Adsorption Performance Of NiCoCr-LDHs And Their Composites On Methyl Orange Dye Wastewater

Dyes are widely used in textile,paper,rubber,plastic and other industries,and a large amount of dye wastewater is discharged into natural waters,causing great harm to human health and natural aquatic systems.In order to reduce the adverse effects of dye wastewater,humans have used various technical methods to solve the problem,among which the adsorption method is widely used because of its high efficiency and low process cost.In this paper,different new ternary NiCoCr-LDHs with high adsorption properties were prepared by urea hydrolysis,constant pH co-precipitation,ultrasonic co-precipitation,SDS modified NiCoCr-LDHs,and TEA-assisted synthesis.NiCoCr-LDHs were characterized by XRD,SEM,EDS,XPS,BET,FTIR,EA,TG-DSC,ICP,and other characterization methods,and the adsorption kinetics and adsorption isotherm models were established to explore its adsorption mechanism for dyes.And the recycling and OER performance of the material were tested.(1)NiCoCr-LDHs with three different synthesis methods were prepared by urea hydrolysis,constant pH co-precipitation,and ultrasonic co-precipitation.The effects of adsorption time,methyl orange concentration,temperature,pH,and material dosage on the adsorption of methyl orange by NiCoCr-LDHs were systematically studied.The maximum adsorption capacities Q_m of Urea,CC-H and U-H were 355 mg/g,390 mg/g,and 278 mg/g,respectively.The adsorption kinetic model was established,and the three materials were more in line with the pseudo-second-order kinetic model,indicating that the three materials were mainly chemisorptions.At the same time,the adsorption isotherm model was also established,and the Langmuir isotherm model was more suitable for the three materials,indicating that the material was dominated by monolayer adsorption.Cycling tests demonstrated that the materials have good cycle performance,and electrochemical tests demonstrated their good OER activity.(2)Using 0.4 mol/L and 0.8 mol/L SDS solutions to intercalate NiCoCr-LDHs to obtain two kinds of SDS-NiCoCr-LDHs,which were tested for adsorption performance and mechanism analysis.The maximum adsorption capacities of SDS-LDH-1 and SDS-LDH-2 were 395.2 mg/g and 403 mg/g,respectively.The adsorption kinetics and isotherm models were established,and the experiments proved that the two materials conformed to the second-order kinetics model,indicating that chemical adsorption was the main method,and the Langmuir isotherm model was consistent,indicating that the materials were mainly monolayer adsorbing.The material was tested to have good cycle performance and OER activity.(3)Three kinds of NiCoCr-LDHs with different TEA content were prepared by TEA,and the characterization test,and adsorption performance test and analysis of the three NiCoCr-LDHs were carried out.Experiments show that the maximum adsorption capacities of NiCoCr-LDHs-T2,NiCoCr-LDHs-T3,and NiCoCr-LDHs-T4 are 1671mg/g,2269 mg/g,and 2035 mg/g,respectively.The adsorption kinetics and adsorption isotherm models were established,and the results proved that the three materials were more in line with the pseudo-second-order kinetic model,indicating that the three materials were dominated by chemisorption.The Langmuir isotherm model is more suitable for the three materials,indicating that the materials are dominated by monolayer adsorption.The three materials have excellent recycling performance and good OER activity.