Preparation Of Modified Chitosan/Polyacrylonitrile Nanofiber Membrane And Its Application In Copper Ion Detection

Copper is an essential trace element for human beings.If the copper intake is too high,it will also cause harm to the human body.Copper ions enter the body mainly through drinking water.Therefore,materials capable of quickly,sensitively and conveniently adsorbing and detecting copper ions in water have attracted widespread attention.Chitosan is an environmentally friendly and non-toxic material with good biocompatibility and is often used in water treatment.At the same time,electrospun nanomaterials have good application prospects in the field of water treatment due to their high specific surface area,high porosity and three-dimensional structure.However,it is difficult to prepare the chitosan nanofiber membrane by electrospinning.Therefore,polyacrylonitrile is used as a spinning aid to prepare a three-dimensional fluffy structure and a certain strength nanofiber membrane for the adsorption of copper ions.Amination,further improve its ability to adsorb copper ions;finally,by doping copper ion fluorescent probes,when the nanofiber membrane meets copper ions,a color change visible to the naked eye occurs.1.The effect of electrostatic spinning parameters on the fineness and strength of chitosan/polyacrylonitrile composite nanofibers was explored,and the spinning surface parameters with good fiber morphology and greater strength were obtained by response surface analysis.The concentration is 20%,the distance is 17.4cm,and the voltage is 80kV.As the optimal spinning conditions,the measured strength is 2.899 MPa,the average fiber diameter is 332.6nm,and the copper ion adsorption capacity is 89.4mg/g.2.Amine modification of polyacrylonitrile to make it also have copper ion affinity.The effects of amination time,reaction temperature,and amination agent concentration on the weight gain and strength of the chitosan/polyacrylonitrile fiber membrane were investigated.It was concluded that the concentration of diethylenetriamine was 30%at the amination parameter and the reaction temperature When the temperature is 120°C and the reaction time is 2 hours,when the weight gain rate is 46%,the copper ion affinity of the nanofiber membrane is good,and a certain strength is retained.When the pH of the copper ion environment is 5-6,the maximum adsorption capacity of the nanofiber membrane can reach 164.3 mg/g,and the adsorption kinetics conforms to the Langmuir isotherm equation.3.A rhodamine hydrazide derivative was synthesized from rhodamine B,hydrazine hydrate and 5-nitrosalicylic aldehyde as a visual copper ion probe.This probe can work stably at a pH value of 4-12,and can realize the selective recognition of copper ions.It is added to the chitosan/polyacrylonitrile spinning solution,and the copper ions in the water are enriched on the surface of the nanofiber membrane by chitosan and aminated polyacrylonitrile,and then doped with copper ions.Fluorescent probes occur to achieve gradient color development of different concentrations of copper ions,and the detection limit can reach 10^-8M.