Adsorption Of Dimethyl Phthalate In Water By Bio-char

The study on the adsorption of organic pollutants of phthalates acid esters(PAEs)in aqueous solution by bio-char can improve the resource utilization rate of agricultural waste in the construction of ecological civilization in China,and at the same time remove phthalates.Put forward green environmental treatment and disposal methods,and have good social and environmental benefits.In the existing adsorption research of bio-char to phthalates,the general adsorption process takes a long time,and the application of hydrophobic bio-char in aqueous solution has drawbacks.This paper is based on agricultural waste as raw material.Above,alkaline pretreatment is performed to increase the adsorption efficiency of bio-char.Peanut shell and lotus stem are mainly used as raw materials to prepare bio-char,and alkaline raw materials are pretreated with sodium hydroxide solution.Taking dimethyl phthalate(DMP)as an example,carbonization temperature,substrate concentration and investment are investigated.The effect of the addition amount on the adsorption,and the response surface optimization method was used to optimize the adsorption effect of bio-char on DMP.At the same time,through the study of adsorption kinetics and adsorption thermodynamics,and by means of elemental analysis,Raman spectroscopy and Fourier transform infrared spectroscopy,the adsorption mechanism of bio-carbon adsorption DMP was further explored.The main conclusions are as follows:(1)Comparing the results obtained by pyrolysis of peanut shell,eucalyptus bark,tea tree seed,tung seed,pine seed and lotus rod at 400 ° C,500 ° C,600 ° C,700 ° C,800 ° C for one hour.The removal of DMP by material charcoal found that the biomass charcoal prepared from peanut shell and lotus stem had better adsorption effect on DMP.The adsorption rate of peanut shell-based biomass charcoal(PBC)could reach 82.18%,and the adsorption amount reached 123.28 mg/ g,the adsorption rate of lotus stem biomass carbon(LBC)can reach 81.27%,and the adsorption amount reaches 121.9mg/g.(2)Elemental analysis and Raman spectroscopy show that as the preparation temperature increases,the aromatic functional groups of bio-char increase,the aromaticity of cellulose increases,the polarity decreases,and the formed carbonized product has stronger hydrophobicity.The degree of graphitization increases,and the orderly carbon structure tends to be more ordered.The pore size and specific surface area decrease,which will affect the adsorption performance of the biomass carbon material,resulting in a better bio-char at 600 °C than 800 °C with a higher degree of graphitization..(3)In the single factor influence and response optimization experiment,the effects of carbonization temperature,substrate concentration and dosage on adsorption were investigated.The optimal condition for bio-char adsorption of DMP was 0.1g/50 mL of adsorbent.The solid-liquid ratio is 2:1g/L,and the biomass charcoal prepared from the untreated raw material reaches the adsorption equilibrium in the adsorption reaction for 24 h,and the adsorption efficiency is 82.18%.The bio-char prepared by the alkali-treated raw material is adsorbed by DMP.In the process,the reaction equilibrium can be achieved in 2h,and the adsorption efficiency is increased to 98.47%.The alkaline pretreatment of raw materials can greatly improve the adsorption efficiency of bio-char to DMP.(4)Further studies on the adsorption experiment found that the adsorption kinetics of bio-char on DMP accords with the quasi-secondary kinetic model,which indicates that the adsorption process is the process of chemisorption rate control.At the same time,the intraparticle diffusion model shows that DMP molecules are first adsorbed onto the outer surface of the bio-char particles during the whole adsorption process.The adsorption rate is fast,and the DMP molecules slowly diffuse into the interior of the bio-char particles and are adsorbed.At the active site on the inner surface,the rate of adsorption during this process is relatively slow.(5)Infrared spectroscopy(FTIR)shows that high temperature carbonization leads to a decrease in a large number of aromatization structures and some carboxyl,ketone,aldehyde and lactone functional groups in the material.The adsorption process changes the substitution position of the substituent group on the benzene ring,and the benzene ring structure may cause intramolecular or intermolecular hydrogen bond cleavage,and π-πEDA interaction occurs with the bio-char graphite sheet structure formed by pyrolysis,thereby forming Strong π-π conjugate.