Fabrication Of Co₃O₄/graphene Foam Heterogeneous Catalyst For Degradation Of Antibiotics

With the increasing demand for health care and food,a large number of antibiotics are used in human health care and feed additives to promote the growth of livestock.As an emerging recalcitrant organic pollutant,traditional water treatment methods are difficult to achieve its effective removal.In recent years,antibiotics have been frequently detected in different water environments around the world.The influence of antibiotics in water on human health and environmental ecological safety has received increasing attention and scientific interest in the field of environmental remediation.Advanced oxidation process（AOPs）,as a deep oxidation technology,has some advantages in the treatment of antibiotic pollutants,but the development of reusable catalysts with high catalytic performance,low metal leakage,easy recovery and stable performance still has a long way to go.Based on the revies of the application of AOPs,graphene-based materials and polyurethane foam in water treatment,two kinds of new three-dimensional graphene foam/Co₃O₄ composites were designed for peroxymonosulfate（PMS）based AOPs.On the one hand,a three-dimensional porous structure is constructed by using graphene or polyurethane foam as the carrier to accelerate the diffusion of substances.On the other hand,active metal oxide particles were anchored by coordination and in-situ polymerization of functional polymer monomers to solve the technical bottlenecks of AOPs process,such as catalyst recovery difficulty,metal desorption leakage and low catalyst activity.The specific research contents are as follows:（1）The Co₃O₄/three-dimension graphene foam composites with hierarchical porous structure has been fabricated by a simple two-step method containing formation of polyurushiol/3D graphene through solvothermal in urushiol/DMF solution and then in situ growth of Co₃O₄ nanoparticles on 3D graphene surface.Meanwhile,polyurethane foam was used as the framework to synthesize Co₃O₄/polyurushiol graphene/polyurethane foam with hierarchical porous structure by one-step solvothermal method.Results demonstrated that the obtained Co₃O₄/graphene foam composite with hierarchical porous structure has excellent catalytic activity for PMS to achieve rapid degradation of tetracycline.When the dosage of PMS was 1.5 m M,the mineralization rate of tetracycline was 70.88%and 80.87%respectively after 5 minutes of degradation.The polyurethane foam framework is beneficial to reduce the amount of graphene and improve the stability of the catalyst.The use of polymerizable monomer urushiol can improve the Co₃O₄ loading,reduce the leakage of metal ions and improve the catalytic performance.Thus,these results are conducive to provide advanced yet low-cost heterogeneous catalysts for eco-friendly treatment of antibiotics-rich industrial waste waters.（2）The Co₃O₄-polypyrrole-3DG and Co₃O₄-polypyrrole-3DG/polyurethane foam were synthesized by using conductive pyrrole instead of urushiol.The effect of polypyrrole on the degradation of tetracycline by PMS was investigated.The results show that the coordination,reduction and in-situ polymerization of pyrrole on the surface of graphene can improve the conductivity of the catalyst and the loading rate of Co₃O₄particles on the surface,thus improving the activity of the catalyst.The obtained Co₃O₄-polypyrrole-3DG and Co₃O₄-polypyrrole-3DG/polyurethane foam has excellent catalytic activity for PMS,which could rapidly activate PMS（1 m M）to degrade tetracycline with the mineralization rate of 80.85%and 90.59%in 5 min,respectively.The results show that the introduction of conductive polymer can improve the catalytic activity of the catalyst,which provides a reference for the design of heterogeneous catalyst.