Application Of Glassy Carbon Foam In The Treatment Of Heavy Metal Wastewater

With the continuous expansion of social development and industrialization,water pollution has become one of the most important issues in environmental security.Among them,because heavy metals are easy to accumulate,difficult to metabolize,and highly toxic,the treatment of heavy metal pollution in water has increasingly become the focus of attention.The adsorption method and three-dimensional electrode method are widely used environmental treatment methods and have broad prospects in the treatment of heavy metal wastewater.Selecting suitable adsorption materials and three-dimensional electrode materials has become an important direction of the filed research.Glassy carbon foam is a carbon material with a highly open-cell structure,which is brittle,black in color,and dense in pores.It can be widely used in batteries,biological scaffolds,and environmental management.In particular,the material has the characteristics of high porosity and huge specific surface area,which makes it have a strong adsorption capacity for pollutants.At the same time,the unique spatial structure of the material also makes it have a good prospect as a three-dimensional electrode.Therefore,glassy carbon foam is a good choice for adsorption or electrochemical treatment of heavy metals in wastewater.In this thesis,the properties of the materials are improved,the electrochemical properties and structural information of the materials are studied,and then the effects of the materials before and after the improvement in the treatment of heavy metal wastewater by the adsorption method and the three-dimensional electrode method are explored.The details are as follows:（1）Using glassy carbon foam as raw materials,the electrochemical performance of the material was enhanced by treating with concentrated HNO₃ at 50°C for 5 days,so that the mass-specific capacitance of the treated material reached 190.25F/g,and after10000 cycles,the capacitance retention after GCD cycle is about 80%.After that,the materials before and after treatment were tested and analyzed by scanning electron microscopy（SEM）,infrared（FTIR）,Raman（Raman）,and X-ray diffraction（XRD）,and it was found that glassy carbon foam is a material with a highly developed pore structure.And the whole shape is irregular,the distribution is random,and the degree of graphitization of the material is not high.In addition,the material treated with concentrated HNO₃ at 50°C for 5 days has no change in the external structure and crystal form of the raw material,but its graphitization degree is slightly higher than that of the untreated material and has C=C,C-O,and other functional groups.In addition,the material has also changed from hydrophobic material to a hydrophilic material.（2）In the process of adsorbing heavy metal ions by glassy carbon foam,the influence of factors such as adsorption time,p H,temperature,and initial concentration on the adsorption of Cu²⁺,Pb²⁺,and Cd²⁺by the materials was explored.The removal efficiency trend of heavy metal ions by two kinds of glassy carbon foam is:Pb²⁺>Cu²⁺>Cd²⁺,and the glassy carbon foam treated with concentrated HNO₃ at 50℃for 5 days has a better adsorption rate and adsorption effect than the untreated glassy carbon foam.In addition,the adsorption process and mechanism of glassy carbon foam were studied through the kinetic model and intraparticle diffusion model.The results show that the adsorption process of heavy metals by glassy carbon foam conforms to the pseudo-second-order kinetic model,which is chemical adsorption,and the whole adsorption process is affected by multiple stages that are jointly controlled.In addition,the experiment also found that in the temperature range of 5～80°C,the temperature change had little effect on the removal of heavy metal ions,and the temperature was not the main factor affecting the adsorption of heavy metal ions by glassy carbon foam.Finally,the experiment also explored the regeneration performance of the materials.Both materials have a good regeneration effect,and the regeneration effect of the glassy carbon foam treated with concentrated HNO₃ at 50°C for 5 days is enhanced to a certain extent.（3）In the process of removing heavy metal ions by glassy carbon foam as a three-dimensional electrode,the effects of three-dimensional electrode material,experimental time,p H,cell current,and electrode spacing on the removal of Cu²⁺,Pb²⁺,and Cd²⁺were studied.The experimental results show that the treatment effect of the three-dimensional electrode method is significantly higher than that of the two-dimensional electrode method,and the effect of glassy carbon foam as a three-dimensional electrode to remove heavy metal ions is also stronger than that of activated carbon.In addition,the effect of the treated glassy carbon foam as a three-dimensional electrode in treating heavy metal ions is enhanced compared with the untreated one.Finally,through kinetic analysis,it was found that glassy carbon foam as a three-dimensional electrode for Cu²⁺,Cd²⁺,and Pb²⁺removal of heavy metal ions confirms the quasi-first-order kinetic model.In summary,this thesis proved that the glassy carbon foam has great removing efficiency and no secondary pollution by both adsorption method and three-dimensional electrode method.And after the material was treated with HNO₃ at 50°C for 5 days,its removing efficiency on heavy metal wastewater was well enhanced.This new material provides potential applications in the treatment of heavy metal industrial wastewater.