Cadmium biosorption potential of shell dust of the fresh water invasive snail Physa acuta Asif Hossain, Gautam Aditya * Ecology Laboratory, Department of Zoology, The University of Burdwan, Golapbag, Burdwan 713104, India Introduction Aquatic pollution owing to heavy metals is a major concern for ecosystem functioning and biodiversity. The cascading effect of metal loads at various trophic levels causes decline in species richness of aquatic community, thereby interfere with ecosystem functions. Empirical evidences suggest that the metals like cadmium, chromium, copper, zinc, mercury, lead and alike, enters into the freshwater ecosystems through various modes as a by- product of several industrial wastes. Considering cadmium as a heavy metal, the identified sources of its entry in freshwater ecosystems are metal refineries, battery industries, corrosion of galvanized pipes, paint industry, mining and natural deposits. Cadmium is a common heavy metal polluting the natural water bodies and ultimately causing severe damage to the human being and wild life. Entry of cadmium in the human body can damage liver and kidney, substitute calcium in bones, cause hypertension, initiate cancerous growth, while its accumulation in food chains may decline wildlife and species diversity [1,2]. Heavy metals as pollutants accumulate in the living system or stay in the environment. Removal of heavy metals from the environment is a sustainable alternative to reduce its ill-effects. Although heavy metal removal methods based on the principle of ion exchange, chemical precipitation and coagulation are well established, electrochemical basis and membrane technology alone or in combination, have evolved in the recent past [3,4]. The risks of generating secondary pollutants, associated with many of the metal removal methods are of great concern. As a consequence, use of biological materials for metal removal has been promoted to minimize the cost with increased efficacy [5]. Application of biological materials that are component of the natural system reduces the possibilities of yielding unwanted chemicals without inferring with the equilibrium state of the ecosystem functions. This is substantiated through the observations on the metal adsorption ability of different microorganisms [6], mushrooms [7] and hydrophytes [8] many of which are hyper accumulators of metals. Application of aquatic animals in metal adsorption [5] is also empirically tested as evident from the studies on living freshwater bivalve [9], bivalve shell [4,10] and the crab and acra shell biomass [11]. Uncontrolled application of living specimens like hydrophytes [8] and their derivatives for removal of heavy metals may facilitate biological invasion or secondary pollution thereby hindering the ecosystem functions. In many instances the use of the live specimens like mushroom [7] and the freshwater mussels Lamellidens marginalis [9] in metal removal may be constrained due to their food value and other economic values. While ability of metal removal may be high in biological species, their potential as aquaculture resources limits their application in metal bioremedi- ation. Earlier studies demonstrate that unlike other approaches, calcium carbonate derivatives may be a potential cost-effective biosorbent for removal of heavy metals [3,10]. Shells of the freshwater snails can be considered as a cheap source of calcium Journal of Environmental Chemical Engineering xxx (2013) xxx–xxx A R T I C L E I N F O Article history: Received 25 February 2013 Accepted 26 June 2013 Keywords: Biosorption Cadmium Physa shell dust (PSD) Isotherm Kinetic A B S T R A C T The ability of shell dust (PSD) of an invasive freshwater snail (Physa acuta) to remove cadmium from contaminated water was evaluated. The results indicate that PSD, a waste biomaterial, bear potential of cadmium removal from contaminated water with biosorption capacity of 16.66 mg g 1 at pH 6. The adsorption data at equilibrium fitted significantly more to Langmuir (R 2 = 0.996) than Freundlich equations (R 2 = 0.969). The kinetics of the adsorption process followed the pseudo-second order model (R 2 = 0.996) better than the Lagergren model (R 2 = 0.833). The FT-IR analyses support that the main mechanism of biosorption was cadmium chelating with different functional groups such as –OH, –C 55 O, –C 55 C, and –C–C. The result obtained from the experiments show that the PSD can be used as an efficient, low cost, environmentally friendly biosorbent for cadmium from aqueous solution. ß 2013 Elsevier Ltd All rights reserved. * Corresponding author. Tel.: +91 342 2656566; fax: +91 342 253045. E-mail addresses: asifhossain.bu@gmail.com (A. Hossain), gautamaditya2001@gmail.com, gautamaditya2001@yahoo.com (G. Aditya). G Model JECE-80; No. of Pages 7 Please cite this article in press as: A. Hossain, G. Aditya, Cadmium biosorption potential of shell dust of the fresh water invasive snail Physa acuta, J. Environ. Chem. Eng. (2013), http://dx.doi.org/10.1016/j.jece.2013.06.030 Contents lists available at SciVerse ScienceDirect Journal of Environmental Chemical Engineering jou r n al h o mep ag e: w ww .elsevier .co m /loc ate/jec e 2213-3437/$ – see front matter ß 2013 Elsevier Ltd All rights reserved. http://dx.doi.org/10.1016/j.jece.2013.06.030