| Palladium is the most popular and widely used platinum group metals in modern high-tech industrial industries.Due to its unique physical and chemical properties,such as strong corrosion resistance,good biocompatibility,and high catalytic activity,it has been specifically applied in emerging fields such as aerospace,pharmaceuticals,and new energy vehicle manufacturing.Because the natural abundance of palladium in the crust is extremely low(<3.7×10-5 ppm),so it is difficult for palladium metal extracted from natural ores to continuously meet the increasing demand of the industrial industry year by year.Therefore,separating and extracting palladium resources from manually manufactured secondary resources（mainly high-level liquid waste）has become a strategic research task.This article selects the adsorption method,which has low environmental pollution and is easy to operate,as the main research method.Two types of adsorbents have been successfully designed and prepared,one is a new XAD functional composite resin material（extraction resin）,and the other is a new silicon based functional composite resin material（chelating resin）.The main research results of both materials are as follows:（1）A novel type of XAD functional composite resin material was prepared using vacuum impregnation method to prepare 16 types of XAD functional composite resin materials.Through performance and characterization screening experiments,MMBT/XAD7HP was ultimately selected as the optimal research object.The optimal nitric acid acidity,adsorption kinetics,adsorption isotherm and adsorption thermodynamics were investigated through static adsorption experiments.The optimal acidity of MMBT/XAD7HP for Pd（II）in nitric acid solution is 1 M,the adsorption kinetics time is 9 hours,and the adsorption capacity is 130.1 mg/g.In addition,the adsorption kinetics of MMBT/XAD7HP on Pd（II）conforms to the second order kinetic model,the adsorption isotherm conforms to the Langmuir model,and the adsorption thermodynamic type is the entropy increase controlled endothermic reaction.Through elution experiments,it was found that a mixed solution of 0.5 M thiourea and 1 M nitric acid had the best elution effect,with an elution rate close to 100%.The separation and enrichment performance of MMBT/XAD7HP for Pd（II）in simulated high-level radioactive waste was evaluated through dynamic column experiments,with a recovery rate of nearly 100%.Finally,the combination of FT-IR,XPS,and DFT calculations was used to analyze the adsorption mechanism.Specifically,the C=N-C and C-S bonds in MMBT/XAD7HP will jointly form a negative potential energy region,attracting positively charged Pd2+to coordinate in this negative region.NO3-ions will maintain the charge balance of the coordination structure during the adsorption process.（2）A novel type of silicon based functional composite resin material,2AT-Si Aa C material,was prepared using a two-step method（in situ polymerization and acylation reaction chemical grafting method）.The optimal nitric acid acidity,adsorption kinetics,adsorption isotherm and adsorption thermodynamics were investigated through static adsorption experiments.The optimal acidity of 2AT Si Aa C for Pd（II）in nitric acid solution is 0.5 M,the adsorption kinetic time is 1h,the saturated adsorption capacity is 62.1 mg/g,and the adsorption thermodynamic type is endothermic reaction controlled by entropy increase.The separation and enrichment recovery performance of 2AT-Si Aa C for Pd（II）in simulated high-level radioactive waste was evaluated through dynamic column experiments,and the recovery rate was close to 100%.Finally,the relevant adsorption mechanism was analyzed through FT-IR and XPS.Specifically,the nitrogen containing functional groups and NO3-ions in 2AT-Si Aa C will participate in the coordination of Pd（II）during the adsorption process.This article provides relevant technical support for the design and preparation of functional composite materials for separating Pd（II）from complex solution environments through the study of MMBT/XAD7HP and 2AT-Si Aa C. |
