Valorization of Coconut Shell-Derived Photocatalyst for Ammoniacal Nitrogen Removal from Wastewater

Biomass waste can serve as a sustainable support material for photocatalysts in wastewater treatment, simultaneously addressing waste valorization and pollution remediation. In this study, coconut shell was converted into activated carbon (AC) and composited with titania (CSAC/TiO2) via a sol–gel method to remove ammoniacal nitrogen. The characterization using Scanning Electron Microscope (SEM) revealed that tiny TiO2 particles are attached at the external surface of the CSAC, whereas the Fourier-Transform Infra-Red (FTIR) analysis exhibited the formation of Ti–O–C bonds over the photocatalyst surface. It was found that the initial concentration of ammoniacal nitrogen pH of the wastewater and ultraviolet irradiation time are crucial to the photocatalytic activity. The maximum removal of 88% was obtained at 5 mg/L initial concentration, pH 10 and 30 min contact time. Furthermore, kinetic studies indicated the adsorption process is chemisorption, fitting the pseudo-second-order model at low concentrations and pseudo-first-order at high concentrations. The findings showed that coconut shell activated carbon doped with TiO2 can be utilized as a photocatalyst for ammoniacal nitrogen removal that demonstrates a viable alternative use of abundant coconut waste.