Preparation Of Titanium Dioxide/rGO Composite Materials And Its Application In The Removal Of Organic Pollutants

There are many organic pollutants in industrial wastewater,because of its strong toxicity,easy enrichment,difficult degradation and other hazards,the study of the removal of these organic pollutants has become an important topic in the field of water treatment.In many water treatment methods,adsorption and photocatalysis are promising methods due to their advantages of high removal efficiency and economic and environmental protection,so the development of a material with good adsorption effect and photocatalytic activity is the key to remove these organic pollutants.TiO₂ is a semiconductor material that has been studied a lot in recent years.However,it has some disadvantages,such as easy compliance of electron holes,low efficiency of optical quantum and difficulty in separation,which restrict its application.At the same time,graphene has attracted people's attention in the field of water treatment due to its advantages of high carrier mobility and large specific surface area.It also lays a theoretical foundation for the application of the two methods in the removal of organic pollutants.In this paper,titanium dioxide/reduced GO?TiO₂/rGO?composites were prepared by one-step hydrothermal method,and the microstructure,phase structure,element composition,optical response and formation mechanism of the materials were investigated by means of XRD,Raman,SEM,TEM,XPS,uv-vis and PL.In the process of synthesis,the functional groups abundant on the surface of GO were used as the active sites for the nucleation growth of titanium dioxide,so that TiO₂ nanoparticles became TiO₂ microspheres with graded nano-structure to grow uniformly on the rGO nanosheet during the synthesis process,and the reduction of GO occurred during the hydrothermal process.Based on this,a new method for removing organic pollutants from water was developed to achieve good results.TiO₂/rGO composite material adsorption and photocatalysis synergistically study the removal of triphenylmethane pollutants rhodamine B?RhB?in water.The wastewater was designed to flow for the first time to explore its removal effect on RhB under total darkness and full light conditions.The results show that:RhB in the wastewater is rapidly absorbed by the TiO₂/rGO composite material after 20 hours of continuous light exposure,and then undergoes photocatalytic oxidation,which maintains 100%removal efficiency for RhB,much higher than that of single nano-TiO₂or pure rGO.The removal effect makes the TiO₂/rGO composite material have a synergistic effect of adsorption and photodegradation.Under dark conditions,the adsorption properties of TiO₂/rGO composite material for RhB are consistent with the pseudo-first-order and pseudo-second-order kinetic models.In addition,the rGO nanosheets in the composite materials improved the photo-quantum efficiency and catalytic activity of TiO₂ by enhancing the light adsorption capacity,stabilizing the separation of electron holes and reducing the band gap energy of TiO₂,and preliminary investigated the mechanism of its removal of RhB.The method is simple in operation,low in cost and is expected to be a material capable of treating triphenylmethane dye wastewater purification in a continuous flow state.Phenol-4-sulfonic acid?PSA?is an important sulfonated aromatic compound that acts as an additive in the electroplating industry.PSA in electroplating wastewater has obvious toxicity to organisms,but its sulfonic acid group?-SO₃H-?may increase resistance to microbial removal.At the same time,the mechanism of the presence of heavy metal ions on photodegradation of organic pollutants is unclear.Taking PSA as the target degradant,the catalytic degradation performance of the prepared TiO₂/rGO composite and the degradation effect of PSA in electroplating wastewater were evaluated.The effect of PSA degradation in the presence of heavy metal ions Cu²⁺was explored.The results show that the TiO₂/rGO composite has a significant removal effect on PSA.At the same time,Cu²⁺ions present in the wastewater have positive and negative effects on the photodegradation of PSA.On the one hand,the electron reduction reaction of Cu?II?consumes a part of the electrons,which can suppress the electron-hole recombination,thereby improving the photon utilization efficiency and catalytic activity.On the other hand,the highly chemically stable PSA-Cu?II?complex hinders the photodegradation of PSA.When the concentration of Cu²⁺is about 25 mg/L,the photodegradation of PSA by TiO₂/rGO composites can be accelerated,and PSA can be completely degraded within 150 minutes.By liquid chromatography,the possible intermediate products in the degradation process were hydroquinone,benzoquinone,maleic acid,and the path in the degradation process was preliminary explored.It is expected to become a new method for degrading organic pollutants containing sulfonic acid phenols.