Mechanism And Application Of Floating Graphitized Carbon Composite Photocatalyst For Removing Tetracycline Pollutants From Water

Antibiotic pollution in surface water has become a focus of water quality and ecological risk assessment.Antibiotic pollutants has also been listed as one of the most concerned new micro pollutants.Effective removal of low concentration antibiotics from surface water is of great significance for water environment purification and ecological health maintenance.Many scholars had focused on the resource utilization of peanut shell-based biochar as a widely sourced agricultural waste.Artificial electrode graphite materials had high electrical conductivity,thermal conductivity,and rich pore structure.The graphite scrap generated during the processing of graphite electrodes had high resource utilization value.The effectiveness of modifying semiconductor photocatalysts with graphite materials to improve catalytic performance had been confirmed by previous studies.Therefore,this topic carries out research on the proportion of raw materials,preparation technology,and other aspects to prepare floating biographize carbon porous materials with good pore structure and high adsorption performance,which could be used to remove low concentration tetracycline pollution in the water bodies.The specific research content was as follows:（1）In order to improve the adsorption and photodegradation of tetracycline antibiotics by purification materials,modified graphitized carbon（GC）was first prepared using peanut shell and electrode graphite powder by a kneading process,and then titanium dioxide graphitized carbon（Ti O₂-GC）photocatalyst was synthesized by impregnation method.The degradation effect of the catalyst on tetracycline in aqueous phase was investigated.As characterized by XRD and SEM,the results showed that the crystal structure of the Ti O₂ film loaded on GC was pure anatase phase.FTIR and XPS showed that after loading,a Ti-C-O valence bond was formed in the catalyst,and UV-Vis DRS showed that the band gap of Ti O₂decreased to 2.67 e V.The electrochemical properties showed that the recombination rate of the photogenerated electron hole pair of the Ti O₂-GC was low.The experimental results of photodegradation of tetracycline hydrochloride showed that the Ti O₂-GC had a high adsorption and degradation ability for TC（the dosage of catalyst was 0.7 g/L,the degradation rate reaches 94.64%after 2 hours of visible light irradiation）.The degradation kinetics study showed that the photodegradation process conforms to the first order kinetics equation.The Ti O₂-GC composite catalyst still maintains high catalytic activity after five consecutive cycles of application.（2）Using peanut shell,electrode graphite and floating beads as raw materials,polyvinyl alcohol as a binder,and phosphoric acid as an activator,floating graphite carbon beads（FGC）were prepared for the adsorption and removal of TC in water bodies.SEM and BET showed that the specific surface area of FGC was 61.39 m²/g,and the surface pore size was mostly mesoporous with a good pore structure.The material had good mechanical strength,low density,and was easy to recycle.When p H was 4-10,the adsorption efficiency of FGC for tetracycline could reach about 80%,and the adsorption kinetic characteristics conform to the quasi second order kinetics and Langmuir isothermal adsorption model.（3）Using FGC as carrier and butyl titanate as raw material,a floating titanium dioxide graphite carbon pellet（FTDGC）photocatalyst was fabricated by impregnation molding calcination process,and was used to conduct visible light irradiation degradation experiments on tetracycline hydrochloride in water.The results showed that the FTDGC had good photodegradation performance for 6.65 mg/L tetracycline.The physical and chemical properties of the FTDGC were characterized by XRD,SEM,FTIR and XPS.The results showed that the Ti O₂ catalyst had a good anatase crystal structure and was uniformly loaded on the surface of carbon-based materials.The adsorption capacity of graphite carbon accelerates the migration rate of pollutants to the surface of the composite material.At a dose of 4.5 g/L,the removal efficiency of xenon lamp irradiation for 3 hours reached 90.08%.When the p H was 6-8,the added carbon-based material had a buffering and regulating effect on the p H of tetracycline wastewater.The recycling experiment showed that FTDGC still had a good degradation ability for tetracycline hydrochloride after five times of reuse.