African Journal of Pure and Applied Chemistry Vol. 6(12), pp. 161-173, 13 October, 2012 Available online at http://www.academicjournals.org/AJPAC DOI: 10.5897/AJPAC11.071 ISSN 1996 - 0840 ©2012 Academic Journals Full Length Research Paper Adsorption of o-nitrophenol onto nano iron oxide and alginate microspheres: Batch and column studies Anjali Soni 1 , Alka Tiwari 1 * and A. K. Bajpai 2 1 Department of Chemistry, Government V.Y.T.PG., Autonomous College Durg (C.G.), 491001, India. 2 Bose Memorial Research Laboratory, Department of Chemistry, Government Autonomous Science College, Jabalpur (M.P.), 482001, India. Accepted 6 January, 2012 In the present study, the adsorption behavior of o-nitrophenol from aqueous medium, using nano iron oxide loaded calcium alginate beads were studied using equilibrium batch and column flow techniques. The effect of pH, adsorbent dose, contact time and temperature on adsorption capacity of the magnetic beads was investigated. The optimum pH value was defined to be 2 at temperature 30°C. The equilibrium data were fitted to Langmuir and Freundlich isotherm models. Batch adsorption data was better described by Freundlich isotherm model than Langmuir model. In column experiments the effect of the initial concentration, bed height and flow rate on o- nitrophenol adsorption were studied. The bed depth service time (BDST) model was used to analyze the experimental data. The sorption capacity per unit bed volume (N 0 ) and rate constant (Ka) were calculated to be 578.4 mg/L and 1.18 L/mg/min, respectively. The characterization of the prepared magnetic beads has been accomplished by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD) measurements. Key words: Adsorption isotherm, magnetic beads, o- nitrophenol. INTRODUCTION Industrial development is associated with the disposal of a large number of toxic pollutants that are difficult to degrade by natural means. Many industries discharge wastewater containing hazardous substances such as phenols, dyes and heavy metals. It is well known that the contamination of water from the industries provides many problems to human health. In our world, organic pollutants are still a problem for the environment and drinking water. A typical group of organic chemicals that are considered as both unwanted by-products as well as raw material in several industries is the phenol. Phenol *Corresponding author. E-mail: alkatiwari18@yahoo.co.in, alkatiwari18@gmail.com. Tel: 07415514000. Fax: 0788- 2324783. and its corresponding substituted compounds are important environmental pollutants because of their toxic effects towards life in the aquatic environment. There are many methods such as oxidation, ion exchange, electrochemical oxidation, reverse osmosis (Goncharuk et al., 2002) and photo-catalytic degradation, which have been used for the removal of phenol and its derivatives. Adsorption is a well established and powerful technique for the removal of organic pollutants from wastewater. Adsorption has been found to be superior choice than other techniques for water re-use because of low initial cost, simplicity of design, ease of operation and insensitivity to toxic substances (Juny et al., 2001). Nitrophenol compounds are common toxic, industrial and persistent pollutants. It is desirable to reduce their concentrations to less than 20 ppb. They are contained in