LAUSR

Abstract The present investigation deals with the biosorption of fluoride from aqueous solutions using calcium-doped Chlorella vulgaris, Chlorella protothecoides, and Nannochloropsis oculata. Effects of the factor variables (initial fluoride concentration, pH, biosorbent dose, and contact time) and their interactions on sorption of fluoride ion were investigated by response surface methodology based on central composite design. Maximum fluoride biosorption of 78.7% was obtained from calcium-doped C. vulgaris biomass. The fluoride biosorption followed pseudo-second-order kinetics. The fluoride sorption capacity was found to be 7.554, 7.549, and 7.827 mg/g for C. vulgaris, C. protothecoides, and N. oculata species, respectively. The biosorbent was characterised using scanning electron microscope with energy-dispersive spectroscopy and Fourier transform infrared. This study provides the efficiency of modified algal biomass for biosorption of fluoride. The positive results encourage extending the usage of the naturally abundant or waste algal biomass to remove other toxic heavy metals from the environment.