Quinoline Adsorption Properties Of Polyethylene Glycol/Graphene Aerogel And Its Surface Molecularly Imprinted Material

Quinoline is a typical toxic and refractory organic compound in coking wastewater.If it is not treated in time,it will directly endanger human health.At the same time,quinoline has a great economic value.Therefore,it is of great significance to realize the removal and recycling of quinoline in coking wastewater.At present,most of the adsorbents used for quinoline adsorption are powder materials,which have some problems,such as poor adsorption performance,difficult solid-liquid separation,low selectivity,and secondary pollution.Graphene aerogel（GA）,as a kind of bulk material,favors solid-liquid separation.However,its structure is easy to collapse because of its inherent brittleness.Therefore,in this thesis,using graphene oxide（GO）as precursor,L-ascorbic acid（LAA）as reducing agent and polyethylene glycol（PEG）as cross-linking agent,polyethylene glycol/graphene aerogel（LPGA）with good structural stability and hydrophilicility was prepared,and used for the adsorption of quinoline in water.On this basis,combined with surface molecular imprinting technology,a surface molecularly imprinted material（MAA/LPGA）with easy solid-liquid separation,high adsorption capacity and selective adsorption of quinoline was synthesized by using LPGA as carrier.The specific research contents and results are as follows:1.Preparation and adsorption properties of LPGALPGA was prepared by the combination of reductive self-assembly and chemical cross-linking,with GO as precursor and PEG as crosslinking agent.The type of reducing agent and the amount of PEG were optimized.Finally,LAA was used as reducing agent,and the mass ratio of LAA to PEG was 1:2.The morphology,structure,and hydrophilicity of LPGA were characterized,and its adsorption performance for quinoline in water was investigated.The results show that LPGA has ultra-light weight(the density is 6.5 mg cm^-3),super hydrophilicity（water contact angle is 0°）,and good structural stability（bearing 2500 times of its own weight）.When the initial concentration of quinoline solution is 50 mg L^-1,the equilibrium adsorption capacity of LPGA for quinoline is 83.62 mg g^-1 at 298 K,and the adsorption equilibrium time is 8 h.The whole adsorbent can be taken out after the adsorption is finished,so that the solid-liquid separation is easy.The results of adsorption kinetics,isotherm,and thermodynamics show that the adsorption of quinoline on LPGA can be described by the pseudo-second-order kinetic model and the Langmuir isotherm model,the adsorption is monolayer chemisorption,and the whole adsorption process shows spontaneous and exothermic characteristics.2.Preparation and adsorption properties of MAA/LPGAIn order to improve the adsorption capacity of adsorbent and realize the selective adsorption of quinoline,through optimization of functional monomer,surface molecularly imprinted material MAA/LPGA was prepared,usingα-methylacrylic acid（MAA）as functional monomer,LPGA as carrier,quinoline as template molecule,ethylene glycol dimethacrylate as cross-linking agent,azobisisobutyronitrile as initiator,and acetonitrile as solvent.The morphology,structure,and hydrophilicity of MAA/LPGA were analyzed,and the adsorption properties of quinoline on MAA/LPGA were investigated.The results show that the specific surface area of MAA/LPGA is 48.77 m²g^-1,which is mainly mesoporous.The material has good structural stability and super hydrophilicity（contact angle is 0°）.The equilibrium adsorption capacity of MAA/LPGA is 102.35 mg g^-1 at 298 K when the initial concentration of quinoline is 50 mg L^-1.The adsorption equilibrium is reached within 8 h,and the monolithic adsorbent easily realizes the solid-liquid separation.The adsorption kinetics show that the adsorption of quinoline on MAA/LPGA follows the pseudo-second-order kinetic model and is mainly chemical adsorption;The results of isothermal adsorption and thermodynamics show that the adsorption process of quinoline is spontaneous and exothermic,mainly monolayer adsorption,which accords with Langmuir isothermal model.The relative selectivity of quinline against phenol is 1.60,indicating that MAA/LPGA has good selectivity.In summary,the introduction of LAA and PEG in the preparation of LPGA improved the structural stability and hydrophilicity of the material,and improved its adsorption properties for quinoline.Using LPGA as carrier,MAA/LPGA prepared by surface molecular imprinting technology exhibited abundant adsorption sites,emhanced adsorption capacity,and selective adsorption of quinoline,which provides a new way for the selective adsorption and resource recycling of quinoline in coking wastewater.