Adsorption Of Phthalic Acid Esters By Modified Biochar

Phthalic acid esters(PAEs)are widely used in plastic products.Humans are exposed to phthalate contaminants through various pathways and consequently affect human health.In this study,lotus stems were used as biomass material,and the biomass was pretreated with sodium hydroxide.In order to obtain a larger specific surface area,biochar with sizes ranging from a few microns to tens of microns were prepared by ball milling.Four phthalate pollutants with different branched chain lengths and containing different amounts of benzene rings were selected as the target pollutants,and the adsorption kinetics and thermodynamics experiments of the two biochar materials on the target pollutants were carried out.The structural characteristics of the biochar materials were also characterized by elemental analysis,specific surface area meter,Fourier infrared spectroscopy analysis,electron microscopy scanning,Raman spectroscopy analysis,and x-ray diffraction analysis.The main findings are as follows.(1)The adsorption experiments of biochar treated with Na OH(Na-LBC)and biochar treated with ball mill(Na-BMLBC)for four kinds of pollutants showed that the removal efficiency of the pollutants gradually decreased with the increase of molecular carbon chain length for the four pollutants.By fitting the experimental data with adsorption kinetic and thermodynamic models,it can be inferred that the adsorption process of the four PAEs was controlled by the intra-molecular diffusion and other adsorption stages,and the adsorption process was monolayer adsorption and probably chemisorption.(2)Na-LBC increased after treatment with Na OH;the surface functional groups increased;more pore structures were added to the surface,the specific surface area increased,and the pore size was transformed from the original macroporous to microporous and mesoporous structures.(3)Na-BMLBC after ball mill mechanical treatment is only a few microns to tens of microns,and the specific surface area increases by 103 m~2/g compared with that of Na-LBC,and its surface is microporous structure;the surface functional groups and crystal structure are not much different from that of Na-LBC.(4)The changes of functional groups on the surface of the materials before and after the adsorption of Phthalic acid esters were analyzed by Fourier infrared spectroscopy,and it was found that hydrogen bonding and?-?EDA were involved in the adsorption process,and the pore filling was a more important adsorption mechanism in the adsorption process by specific surface area analysis.