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A sustainable solution for removal of glutaraldehyde in saline water with visible light photocatalysis
- Hong, Soklida, Ratpukdi, Thunyalux, Sungthong, Bunleu, Sivaguru, Jayaraman, Khan, Eakalak
- Chemosphere 2019 v.220 pp. 1083-1090
- biocides, bromides, dissolved organic carbon, glutaraldehyde, humic acids, irradiation, oils, pH, photocatalysis, photocatalysts, saline water, silver, silver chloride, sodium chloride, ultraviolet radiation
- Glutaraldehyde (GA) is the most common biocide used in unconventional oil and gas production. Photocatalytic degradation of GA in brine simulating oil and gas produced water using Ag/AgCl/BiOCl composite as a photocatalyst with visible light was investigated. Removal of GA at 0.1 mM in 200 g/L NaCl solution at pH 7 was 90% after 75 min irradiation using 5 g/L of the photocatalyst. The GA removal followed pseudo-first order reaction with a rate constant of 0.0303 min−1. At pH 5 or at 300 g/L NaCl, the photocatalytic removal of GA was almost completely inhibited. Similar inhibitions were observed when adding dissolved organic carbon (from humic acid) at 10 and 200 mg/L, or Br− at 120 mg/L to the system. The removal rate of GA markedly increased with increasing pH (5–9), photocatalyst loading (2–8 g/L) and under 350 nm UV (compared to visible light). On the contrary, the removal rate of GA markedly decreased with increasing NaCl and initial GA concentrations (0–300 g/L for NaCl and 0.1–0.4 mM for GA). A quenching experiment was also conducted; electron holes (h+) and superoxide (▪) were found as the main reactive species responsible for the removal of GA while OH had a very limited effect.