| In the purification process of wet-process phosphoric acid,activated carbon must be used to decolorize wet-process phosphoric acid and recycled extractant.How to treat the saturated activated carbon after decolorization and adsorption directly affects the environmental security,sustainable utilization of resources and social and economic benefits.Therefore,in this paper,activated carbon was used for the decolorization of tributyl phosphate（TBP）,a wet phosphoric acid extractant,and the effects of regeneration conditions on the regeneration of activated carbon were investigated by high temperature pyrolysis regeneration and ultrasonic electrochemical regeneration,and the adsorption properties of activated carbon before and after regeneration were studied.The main research contents include:（1）Explore the influence of pyrolysis regeneration on the adsorption performance of activated carbon.By measuring the thermogravimetric curve of the waste activated carbon,it is found that the weight loss process is divided into three stages.The obvious weight loss peaks appear at 175℃,325℃and 484℃respectively,which belong to exothermic peaks.This indicates that the pyrolytic organic matter adsorbed by activated carbon is basically desorbed near 500℃.Taking iodine value and methylene blue adsorption value as evaluation criteria,the influence of temperature,regeneration time and frequency on the regeneration effect of TBP decolorized activated carbon was explored.The specific surface area and aperture analyzer（BET）,Fourier infrared spectrometer（FTIR）and electron microscopy（SEM-EDS）were used to characterize the activated carbon before and after regeneration to verify its regeneration effect.It was proved that the waste activated carbon regenerated at 500℃for 90min had the best effect.（2）Explore the influence of ultrasound-electrochemical regenerative method on the adsorption property of activated carbon.The waste activated carbon was pretreated by ultrasonic method,and the orthogonal experiment was designed to regenerate activated carbon by electrochemical method.The influence of electrolytic conditions（including the type of electrolyte,plate spacing,reaction time,current density,etc.）on the regeneration of activated carbon was studied.The variance analysis method was adopted.It was found that electrolyte type and regeneration time had the most significant effect on activated carbon adsorption of methylene blue.Orthogonal experiments show that the optimal experimental conditions are current density of 4m A/cm2,electrolyte concentration of 1%Na2SO4,regeneration time of 3h,plate spacing of 40cm.According to the optimal regeneration conditions,the MB adsorption recovery rate of activated carbon can reach 70.32%.The regeneration effect of WAC increased with the increase of electrolyte concentration,and PH also had a certain effect on the regeneration effect.The addition amount of H2O2also promoted the regeneration of activated carbon,and 1m LH2O2per 100m L electrolyte had the best enhancement effect.（3）Explore the adsorption properties of activated carbon before and after regeneration.After fitting the adsorption isotherm data,it is found that it is more consistent with the Langmuir model.The adsorption process of activated carbon is best simulated by quasi second-order kinetics,and has a higher initial adsorption capacity,accompanied by exothermic phenomenon.Therefore,the adsorption properties of TBP decolorized activated carbon can be restored to a certain extent by both thermal regeneration and ultrasound-electrochemical methods.Compared with each other,the two have advantages and disadvantages.The adsorption property regeneration effect of hot regenerated activated carbon is better than that of ultrasonic and electrochemical combined,but there is a problem of mass loss at high temperature.The electrochemical method has a fast reaction time,but it will produce colored liquid waste,and the electrodes need to be replaced regularly. |
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