The Research On Adsorption Of Lead Ion From Aqueous Solution By Modified Sugarcane Bagasse

The emission of polluted water brings out serious ecological pollution with the growing of industry, and among the most urgent environmental problem including the discharge of wastewater containing heavy metal. At the moment, The commonly means used to govern heavy metal effluent including electrolysis、solvent extraction、ion exchange、 chemical precipitation、membrane separation、oxidation-reduction. However, Some disadvantages restrict the application of these commonly means, such as complicated operation, expensive cost and secondary effluent. The bio-adsorbent becomes the treatment focus of heavy metal effluent owing to its environmental-friendly and convenience. However, the adsorption efficiency and capacity of unmodified bio-adsorbents is low, and the study of modified adsorbents has been the research hot spot in recent years.This work describes the preparation of new materials derived from sugarcane bagasse for adsorption of Pb2+ ions from aqueous solution. In this thesis, two methods were applied for preparing the carboxyl-modified sugarcane bagasse, every methods required a two-step react. The first part consisted of smashing the sugarcane bagasse by grinder and sieving through a 185 μm sieve.In the first method, the prepared sugarcane bagasse were then reacted with epichlorohydrin and iminodiacetic acid in order to synthesize a low-cost adsorbent. And KH550 and Carboxymethyl chloride are modifiers for the second modified approach. These modified materials were evaluated by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetry analysis (TGA). The other part involved the characterization of the adsorption capacity of the modified sugarcane bagasse for Pb2+ ions from aqueous medium. Batch adsorption experiments were carried out in function of various pH values, contact times, temperatures and initial Pb2+ concentrations.(1) We can characterized the modified sugarcane bagasse with scanning electron microscopy、FTIR、XRD and thermogravimetry analysis. The results indicated the increasing of materials’ surface. The surface of modified sugarcane bagasse is occupied by carboxyl, hydroxyl groups. the degree of crystallinity and thermal stability has been improved.(2) The results showed that the suitable condition of adsorption is at 4<pH<6, and then maintained high level two hours later.(3) The favorable kinetics of adsorption was found to fit the pseudo-second-order kinetic model, it indicated that the adsorption rates were mainly controlled by the concentration of the active sites on the surface of modified sugarcane bagasse.(4) The equilibrium adsorption dates were fitted to Langmuir isotherms very well. It showed that the adsorption obeyed the formation of monolayer adsorption. Thermodynamic parameters showed that the adsorption of Pb2+ on modified sugarcane bagasse was a spontaneous endothermic process.