| Activated carbon,with specific surface area,pore structure developed and strong surface activity and adsorption capacity,is widely used in all kinds of industrial organic volatile gas purification treatment.After adsorbing a large number of pollutants,the functional groups on the surface and the internal pore structure of activated carbon will change correspondingly,resulting in the decline of the activity of activated carbon,which needs regeneration to recover.However,the regeneration process can not restore 100%of the adsorption capacity of activated carbon.After repeated regeneration,the activity of activated carbon decreases and can not continue to be used.As a hazardous solid waste,it needs centralized disposal.In this paper,the regeneration method of waste activated carbon,which has been regenerated on site for many times and has seriously degraded its adsorption performance,is screened and optimized,and the regenerated activated carbon is applied to adsorb odorous gases in different departments of paper mills.The structure and properties of waste activated carbon were discussed through characterization of raw materials.Infrared characterization showed that carbonyl group disappeared on the surface of saturated waste activated carbon,C=C group and C-O group appeared,indicating that activated carbon successfully adsorbed pollutants;XRD and pore analysis showed that the pollutants adsorbed by activated carbon could reduce the graphitization degree of activated carbon,block micro-pore,reduce the number of micro-pore,increase the average pore size and decrease the specific surface area.The results of desorption test showed that the volatile organic gases in coatings were complex,mainly benzene,aldehydes and alkanes,among which ethylbenzene,p-xylene,m-xylene and o-xylene had the highest content,about 55.53%of the total content.By comparing the methods of thermal regeneration,chemical regeneration and steam regeneration,the optimum regeneration method of saturated waste activated carbon was determined.The iodine adsorption value and methylene blue adsorption value of regenerated activated carbon were 329.69 mg/g and 83.95 mg/g after treated at 800℃ for 60 min.And the yield of regenerated activated carbon was 75.19%at the same time.The recovery rates of iodine adsorption and methylene blue adsorption were 70.03%and 68.83%compared with the new activated carbon,respectively.FTIR analysis showed that C=C and C-O groups of regenerated activated carbon disappeared after themal regeneration treatment.This indicated that the adsorbate was successfully removed in the themal treatment.The changes of XRD analysis result between regenerated activated carbon and waste activated carbon indicated that thermal regeneration treatment can improve the degree of graphitization of the carbon materials,but had no destroying on activated carbon construction.The specific surface and aperture distribution analysis shown that the average aperture was reduced from 6.85 nm to 2.26 nm;the specific surface area from 520.67 m2/g increased to 1143.43 m2/g,and the pore capacity increased from 0.21 cm3/g to 0.39 cm3/g after thermal regeneration treatment.The recycled carbon is used for the adsorption control of odor source gas in the paper workshop.Under the 7-day active filtration adsorption condition,the GC-MS analysis shows that there are 14 kinds of adsorption gas components in the oblique sieve.Among them,chloroisoamane,1-ethylcyclobutane,and benzene accounted for 40.03%.There are 9 kinds of adsorption gases in the mesh,of which four substances,propanediol,ethyl acetate,1-ethylcyclobutane,and cyclohexane,account for 74.29%.There are 8 kinds of adsorption gas components in the drying part,of which acetic acid accounts for 75.43%.There are 15 kinds of adsorption gas components in the sewage treatment department,of which 3-methyl furan,acetic acid and benzene account for 39.27%.Therefore,the main odor gases in the papermaking plant are acetic acid,benzene,and some alkanes.Through the thermal weightlessness experiment,it was determined that the adsorption capacity of activated carbon reached 13.66%in the 15-day active filtration adsorption.After the 25.4 day adsorption experiment,it was close to the saturation value of the general activated carbon adsorption and needed to be recycled. |
