Collaborative Removal Of Phenol And Cr(Ⅵ) From Wastewater Using Silica Gel Material Modified With EDTA

Phenol as a representative of organic pollutants,its industrial wastewater involves many fields.However,carcinogenic Cr（Ⅵ）still exists in phenol wastewater involves paint,ink,leather,textile and etc.At present,the treatment of such wastewater based on the classical Fenton reaction is often adopted.These treatment methods have the advantages of economic,availability of reagents and low site requirements.At the same time,there are some limitations:（1）under high p H conditions,iron ions in Fenton reagent will precipitate,resulting in blocked reaction,which greatly reduces the treatment effect of target pollutants;（2）Although the highly toxic metal Cr（Ⅵ）is reduced,the low-valent metal Cr still exists in the wastewater.In order to solve the above problems,this study used self-made EDTA functionalized silica gel as raw material to efficiently remove phenol and Cr（Ⅵ）from wastewater by the combination of improved Fenton and adsorption method.In this study,modified materials in two different forms,EDTA-Silica and EDTA-Fe²⁺-Silica,were prepared and characterized.The modified Silica gels as the base material are used to improve classical FENTON reaction and applied to the removal of phenol organic pollutants.Compared with IDA-Silica,Asp-Silica,Glu-Silica and IDS-Silica,the catalytic property of EDTA functionalized Silica gel for promoting the Fenton reaction was demonstrated,the p H application range of the reaction could be expanded.At the same time,excess Fenton reagents could also be effectively removed by using the strongly chelating property of EDTA,the modified material has excellent reusability in this process.This study successfully improved the classical Fenton reaction and confirmed that hydroxyl radical is the main active substance in the improved Fenton reaction,providing a more efficient method and theoretical basis for the removal of organic pollutants.Taking into account the presence of strong oxidizing Cr（Ⅵ）in the phenol wastewater.In order to evaluate the adsorption performance of Cr（Ⅵ）on modified materials,a series of adsorption experiments were conducted.The optimum adsorption conditions were obtained,The adsorption selectivity and reusability of the modified materials in the adsorption process were evaluated.This study confirmed the strong metal chelation of EDTA-Silica and provided a theoretical foundation for the removal of phenol-Cr（Ⅵ）two-component system.Theoretically,it is inferred that the existence of Cr（Ⅵ）with strong oxidation ability may affect the removal of phenol.Therefore,the subsequent study focused on the removal effect of phenol-Cr（Ⅵ）two-component system based on modified silica gel combined with improved Fenton and adsorption method.The study not only obtained the optimal conditions of the two-component system,but also confirmed that there was a positive synergy between phenol and Cr（Ⅵ）,and the total Cr（Ⅵ）before and after the redox reaction could be effectively adsorbed with the materials.The results show that the material has catalytic and adsorption properties of metal ions,and can effectively remove phenol and metal Cr in the two-component system.The content of residual metal ions in the two-component simulation solution can meet the national emission requirements.In addition,the modified materials show excellent stability and reusable performance in this process.In this work,EDTA functionalized silica gel was used as catalyst to improve Fenton,providing a new idea for the removal of organic pollutants.EDTA functionalized silica gel was also used as adsorbent to provide a new material for the removal of heavy metal ions.In addition,EDTA functionalized silica gel is used to combine improved Fenton and adsorption method.A new combined process was proposed for the synergistic removal of phenol and Cr（Ⅵ）complex wastewater.The modified materials prepared and the innovative process proposed in this study have certain industrial application value.