Preparation Of ZIF-8 Composite Nanomaterials And Its Removal Of Typical Organic Pollutants In Water

With the rapid development of the global economy,the problem of environmental pollution has become more and more serious.Among them,organic pollution in environmental water bodies directly threatens the health of animals and plants.At present,researchers have developed many materials and treatment methods,which are widely used in environmental water treatment.In this study,nanomaterials with different properties were prepared as composite materials,and advanced oxidation technology and microbial treatment technology were used to degrade and remove typical organic compounds in water,which broke through the limitations of single nanomaterials in water treatment process.Firstly,ZIF-8 with high porosity and specific surface area and Fe/Ni NPs with catalytic reduction properties were constructed as a new type of nanomaterial ZIF-8@Fe/Ni.In the treatment of malachite green as the target pollutant,the performance advantages of two nanomaterials are brought into play when dealing with malachite green as the target pollutant.The malachite green with an initial MG concentration of 50 mg L^-1 and a p H of 6.98 can be removed by more than 99%within 120 minutes,and the maximum theoretical adsorption capacity is 151.520 mg g^-1 at a temperature of 318 K.To understand the removal mechanism of organic dyes based on adsorption and catalytic reduction,ZIF-8@Fe/Ni was characterized and tested.XRD results showed that ZIF-8@Fe/Ni composite material had a characteristic peak of Fe⁰ and Ni⁰ near 2?=44.8°,which proved that Fe/Ni NPs were successfully introduced without affecting the structure of ZIF-8;FTIR results showed that after introducing Fe/Ni NPs,the structure of ZIF-8@Fe/Ni remained stable and the adsorption of malachite green had a?-?bond mutual accumulation effect;XPS results showed that the Fe/Ni NPs in ZIF-8@Fe/Ni undergoes electron transfer when removing malachite green,and it had catalytic reduction effect;The overall adsorption process of ZIF-8@Fe/Ni on malachite green conforms to pseudo-second-order kinetics,and the degradation process follows pseudo-first-order reduction kinetics.GC-MS results confirmed that the two main products of malachite green degradation were(4-aminophenyl)(phenyl)methane and 4-aminophenol.,the removal rate of malachite green by ZIF-8@Fe/Ni dropped from 99%to 73%when after 5 cycles;when ZIF-8@Fe/Ni was used for the remediation of printing and dyeing wastewater,the removal of malachite green the rate reached 92%.In conclusion,this study shows that ZIF-8@Fe/Ni has adsorption and catalytic reduction properties for the removal of malachite green,and it is a promising wastewater treatment material.Secondly,used the previously prepared ZIF-8@Fe/Ni nanocomposite material combined with advanced oxidation technology,a Box-Benhnken response surface optimization model was established to optimize various conditions for the removal of ofloxacin,such as reaction temperature,p H,H₂O₂ concentration and the initial concentration of ofloxacin.The results showed that the optimal parameters were as follows:reaction temperature 300.5 K,p H 6.5,H₂O₂ concentration 9.1 mM,ofloxacin initial concentration 26.1 mg L^-1 ZIF-8@Fe/Ni The removal rate of ofloxacin can reach99%in 200 min.SEM results showed that the edge morphology of the nanoparticles of ZIF-8@Fe/Ni nanomaterials after the reaction tend to be smooth,and it had obvious three-dimensional polygon morphology;FTIR results showed that ZIF-8@Fe/Ni had a?-?bond stacking effect on the removal of ofloxacin;XPS results showed that Fe/Ni NPs in ZIF-8@Fe/Ni nanomaterials are involved in oxidation.The reaction showed that the removal of ofloxacin by ZIF-8@Fe/Ni was a combination of adsorption and oxidation.Through kinetic calculation and analysis,the adsorption process of ofloxacin by ZIF-8@Fe/Ni conformed to the pseudo-second-order kinetics and Freundlich adsorption model.Finally,ZIF-8 with high porosity and specific surface area was synthesized on the graphene oxide sheet structure in a certain proportion,combined with microbial treatment technology to load the microorganism Burkholderia cepacia bacillus which can degrade the dye malachite green on GO/ZIF-8 hybrid nanomaterials,a new type of bio-nanomaterial Burkholderia cepacia@GO/ZIF-8 was successfully prepared.XRD structure shows that ZIF-8 crystals have successfully grown in hybrid nanocomposites;FTIR analysis results showed that the main absorption peaks on ZIF-8 and GO are contained on the surface structure of hybrid nanomaterial GO/ZIF-8;BET results showed that the specific surface area of hybrid nanomaterial GO/ZIF-8 is much larger than that of GO and ZIF-8.The decrease in specific surface area of bio-nanomaterial Burkholderia cepacia@GO/ZIF-8 may be due to the loading of microorganisms on its surface.When the reaction time is 60 h,the initial concentration of malachite green is50 mg L^-1,Burkholderia cepacia@GO/ZIF-8 dosage is 1.0 g L^-1,and the reaction temperature is 308 K,Burkholderia cepacia@GO/ZIF-8 removed malachite green of efficiency reached more than 95%.The kinetic calculation showed that the adsorption process of Burkholderia cepacia@GO/ZIF-8 on malachite green conformed to the pseudo-second-order adsorption kinetics,and the degradation process conformed to the pseudo-first-order degradation kinetics.