Study On Mechanism Of The Efficient Adsorptive Removal Of Organic Pollutants Onto Biochars

The SEM,EDX and FTIR characterization of biochar prepared by pyrolysis of agricultural wastes showed that the biomass carbon particles became smaller and thinner,the yield of biomass carbon decreased significantly with the increase of pyrolysis temperature;the content of C increased,the content of O decreased and the content of C = O in the oxygen-containing functional groups increased and biomass charcoal became more hydrophobic.With the increase of pyrolysis temperature,the biodegradability of bagasse biomass charcoal improved the adsorption affinity of organic pollutants,such as benzoquinone,tetracycline and polyvinyl alcohol.The p H value of solution had little effect on the adsorption of low polarity tetracycline by biochar.The interaction mechanism of ?-?electron donor-acceptor may contribute to the adsorption of tetracycline and p-benzoquinone,while the hydrogen-bond interaction between PVA and biomass charcoal may dominate the adsorption.The Elovich model can well fit the kinetics,indicating that the adsorption process is obviously determined by the diffusion rate.In addition,the magnetic field is a kind of auxiliary condition for efficient removal of organic pollutants onto biochars,magnetic field assisted adsorption technique is applied to the field of organic pollutants treatment.The effect of magnetic field on the adsorption of methylene blue on wheat straw biomass carbon was investigated,and the mechanism of magnetic field assisted adsorption was investigated.The results show that the adsorption effect of wheat straw biomass carbon pyrolyzed under 200?degrees is best,The removal rate of methylene blue increased with the increase of the amount of biomass carbon and external magnetic field is applied,the biomass carbon adsorption of methylene blue has been significantly improved;the length of magnetic field pretreatment had little effect on the removal rate of methylene blue;Increasing the initial concentration of the dye can significantly increase the adsorption capacity of biomass carbon;adsorption ofmethylene blue in alkaline environment is better than that under acidic conditions;The quasi-second-order linear model and the double constants dynamic model are more suitable for describing the adsorption kinetics of methylene blue onto wheat straw biomass carbon,the diffusion rate controls the adsorption process;Langmuir model is more suitable for describing the adsorption thermodynamic of methylene blue onto wheat straw biomass carbon,indicating that adsorption may be multi-molecular layer adsorption;After applying the magnetic field,the magnetization of water changes the bond angle of water molecules,increases their dipole moments,reduces the cluster structure of water molecules,small water molecules increase the mobility of the dye,more dye molecules can be adsorbed on the surface of biomass carbon;On the other hand,the acidic functional groups(carboxyl,lactone,phenolic group)on the surface of biomass carbon are particularly sensitive to magnetic,The adsorption of methylene blue on biomass carbon exhibited the same trend as the surface acidic functional groups,indicating that the surface acidic functional groups of biomass charcoal has a great influence on the adsorption of methylene blue,but it can not exclude the role of amino groups on the surface of biomass carbon.