Preparation Of Magnesium-based Layered Double Hydroxides And Expioration Of Their Catalytic Performance

Layered double hydroxides?LDHs?have the advantages of stronger ion exchange capacity,unique “memory effect” and controllable band gap.Therefore,it is widely used in the fields of catalysis,adsorption,electrochemistry,anion exchange,new polymer materials and etc.Among the many LDHs,the synthesis and application of magnesium-based LDHs?Mg M-LDHs?are utilized in the development of magnesium salt resources in salt lakes.In this paper,Mg M-LDHs?M=Al,Ga,In?,Au/MgAl-LDHs and TiO₂/RGO/MgAl-LDHs composite materials were prepared and their catalytic performance were investigated.The main research contents are as follows:?1?Mg M-LDHs?M=Al,Ga,In?were prepared by one-step co-precipitation method,and the catalytic performance of photocatalytic degradation of antibiotics?ciprofloxacin and tetracycline hydrochloride?was explored.Furthermore,the performance of adsorption of phosphorus compounds and photocatalytic degradation of ciprofloxacin was studied.The studied show that there was no significant difference of the catalystic activities among three catalysts in the synthesized Mg M-LDHs materials,and the degradation performance of MgAl-LDHs to antibiotics was slightly better.In addition,the adsorption of phosphorus compounds by MgAl-LDHs helped to improve the catalytic activity of photocatalytic degradation of ciprofloxacin.A series of characterizations were carried out on the catalyst,and the possible photocatalytic mechanism of MgAl-LDHs was studied.?2?Au/MgAl-LDHs were prepared by impregnation-reduction method and used as photocatalysts for the degradation of ciprofloxacin and thermocatalytic for hydrogen production form formic acid at low temperature.The catalytic performance of Au/MgAl-LDHs,?PVP@Au?/MgAl-LDHs and MgAl-LDHs ware studied systematically.It was found that when the size of the supported Au nanoparticles was similar,the addition of PVP has significant inhibitory effect on the catalytic activity of the catalyst,indicating that the surface composition of the catalyst has a significant effect on the catalytic activity of the catalyst.In addition,the plasmon resonance effect wasn't found in the activity investigation of Au/MgAl-LDHs.Therefore,the photocatalytic reaction mechanism of Au/MgAl-LDHs was proposed.?3?TiO₂/RGO/MgAl-LDHs was synthesized by hydrothermal method form TiO₂ colloidal particles and graphene oxide/MgAl-LDHs?GO/MgAl-LDHs?,and the catalytic performance of photocatalytic degradation of ciprofloxacin and formaldehyde was studied.Different reduction methods of GO/MgAl-LDHs to RGO/MgAl-LDHs were investigated,and the photocatalytic activity was the best when hydrothermal method was used.The composite materials of different proportions with TiO₂ and MgAl-LDHs ware explored,and the photocatalytic performance was found to be the best when supported with 10%TiO₂.Furthermore,it was found that the catalytic activity of photocatalytic degradation of ciprofloxacin and formaldehyde in the ternary composite system was further improved.