Photocatalytic performance of B-gC3N4/BiOCl nanocomposite in Rhodamine B degradation for water treatment: Synthesis, characterization, and optimization

Graphitic carbon nitride (gC 3 N 4 ) is a promising photocatalyst for degrading organic pollutants, but its efficiency is limited by the fast recombination of photogenerated electron-hole pairs. In this study, we report the synthesis of boron-doped graphitic carbon nitride (B-gC 3 N 4 ) coupled with BiOCl to form B-gC 3 N 4 /BiOCl (60 %) nanocomposites as efficient visible-light-driven photocatalysts for RhB degradation. The nanocomposites were prepared via a facile method and characterized by XRD, FE-SEM, EDX, TGA, PL, BET, and DRS analyses. The optimized B-gC 3 N 4 /BiOCl (60 %) exhibited significantly enhanced photocatalytic activity, achieving 91 % RhB removal under visible light irradiation within 30 min, approximately 6.5 times higher than pristine gC 3 N 4 (14 % removal). This improvement is attributed to efficient charge separation at the B-gC 3 N 4 /BiOCl (60 %) heterojunction and increased dye adsorption and light absorption due to boron doping. Trapping experiments confirmed that • O₂ − and h + were the main active species in RhB degradation. A central composite design (CCD) and response surface methodology (RSM) optimized key parameters (photocatalyst amount, pH, irradiation time, and RhB concentration), with the quadratic model fitting well. Under optimal conditions (pH = 3, 40 mg photocatalyst, 14 ppm RhB, 45 min irradiation), 99.27 % RhB removal was achieved. The photocatalyst also showed stable performance over five consecutive cycles. These results highlight B-gC 3 N 4 /BiOCl (60 %) as a promising visible-light photocatalyst for efficient dye degradation. • B-gC₃N₄/BiOCl nanocomposites were synthesized via a facile method for RhB degradation. • The B-gC₃N₄/BiOCl (60 %) showed the highest activity for RhB removal. • Optimized composite removed 91 % RhB in 30 min, 6.5× higher than g-C 3 N 4 . • Heterojunction and boron doping improved charge separation and light absorption. • CCD and RSM identified optimal conditions for 99.27 % RhB removal.