Preparation Of Modified Zero-valent Iron And Its Application In Treatment Of Oxytetracycline And Chloramphenicol

In order to solve the problems of aggregation,oxidation,and lower reactivity during the reaction of nanoscale zero-valent iron(nZVI),the nanoscale zero-valent iron was modified by using activated carbon and inert metals,such as copper,to prepare nanoscale zero-valent/activated carbon(nZVI/AC)and bi-metal modified nZVI.The modified zero-valent iron was used in the removal of chloramphenicol(CAP)and Oxytetracycline(OTC).The removal performance of modified zero-valent iron on antibiotics was studied,and its removal mechanism was explored.The main contents are as follows:Nanoscale zero-valent iron(nZVI),bimetallic modified nZVI,and nZVI/AC were prepared by liquid-phase reduction method;scanning electron microscope(SEM),transmission electron microscope(TEM),specific surface area analyzer,X-X-ray diffraction(XRD),X-ray photoelectron spectroscopy.(XPS),and energy dispersive spectroscopy(EDS)were used to analyze the structure,specific surface area,the surface functional groups and pore size of the nZVI,AC and modified zero-valent iron.The results showed that the loading of activated carbon and the dispersion of PEG-4000 effectively reduced the agglomeration of nano-iron particles.The results of SEM and TEM showed that the as-prepared nano-scaled iron particles size was 30-100 nm.iron particles have a generally spherical morphology,some on the outer surface of activated carbon and some entering the pores of activated carbon.The results of XRD and XPS confirm that the nano-zero-valent iron is successfully loaded onto activated carbon,and the load The nano-iron has good anti-oxidation ability and can be stored stably;and the addition of inert metal can effectively alleviate the oxidation of zero-valent iron,but the morphology characteristics of the zero-valent iron modified by bi-metal have not changed significantly.EDS spectra were used to analyze the morphology and content of various elements on the surface of modified zero-valent iron particles.The experimental results showed that the inert metal was loaded on zero-valent iron.The effect of nano-zero-valent iron(nZVI),activated carbon(AC)and activated carbon(nZVI/AC)loaded nano-zero-valent iron(nZVI/AC)on the removal of chloramphenicol(CAP)was compared,and the reaction time and reaction temperature were examined for adsorbent removal.The effect of chloramphenicol effects was simultaneously analyzed by kinetics and thermodynamics.The results show that the activated carbon loaded zero-valent iron has the highest removal capacity(545.25 mg/g).The removal capacity and removal rate of chloramphenicol for the three materials are nZVI/AC>nZVI>AC and AC>nZVI/AC>nZVI.The removal of CAP from all three materials can well be desicribed by the pseudo-second-order kinetics model and the adsorption isotherms of chloramphenicol for AC and nZVI/AC by Langmuir model.Temkin shows that the CAP adsorption by nZVI/AC is chemical adsorption,while the adsorption by AC is not.Three-dimensional fluorescence analysis and ultraviolet-visible spectrum analysis showed that loaded zero-valent iron exhibits more complete degradation than unmodified zero-valent iron.At the mean time,mass spectrometry analysis was used to identify the degradation products of chloramphenicol.One of the main products is P-nitrophenol.The dechlorination by free radicals is the degradation mechanism of chloramphenicol by nZVI/AC.The effect of bivalent metal-modified zero-valent iron on the removal of oxytetracycline(OTC)was comparatively studied.The results show that the modified zero-valent iron has a higher removal effect on oxytetracycline than unmodified zero-valent iron because inert metals are The protective effect of iron slows the oxidation of iron,enhances the reactivity of iron,and it can promote the formation of electron transfer,thereby improving the reaction efficiency.The initial pH of the solution has an important effect on the ability of the modified zero-valent iron to remove oxytetracycline,with the pH being 5-6,the strongest removal ability,and the bimetallic modification under strong acidic conditions and alkaline conditions.Zero-valent iron has suppressed the ability to remove oxytetracycline.XPS and MS analysis showed that the OH radical generated by the oxidation of oxytetracycline by the OH radical forms small molecules.This study demonstrated that Cu/nZVI and Ni/nZVI have a strong ability to degrade oxytetracycline and have potential application prospects for removing oxytetracycline.