Graphene Oxide-based Composites Combined With Bio-immobilization For The Treatment Of Organic Wastewaters

Nowadays,with the increase of organic wastewaters discharged into the environment,the environmental pollution problems are getting worse.A number of multifunctional nanocomposites with the characterization of eco-friendly and efficient have been developed.As a derivative of graphene,graphene oxide?GO?has a large specific surface area.Moreover,GO is heavily decorated by functional groups on its surface,which makes it chemical active and easily modified.Thus,the applications of graphene oxide-based nanocomposites in the treatment of environmental pollutants have become a hot point gradually.In this thesis,modified graphene oxide and its composites were synthesized to deal with organic wastewaters efficiently.However,ordinary adsorbents could reach adsorption equilibrium but could not remove pollutants completely.In this thesis,microorganisms were immobilized on nanocomposites to overcome these problems.High concentration organic wastewaters could be removed efficiently by simultaneous adsorption-biodegradation process.?1?A new adsorption material?PGO?was successfully prepared by modifying polymers on the surface of GO via free radical solution polymerization for improve adsorption capacity to DMF.The bacteria?Paracoccus denitrificans?which could biodegrade DMF efficiently were immobilized on PGO by covalent coupling process.The experimental results showed that highly-concentrated DMF?2000 mg/L?could be removed completely by cells immobilized on PGO within 14 h.Moreover,after recycling for 3times,DMF?2000 mg/L?could be removed with a respectable efficiency of about 100%by cells immobilized on PGO during the whole process.?2?Dyeing wastewater is one of the major sources of industrial wastewater.A magnetic nanocomposite Fe₃O₄@SiO₂-GO was successfully fabricated via a simple chemical binding method.The amino groups of Fe₃O₄@SiO₂-NH₂ nanoparticles and carboxyl groups of GO were linked to obtain Fe₃O₄@SiO₂-GO.The bacterial cells were immobilized on the composites firmly by covalent coupling process.Cells immobilized on Fe₃O₄@SiO₂-GO could remove MB efficiently.The rapid adsorption occurred through?-?conjugated effect and anion-cation interaction between composites and MB molecules.And residual MB molecules could be removed continually by biodegradation process of bacteria cells.Moreover,magnetic biological nanocomposite could be separated easily in the external magnetic field,which showed a higher value in the practical application.?3?It is well known that wastewaters containing anionic azo dyes are difficult to deal with.Mesoporous high-surface-area activated carbon?MHSA-AC?was produced from coconut shells by simultaneous chemical and physical activation,which was used for the rapid adsorption of highly-concentrated anionic dye,namely acid orange 10?AO10?.MHSA-AC acts as an efficient adsorbent and a carrier for immobilization of bacterial?Pseudomonas putida?.The results showed that AO10 could be removed with a respectable efficiency of about 100%by cells immobilized on MHSA-AC within 30 and 84 h for initial concentrations of 5000 and 6000 mg L^-1,respectively.The utilization of natural agricultural waste to deal with the wastewater in the environment achieves the value of waste recycling.