The Preparation Of Carbon Material Based On Oily Sludge And Its Ability Of Removing Crude Oil

Oily sludge,a kind of hazardous waste produced in the production process of petroleum industry with strong stability,large changes in oil and water content and complex ingredients,is hard to be treated.Therefore,it has been listed in the list of hazardous wastes by many countries and regions.It has become one of the key contents of environmental protection in petroleum industry to treat it innocuously and use it as a resource.In this paper,oily sludge is used as raw material and sawdust as carbon enhancer to prepare adsorbed carbon materials based on oily sludge.The effects of five activators,ZnCl2,K2CO3,NaOH,H2SO4 and K2CO3,on the removal of oil of adsorbed carbon materials are compared.The results show that ZnC12 is the best activator among five kinds of activators.The results of physical adsorption,surface functional group determination and Fourier transform infrared analysis show that the adsorption ability of the prepared carbon material is closely related to their mesopore volume.The functional groups-OH of phenoles?-C=O and-C=C-on the benzene ring located in the pore surface of carbon materials show that carbon materials can be used for the adsorption and removal of petroleum substances in the oily wastewater.After that,the optimum preparation conditions of adsorbed carbon materials with are determined by single factor method when ZnC12 and NaOH are used as activators.Among them,the optimal conditions for the preparation of adsorbed carbon materials with ZnC12 are summed up as following.The condition of carbonization temperature,carbonization time,heating rate,solid-liquid ratio,ZnCl2 concentration and mass ratio of oily sludge and sawdust is 510?,2.5 h,15 ?/min,1:2.5,5 mol/L and 1:1 respectively.Similarly,the optimal conditions for the preparation of adsorbed carbon materials with NaOH are:carbonization temperature 550?,carbonization time 3 h,heating rate 10?/min,solid-liquid is 1:1.5,the concentration of NaOH 5 mol/L,and the ratio of oily sludge to sawdust is 1:1.The best conditions for the preparation of adsorbed carbon materials by the combination of ZnCl2 and NaOH are as follows:carbonization temperature 530?,carbonization time 3 h,heating rate 15 ?/min,solid-liquid 1:2.5,the concentration of NaOH and ZnCl2 5 mol/L,and the ratio of oily sludge and sawdust 1:1.Under those conditions above,the crude oil equilibrium adsorption capacity of the three adsorbed carbon materials are 371.93,341.12 and 361.83 mg/g respectively.By means of BET,FTIR,SEM,TGA-DTG and so on,the pore structure and surface functional groups and other characters of the carbon materials are analyzed.The addition of activator is more conducive to the formation of more abundant pore structure of carbonized products.In addition,the formation of functional groups of-OH,-NH,-C=O and-C=C-on the surface of carbon materials and pore surface,is beneficial to the adsorption of crude oil in water.The most reasonable adsorption isothermal models firs of adsorption process of the three kinds of carbon materials for crude oil is the Langmuir model,and the adsorption process belongs to preferential type.The adsorption rate model of carbon materials for petroleum substances accords with the second-order dynamic model,and the adsorption process is controlled by both the surface liquid film diffusion and the particle internal diffusion.After the heating regeneration of three kinds of carbon adsorption materials saturated with crude oil,it can be seen that the adsorption efficiency of three kinds of carbon adsorption materials still can reach 64.82%,77.77%and 87.23%respectively after three times of regeneration,which can meet the requirements of recycling.