A Rapid Color Detection Method Of Copper Ions In Water Based On Ion-imprinted Materials

Copper has been one of the most commonly used metal elements in human production since ancient times.With the widespread use of copper and its alloys,a large number of copper-containing wastes enter the natural environment.Copper ion is needed by humans as a trace element,but excessive intake can cause health problems.Therefore,in all kinds of environmental standards,copper is strictly controlled as a pollutant.As a result,the research of sensitive and rapid copper ion detection materials and methods has important application value.In this paper,an ion-imprinted material for rapid and specific color detection of copper ions has been synthesized,and its adsorption characteristics for copper ions have been studied.It has been successfully applied to the detection of water samples,and the results are consistent with the analysis data of large precision instruments.The research content of this paper mainly includes the following parts:（1）Diphenylcarbazide,diphenylcarbazone and dithizone as a functional monomer,copper ions(Cu²⁺)as the target ions,2,2’-azobis（2-methylpropionitrile）（AIBN）as initiator,ethylene glycol dimethacrylate（EGDMA）as crosslinking agent,toluene as the pore system and hydroxyethyl cellulose as dispersant,using suspension imprinting technology synthesized the new ion imprinted materials(Cu²⁺-IIPs)with specific adsorption ability.The material with diphenylcarbazide as the functional monomer has better adsorption and color rendering effect,so it was selected as the final monomer for optimal synthesis.The corresponding non-imprinted materials(Cu²⁺-NIPs)were prepared by the same process.（2）The synthesized materials were characterized by Fourier transform infrared spectroscopy（FT-IR）,scanning electron microscopy（SEM）,and thermogravimetric analysis（TGA）.The results showed that the imprinted materials had different morphological structures,more imprinted binding sites and better thermal stability compared with non-imprinted materials.（3）The adsorption capacity of materials for copper ions was studied.The adsorption parameters were obtained through the experiments of adsorption kinetics and adsorption thermodynamics.It can be seen that with the rise of adsorption time,the adsorption amount of Cu²⁺by Cu²⁺-IIPs also increases,and the adsorption reaches equilibrium at 120 min,which has the highest correlation with the pseudo-second-order kinetic model.In addition,the adsorption capacity increased with the rise of temperature,which is an endothermic process.The adsorption isotherm fits the Freundlich model,and the adsorption capacity of copper ions on the material can reach 22.49 mg g^-1.It aiso has a good specific adsorption capacity for metal ions with similar properties to Cu²⁺ions.（4）In order to achieve the best color rendering effect,the detection conditions（p H value,adsorption time,reaction temperature,etc.）and the stability of the material were optimized and determined.It was found that the material only needed to be adsorbed in 5 m L water sample with p H greater than 4 for 1 minute to get the detection result.The material can be detected stably in the temperature range of 0-45℃,the fading will not occur within three days,and the color rendering results are reliable.After 5 times of adsorption-desorption reaction,the adsorption capacity did not decrease significantly.（5）The coloration detection range of the material for copper ions is 0-1 mg L^-1,the corresponding concentration can be obtained according to the standard color scale of copper ion.The lowest chromogenic detection concentration was 0.01 mg L^-1,which meets the detection requirements of all standards.（6）The material was applied to the detection of copper ions in real water,and the results showed that the color detection results of the ion-imprinted material were consistent with the detection results of large precision instruments,which could realize the rapid qualitative and semi-quantitative detection of copper ions in water.Compared with the literature and the copper ions detection materials sold in the market,the material synthesis method proposed in this study has simple steps,low raw material price,good reusability,reliable detection results,strong anti-interference ability,and low detection concentration of 0.01mg L^-1,which can meet the detection requirements of various environmental water sample.