Design And Catalytic Degradation Performance Of Wood-based MOF Composite Fenton-like Catalysts

With the rapid expansion of industry and the rapid growth of population,environmental and ecological problems are also following.In particular,organic pollutants in industrial wastewater are one of the difficult problems in water treatment.Therefore,seeking new materials and effective techniques for removing organic pollutants from wastewater has become a hot topic in the fields of global materials and environmental sciences.Metal-organic frameworks(MOFs)have been widely used in environmental fields due to their high porosity,structural diversity/tunability,and controllable chemical composition.However,the biggest drawback of metal organic frameworks in water treatment is that it is not easy to recycle and cause secondary pollution,which brings certain challenges to the practical application of this catalyst.Therefore,a suitable carrier is very necessary to solve the problems of aggregation and recovery of nanoparticles and to construct a class of efficient composite catalysts.Biomass materials have attracted great interest in water treatment due to their variety,low cost,and inherently high porosity.Wood is one of the most common and abundant biomass materials with high specific surface area,abundant capillary pore structure and functional groups.Furthermore,wood is used as a carrier and functionalized,which can well solve the problem of secondary recycling of MOF materials.This thesis aims to use MOFs,biomass materials and their derived complexes as experimental objects and organic dyes as experimental treatment objects to explore their catalytic properties.The main research contents of the paper are as follows:(1)Preparation and properties of zeolite imidazole framework-67(ZIF-67)ZIF-67 was synthesized by self-assembly of cobalt ions in cobalt salts with 2-methylimidazole through coordination.Through the analysis of specific surface area,it was found that ZIF-67 has mesopores and the specific surface area is as high as 1238 m2/g,which is conducive to the enrichment of PMS and the transfer of electrons.ZIF-67 showed good catalytic performance.The catalytic efficiency for methylene blue(MB)reaches 100%within 60 min.In addition,after four cycle tests,ZIF-67 still maintains good cycling stability and its catalytic efficiency can reach 88%.Studies have shown that ZIF-67 has good application prospects as a heterogeneous catalyst to activate PMS to degrade methylene blue(2)Preparation and properties of ZIF-67 modified poplar skeleton-derived Co-based porous magnetic carbon compositesA Co-based porous magnetic carbon composite catalyst(Co@N-PC)was successfully synthesized by a two-step route of in-situ synthesis and thermal reduction using wood processing residues of poplar waste wood chips as a carrier to construct Fenton-like catalytic system for the efficient degradation of methylene blue(MB)by activating PMS.The prepared catalyst(Co@N-PC)was evaluated by the catalytic degradation reaction of MB.It was found that the degradation efficiency of MB by the catalyst(Co@N-PC)reached 100%within 30 minutes.The excellent catalytic performance of this material is related to its unique porous structure and abundant cobalt nanoparticles exposed on the surface of Co@N-PC.In addition,the magnetic property analysis shows that Co@N-PC has good magnetic properties,which is beneficial to the separation of the catalyst from the treated water by using an external magnetic field.The Co@N-PC catalyst can still maintain 84.02%of the catalytic performance after four cycle tests.To this end,this experiment proposes a feasible strategy to utilize waste biomass resources to prepare low-cost and scalable MOFs-based materials for efficient and large-scale wastewater treatment.(3)Preparation and properties of Cu-doped ZIF-67/wood aerogel compositesPartial removal of lignin and hemicellulose from anisotropic balse wood to prepare porous low-density compressible wood aerogels as a carrier and in situ wet chemical deposition to prepare Cu-doped ZIF-67/wood aerogel composites.Rhodamine B(RhB)was used as a model dye to investigate the catalytic efficiency of Cu-doped ZIF-67/wood aerogels.It was found that the Cu-doped ZIF-67/wood aerogel composite catalysts with different doping ratios could completely degrade RhB within 15 minutes.At the same time,when the molar mass ratio of Co/Cu is 3:2,it can reach 100%in 7 minutes,and the reaction rate can also reach 0.467 min-1,which is much higher than that of the undoped catalyst.In addition,due to the electron transfer between the active site of Cu and the active site of cobalt in Co-MOFs,the efficient redox cycle of Co2+ and Co3+ is led to promote its catalytic degradation efficiency.