Abstract

One of the major applications of chitosan and its many derivatives is based on its ability to bind strongly heavy and toxic metal ions. Chitosan is made from chitin by a chemical process involving demineralization(DM),deproteinization (DP), decolorization (DC), and deacetylation (DA). In this research natural bio polymer “chitosan” was synthesized using fish shells and adsorption of cadmium by chitosan was studied. Chitosan was characterized using Fourier Transform Infrared Spectroscopy (FTIR) and solubility in 1% acetic acid. The affinity of chitosan for cadmium was studied using CdCl2 solution as the heavy metal solution containing Cd (II) ions. The Infra red spectroscopic study on the chitosan and the metal-chitosan complexes reveal a metal coordination based on the observed characteristic band changes. At initial cadmium concentrations of 3, 5, 8 mg/L, the adsorbed cadmium ion concentrations are 2.5, 4.2 and 7.4 mg/L, respectively.
Key words; chitosan. Chitin, aqueous solution, adsorption, deacytelation,

1.INTRODUCTION

Chitosan is a natural carbohydrate biopolymer derived by deacetylation (DA) of chitin, a major component of the shells of crustacean such as crab, shrimp, and crawfish. After cellulose, chitin is the second most abundant natural biopolymer found in nature (No and Meyers, 1989).

CHITIN CHITOSAN


Figure 1. Structure of Chitin and Chitosan (Stephenie Akkalut 2008).Due to increase in the world population and development of industrial applications, environmental pollution problem became important. Communities produce both liquid and solid wastes. The liquid waste-wastewater- is essentially the water supply of the community after it has been used in a variety of applications. In recent years, heavy metal concentrations, besides other pollutants, have increased to reach dangerous levels for living environment in many regions.

The presence of toxic and polluting heavy metals in wastewaters from industrial effluents, water supplies and mine waters and their removal has received much attention in recent years. The amount of heavy metals that industrial wastewaters often contain is considerable and would endanger public health and the environment if discharged without adequate treatment. Cadmium does not exist in nature as the native metal but principally as the sulphide ore greenockite (CdS), which is strongly associated with zinc sulphide ore sphalerite. Cadmium enters the environment in the waste waters of industries using cadmium, but also in discharge from the iron and steel industry (Bamgbose J. T). Various soluble forms of cadmium exist in water. It exist mainly as Cd2+, but also as [CdCO+ (aq)]0, [CdCl]+, [Cd(OH)]+ and [CdSO4(aq)]. Free Cd2+ ion occurs at pH levels below 8. At higher pH values, [Cd(OH)]+ is formed and in very alkaline solutions [Cd(OH)3]- and [Cd(OH)4]2- are formed (Dojlido and Best 1993, Serkan Keleulo). The aim of this study is the characterization of chitin biopolymer, preparation and characterization of chitosan biopolymer from chitin biopolymer in controlled experimental condition to use these biopolymers as adsorbent materials and investigate the uptake performance for heavy metal ions (Cd2+).