The Research Of Extraction And Adsorption For Phenolic Compounds In Weitian Coking Wastewater

Direct biochemical treatment of coking wastewater often leads to the microbe poisoning due to its high concentration of pollutants and difficult treatment,it is particularly important to explore a new method for reduction of highly toxic organic compounds and concentration of valuable products,especially phenols.This paper focuses on the technology of Weitian coking wastewater extraction and adsorption,including the optimization of extraction conditions,adsorption of phenol solution and coking wastewater,adsorption theory,and resin regeneration.Multi-parameter water quality analyzer,total organic carbon analyzer,FTIR,BET,thermogravimetry,and GC/MS were used for characterization of water and resin structure to provide data for the optimization of experimental parameters.High value-added utilization of by-products can be achieved by the concentration of phenols in coking wastewater through extraction and adsorption.10 solvents were selected as extraction agent in the optimization experiment of extraction conditions,among them,ethyl acetate and dichloromethane were considered to be efficient.The pH of the coking wastewater is 8.38,under which the extraction rate is high and no need to further acidification.Increasing the extract phase ratio and extraction series can improve the extraction rate,but also raise the processing cost,thus the extract phase ratio and extraction series were finally determined as 4:1 and 4,respectively.In these conditions,the content of phenols was reduced to 23.7 mg/L and the recovery was 56.31%.The chemical oxygen demand(COD)and total organic carbon(TOC)were reduced to 450 and 79 mg/L,respectively.Macroporous resin(MAR)owns excellent adsorption performance due to its high specific surface area and uniform pore structure.4 MARs were used for adsorption of phenol solution,among them,H103 resin exhibited higher efficiency and faster adsorption rate,and its equilibrium absorption capacity was up to 88.47 mg/g.The concentration difference of liquid-solid phase can be increased by the high concentration of phenol solution,which can also enhance the adsorbing phenol ability of the resin.The exploration of resin adsorption mechanism followed 3 ways.Firstly,the adsorbing phenol ability of the resin could be confirmed by the comparison between the FTIR spectras of the raw and adsorbed H103 resin.Secondly,the adsorptive behavior of H103 resin was determined as the pseudo-second-order absorption kinetic study.Finally,the phenol adsorption isothermal process of H103 resin conformed to the Langmuir thermodynamic model,as the result,the surface of H103 resin was uniform,the adsorption process was close to monolayer adsorption and spontaneous exothermic.Combining the phenol adsorption and adsorption theory of H103 resin,the adsorption-desorption-regeneration experiment of the coking wastewater proceeded.The optimal experimental conditions were determined as 280 m L of volume,4 BV/h of flow velocity,and methanol as desorption agent.The regeneration of the H103 resin proceeded after adsorption-desorption,and the resin structure had no obvious change and still owned well dephenolization and recycling ability even after 5 regenerations.In this technology,the total recovery rate of phenols in coking wastewater is 85%,which exhibits the excellent enrichment of phenols.