Ball Milling Method Modified Montmorillonite And Its Adsorption Performance On VOCs

In recent years,the accelerated urbanization process and industrial restructuring have led to the relocation of many enterprises in the central city,leaving behind a large number of polluted plots.In the treatment process,the volatile organic pollutants（VOCs）contained in these polluted sites will diffuse into the atmosphere in the form of gas,causing secondary pollution.Due to its porous structure and low price,montmorillonite has been widely used in the adsorption and removal of pollutants in large contaminated areas.However,the disadvantages of low specific surface area and small porosity of montmorillonite make it difficult to achieve effective adsorption of volatile gaseous substances.Therefore,in this study,montmorillonite modified materials with excellent pore structure and abundant functional groups were prepared by dry ball milling method using typical volatile organic compounds as the target pollutants to improve their application limitations in gas adsorption.In this paper,typical non-polar gases（toluene）and polar gases（acetone）were selected as the target pollutants,and montmorillonite was organically modified for the polarity difference of VOCs.First,organic montmorillonite（BTMt）was prepared using tetramethylammonium bromide to investigate its adsorption performance on the weakly polar organic toluene.In order to improve the adsorption effect on the polar gaseous pollutant acetone,the organic montmorillonite was modified by using H₂O₂to prepare modified organic montmorillonite material（BHTMt）and to investigate the effect of H₂O₂addition on the adsorption performance of acetone.The materials were characterized by SEM,XRD,BET and FTIR methods.The adsorption behavior and reusable performance of the materials were investigated by dynamic adsorption experiments on different VOCs.The adsorption behaviors of different materials on VOCs were investigated by adsorption kinetics and adsorption isotherm systems.The modification mechanism and adsorption performance of the materials were investigated by DRIFTS and DFT computational chemistry methods.The main research results obtained are as follows.1.The best adsorption effect of the prepared BTMt on toluene was achieved when the modifier addition was 1.5 times of the cation exchange capacity of montmorillonite,the ball milling time was 5 h and the rotational speed was 400 r/min.After ball milling,the specific surface area of BTMt increased from 20.6 m²/g to 186.4 m²/g,and the microporosity was up to 47%.the best adsorption performance of BTMt on toluene（55.9 mg/g）was 6 times higher compared to unmodified Mt.The adsorption studies showed that the intraparticle diffusion stage was the main rate-limiting step for toluene adsorption on BTMt,and the pseudo-first order kinetic model and Langmuir isotherm model could better describe the toluene adsorption behavior on BTMt.BTMt-5 exhibited the highest toluene adsorption capacity and good regeneration performance.The mechanism study showed that the interaction between TMAB and Mt was mainly electrostatic,and the enhanced adsorption performance of the material on toluene was mainly microporous filling.2.The modified organic montmorillonite（BHTMt）with abundant functional groups was prepared by using H₂O₂with acetone as the target pollutant.The experiments showed that the best adsorption effect of BHTMt on acetone was achieved with the addition of hydrogen peroxide at 0.75 m L/g.The BET results indicated that the addition of H₂O₂had a small effect on the specific surface area of the material and the average micropore pore size increased.The adsorption isotherm and adsorption kinetic fitting results demonstrated both physical and chemical influences on the adsorption of acetone by BHTMt,with acetone undergoing adsorption on BHTMt in a multilayer.¹H MAS NMR results showed a significant increase of Si-OH in BHTMt.Since BHTMt was strongly adsorbed with acetone,the cyclic adsorption performance of the material showed a trend of decreasing and then constant.The interaction between acetone and the silanol structure in montmorillonite was mainly hydrogen bonding.