Enhanced photocatalytic activity of Fe 3 O 4 -WO 3 -APTES for azo dye removal from aqueous solutions in the presence of visible irradiation

Abstract

Development of highly active photocatalysts for treatment of dye-laden wastewaters is vital. The photocatalytic removal of azo dye Reactive Black 5 was investigated by Fe 3 O 4 -WO 3 -3-aminopropyltriethoxysilane (APTES) nanoparticles in the presence of visible light. The Fe 3 O 4 -WO 3 -APTES nanoparticles were synthesized via a facile coprecipitation method. The photocatalyst was characterized by XRD, FT-IR, SEM, EDX, VSM, UV�Vis, and pH PZC techniques. The effects of some operational parameters such as solution pH, nanophotocatalyst dosage, initial RB5 concentration, H 2 O 2 concentration, different purging gases, and type of organic compounds on the removal efficiency were studied by the Fe 3 O 4 -WO 3 -APTES nanoparticles as a photocatalyst. Maximum phtocatalytic activity was obtained at pH 3. The photocatalytic removal of RB5 increased with increasing H 2 O 2 concentration up to 5 mM. The removal efficiency declined in the presence of different purging gases and all types of organic compounds. First-order rate constant (k obs ) decreased from 0.027 to 0.0022 min �1 and electrical energy per order (E Eo ) increased from 21.33 to 261.82 (kWh/m 3 ) with increasing RB5 concentration from 10 to 100 mg/L, respectively. The efficiency of LED/Fe 3 O 4 -WO 3 -APTES process for RB5 removal was approximately 89.9, which was more effective than the LED/Fe 3 O 4 -WO 3 process (60.72). Also, photocatalytic activity decreased after five successive cycles. © 2018, © 2018 Taylor & Francis