Short Communication Highly enhanced adsorption for decontamination of lead ions from battery wastewaters using chitosan functionalized with xanthate Divya Chauhan, Nalini Sankararamakrishnan * Facility for Ecological and Analytical Testing, 302 Southern Laboratories, India Institute of Technology, Kanpur, UP 208016, India article info Article history: Received 15 February 2008 Received in revised form 9 April 2008 Accepted 9 April 2008 Available online 19 May 2008 Keywords: Lead Decontamination Battery wastewater Chitosan abstract Decontamination of lead ions from aqueous media has been investigated using cross linked xanthated chitosan (CMC) as an adsorbent. Various physico-chemical parameters such as contact time, amount of adsorbent, concentration of adsorbate were optimized to simulate the best conditions which can be used to decontaminate lead from aqueous media using CMC as an adsorbent. The atomic absorption spectro- metric technique was used to determine the distribution of lead. Maximum adsorption was observed at both pH 4 and 5. The adsorption data followed both Freundlich and Langmuir isotherms. Langmuir iso- therm gave a saturated capacity of 322.6 ± 1.2 mg/g at pH 4. From the FTIR spectra analysis, it was con- cluded that xanthate and amino group participate in the adsorption process. The developed procedure was successfully applied for the removal of lead ions from real battery wastewater samples. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction Lead is suitable for batteries, because of its specific characteris- tics (conductivity, resistance to corrosion and the special reversible reaction between lead oxide and sulfuric acid). Due to its toxicity the US Environmental Protection Agency (EPA) has set the maxi- mum contaminant level (MCL) of lead ions in drinking water to be 0.015 mg/L (Primary Drinking Water Rules, 1992). Lead removal from acidic wastewaters is typically accomplished by neutraliza- tion and precipitation (Wallace and Singer, 1981; Patterson, 1985). However, this process suffers from the disadvantage of incomplete metal removal and generation of toxic sludge or other waste products that require safe disposal. Chitosan, a derivative from N-deacetylation of chitin-a naturally occurring and abundant biopolymer has been found to be capable of adsorbing various hea- vy metal ions, including copper, lead, mercury, cadmium, chro- mium, and so on; this is largely attributed to the presence of the amine groups of chitosan that have strong affinity to and can form complexes with various heavy metal ions (Guibal, 2004; Varma et al., 2004). In the past decade, the rapid development of chemical modification technologies used as popular methods to provide materials with improved or desirable properties for practical appli- cations has been observed (Uyama et al., 1998). Xanthation has been used previously on cellulose and sawdust (Bailey et al., 1999), brown marine algae (Kim et al., 1999) and chitin (Kim et al., 2006) to increase the adsorption the adsorption capacity. In this study, chemical modification of cross linked chitosan through introduction of xanthate was investigated in order to achieve highly enhanced adsorption performance for lead ions un- der acidic solution conditions. The choice of xanthate group is due to the presence of sulfur atoms and it is well known that sulfur groups has a very strong affinity for most heavy metals, the me- tal–sulfur complex is very stable in basic condition. A series of batch adsorption experiments were conducted in the laboratory to evaluate the adsorption and desorption performance of lead ions on the chemically modified chitosan and Fourier transform infra- red spectroscopy was used to elucidate the mechanisms of chem- ical modification and lead ion adsorption in the study. 2. Methods 2.1. Materials Chitosan flakes was acquired from India Sea Food, Cochin, India and used in the present study without any further purification. The degree of deacetylation was reported to be 85% by the manufac- turer. Glutaraldehyde and carbon disulfide were purchased from Sigma–Aldrich and used without further purification. Stock solu- tion of Pb(II) was prepared using Pb(NO 3 ) 2 (BDH chemicals). All the inorganic chemicals used were anular grade and all the re- agents were prepared in Millipore milli-Q deionised water. 2.2. Chemical modification of the chitosan (CMC) Chitosan flakes were cross linked with glutaraldehyde, chemically modified and characterized as described earlier 0960-8524/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.biortech.2008.04.024 * Corresponding author. Tel./fax: +91 512 2597844. E-mail address: nalini@iitk.ac.in (N. Sankararamakrishnan). Bioresource Technology 99 (2008) 9021–9024 Contents lists available at ScienceDirect Bioresource Technology journal homepage: www.elsevier.com/locate/biortech