Adsorbent ( silica molybdate) for removal of phosphates from water

Abstract

Pollution by phosphates affect aquatic life as they have side effects even at very low concentrations. Silica molybdate is prepared by first chlorinating silica sand using phosphorous pentachloride to give chlorinated silica which is aminated using ethylenediamine and thereafter treated with sodium molybdate. The molecular structure of the silica molybdate was characterized using Fourier Transform Infrared (FT-IR). FT-IR results showed Adsorption bands at 854cm-l and 542cm-l which were attributed to Mo=O and Mo-O stretching in molybdate. Peaks observed at 1388 and 1662cm-1 were attributed with the vibration mode of Mo-OH bond and bending mode of adsorbed water. Spectra peaks observed at 542, 634.58 and 898.97 cm-1 were attributed to the adsorption of molybdate. The physical adsorption parameters which were examined using batch adsorption system were; temperature, pH, contact, time, initial concentration using sorption models, adsorption kinetics and thermodynamics. Results showed that optimum pH for biosorption of P042- was 6.0, optimal contact time was 30 minutes, optimum temperature was 45°C. The experimental results obtained showed that the maximum phosphate adsorption of silica molybdate at optimum conditions was found to be 94.73% in water.