Enhanced Photocatalytic Performance of g‐C3N4@MnFe2O4 Nanocomposite for Crystal Violet Dye Degradation under Solar Light

Abstract Crystal violet (CV) dye has been used in the textile industry, as printing ink, biological stain, and antimicrobial agent. CV dye persists in water for a long time and poses a serious threat to humans and aquatic life. In this study, g‐C 3 N 4 , MnFe 2 O 4 nanoparticles, and g‐C 3 N 4 @MnFe 2 O 4 (80 : 20 wt %) nanocomposite were synthesized via thermal decomposition and chemical co‐precipitation routes. The crystallite size was found 36.31 nm and 30 nm for bare MnFe 2 O 4 nanoparticle and g‐C 3 N 4 @MnFe 2 O 4 nanocomposite respectively. The optical band gaps of MnFe 2 O 4 , g‐C 3 N 4 , and g‐C 3 N 4 @MnFe 2 O 4 were 1.8 eV, 2.7 eV, and 2.4 eV, respectively. The photoluminescence intensity decreases in the following order: g‐C 3 N 4 >g‐C 3 N 4 @MnFe 2 O 4 nanocomposite>MnFe 2 O 4 . The degradation efficiency of MnFe 2 O 4 , g‐C 3 N 4 , and g‐C 3 N 4 @MnFe 2 O 4 nanocomposite was found to be 25.13 %, 58.11 %, and 98.42 % respectively, and followed first‐order kinetics. The value of the rate constant for g‐C 3 N 4 @MnFe 2 O 4 was 0.022 min −1 which was around ten times higher than g‐C 3 N 4 and MnFe 2 O 4 . By adding three scavengers, the degradation capacity of nanocomposite was decreased in the order AA (L‐ascorbic acid)>EDTA (ethylenediaminetetraacetic acid)>TBA (t‐butyl alcohol). A slight reduction in degradation efficiency was observed after five consecutive cycles. Thus, this new finding can be applied to the degradation of CV dye‐contaminated industrial wastewater under solar light.