A Study On The Adsorption Property Of Methyl Orange And Congo Red By Chitosan Immobilized On Quartz Sand And CTAB Motified Wheat Staw

Based on the related literatures and synthetizing references, the adsorbents(CIS and MWS) were made with the method of chemical and physical treatment in this research. The characterization of sand, CIS, wheat staw and MWS was analyzed by FTIR, element analysis, XRD and XRF and the adsorption properties for MO and CR onto CIS and MWS were performed, resectively. The results indicated that chitosan had been immobilized on quartz sand and Hexadecyl trimethyl ammonium Bromide had get into the structure of wheat staw.The adsorption process for CIS-MO, CIS-CR, MWS-MO and MWS-CR was operated in two ways:batch and column mode. The effect of various experimental conditions, such as adsorbent dosage, pH, coexisting ions, contact time, initial concentration of the adsorbate and temperature were studied in batch adsorption. Then the competitive adsorption between MO and CR,. desorption and reuse for the modified adsorbent were also studied. The results are following:When the pH value was 4, it would get better removal efficiency for CIS-MO and CIS-CR, while the pH values of 3 and 5 were favorable for MWS-MO and MWS-CR, respectively. The high temperture is disadvantage of the adsorption capacity for the four systems. The equilibrium time of the four systerm was 720min,180min,520min and 480min, and the adsorption capacity for CIS-MO, CIS-CR, MWS-MO, MWS-CR was 25.4 mg·g-1, 22.2 mg·g-1,48.6 mg·g-1 and 72.2 mg·g-1 at 295 K, respectively. The presence of Na+ and Ca2+ had different influence on the four adsorption behavior. In the binary dye system, MO and CR were simultaneously adsorbed, and there was competitive adsorption. In addition, the best desorption method for CIS-MO and MWS-MO was hot water, and CIS-CR and MWS-CR can be regenerated by hot NaOH solution(0.01 mol·L-1,60℃). The study of the desorption and reuse experiment indicated that CIS and MWS had good futures because of the properties of faster adsorption and desorption, reuse and easy regenerating methods. In the study of fixed-bed column, adsorption of the four systerms was strongly depended on bed height, flow rate, initial concentration of adsorbate, pH and the concentration of salt.The adsorption of the four systems was spontaneous and exothermic according to the thermodynamic parameters, and there was no abvious change of the chemical structure of moleculars. The equilibrium data for CIS-MO and CIS-CR was fitted well to the Langmuir(nonlinear) and Freundlich(linear) isotherm models and the Freundlich(linear) and Temkin model fitted the adsorption of MO and CR well for MWS. Pseudo-first-order kintic model, pseudo-second-order kintic model, Elovich-type equation and intraparticle diffusion models were used to fit the experiment data. The Elovich-type equation was the best choice to describe the adsorption behavior of CIS-MO,MWS-MO and MWS-CR, and the pseudo-second-order model fitted CIS-CR very well. The Thomas and Yan models were the best choices to describe the adsorption behavior of the four systerms.