Defluoridation of water with a coagulant, Strychnos potatorum L. seed –agglutinin

Abstract The aim of the present study is to assess the suitability of Strychnos potatorum L. seed protein for defluoridation of potable water. Protein was isolated from Strychnos potatorum L. seed by using Ammonium sulphate precipitation method and coagulation activity was confirmed. Later the extracted protein was used for defluoridation studies of aqueous fluoride solution and real potable water. The effect of three parameters including pH, time and coagulant dosage of protein on the fluoride removal were studied in fluoride aqueous solution. About 52 potable water samples in and around Kodaikanal were collected from tribal and non-tribal areas and water quality was assessed. The exceeding amount of fluoride among 5 water samples was found when compared with BIS standard for drinking water and subjected to defluoridation process with coagulant protein. Strychnos potatorum L. seed coagulant protein removed about 75% of fluoride from aqueous fluoride solution (2 ppm) by 2 hr treatment time, at 6.6 pH with 0.1 g of coagulant dose, treatment. Potable water defluoridation also showed 75% of fluoride reduction with 0.1 g of coagulant dose treatment. Seed characterization was performed using GC-MS and FT-IR, also proteomic studies carried out using MALDI-TOF. The seed coagulant protein showed, horcolin, a lectin type agglutinin protein (15.1 kDa) with 146 amino acid residues. This study suggests, the horcolin agglutinin protein in seeds is capable to remove fluoride effectively from drinking water samples due to the presence of its metal binding sites.