Removal of Fluoride Ion by Silicon Nitride Powder

Adsorption of fluoride was done from its aqueous solution by using silicon nitride. In this study, silicon nitrides, SNA, SNB, SNC and SND were synthesized by hydrothermal process done at temperature of 100°C, 150°C, 200°C and 300°C using Rice husk ash (RHA) and sugarcane bagasse ash (SBA) respectively. A batch study on fluoride sorption was carried out at various experimental conditions, including different pH, initial fluoride concentration, and adsorbent dose, shaking speed, contact time and temperatures. Optimum adsorption efficiencies were achieved at pH 2 for SNA, SNB, SNC and pH 4 for SND, contact time 100 minutes, temperature 25°C and shaking speed 600 rpm. The sorption data was found to best into Langmuir isotherm. The adsorption capacities for fluoride ions were 7.9, 8.9, 13.9 and 49.8 mg/g for SNA, SNB, SNC and SND respectively. This results indicate that the silicon nitride constitute a promising material for the development of an adsorption technology for the removal of fluoride ions from aqueous systems.