Int. J. Environment and Pollution, Vol. 49, Nos. 3/4, 2012 179 Copyright © 2012 Inderscience Enterprises Ltd. Biosorption of heavy metals by utilising onion and garlic wastes Rahul Negi, Gouri Satpathy, Yogesh K. Tyagi and Rajinder K. Gupta* University School of Biotechnology, GGS Indraprastha University, Dwarka Sector-16, Delhi-110078, India E-mail: rahulnegi369@gmail.com E-mail: gourisatpathy@gmail.com E-mail: drtyagi@gmail.com E-mail: rkg67ap@yahoo.com *Corresponding author Abstract: Onion (Allium cepa L.) and garlic (Allium sativum L.) wastes from market and food canning processes were used for adsorption of Pb 2+ , Sn 2+ , Fe 2+ , Hg 2+ , As 3+ and Cd 2+ from multi-component systems at different adsorbent/metal ion ratios. The influence of pH, contact time, temperature and the concentration of adsorbent and adsorbate were studied to optimise the conditions to be utilised on a commercial scale for the decontamination of effluents in a batch adsorption technique. The study was carried out at 50°C and efficiencies were found to be pH dependent. The equilibrium time was 30 minutes and kinetic parameters were calculated using a second order model. The maximum q value was 10.47 ± 0.52 mg g –1 obtained for Pb 2+ at an adsorbent loading weight of 0.5 g/100 ml mixed ion solution. Desorption indicates maximum 71% recovery of metal ions, making the remediation process cost effective and reusable. The biomasses were used for removal of heavy metals from both synthetic and industrial effluents and the technique appears industrially applicable and viable. Keywords: heavy metal biosorption; onion wastes; OW; garlic wastes; GW; wastewater. Reference to this paper should be made as follows: Negi, R., Satpathy, G., Tyagi, Y.K. and Gupta, R.K. (2012) ‘Biosorption of heavy metals by utilising onion and garlic wastes’, Int. J. Environment and Pollution, Vol. 49, Nos. 3/4, pp.179–196. Biographical notes: Rahul Negi received his BTech in Biotechnology from University School of Biotechnology, GGS Indraprastha University, Kashmere Gate, Delhi-110043, India. His area of research is biotechnology and waste management. Gouri Satpathy is currently a PhD in Chemistry in the University School of Basic and Applied Sciences, GGS Indraprastha University, Kashmere Gate, Delhi-110043, India. His area of research is food and analytical chemistry and nutraceuticals. Yogesh K. Tyagi is an Assistant Professor in University School of Basic and Applied Sciences, GGS Indraprastha University, Kashmere Gate, Delhi-110043, India. His area of research is biochemistry.