Removal of Heavy Metals by Natural Polymer: Pectin, under Laboratory Conditions
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Removal of Heavy Metals by Natural Polymer: Pectin, under Laboratory Conditions Arévalo-Niño. K.*, Salazar-González H.I., Rojas-Verde. G., Flores-González M.S., Solís- Rojas C. Instituto de Biotecnología, Facultad de Ciencias Biológicas, UANL, Pedro de Alba y Manuel L. Barragán S/N, Cd. Universitaria, San Nicolás de los Garza, N.L. C.P. 66450. México.Fax (81) 83-29-41-00 ext. 7302. * Corresponding author: [email protected] ABSTRACT Major adsorbent materials used in heavy metal ion removal from polluted aqueous streams are expensive and difficult to regenerate. In this study, the possibility of using pectin, as an alternative biosorbent material to remediate heavy metal pollution was investigated. The effects of different parameters such as pH, concentration and temperature of metal solution, and contact time on the biosorption process were studied. The maximum removal efficiency was obtained at pH 2.0 for lead and zinc and pH 4.0 for cadmium. For most of the metals tested, a contact time of 15 minutes was sufficient for achieving the maximum removal. There was no significant influence on the removal capacity of pectin by the concentration and temperature of the metal solution. Under these experimental conditions the biosorption was favorable (65% lead, 42% zinc and 55% cadmium). The ability to use pectin for the removal or recovery of metals from aqueous solutions is evident. Key words: adsorption, Pb, Zn INTRODUCTION Globally, the amount of available freshwater is unevenly distributed due to problems associated with climate change, inefficient water management and pollution. Heavy metals, in particular, are a group of pollutants of concern in the environment due to its toxicity primarily by domestic, agricultural and industrial activities. Metals can be distinguished from other toxic pollutants, since they are not biodegradable and can accumulate in living tissues, biomagnifying through the food chain [1]. The main techniques used to reduce the content of heavy metal ions from effluents include lime precipitation, ion exchange, activated carbon adsorption, membrane processing and electrolyte methods. These methods have been limited, as they often involve high operational costs and may be associated with the generation of secondary wastes which present treatment problems, such as the large amount of sludge generated by the processes of precipitation [2].The need to find alternative effective and low cost methods for reducing heavy metals from water in inevitable and biosorption is an emerging field in this direction and has great potential for application in developing economies. Biosorption is a property of certain types of molecules to bind and concentrate heavy metals from even very dilute aqueous solutions [3].The biopolymers have this property, acting as a chemical such as an ion exchanger of biological origin [4].
Pectin, a natural polymer, is one of the most important sources of dietary fiber. It is present in vegetables and fruits as a component of the plant cell wall. Pectin consists mainly of long l
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