研究目的
To investigate the effects of operational parameters on PRC degradation efficiency and rate in water media using the UV/chlorine process, apply the response surface methodology to evaluate the interactions of four independent factors (i.e., UV, pH, NaOCl, and dissolved organic matter) on the PRC degradation process, and postulate the probable degradation pathways of PRC under the UV/chlorine treatment by the LC-MS/MS methodology.
研究成果
The UV/chlorine process was more effective in degrading PRC compared to UV/H2O2, chlorination alone, or UV alone. The degradation rate was influenced by operational parameters such as chlorine dosage, UV intensity, and solution pH. The study successfully identified twenty transformation products and proposed degradation pathways. However, further research is needed to assess the toxicity of these transformation products.
研究不足
The study did not evaluate the toxicity of PRC transformation products and its variation during the UV/chlorine process, which is crucial for understanding the environmental impact of the degradation process.
1：Experimental Design and Method Selection
The study employed a UV/chlorine advanced oxidation process (AOP) to degrade paracetamol (PRC) in water. The experimental design included varying operational conditions such as chlorine dosage, solution pH, UV intensity, and the presence of natural organic matter (NOM). The methodology involved the use of a low-pressure mercury lamp for UV irradiation and sodium hypochlorite (NaOCl) as the chlorine source.
2：Sample Selection and Data Sources
The samples consisted of PRC solutions (~10 μmol/L) prepared in deionized water. The effects of various water matrices, including tap water and surface water, were also examined.
3：List of Experimental Equipment and Materials
A 2-L cylindrical double-wall jacketed vessel reactor, low-pressure mercury lamp (G6 T5, TUV 6W, 254 nm, Philips), magnetic stirrer, thermostatic water bath, HPLC (Dionex 3000 Thermo) coupled with a photo-diode array, LC/HRMS Q-Exactive Focus system (Thermo), and various chemicals including sodium hypochlorite solution (5% NaOCl), sodium chloride (NaCl), hydroxyl peroxide (H2O2), and others.
4：Experimental Procedures and Operational Workflow
Experiments were initiated by spiking a designed amount of NaClO into the initial PRC solution. The solution was homogeneously stirred, and samples were taken at target time intervals for analysis. The samples were quenched with sodium sulphite to stop further reactions.
5：Data Analysis Methods
The concentration of PRC was determined using HPLC, and intermediates were identified by LC-HRMS. Response surface methodology (RSM) was used for optimization of operational conditions. The degradation kinetics were analyzed using pseudo-first-order kinetics.
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