研究目的
To study the degradation of tannic acid (TA) in aqueous solution using UV/persulfate and photo-Fenton processes, and to evaluate the influence of experimental parameters such as concentrations of oxidants, pH, and temperature on degradation and mineralization efficiency.
研究成果
The photo-Fenton process is more effective than UV/persulfate for degrading and mineralizing tannic acid, achieving near-complete aromatics removal and high TOC removal under optimal conditions (pH 3, 0.18 mM Fe^2+, 29.4 mM H2O2, 25°C). Hydroxyl radicals are more powerful oxidants than sulfate radicals. The findings suggest that photo-Fenton is a viable method for treating TA-contaminated wastewater, with potential for cost-effective application in water treatment.
研究不足
The UV/persulfate process showed lower mineralization efficiency (54.41% TOC removal) compared to photo-Fenton (94.27%), indicating limitations in complete organic matter degradation. High oxidant doses and specific pH conditions were required, which could increase operational costs. The study was conducted on synthetic wastewater, and applicability to real industrial effluents may require further optimization.
1：Experimental Design and Method Selection:
The study compared two advanced oxidation processes (AOPs): UV/persulfate (UV/PS) and photo-Fenton (UV/H2O2/Fe^2+). UV irradiation at 254 nm was used to activate persulfate or hydrogen peroxide in the presence of ferrous iron. The degradation was monitored by UV absorbance at 276 nm for aromatics removal and TOC analysis for mineralization.
2：Sample Selection and Data Sources:
Aqueous solutions of tannic acid (TA) at various concentrations (0.05-0.4 mM) were prepared. Chemicals were of analytical grade from Sigma-Aldrich and Fluka.
3：05-4 mM) were prepared. Chemicals were of analytical grade from Sigma-Aldrich and Fluka.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Equipment included a photo-reactor with a 125-W mercury vapor lamp (Heraeus Noblelight TNN 15/32), UV-Visible spectrophotometer, TOC analyzer (Shimadzu TOC-5050), pH meter (Micronal model B474), HPLC with Nucleosil C18 column, and PTFE filters (0.20 μm). Materials included tannic acid, hydrogen peroxide, ferrous sulfate, potassium persulfate, sulfuric acid, sodium hydroxide, ethanol, tert-butyl alcohol, and sodium sulfite.
4：20 μm). Materials included tannic acid, hydrogen peroxide, ferrous sulfate, potassium persulfate, sulfuric acid, sodium hydroxide, ethanol, tert-butyl alcohol, and sodium sulfite.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: Experiments were conducted in a 2 L photo-reactor with magnetic stirring. For UV/PS, K2S2O8 was added to TA solution at adjusted pH, and UV lamp was switched on. For photo-Fenton, FeSO4·7H2O and H2O2 were added to TA solution at natural pH, followed by UV irradiation. Samples were taken at intervals, quenched with Na2SO3, filtered, and analyzed for pH, TOC, and UV absorbance.
5：Data Analysis Methods:
Data were analyzed to calculate percentage removals of aromatics and TOC. Statistical analysis involved duplicate experiments to ensure reproducibility.
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