Study On Preparation And Properties Of Chitosan/Sodium Alginate Adsorbent

With the pollution caused by industrialization and urbanization becoming more and more severe, heavy metal pollution has been a global problem. Therefore, dealing with heavy metal pollution has become an important facet of protecting environment for every country. Furthermore, Adsorption heavy metal will solve the environmental problems, which has been a critical aspect of protecting environment.Chitosan has been widely used in many fields for its good environmental compatibility, renewability, abundant resources and low cost. A series of chelate resins were prepared by chitosan's chemical modification, and the resins have been testified that they can selectively adsorb many kinds of heavy metals. Sodium alginate also has been widely used in many fields for its low toxicity, good environmental compatibility, thickening, excellent ball-forming, gel performances and degradation. Its internal porous structure makes it as a good absorbent material.Chitosan/Sodium alginate gel particle (CS/SA) was prepared via electrostatic interaction between chitosan and sodium alginate, and characterized by Fourier Transform Infrared Spectroscopy (FTIR) and X-Ray Diffraction (XRD). The results show that CS/SA present amorphous state. The physical properties indicated that the CS/SA have porosity and good hydroscopic property. The absorbability of Cu(Ⅱ) and Cr(Ⅵ) on CS/SA was also investigated. The absorbabilities increased with increasing of concentration of Cu(Ⅱ) and Cr(Ⅵ),and both the two adsorption isotherms were the optimal adsorption isotherm. The adsorption of Cu(Ⅱ) was followed the pseudo-first-order dynamics and the best technical condition was adsorbent dosage is 0.10 g, adsorption time is 90 min, and pH value is range fron 5.0 to 6.0, then qe is 39.96 mg·g^-1. The adsorption of Cr(Ⅵ)was followed the pseudo-second-order dynamics and the best technical condition was CS/SA dosage is 0.10 g, adsorption time is 150 min, and pH value is range fron 5.0 to 6.0, then qe is 18.46 mg·g^-1.A new absorbent (CCS/SA) was prepared using chitosan and sodium alginate as raw material and epichlorohydrin as cross-linking agent. The influences of weight ratio of CSS and SA, amount of epichlorohydrin, reaction temperature and time on the degree of crosslinking was emphatically discussed. CCS/SA was characterized by FTIR to observe changes in chemical structure, and it showed that the synthetic route should be as expected. The optimum conditions of the crosslinking reaction were weight ratio of CSS and SA is 2:1, amount of epichlorohydrin is 10 mL, reaction temperature is 55℃, time is 16 hr and the degree of crosslinking is 77.68%. The surface of CCS/SA has been observed with Scanning Electron Microscope (SEM), and large amounts of pore structure have been found. This can enhance the adsorption capacity.The influence of adsorption time, PH value, the initial concentration of Cu(Ⅱ) and CSS/SA dosage on absorbability of Cu(Ⅱ) has been studied. It showed that the best technical condition was adsorbent dosage is 0.10 g, adsorption time is 120 min, pH value is range fron 4.0 to 6.0 and qe=46.36 mg·g^-1. The adsorption isotherm was the optimal adsorption isotherm and the adsorption kinetic followed the pseudo-second-order dynamics.