Application of the Fenton’s process in a bubble column reactor for hydroquinone degradation

• Published in: Environmental science and pollution research international 2018-12, Vol.25 (35), p.34851-34862
• Main Authors: Lima, Vanessa N., Rodrigues, Carmen S. D., Madeira, Luis M.
• Format: Article
• Language: English
• Subjects: Advanced Oxidation Processes for Water/Wastewater Treatment; Air flow; Air temperature; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; bioreactors; Bubble columns; Carboxylic acids; catalysts; Columns (process); Concentration gradient; Degradation; Distilled water; Dosage; Earth and Environmental Science; Ecotoxicology; Effluents; Environment; Environmental Chemistry; Environmental Health; Environmental science; Flow rates; Flow velocity; Hydrogen peroxide; Hydrogen Peroxide - chemistry; Hydroquinone; Hydroquinones - chemistry; Intermediates; Iron; Iron - chemistry; Mineralization; Models, Chemical; Organic carbon; oxidants; Oxidation; Oxidation-Reduction; Oxidizing agents; pH effects; Reactors; stoichiometry; temperature; Total organic carbon; Waste Water; Waste Water Technology; Wastewater; Water Management; Water Pollution Control
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-017-0746-z

The aim of this study was to assess the degradation and mineralization of hydroquinone (HQ) by the Fenton’s process in a bubble column reactor (BCR). The effect of the main operating variables, namely, air flow rate, effluent volume, hydrogen peroxide (H 2 O 2 ) concentration, catalyst (Fe 2+ ) dose, initial pH, and temperature, were assessed. For all air flow rates tested, no concentration gradients along the column were noticed, evidencing that a good mixing was reached in the BCR. For the best conditions tested ([H 2 O 2 ] = 500 mg/L, [Fe 2+ ] = 45 mg/L, T  = 24 °C, Q air  = 2.5 mL/min, pH = 3.0, and V = 5 L), complete HQ degradation was reached, with ~ 39% of total organic carbon (TOC) removal, and an efficiency of the oxidant use— η H2O2 —of 0.39 (ratio between TOC removed per H 2 O 2 consumed normalized by the theoretical stoichiometric value); moreover, a non-toxic effluent was generated. Under these conditions, the intermediates and final oxidation compounds identified and quantified were a few carboxylic acids, namely, maleic, pyruvic, and oxalic. As a strategy to improve the TOC removal, a gradual dosage of the optimal H 2 O 2 concentration was implemented, being obtained ~ 55% of mineralization (with complete HQ degradation). Finally, the matrix effect was evaluated, for which a real wastewater was spiked with 100 mg/L of HQ; no reduction in terms of HQ degradation and mineralization was observed compared to the solution in distilled water.