Experimental Research On Preparation Of Activated Carbon By Using Microwave Irradiation And The Effect Of Pressure On The Properties Of Activated Carbon

The microwave heating technology has been widely concerned in the preparation of activated carbon due to its fast heating speed,short heating time,low energy consumption,easy process control,etc.Recently,there are too much researchs about the effects of microwave power,radiation time,immersion on the asorption of activated carbon which made from coal and biomass.However,the activated carbon preparation raw materials is noy only coal and biomass,but also plastic.And the pressure has a great impact on the adsorption performance of activated carbon.Therefore,it is necessary to study the preparation activated carbon from plastic,and explore the effect of pressure on the adsorption performance of activated carbon by using microwave heating technology.Firstly,this paper studied the effects of activator type,microwave power,impregnation ratio,pressure and irradiation time on the adsorption performance of activated carbon was made from waste plastic bottles(PET)by using microwave heating technology and analyzed the effects of various factors on the adsorption performance of activated carbon through orthogonal test.The adsorption performance of activated carbon was measured by the iodineadsorption value.The iodine adsorption value of activated carbon increased first and then decreased with increased of microwave power,immersion ratio and radiation time,and the iodine adsorption value of activated carbon was changed in M shape with the increased of pressures.The best experimental conditions were obtained through the orthogonal test.Under this condition,the activated carbon was microporous activated carbon,the specific surface area was527.0337m2/g and the surface contains a large amount of oxygen-containing functional groups.Then,this paper studied the effect of pressure on the adsorption performance of activated carbon,which made from the waste plastic bottles(PET),Fugu bituminous coal and Hainan coconut shell by using KOH as activator and microwave heating technology under the pressure between 10 k Pa to 180 kPa.The properties of activated carbon were characterized by iodine adsorption,low temperature nitrogen adsorption-desorption and FT-IR.The important results are as follows:(1)For the activated carbon made from waste plastic bottles(PET):Under the negative pressure,the iodine adsorption value,surface area and pore volume of activated carbon increased gradually with the decreased of pressure beacause of the average activation temperature and the relative activation time increased,but the pore size decreased gradually.Under positive pressure,the iodine adsorption value and specific surface area of activated carbon reached the peak at 120 kPa because of average activation temperature and the relative activationtime reached highest,but the average pore size was the smallest.The activated carbon surface oxygen-containing functional groups was generated by activator reaction with C atoms on the active point due to it had little volatile.Therefore,with the increase of pressure,the hydroxyl groups of the activated carbon remained unchanged,but the surface oxygen-containing functional groups increased first and then decreased and reached the maximum at 120 k Pa.At this time,the oxidation capacity of heavy metal and the adsorption capacity of organic matter were the highest.(2)For the activated carbon made from Fugu bituminous coal:Under the negative pressure,with the decrease of pressure,the activated carbon iodine adsorption value and the specific surface area gradually increased because the average heating rate decreased first and then increased,and the relative activation time increased first and then decreased,but the relative activation time was longer at 10 kPa and the organic gas,the activated gas had less damage to the pore structure.Under the positive pressure,the average heating rate was the lowest at 120 kPa and the average activation temperature was gradually increased,so that the adsorption value of activated carbon and surface area reached peak;With the increase of pressure,the hydroxyl and oxygen-containing functional groups increased first and then decreased,and the peak value was found at 120 kPa because of the volatile analysis and the degree of activation reaction.(3)For the activated carbon made from Hainan coconut shell:Under thenegative pressure,the iodine adsorption value and the specific surface area of the activated carbon reached the maximum value at 30 kPa because the average activation temperature and the relative activation time increased first and then decreased.Under the positive pressure,the iodine adsorption value and the specific surface area of the activated carbon decreased with the increasing of the pressure.Moreover,the average pore size,mesoporous and macroporous volume of the activated carbon increased gradually.With the increasing of pressure,activated carbon hydroxyl content slowly increased firstly and then remain unchanged,and oxygen-containing functional groups increased firstly and then decreased because of residual volatiles analyze the situation and the degree of activation reaction.And the increase in pressure inhibits the formation of secondary alcohols.