of the 2,4-DCP decomposition rate. The decomposition rate of 2,4-DCP with the medium pressure UV lamp alone was about 3–6 times greater than the low pressure UV lamp alone. In the direct photolysis of aqueous CCl₄, the medium pressure UV lamp had advantage over the low pressure UV lamp because the molar extinction coefficient of CCl₄ at shorter wavelength (210–220 nm) is about 20 to 50 times higher than that at 254 nm. However, adding H₂O₂ to the medium pressure UV lamp system rendered a negative oxidation rate because H₂O₂ acted as a UV absorber being competitive with CCl₄ due to negligible reaction between CCl₄ and OH radicals. The results from the present study indicated significant influence of the photochemical properties of the target contaminants on the photochemical treatment characteristics for designing cost-effective UV-based degradation of toxic contaminants.     

Waste control by waste: efficient removal of bisphenol A with steel slag,a novel activator of peroxydisulfate

Activated persulfates are efficient reagents for oxidation of organic contaminants and water treatment. Various compounds are currently used to activate persulfates, but there is a need for cheap and efficient activators. Here, we report the first use of steel slag, an industrial solid waste, as a solid activator for peroxydisulfate activation. We tested this system for bisphenol A degradation. Results indicate that about 70% of bisphenol A can be removed within 1 h. Conditions were 50 μg/L of bisphenol A, 2 g/L of peroxydisulfate, 3 g/L of steel slag and temperature of 298 K. The components and surface morphology of unused and recycled steel slag were analyzed by X-ray diffraction and scanning electron microscopy, whereas the main reactive oxygen species were elucidated by using radical scavengers. Findings show that both base oxides and iron oxides are responsible for peroxydisulfate activation. A redox mechanism involving liquid and solid phases is proposed. Overall, this study reveals the successful recycling of steel slag to activate persulfates for water treatment, following the principle of ‘waste control by waste.’