焦油渣基活性炭的制备及其对生化废水COD的脱除性能OA

As a hazardous waste,tar residue lacks effective utilization methods,and its long-term stacking causes severe air and groundwater pollution.The high treatment costs also con-strain the large-scale development of coal chemical enterprises.To develop its efficient and environ-mentally friendly technology,a study on the preparation of tar residue-based activated carbon was car-ried out using dry tar residue,modified asphalt and KOH activator in a mass ratio of 100∶10∶5.The effects of activation temperature,activation time,and heating rate on the surface adsorption perfor-mance and pore development of activated carbon products were investigated in a horizontal tube alun-dum furnace.The morphology and surface chemical properties of the activated carbon were compre-hensively analyzed using infrared spectroscopy,N2 adsorption-desorption,scanning electron micros-copy(SEM)and X-ray photoelectron spectroscopy(XPS).The activated carbon product was tested for COD removal efficiency in biochemical wastewater.The results show that the tar residue forms a dry residue after heat treatment at 260℃for 1 h.For the dry residue carbonized by rising from room temperature to 550℃at a heating rate of 5℃/min for 30 min,the optimal steam activation process parameters are:steam flow rate 2 mL/(h·g),activation temperature 900℃,activation time 1.5 h and heating rate 5℃/min.The surface carbon component of the tar residue-based activated carbon is loose with distinct pores and abundant oxygen functional groups such as carbonyl,hydroxyl,ester and carboxyl.The specific surface area is 1 045.10 m2/g,iodine value is 939 mg/g,methylene blue value is 125 mg/g,ash content is 8.46%and compressive strength is 90%,all of which reach the national standard requirements of"Granular activated carbon from coal for the treatment of water"(GB/T 7701.4-1997).The total pore volume is 0.654 cm3/g and the average pore size is 3.94 nm with 63.57%of the concentrated mesopore distribution.The COD in biochemical waste water treated by the the tar residue-based activated carbon for 60 min with a solid-to-liquid ratio of 0.6 g/L is reduced from 312 mg/L to 35 mg/L.The transparent and odorless water meets the class B water quality requirements of the Chinese standard"Integrated Discharge Standard of Water Pollutants"(DB11/307-2013).