Adsorption of fluoride in aqueous solutions using saline water algae (Rhodophyta sp.): an insight into isotherm, kinetics, thermodynamics and optimization studies

Abstract

Present study focused on the effective utilization of red algae (Rhodophyta sp.) towards removal of fluoride from contaminated medium by varying the operating variables (pH, adsorbent dose, initial concentration, contact time and temperature) and screen out the best condition for removal of fluoride through response surface optimization technique. The algal biomass was characterized by various analytical instruments, such as scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectrometry and point of zero charge (pHZPC). Results revealed that the equilibrium data nicely fitted with Langmuir model with biosorption capacity 5.484 mg g−1. The optimized values was screed from response surface methodology as initial concentration, temperature, dose and contact time are 9.77 mg L−1, 302.63 K, 10.8 g L−1, and 23.17 min, respectively. Finally, optimized condition was applied for removal of fluoride from fluoride contaminated villages of Birbhum district and average 80% fluoride was removed. The exhausted adsorbent was regenerated (95%) using 0.1 N NaOH solution. Therefore, present finding suggest that the red algae (Rhodophyta sp.) could be an excellent biosource for decontamination of fluoride from underground water.