REMEDIATION OF HOME-TREATED WATER BY REMOVAL OF RESIDUAL ALUMINIUM AND PHENOLIC COMPOUNDS USING GREEN SYNTHESIZED MAGHEMITE (γFe2O3) NANO PARTICLES

Abstract

Water is an essential natural resource for support of life. To make water safe for human consumption, water needs to be treated. However, small-scale consumers, use home water treatment coagulants obtained from commercial shops. Example of coagulants include 'Rock Alum’ available in Kenyan retail shops. The use of aluminium based coagulants leaves residual aluminium in water. Aluminium exposure through contaminated water results in neurological disorders. Phenolic compounds occur naturally in water mainly from plants and environment. Their presence in drinking water causes muscles weakness and respiratory disorders. This study explored the preparation of maghemite (γFe2O3) nanoparticle by a green method using pineapple (Ananas comosus) peels extract and their application in remediation of treated water by removal of residual aluminium ions and phenolic compounds. The nanoparticles were characterized using X-Ray Diffraction (XRD), Ultra-Violet visible light Spectrometer (UV-Vis) and Fourier Transform Infra-Red spectrometer (FTIR). The maghemite nanoparticles (0.5 g) were used in batch adsorption of residual aluminium ions and phenolic compounds from water samples at varying pH, contact time and temperature. The de-ionized water samples treated with ‘Rock Alum’ coagulants gave residual aluminium ions at concentration of 1.9 ppm when 0.0125 g of coagulant (Rock Alum) was used. This concentration of aluminium ions was higher than permissible limits by the World Health Organization of 0.1 ppm. On characterization of maghemite (γFe2O3) nanoparticles using XRD, FTIR and UV-Vis, it was found that at high calcinating temperature of 400-450 0C gave nanoparticles with improved crystallinity and enhanced ordering of the maghemite structure. The percentage adsorption of aluminium ions was determined using Atomic Absorption Spectrometer (AAS) and UV-Vis for phenolic compounds. It was found that adsorption decreases with increase in pH for aluminium ions. Temperature had little effect on adsorption, while rate of adsorption increased with increase in contact time. Adsorption of aluminium was multilayer and fitted to Freundlich adsorption isotherm. Maghemite was found to be efficient in adsorption of phenolic compounds (Phenol and resorcinol) from spiked de-ionized water samples. Phenol was best adsorbed at pH of 5 and 7 for resorcinol. Rate of adsorption decreased slightly in both phenol (3.6%) and resorcinol (15.2%) with increase in adsorption temperature. At optimum adsorption conditions pH, temperature and contact time, mean adsorption of aluminium, phenol and resorcinol was 75.63, 72.61 and 80.09% respectively. This study recommends use of alternative water coagulants which are not aluminium-based.