www.scholarsresearchlibrary.com t Available online a Scholars Research Library Archives of Applied Science Research, 2015, 7 (6):74-80 (http://scholarsresearchlibrary.com/archive.html) ISSN 0975-508X CODEN (USA) AASRC9 74 Scholars Research Library Equilibrium sorption isotherm for Cu(II) on Adenanthera pavonina seeds Bahnika Sen 1* , H. P. Sarma 1 and K. G. Bhattacharyya 2 1 Department of Environmental Science, Gauhati University, Guwahati, Assam, India 2 Department of Chemistry, Gauhati University, Guwahati, Assam, India _____________________________________________________________________________________________ ABSTRACT The powdered seeds of Adenanthera pavonina have been used to investigate the sorption of Cu(II) from aqueous solution. The process variable included the change of initial metal ion concentration from 10mg/L-70mg/L. it is noted that there is a decrease in percentage removal of Cu(II) with the increase in initial concentration of Cu(II). The Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models have been obtained from the experimental data. The Langmuir isotherm model is found to be the best fit for the current study with a maximum adsorption capacity of 10.71mg/g. The Dubinin-Radushkevich isotherm model suggests physical adsorption process. Keywords: Copper, Langmuir, Freundlich, Temkin, Dubinin-Radushkevich _____________________________________________________________________________________________ INTRODUCTION The contamination of the environment due to metallic compounds released from various industrial operations is a worldwide phenomenon. The use of pesticides, fertilizers, sludge, discharge from metalliferous mines and metallurgical operations, automobile exhausts and emissions from incinerators have lead to the release of heavy metals into the environment [1]. The runoff from the lands contaminated with toxic heavy metal residues has lead to the contamination of water bodies [2]. The transition and the inner transitional metals of the periodic table are mostly carcinogenic and this carcinogenicity can be associated to the electronic structure of the metals [3]. Copper is an important element that helps in various physiological operations and hence is biologically significant. It is an important constituent in many critical enzymes across all life forms. Copper helps in the production of haemoglobin, myelin, melanin, and plays an important role in the proper functioning of the thyroid gland. Apart from these, copper also helps in metabolism of the living bodies [4]. Copper is also an essential micronutrient in plants and acts as the electron donor in photosynthesis [5]. However, both deficiency and excess of copper can lead to several disorders in the physiological functions of the living organisms. Accumulation of excess copper takes place in the liver and Cu + is considered to be the most toxic form of copper. Studies have found that the incidence of cancer among coppersmiths is higher which suggests the carcinogenic character of copper [6]. In plants, excess of copper accumulates in the plant bodies and retards growth of plants and causes leaf chlorosis [7]. Several techniques of metal sequestration have been developed of which biosorption is the most effective and economical process for removal of toxic heavy metals from waste water [8]. A number of novel materials of biological origin have been explored which prove to effective and low cost alternatives for removal of heavy metals