Preparation Of Pomelo Peel Activated Carbon And Study On Ammonia Adsorption Performance

The problem of atmospheric pollution caused by ammonia?NH₃?emissions continues to increase.NH₃not only directly harms human health in the atmosphere,but also plays an important role in the formation of atmospheric haze and photochemical smog.The efficient and convenient activated carbon adsorption technology has attracted widespread attention.Traditional activated carbon is prepared with non-renewable fossil energy,and the cost is very high.Finding a new source of raw materials is the key to adsorption technology.Grapefruit is one of the most widely grown crops in the world.Usually the grapefruit peel is discarded without being used.It is rich in dietary fiber and is a good raw material for preparing activated carbon.Recycling the pomelo peel,which can be used as an adsorbent material after carbonization treatment,not only reduces the pollution to the environment,but also improves the utilization value of pomelo waste.Many scholars have focused their attention on pomelo peel,but there are few reports on the use of zinc chloride to activate pomelo peel to prepare activated carbon and apply it to ammonia adsorption.In this paper,first,pomelo peel is used as the raw material,and zinc chloride was used as the activator to prepare activated carbon by carbonization at high temperature.The effects of the raw material ethanol treatment and the preparation of the comparative surface area under two atmospheres of air and nitrogen were discussed.The effects of activation temperature,agent-to-material ratio and activation time on the appearance and pore characteristics of the product were studied.The results show that the treatment of pomelo peel with ethanol helps increase the specific surface area of activated carbon and the formation of pore structure;under a nitrogen atmosphere,it can inhibit oxidation and prevent the destruction of pore structure and reduce blockage of pore structure,resulting in high specific surface area and pores.Developed activated carbon.At an activation temperature of 400?,an impregnation ratio of 1.25,and an activation time of 60 minutes,the specific surface area of the activated carbon prepared can reach 1325.9m²/g.There are a large number of carboxyl,hydroxyl and amine groups on the surface of the product.Secondly,the DM design was used to improve the preparation process of pomelo peel charcoal,and a second-order prediction model of activated carbon yield and ammonia adsorption performance was obtained.The results show that within the range of activation temperature and impregnation ratio selected in the DM design experiment,all response results indicate that the influence of activation temperature is greater than the impregnation ratio,and the yield of activated carbon obtained is more than 31%;the ammonia adsorption value of activated carbon is selected for optimization.The optimal preparation conditions are:activation temperature 417?,impregnation ratio 1.27,yield of pomelo peel charcoal prepared under this condition is 37.89%,and ammonia concentration is 200ppm?1.0L/min,Air?,ammonia adsorption is predicted.The value is5.23mg/g,the actual value is 5.28mg/g.The prepared pomelo charcoal is superior to ordinary commercial activated carbon in appearance,pore structure and ammonia adsorption effect.Finally,the impregnated method was used to modify the PPAC prepared by the optimized pomelo peel charcoal.The effects of different chlorides and their concentrations as the modifying operation parameters on ammonia adsorption performance were discussed,and its adsorption-regeneration cycle performance was studied.The results show that after loading metal chloride,pomelo peel charcoal still has a high specific surface area and pore volume.TG results show that the loading quality is very close to the theoretical value.Among the different metal chloride loads,the performance of the adsorbent prepared by nickel chloride on PPAC is the best;under different concentrations of nickel chloride,PPAC-NiCl₂-20%has the highest ammonia adsorption performance,and the breaking point capacity and equilibrium capacity are50.05 mg/g,64.82mg/g.After 5 cycles of adsorbent,the pore structure did not change much.After multiple regenerations,the ammonia adsorption performance decreases,the breaking point capacity and equilibrium capacity are stable at around 42mg/g and 58mg/g,the adsorption capacity is still in a relatively high range,and NiCl₂loaded on PPAC contributes to the main ammonia adsorption capacity.