Visible light-responsive nanocomposite g-C3N4/CNC/PAM aerogel constructed through in-situ photoinitiation for management of wastewater containing organic/heavy metal compound contaminants

Facing the increasingly serious water pollution problem, photocatalytic method has been recognized as one of the best solutions due to its convenience, efficiency and low consumption. Graphitic carbon nitride (g-C3N4), a metal-free and visible light-responsive photocatalyst, has shown great potential in the photocatalytic treatment of water pollution. This study describes a novel bottom-up strategy for constructing visible light-responsive photoactive nanocomposite g-C3N4/CNC/PAM aerogel with the g-C3N4 uniformly loaded throughout a polymeric network, perfect mechanical property and high performance in treating wastewater containing organic/heavy metal compound contaminants. Aldehyde-modified negatively charged natural nanoparticle cellulose nanocrystal (CNC-CHO) was used to achieve uniform dispersion of g-C3N4, and also participate in the subsequent formation of aerogel through chemical crosslinking with photoinitiated polyacrylamide (PAM) catalyzed by g-C3N4 without additional crosslinkers. The optimized porous structure of the prepared aerogel ensured high swelling rate of up to 2500%, excellent pollutant adsorption performance and high light transmittance, thus achieved high removal rate and removal efficiency for different types of pollutants including organic dyes (RhB, MB and CR) and heavy metal Cr(VI). The removal efficiency could get 99% for RhB (5 mg/L) in 6 h, and 95% for Cr (VI) (10 mg/L) in 100 min under visible light. Further more, the aerogel showed excellent mechanical stability and reusability, with no loss in activity observed after over 5 cycles of dye degradation.