Photocatalytic degradation of azo dye assisted by Fe2O3/FeS2 fabricated on biomass-derived nanobiochar: Experimental and kinetic evaluation

In the present study, the synthesis, characterization and successful application of magnetic coupled Fe 2 O 3 /FeS 2 biochar composites from waste Citrus sinensis peels for photocatalytic degradation of crystal violet dye contaminated wastewater. The waste-derived photocatalyst was capable of degrading Crystal Violet (CrV) dye with an efficiency of 97.8% under UV light range at acidic pH (pH 3) in comparison to the iron nanoparticles alone. The degradation followed pseudo-first-order kinetic rate constant of 0.2005 min −1 . The high degradation efficiency of the catalyst was owing to the Fe 2 O 3 , FeS 2 induced charge separation and NBC-accelerated electron transfer, which together led to the production of • OH radicals. The combined effect of Fe 2 O 3 and FeS 2 , facilitated the charge separation with a band gap of 1.99 eV and a total surface area of 97.64 m 2 /g (electroactive surface area 1.957 cm 2 ), further providing a plentiful number of active sites for adsorption and photo-activation. Degradation followed pseudo-first-order kinetics, and the photocatalyst remained highly active even in the presence of co-existing ions; thus, it was confirmed to be suitable for real wastewater applications. Further, the catalyst is highly stable and magnetically recoverable, and reused for 5 cycles without significant loss in activity.