Photocatalytic Degradation of Dyes from Mixed Dye Contaminated Water using Visible Light Active Bismuth Ferrite@Tio2 and Bismuth Ferrite@Polyaniline Heterostructured Nanocomposites

Abstract

The wastewater containing dye released from industries, when discharged to water bodies without any adequate prior treatment, ultimately leads to human health risk and threat to the environment. A proper wastewater treatment for Chemical Oxygen Demand (COD) and dye removal is essential. Photocatalysis with TiO2 which utilizes ultraviolet light, is a well-known treatment method for dye wastewater. The development of visible light active photocatalysts is gaining importance to harness solar energy. The present study reports the synthesis of bismuth ferrite@ titanium dioxide (BFO@TiO2), bismuth ferrite@polyaniline (BFO@PANI) heterostructured nanocomposites and their application in degradation of dyes from mixed dye contaminated water (MDCW) containing Methylene Blue (MB), Acid Yellow-17 (AY) and Rhodamine-B (Rh-B). The mixed phase BFO nanoparticles were synthesized by auto combustion method and were used in the synthesis of BFO@TiO2 and BFO@PANI. The synthesis/calcination parameters were optimized based on maximum photocatalytic activity in terms of degradation of dyes from MDCW. BFO@TiO2 particles synthesized with BFO:Ti molar ratio of 1:2, calcined at 400°C for 2 h (BFO@TiO2opt) and BFO@PANI particles synthesized with BFO: aniline molar ratio of 1:0.0041 (BFO@PANIopt) exhibited a maximum photocatalytic activity. The BFO@TiO2opt and BFO@PANIopt nanocomposites exhibited superior visible light assisted photocatalytic activity than BFO, TiO2 and PANI. BFO@TiO2opt and BFO@PANIopt nanocomposites were found to form core-shell heterostructures and exhibited a band gap energy of 1.2 eV and 1.4 eV respectively. The parameters such as pH, catalyst loading and light intensity were optimized to maximize dye degradation. The COD removal of 96.7% and 97% were achieved with BFO@TiO2opt and BFO@PANIopt, respectively. These particles were found to be very effective even under solar light. The presence and increasing concentrations of other dyes were found to decrease the degradation of a target dye. The COD removal followed Langmuir–Hinshelwood (L-H) kinetics. BFO@TiO2opt and BFO@PANIopt nanocomposites can be adopted for treatment of wastewater containing multiple dyes by harnessing solar energy for photocatalytic degradation.