| A series of activated carbon was prepared with nutshell as raw materials and ZnCl2and H2SO4as activating agent, using microwave radiation method. The effect of process variables, such as the time of impregnating, the ratio of activating agent to nutshell, microwave power and time on the yield were performed. The optimum conditions for preparing activated carbon by microwave were obtained:soaking for24h, microwave power was640W, microwave radiation time was5min and the ratio of activating agent to nutshell was3:1. The yield of the activated carbon was34.7%while the methlene blue adsorption reached155mg·g-1The characterization of the activated carbon prepared from nutshell(NSAC) and nutshell(NS) were analyzed by FTIR, XRD, XRF, elemental analysis, differential thermal analysis, specific surface area analysis, SEM, determination of surface functional groups.The adsorption process for malachite green(MG) and p-Chlorophenol(p-CP) by NSAC was operated in two ways of batch and column mode. The effect of various experimental conditions, such as adsorbent dosage, pH, coexisting ions, contact time, initial concentration of the adsorbate solution and tempreture were studied in batch adsoption. The results showed that the favorable pH value was pH=5and pH<10, respectly. The presence of Na+and Ca2+had little influence on the adsorption behavior. The adsorption capacity for MG and p-CP was190mg·g-1and160mg-g"1at303K, respectively. The best desorption method for NSAC-MG, NSAC-p-CP was microwave power480W radiating5min and0.1mol-L"1NaOH solution, respectly. The study of the desorption and reuse experiment indicated that NSAC had good future because of the properties of reuse and easy regenerating methods.The adsorption of MG by NSAC was spontaneous and endothermic according to the thermodynamic parameters. Chemical adsorption may be predominant during the adsorption of MG onto NSAC. The equlibrium data for NSAC-MG was fitted well to the Koble-Corrrigan and Freundlich isotherm models. Pseudo-second-order model and Elovich-type equation were the best choice to fit the experimental data. The adsorption of p-CP onto NSAC was spontaneous and exothermic, and physical adsorption may be the main process. The equilibrium data for p-CP was fitted well to the Koble-Corrrigan isotherm model, the kinetics adsorption process of p-CP was fitted well to pseudo-second-order model. In the study of fix-bed column, adsorption of MG and p-CP onto NSAC mainly depended on column height, flow rate, initial concentration of adsorbate, salt concentration, pH and so on. Various dynamic models were used to predict the breakthrough curves, and the Yan and BDST models can be well described the adsorption behavior of MG and p-CP onto NSAC. |
