Application Study On Heavy Metal Cu²⁺ Adsorption And Detection Based On Chitosan Based Gel Composites

With the advancement of technology and the development of human society,heavy metal pollution caused by industrial production has become increasingly serious.Due to the non degradability of heavy metals,the heavy metals released into the environment cannot be degraded through metabolic pathways.With the enrichment of the food chain,they enter the human body and pose great harm to human life and health.Copper ion(Cu²⁺),as a typical heavy metal,excessive intake can lead to symptoms such as nausea and vomiting,causing irreversible harm to the nervous system,and even posing a risk of cancer.In order to quickly identify and reduce the pollution of Cu²⁺in the matrix,based on a wide range of sources,large adsorption capacity,non-toxic and harmless chitosan（CS）gel,through the integration of carbon dots（CDs）and the combination of iron based nanomaterials,a variety of composite materials for Cu²⁺fluorescence response and adsorption removal were prepared,and their mechanisms were discussed,It can provide certain assistance and scientific guidance for the rapid identification,detection,and removal of Cu²⁺.The main research content and results can be summarized as follows:（1）Diethylenetriamine grafted magnetic chitosan gel microspheres（DETA-MCGMs）were prepared by mixing chitosan with polyvinyl alcohol and magnetic Fe₃O₄ nanoparticles through transient gelation,crosslinking and grafting techniques.The maximum adsorption capacity of the composite microspheres for Cu²⁺can reach 303.08 mg/g,and the adsorption equilibrium can be reached within 60 min.Moreover,the recycling performance was good,the adsorption amount of Cu²⁺only decreased by 5%after five adsorption-desorption cycles.The adsorption process of the Gel Microspheres for Cu²⁺conformed to the pseudo second order kinetic model and Freundlich model,which is a chemisorption-based multilayer adsorption.DETA-MCGMs also showed excellent adsorption performance in the actual sample application of tap water and tea drinks.The Cu²⁺content in the treated sample was lower than the specified limit,which was a composite material with good application prospects.（2）In order to integrate the prevention and control of Cu²⁺contamination and to achieve the recognition detection and adsorption removal of Cu²⁺,Cu²⁺responsive bright blue CDs fluorescent probes were successfully prepared by using urea and citric acid as precursors.Meanwhile,CDs were encapsulated into chitosan based hydrogels with the aid of a crosslinking agent,epichlorohydrin,to develop a composite hydrogel with both Cu²⁺recognition and adsorption properties.This composite hydrogel is a three-dimensional pore structure with excellent fluorescence performance,which can specifically identify Cu²⁺and quantify the Cu²⁺content by fluorescence intensity variation,with a linear range of 0.05～5μmol/L,R² of 0.954 and detection limit of 0.45μmol/L.In addition,the composite hydrogel has a good removal effect on Cu²⁺in ultrapure water,tap water and tea drinks,indicating that the specific fluorescent gel strategy can provide scientific guidance and rapid quantitative assessment for the integrated identification and prevention of Cu²⁺in drinking water and some liquid foods.