Adsoption Properties Of Magnetic Activated Carbon Preparated By Microwave Solvothermal Method

Activated carbon is a common adsorbent with developed pore and huge specific surface area.It is widely used in dyestuffs wastewater,heavy metal wastewater,solid waste treatment and Waste gas treatment.However,it is very difficult to recover and separate activated carbon in practical application,which can easily cause blockage of sieve and loss of activated carbon.Magnetic activeted carbon has the advantages of fast separation and low cost.Therefore,magnetic activated carbon has become a hot topic in the field of activated carbon.Activated carbon based on melon seed shell inherits oxygen rich groups such as hydroxyl group and carboxylic acid group of melon seed shell itself,which can adsorb dyes and heavy metals.The magnetism of the adsorbent makes it easy to separate in the process of sewage treatment,and becomes a kind of adsorbent with high efficiency and fast separation.In this paper,magnetic activated carbon based on melon seed shell was prepared by using phosphoric acid as activator and ferric oxide as magnetic bond.The adsorption properties of magnetic activated carbon based on melon seed shell for methylene blue and heavy metal Cr?VI?were investigated,and the adsorption mechanism was discussed.The research contents are as follows:1.Using melon seed shell as raw material,activated carbon based on melon seed shell was prepared by phosphoric acid activation combined with microwave carbonization.The optimum preparation conditions were studied by orthogonal experiment.?The phosphoric acid co-ncentration is 20%,the impregnation ratio is4g/15ml,the activation temperature is 110?,and the microwave time is 25min.?The magnetic activated carbon based on melon seed shell with a mass ratio of 60%was prepared by solvothermal method.The specific surface area of the magnetic melon seed shell activated carbon is 433cm²/g and the total pore volume is 0.4cm³/g.2.The structure characteristics of the product were described by analyzing the XRD,IR and SEM spectra and measuring the specific surface area and pore structure of the product.Activated carbon combines with ferric oxide.A large number of phenolic hydroxyl groups and carboxylic acid groups in magnetic activated carbon.Ferric oxide are combined with activated carbon in the form of C-O-Fe.Fe₃O₄particles are spherical,activated carbon is smooth layered structure.Irregular composite particles are formed by the combination of Fe₃O₄ and activated carbon based on melon seed shell.It is a microporous structure with pore size ranging from0.6nm to 0.7 nm.t is a microporous and mesoporous structure with pore size ranging from 0.6nm to 2.5 nm.3.The optimum conditions for adsorption of methylene blue by magnetic melon seed shell-based activated carbon are as follows:adsorption time 3 hours,adsorption temperature 25?,dosage of magnetic activated carbon 1g/L,initial concentration of solution 50mg/L.The maximum adsorption capacity was 62.1mg/g at 25?.The optimum conditions for adsorption of Cr?VI?by magnetic melon seed shell-based activated carbon are as follows:adsorption time 12h,pH=3,adsorption temperature50?,dosage of magnetic activated carbon 2g/L,initial concentration of solution70mg/L.The maximum adsorption capacity is 50?at 60.6mg/g.4.The adsorption process of methylene blue on magnetic melon seed shell-based activated carbon conforms to quasi-second-order kinetic model and Langmuir adsorption isotherm equation.The reaction is a homogeneous chemical adsorption with controlled chemical reaction rate.According to the study of adsorption thermodynamics,it is found that the adsorption process is exothermic reaction,and low temperature is favorable for adsorption.The adsorption process of Cr?VI?on magnetic melon seed shell-based activated carbon conforms to quasi-second-order kinetic model and Freundlich adsorption isotherm equation.1/n at each temperature is between 0 and 1,indicating that adsorption is a chemical adsorption controlled by chemical reaction rate,and the adsorption effect is good.According to thermodynamic study,the adsorption process is endothermic reaction,and high temperature is conducive to the adsorption process.