Abstract:
Removal of Reactive Red 120 (RR120) dye in aqueous solution was investigated using immobilized TiO2 in the presence of UV light. TiO2 was deposited onto microscope slides by heat attachment method. SEM analyses confirmed that all microscope slides were coated with TiO2 particles completely after single, two, three and four layers coating. The removal efficiency increased with repetitive coating up to three layers. The highest removal efficiency of 94% was obtained at pH 3 within 300 min of reaction time. Complete removal was observed with 5 and 10 mg dm−3 dye concentrations whereas removal efficiency decreased from 96 to 52% when initial RR120 concentration increased 15 mg dm−3 to 30 mg dm−3. The results of nonlinear optimization showed that the kinetics of removal of RR120 in the range of concentration studied described by L–H kinetic expression. The experiments conducted with radical scavengers indicated that hydroxyl radicals and photogenerated hole and electrons were main reactive species in photocatalytic removal of RR120. The photonic efficiency of immobilized system was lower than that of suspended system. Minor drop (6%) in the removal of RR120 with three layers coated slide after four consecutive cycles of 300 min indicated the reusability and stability of coated slides. A possible degradation mechanism for degradation of RR120 was proposed according to detected intermediate compounds. Mineralization of RR120 was monitored by generation of NO3− and SO42− ions in solution during photocatalytic reaction. © 2022, Akadémiai Kiadó, Budapest, Hungary.