Adsorption Of Organic Compounds From Reverse Osmosis Concentrate In Petrochemical Wastewater Treatment Plant Based On Modified Activated Carbon

Reverse osmosis concentrate（ROC）is high risk to the water environment duo to its high salt content,low molecular weight and strong inhibition to microorganism.Activated carbon adsorption is a convenient,economical and effective method for treating ROC,however,commercial activated carbon is difficult to achieve the desired results in practice.Therefore,this study is devoted to preparing modified activated carbon and focuses on the removal of organic compounds from ROC generated from petrochemical wastewater treatment plants.The main contents and results are as follows:1.The raw material of activated carbon made from apricot shell was fired at 900°C,modified with mixed acids and loaded with iron oxides to obtain AC-Fe material.Iron oxide active substance loaded on activated carbon skeleton,mainly forming Fe₂O₃and Fe₃O₄.The specific surface area of the AC-Fe material was 482.96 m²/g,with 91.97%of the total specific surface area being microporous.The surface of the material contains a great number of oxygen-containing functional groups and has a high degree of thermal stability.2.The effect of different factors（p H,temperature and ionic strength）on the adsorption performance of AC-Fe materials was investigated with the single-factor experiments and response surface model.The results showed that the solution p H was the main factor affecting the adsorption performance of the AC-Fe material when ROC containing higher ionic strength.3.The adsorption process of organic compounds on AC-Fe was fitted with pseudo-second-order and Langmuir isotherm models,with the active site playing an important role in the adsorption capacity.Organic compounds were adsorbed on the surface of the activated carbon in a monolayer,with adsorption occurring on a limited,fixed number of active sites.The thermodynamic parameters indicated that the adsorption of organic compounds on AC-Fe was spontaneous and endothermic,controlled by an entropic change.4.Analysis of the adsorption mechanism combined with the refractory characteristics of the wastewater quality.Electrostatic interactions,hydrogen bonding,functional group complexation and acid-base interactions were the main forces involved in the adsorption process,taking into account the refractory nature of the wastewater.The formation of extra-spherical complexes by electrostatic adsorption,the formation of O-H functional groups by hydrogen bonding and the involvement of Fe-O in the complexation of functional groups played an important role in the adsorption process.The prepared modified activated carbon has good adsorption performance on organic compounds in the ROC of the petrochemical wastewater treatment plant.