Study On The Regeneration And Modification Of Powdered Carbon With Calcium Accumulation By Cavitation Coupled Ion Exchange

Activated carbon?AC?has plenty of pore structure,large specific surface area and a wide variety of surface chemical functional groups,so it is a one of the common adsorbents in various fields because of these special physical structures and chemical properties.The consumption of AC increased annually at the rate of 15%and the abandoned AC caused the great waste of resources,as well as the serious environmental secondary pollution.At present,the commonly used technologies of AC regeneration achieve the regeneration of AC mainly by degrading organic pollutants adsorbed on the carbon materials.However,5%-15%of inorganic metal ions are also adsorbed on the AC by electrostatic and non-electrostatic forces,which not only reduce the activity of AC,but also affect AC regeneration efficiency because of their catalytic properties.So it is a difficult problem that cannot be solved by the thermal regeneration,which is the representative of the traditional regeneration technologies.To solve the above problems,the powdered AC was used as the research object because of its high specific surface area and excellent surface chemical characteristics.Through the analysis of the cumulative adsorption effect of calcium on powdered carbon,study on the recovery and modification of powdered AC with accumulated calcium by using of cavitation coupled ion exchange resin were firstly proposed in this paper.The effects of the regeneration time,apparent pH value,material ratio of powdered carbon and resin,filter screen diameter and true air flow rate on the regeneration of powdered carbon by cavitation were investigated,the technology theory of the mass transfer process of ion exchange reaction enhanced by cavitation was proved,and regeneration process conditions were optimized by the changes of adsorption properties,physical and chemical properties of powdered carbon before and after regeneration.The mechanism of regeneration process was illustrated in the end.The results obtained were as follows:Results related to accumulation of calcium on powdered carbon showed that the accumulative adsorption of single-component calcium on the powdered carbon was in accordance with the Freundlich adsorption model,and the adsorption kinetics was consistent with the pseudo first-order kinetic model.Adsorption function mainly included chemical adsorption such as ion exchange processes and coverage of Ca?OH?₂ and CaCO₃ precipitation.When Ca and linear alkylbenzene sulfonate?LAS?coexisted,with the increase of the initial concentration of calcium,the amount of calcium adsorbed on the powdered carbon increased but adsorption amount of LAS decreased.Results on regeneration of powdered AC with accumulated calcium by cavitation coupled ion exchange resin indicated that the regeneration rate of powdered carbon increased with the increase of cavitation contact time and the decrease of the apparent pH of resin,while decreased with the reduction of the material ratio of carbon and resin.When the apparent pH of resin was 5,the material ratio of carbon and resin was 1:1 and the regeneration time was 90min,the regeneration rate of single-component calcium accumulated powdered carbon would be 130%and the one of powdered carbon with calcium and LAS accumulation would be 90%.In addition,the regeneration rate decreased with the increase of mesh diameter,and increased with more vacuum gas flow and slightly decreased with the increase of regeneration cycle.Regeneration of calcium accumulated powdered carbon was based on cavitation,which dissolved gas to form mechanical disturbance physical field including turbulent gas,liquid and solid,and accelerated the update of interface,so decreased the effect of ions exchange resin and thickness of AC surface film on the membrane mass transfer.By strengthening the mass transfer process of ion exchange reaction,the solid phase transition of adsorbed calcium from powdered carbon to resin was realized.Characterization results of BET,IR,functional groups contents and zero charge value indicated that when powdered carbon was modified by cavitation coupled ion exchange,the micro environment of chemical oxidation reaction was formed by extreme physical field of high temperature and high pressure which caused by bubble collapse under the condition of resin exchange group medium,so as to improve the physical and chemical properties of the powdered carbon,increase the number of micro holes and the oxyacid groups such as carboxyl group,and improve the surface active points and the adsorption capacity of the powdered carbon.The mechanism on regeneration and modification of powdered AC by cavitation coupled ion exchange was physical and chemical synergistic effect between vacuum cavitation and ion exchange reaction.In summary,this thesis proposed the optimized process conditions on regeneration and modification of PAC with calcium accumulation by cavitation coupled ion exchange,and illustrated the mechanism of the synergistic action of vacuum cavitation and ion exchange reaction.These investigations are expected to provide technical support and theoretical guidance for the regeneration of PAC and are of positive significance in the situation of the currently increasing shortage of energy materials and environmental pollution.