Study On The Modified Activated Carbons And Its Adsorption Capacity Of VOCs

Furniture coating industry is one of the major industrial sources of VOCs,and its VOCs treatment process has also been paid more and more attention.Adsorption process is the most important VOCs treatment process in furniture coating industry,and activated carbon is the most common adsorbent.The adsorption treatment process has the advantages of high purification efficiency and simple equipment.However,there are still many problems need to be improved in the process of adsorption,such as it need large adsorption dose and regular replacement,etc.How to improve the adsorption performance of adsorbent becomes the main measure to reduce the cost of adsorption process.In this paper,activated carbon was modified by nitric acid,sodium hydroxide and high temperature.The changes of oxygen functional groups on the modified activated carbon were studied by Boehm titration.At the same time,the adsorption capacity of activated carbon to toluene was studied.The results are as follows:(1)Boehm titration test:Activated carbon modified by nitric acid,its surface acid groups were increased and the basic group were decreased,and the proportion of surface acidic groups increased.Activated carbon modified by sodium hydroxide,its surface acid groups were decreased and the basic group did not change obviously,and the proportion of surface basic groups increased.For nitric acid modification and sodium hydroxide modification,the surface oxygen groups of the activated carbon increased with the increase of the concentration of the modified liquid.With the increase of temperature,with the increase of temperature and the basic group increased gradually,and the proportion of surface basic group increased.(2)Static adsorption test of activated carbon:The adsorption saturation of toluene on the activated carbon modified by nitric acid and sodium hydroxide did not significant change.The higher modified temperature of activated carbon,the higher the adsorption saturation of toluene,and 195 mg/g at 800?.(3)Dynamic experiment of activated carbon adsorption:The adsorption traversing curves of activated carbon,20%nitric acid modified,20%sodium hydroxide modified and 800 ? modified activated carbon were determined respectively.Among them,the adsorption time of the activated carbon was 120 min,the nitric acid modification and the high temperature modification activity were delayed by 30 min and 60 min.(4)The different adsorption bed height affects the adsorption penetration time,with the increase of the height of the adsorbent bed,the penetration time increases accordingly.According to the linear relationship between the two formulas,the penetrating coefficient K=25.5 min/cm and the adsorption flux time to =110 min of 800? modified activated carbon were obtained.