Study On The Adsorption Properties Of Methylene Blue On Bean Dregs Activated Carbon And Chitosan Complex

with the further development of modern society and economy,a huge amount of dyes is discharged into the aquatic environment.Most of the components of dyes are aromatic hydrocarbons,which is organic pollutants that is difficult to degrade.Therefore,industrial wastewater pollution has become one of the sources of environmental pollution.Several wastewater treatment methods such as advanced oxidation method,membrane method,adsorption method,photocatalytic degradation method have been explored to remove the pollutants from wastewater.Among them,the adsorption method is the most widespread wastewater treatment approach due to their high efficiency,simple operations and low cost.This method does not produce secondary pollution.Activated carbon is a carbon material with large specific surface area,developed pore structure,variable surface properties and strong selective adsorption capacity.It is widely used in sewage treatment.As a natural linear polymer,chitosan has been widely used in food,environmental protection,agriculture and pharmaceutical industry.However,its acid resistance is poor,which brings great limitations to the application of chitosan.It needs to be modified to improve its acid solubility.It is an ideal way to make cross-linked chitosan after cross-linking.In the process of soybean processing,a large amount of bean dregs waste will be produced every year.It will cause serious pollution to the environment,if it is directly disposed.It is necessary to modify the bean dregs to exert its preferable economic and environmental benefits.In this study,SD was utilized as the raw material for the production of AC by chemical activation and its adsorption capacity for cationic MB was evaluated.ZnCl₂ was chosen as the activating agent.The bean dregs activated carbon and the activated carbon/chitosan composite porous beads were prepared and used for the adsorption treatment of dye wastewater.The main results are as follows:?1?soybean dregs were pyrolyzed to prepare activated carbon using chemical activation by zinc chloride.The experimental result shows that the activation temperature of 500?at holding time of 1 h and impregnation ratio of 2:1 can give the preferable dye adsorption properties of AC.SEM showed that a large number of pore structures were formed on the surface of the bean dregs activated carbon,which increased the specific surface area of the material.The BET measurement showed that the specific surface area of the bean dregs activated carbon was 643.58 m²/g and the average pore diameter was1.85 nm.The results of FTIR analysis indicate that oxygen containing groups such as hydroxyl,carbonyl and carboxyl groups appear on the surface of AC.The adsorption equilibrium data of methylene blue onto activated carbon were well fitted to the Langmuir model,giving a maximum adsorption capacity of 255.10 mg/g.It indicates that activated carbon is a promising adsorbent for removing methylene blue from aqueous solution.The kinetic data were well described by the pseudo-second order model.Thermodynamic parameters indicate that adsorption process is spontaneous and endothermic.?2?The activated carbon/chitosan?AC/CHI?composite porous beads were prepared by cross-linking,curing and freeze-drying methods.The properties of the synthesized AC/CHI were characterized by scanning electron microscope?SEM?and Fourier transform infrared spectroscopy?FTIR?.The effect factors including temperature,dosage,contact time,and pH on the adsorption properties of methylene blue onto AC/CHI were studied.The kinetic data were well described by the pseudo-second-order model.Thermodynamic parameters indicate that adsorption process is spontaneous and endothermic.It indicates that AC/CHI is a promising adsorbent for removing methylene blue from aqueous solution.