Solar light-driven photocatalysis using BaFe₂O₄/rGO for chlorhexidine digluconate-contaminated water: comparison with...

Synthesis and characterization of dual functioning material is an effective approach for the promotion of organic pollutant degradation through adsorption as well as photocatalysis. Herein, graphene oxide was modified by the addition of barium nitrate and iron to construct a smooth sheet-like structure (BaFe₂O₄/rGO) for the removal of chlorhexidine digluconate (CHD). Compared with GO (75.69%-UV light; 88.17%-visible light), BaFe₂O₄/rGO showed significant adsorption-photocatalysis effect under visible light (93.95%) than that under UV light (78.17%). The introduction of barium nitrate and iron into graphene oxide leads to a smooth porous structure with increased surface area (93.66 m² g^-1), which resulted in a large number of adsorption active sites and great photocatalytic activity with efficient charge separation. Although catalysts did not mineralize CHD completely, but the parent compound mineralized to some extent, which was confirmed by the TOC measurement and UV₂₅₄ absorbance variation. In addition, toxicity of degraded products was analysed by bacterial susceptibility test on Bacillus cereus DPAML065, suggesting that nontoxic by-products of CHD were formed, which leads to their safe disposal. Based on the identified transformed products, the possible degradation pathway was proposed. Batch studies demonstrated that BaFe₂O₄/rGO is highly photoactive based on reaction rate constant (R² = 0.984), where the kinetics data were well-fitted using the pseudo-first order. Moreover, efficiency of catalysts was examined under solar light to achieve the sustainability.