Preparation Of Activated Carbon From Rubber Pyrolysis Residue And Its Application To P-nitrophenol Wastewater Treatment

This paper is based on the current situation of high yield of pyrolysis residue in waste tire pyrolysis treatment,narrow application and poor resource treatment,as well as the current reality that biological treatment of nitroaromatic compounds is difficult and chemical treatment is costly.We hoped to use the waste tire pyrolysis residue to prepare activated carbon for the treatment of nitroaromatic compounds,to carry out targeted research on p-nitrophenol wastewater treatment technology,and to develop an economical and efficient alternative to activated carbon-rubber activated carbon.The effects of heating rate,impregnation ratio and activation temperature on the elemental composition,surface functional group distribution,pore structure distribution and state,and thermal stability of rubber activated carbon were discussed.The adsorption mechanism and feasibility of application were investigated for a typical nitroaromatic compound-p-nitrophenol.The main research contents and results are as follows.1.Preparation process of high-performance rubber activated carbon.The optimal conditions for the preparation of rubber activated carbon by transient heating method and KOH chemical activation method were investigated by using orthogonal and single-factor experiments with iodine absorption value as the specific surface area reference.Based on the traditional chemical activation method,the disadvantages of slow and time-consuming heating by traditional chemical activation were improved.The new method now has the advantages of simple process flow,low production cost,low investment in equipment and good adsorption performance,and the iodine absorption value of the adsorbent is 400～500 mg g^-1.2.The mechanisms of the effects of the temperature rise rate,impregnation ratio and activation temperature on the preparation of activated carbon.The results show that when the temperature is greater than 700℃,the increase of impregnation ratio will promote the volatilization of S elements in rubber activated carbon and the elimination of-CH₃ functional groups on the surface of rubber activated carbon,and accelerate the activation process,while the superposition of high impregnation ratio and high temperature rise rate will promote the generation of microporous pores on the surface of the samples and help the mesopores to become macropores to secure the formation of microporous channels.Also the impregnation ratio promotes the generation of-OH and aromatic C=C,C=O on the surface of activated carbon,which enhances the polar samples and can pave the way for subsequent adsorption experiments3.Based on the experimental study on the adsorption of p-nitrophenol by rubber activated carbon,the effects of factors such as the initial concentration of adsorption and the p H of the solution on the adsorption performance of rubber activated carbon were investigated,and the adsorption mechanism and the adsorption kinetic equations were explained.The results indicated that the adsorption of p-nitrophenol by rubber activated carbon is characterized by physical adsorption and has some chemisorption effect.When the adsorption time reached 36 h,the solution p H was in the range of 2-6,and the initial concentration was 10-300 mg g^-1,the removal rate of p-nitrophenol by rubber activated carbon could reach more than 95%.The equilibrium adsorption of rubber activated carbon can be estimated using the Langmuir isotherm equation at low initial concentrations under ambient conditions,but its adsorption kinetics can be described by quasi-secondary kinetic equations,indicating that chemisorption may exist,mainly caused by the functional groups such as-OH and-C=C on the surface of rubber activated carbon that can form hydrogen bonds with several H-containing groups in p-nitrophenol.