Bioremediation: Removal of fluoride and methylene blue from water using eco-friendly bio-adsorbents

Abstract

Fluoride has either detrimental or beneficial effects based on the concentrations, whereas methylene blue (MB) is a harmful cationic dye found in industrial effluents. Recently, distinct interests have been developed in removing water pollutants using bio adsorbents than synthetic adsorbents. This work reveals the removal of fluoride and MB from water using Moringa Pterygosperma (MP), Phyllanthus Emblica (PE), and Strychnos Potatorum (SP) as adsorbents by the batch adsorption process. The respective maximum fluoride adsorption capacity of MP, PE, and SP was 23 mg/g, 24 mg/g, and 31 mg/g, at 30 min (pH 9). Similarly, maximum MB adsorption capacity of MP, PE, and SP is 2 mg/g, 3 mg/g, and 1 mg/g, respectively. The adsorption of fluoride and MB depends strongly on the surface charges and adsorbent colloidally stability. The fluoride and MB adsorption are monolayer and by chemisorption as confirmed by the Langmuir and pseudo-second-order kinetics, respectively. Moreover the final pH of the MP and SP adsorbent treated solutions, after the adsorption of fluoride and MB was found to be 7 ± 0.5. The presence of other competing ions did not have any influence on the MB adsorption. Furthermore, MP, PE, and SP could be considered as the best adsorbents for water purification owing to their efficiency, cost effectiveness and abundant availability.