| Since the 21st century,with the development of petrochemical industry,petroleum products are more and more widely used all over the world.P-xylene?PX?,as a common petrochemical product[1],[2],is the main raw material for producing all kinds of industrial plastics.With the increase of PX output,the problem of pollution and leakage is becoming more and more serious.It causes great trouble to the safety of human life and property and environmental problems[3-5].Therefore,the removal of PX has always been the focus of researchers.At present,adsorption is the most economical and widely used method to remove PX.Biochar is a carbon-rich product prepared by pyrolysis of biomass under anoxic or anoxic conditions.it has large specific surface area,rich pore structure and rich surface active groups,so it can be used as an excellent adsorbent material.In this paper,taking porphyra yezoensis,a red algae plant in Zhoushan sea area,as the research object,a series of porphyra-based biochar nanomaterials with high specific surface area and rich pore structure were prepared by high temperature anaerobic carbonization and activation,and the series of biocarbon materials were characterized by scanning electron microscope??SEM?,?,Fourier transform infrared spectroscopy??FTIR?,?,specific surface area and pore size analysis?BET?.The effects of solution pH,adsorbent addition,adsorption time and adsorption temperature on the adsorption performance of PX were discussed through batch adsorption experiments.finally,the experimental data were fitted and analyzed by Langmuir and Freundlich isotherm equations,quasi-first-order,quasi-second-order and intra-particle diffusion kinetics equations,and the adsorption thermodynamics and kinetics behavior of porphyra-based biochar for PX were studied,and the thermodynamic parameters of the adsorption process were also investigated.This project will provide new ideas for the high-value utilization of seaweed resources,and develop new adsorption materials for the removal of PX,which is of great significance to solve the increasingly serious problem of PX pollution in China.The research results of this paper are as follows:1.The biochar materials of porphyra yezoensis were prepared by carbonation pyrolysis of raw material porphyra yezoensis at 600,700,800,900?.The biochar materials were characterized by field emission scanning electron microscope??SEM??and specific surface area and pore size analysis?BET?.It was found that the specific surface area of porphyra yezoensis-based biochar materials after carbonation pyrolysis was relatively large.?600?:2752.76m2/g;700?:2147.19m2/g;800?:1878.35m2/g;900?:845.96m2/g?,which is beneficial to increase the adsorption performance of p-xylene?PX?.2.Through the batch adsorption experiments of p-xylene,it was found that the adsorption amount of p-xylene was higher when the adsorption equilibrium was reached at800?.The subsequent single factor experiments found that the adsorption conditions of Laver-based biochar nanomaterials for p-xylene were as follows:solution pH=7,adsorbent dosage 0.02g,adsorption time 2h,temperature about 20?.3.Through the kinetic and thermodynamic fitting of the related experiments,it is found that the two kinetic models of the adsorption kinetics of p-xylene on porphyra-based biocarbon composites have a good linear correlation,but the quasi-second-order kinetic model is more consistent with the quasi-second-order kinetic model.the fitting coefficient is higher.At the same time,the fitting data of intra-particle diffusion model do not have linear correlation.The adsorption isotherm is more consistent with the Langmuir model.Thermodynamic fitting shows that the adsorption process of p-xylene on porphyra-based biochar belongs to the physical adsorption process,and the whole process is endothermic. |
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