Adsorption Equilibrium And Kinetics Studies Of Multi-component Organic Matters In Ethanol-water Solvent Onto Rice Husk-based Activated Carbon

Rice husk-based activated carbon is a kind of high quality adsorption material,which is widely used in the treatment of industrial dye wastewater.Industrial solvent dyes(used for dyeing leather,wood,plastics and cells,etc.)often use alcohols as solvents,and the content of alcohols in wastewater ranges from 10% to 15%.However,aqueous solutions were used as solvents in most adsorption studies of rice husk-based activated carbon,which is far from the practical situation that the adsorbent needs to remove organic pollutants from alcohol-water system.As a result,it causes a deviation between the theoretical model and the actual situation.Furthermore,these adsorption studies are focused on one-component system,and two-component and three-component systems were less studied.Therefore,it is necessary to explore the adsorption theoretical model of multi-component organic pollutants onto rice husk-based activated carbon in the alcohol-water system,so as to provide theoretical basis for the practical application in which activated carbons remove organic pollutants from wastewater.Firstly,in the adsorption experiment of one-component organic matters from alcohol-water solvent onto rice husk-based activated carbon,methylene blue was adsorbed in the form of monolayer with a maximum adsorption amount of 85.6 mg/g.The results of kinetics study indicated that the data predicted by pseudo-second-order kinetic model fit the experimental data well.The adsorption behavior of methyl orange onto activated carbon was similar to that of methylene blue with a maximum monolayer adsorption amount of 80.4 mg/g.The pseudo-second-order kinetic model had a good prediction effect on the adsorption process of methyl orange onto activated carbon.Secondly,in the adsorption experiment of two-component organic matters from alcohol-water solvent(methylene blue and methyl orange)onto rice husk-based activated carbon,the maximum equilibrium adsorption amount of methylene blue and methyl orange onto activated carbon was 109.8 mg/g and 105.4 mg/g,respectively,which indicated that “synergistic adsorption” effect existed in the adsorption process of two-component system.Langmuir-freundlich isotherm model can describe the adsorption process of methylene blue and methyl orange onto activated carbon.These two components were adsorbed in the form of multilayer.The results of kinetics study indicated that,in the two-component system,the adsorption behavior of methylene blue and methyl orange onto rice husk-based activated carbon followed thepseudo-second-order kinetic model.Lastly,in the adsorption experiment of three-component organic matters from alcohol-water solvent(methylene blue,methyl orange and phenol)onto rice husk-based activated carbon,the equilibrium adsorption amount of methylene blue was close to that of the two-component system,but the equilibrium adsorption amount of methyl orange was significantly reduced compared with that in the two-component system.It indicated that “competitive adsorption” effect existed between methyl orange and phenol.Freundlich model can describe the adsorption behavior of methyl blue,methyl orange and phenol onto activated carbon.The results of kinetics study indicated that the pseudo-second-order kinetic model can describe the adsorption process of rice husk-based activated carbon in the three-component system.