Preparation And Adsorption Properties Of Attapulgite-based Three-dimensional Support

With the continuous improvement of China's industrialization level,the environmental pollution problems it has gradually emerged in people's attention.The most serious one is the pollution of water environment.A large amount of industrial wastewater is discharged into natural water bodies such as rivers and lakes.In these wastewaters,there are often a lot of organic matter,which is difficult to degrade and has high chroma,which is a deadly threat to the water environment,aquatic organisms and human health.In this paper,attapulgite with large specific surface area and special pore structure is selected as the matrix,toluene diisocyanate is used as the coupling agent,and diols with different chain lengths are used as the bonding agent to chemically modify the attapulgite.Prepared a series of three-dimensional attapulgite?TATP?;because the flexible carbon chain of the prepared three-dimensional attapulgite is easy to curl,and graphene oxide has better dispersion properties,the three-dimensional attapulgite/graphene oxide?TATP-GO?was prepared by hydrothermal method composite materials;in order to further improve the ability of the three-dimensional attapulgite-based carrier to deal with organic matter in wastewater,using a three-dimensional attapulgite/graphene oxide as a carrier,a heterogeneous Fenton catalyst loaded with ferric oxide was prepared by a hydrothermal method?Fe₂O₃/TATP-GO?,the structural characterization and morphology analysis of the prepared TATP,TATP-GO and Fe₂O₃/TATP-GO were carried out,the adsorption performance of the composite materials for pollutants in water was studied,and the adsorption thermodynamics and kinetics were explored research and research work provide new ideas for the high-value utilization of attapulgite.The main research contents are as follows:A series of three-dimensional attapulgite?TATP?was constructed using toluene diisocyanate?TDI?as a coupling agent and diols with different segment lengths as a bonding agent by chemical grafting.Infrared spectroscopy?FT-IR?,transmission electron microscopy?TEM?,X-ray spectroscopy?XPS?and thermogravimetric analysis?TG?were used to analyze the structure,micro-morphology,element composition and stability of TATP.On this basis,with malachite green as the target pollutant,the adsorption performance of TATP and the thermodynamics and kinetics of the adsorption reaction were studied.The results show that the functionalization of attapulgite is achieved through the reaction between isocyanate groups and silanols on the surface of attapulgite,and the three-dimensional embossed structure is successfully constructed by the reaction between the isocyanate groups on the surface of attapulgite and the bonding molecules.During the construction of three-dimensional attapulgite,the crystal structure of attapulgite has not changed,but due to the supporting effect of the bonding molecules,the pore volume and average pore diameter of TATP have increased.When the bonding agent is polyethylene glycol 600 and the molar ratio of TDI to glycol is 1:0.5,TATP prepared has the largest adsorption capacity for malachite green.The adsorption of TATP to malachite green is an endothermic reaction,and the adsorption thermodynamics conform to the Langmuir equation,and the kinetics satisfy the quasi-second-order kinetic model.The maximum adsorption capacity of malachite green for TATP at pH=7 is 298.51mg/g,which has excellent adsorption capacity.In order to avoid the curling of the flexible carbon chain of three-dimensional attapulgite,the good dispersibility of graphene oxide?GO?was used to prepare the three-dimensional attapulgite/graphene oxide composite material?TATP-GO?by hydrothermal method,TEM,X-ray diffraction?XRD?characterize the structure and morphology of the carrier.Using ciprofloxacin as the target pollutant,the effects of glycol segment length,molar ratio of TDI to glycol and the mass ratio of GO to TATP on the adsorption of ciprofloxacin by TATP-GO were studied,and was studied TATP-GO adsorption performance and thermodynamics and kinetics of adsorption reaction.The research results show that the three-dimensional attapulgite-graphene oxide composite material was successfully prepared by using the dispersion properties of graphene oxide.During the preparation of three-dimensional attapulgite-graphene oxide,the crystal structure of the three-dimensional attapulgite has not changed,and it is only physically compounded with graphene oxide.The TATP-GO prepared from the bonding agent of hexanediol,the molar ratio of TDI to hexanediol of 1:0.5,and the TATP-GO prepared by the mass ratio of GO to TATP of 6:4 has the best adsorption effect on ciprofloxacin.The adsorption of TATP-GO to ciprofloxacin is an exothermic reaction.The results of adsorption thermodynamics fit the Langmuir adsorption model,and the results of kinetics fit the quasi-second-order kinetic model.The maximum adsorption capacity of TATP-GO to ciprofloxacin at pH=7-8 is95.60mg/g,which has good adsorption performance.Using a three-dimensional attapulgite-graphene oxide composite material as a carrier,a heterogeneous Fenton catalyst?Fe₂O₃/TATP-GO?loaded with ferric oxide was prepared and by various test methods such as FT-IR,TEM,XPS were used to characterize the morphology and structure of the catalyst.Taking ciprofloxacin as the target pollutant,the effects of Fe³⁺loading,H₂O₂ dosage,reaction temperature and initial concentration of ciprofloxacin wastewater on the removal of ciprofloxacin by Fe₂O₃/TATP-GO were investigated by single factor experiments influences.The results show that the successfully prepared Fe₂O₃ supported heterogeneous catalyst.When the loading of Fe³⁺is 10%of the mass of the carrier,the molar ratio of H₂O₂ to Fe³⁺is 5.55,and the reaction temperature is 60?,the removal rate of ciprofloxacin by Fe₂O₃/TATP-GO can reach up to 97.49%.The removal of ciprofloxacin is an endothermic reaction,and the removal process satisfies the first-order kinetic equation.The activation energy of the reaction of removing ciprofloxacin by Fe₂O₃/TATP-GO is 28.39KJ/mol.The removal rate of Fe₂O₃/TATP-GO to ciprofloxacin was 64%,which further demonstrated the advantages of the prepared catalyst materials in wastewater treatment.