New Functional Materials To Enrich And Treat Cobalt In Water

Cobalt is an essential trace element for humans and living organisms,but it can be toxic to humans and living organisms when amplified by bioaccumulation.The low levels of cobalt in natural waters are usually below the detection limit of the instrument and cannot be accurately detected,so it is important to find an adsorbent material to enrich it for post-detection.At the same time,cobalt is an important metal material that is widely used in industry,and the consequent adsorption of cobalt-containing wastewater by a functional material after the previous water treatment process is an effective means of meeting the discharge standards.Therefore,it is important to find one or several good-performing adsorbent materials.Adsorption is a traditional method of enrichment and treatment.Activated carbon and cellulose are commonly used as adsorbents and are widely available,inexpensive,and easy to obtain,but have poor adsorption capacity when used directly.Therefore,in order to improve the adsorption power and increase the adsorption capacity,a new functional material has been developed for this project.This material can be used to enrich trace cobalt in natural waters,solving the problem of low cobalt content and failure to meet detection limits,and also to adsorb cobalt in industrial wastewater,thus reducing environmental risks.In this project,five new functional materials were successfully prepared by modifying activated carbon and hydroxyethyl cellulose with polyethyleneimine,glutamic acid,p-aminobenzene sulfonic acid,and sodium hydroxide solution respectively,and conducting static adsorption,dynamic desorption,stability,and regeneration experiments on the five materials to investigate their enrichment and treatment ability of cobalt in water bodies.The five new functional materials were characterized by FT-IR and SEM.The study shows that:(1)Activated carbon was modified by hydrothermal and ultrasonic methods,and polyethyleneimine and glutamic acid were introduced on its surface to obtain modified activated carbon material 1 and modified activated carbon material 2.The optimum adsorption conditions for modified activated carbon material 1: p H= 7,concussion time is 120 min,the dosage is 0.40 g,the initial concentration is 50.00 μg/m L,and the adsorption rate could reach about 73.35 %;The optimum adsorption conditions for modified activated carbon material 2: p H= 3,concussion time is 15 min,the dosage is 0.40 g,the initial concentration is 5.00 μg/m L,and the adsorption rate could reach about 99.00 %.The adsorption-elution experiments were carried out on 10.00 m L and 10.00 μg/m LCo solutions using 5.00 m L and2.00 mol/L hydrochloric acid solutions in a solid phase extraction column,and the recoveries were measured as 71.06 % and 84.10 %,respectively.(2)Modified cellulose material 1,modified cellulose material 2,and modified cellulose material 3 were obtained by introducing polyethyleneimine,p-amino benzene sulphonic acid,and sodium hydroxide on the surface of hydroxyethyl cellulose as the substrate by hydrothermal method.The optimum adsorption conditions for modified cellulose material 1:p H= 7,concussion time is 90 min,the dosage is 0.28 g,the initial concentration is 5.00 μg/m L,and the adsorption rate could reach about 85.33 %;the optimum adsorption conditions for modified cellulose material 2: p H= 3,concussion time is 120 min,the dosage is 0.14 g,the initial concentration is 50.00 μg/m L,and the adsorption rate could reach about 71.45 %;The optimum adsorption conditions for modified cellulose material 3 : p H= 5,concussion time is60 min,the dosage is 0.40 g,the initial concentration is 5.00 μg/m L,and the adsorption rate could reach about 99.00%.The adsorption-elution experiments were carried out using 5.00 m L and 2.00 mol/L hydrochloric acid solutions in a solid phase extraction column on 10.00 m L and 10.00 μg/m L Co solutions,and the recoveries were measured as 80.72 %,57.14 %,and 98.87 %,respectively.(3)The adsorption process of modified activated carbon material 1 for cobalt is in accordance with the Freundlich isothermal adsorption model,with multi-molecular layer adsorption as the dominant factor;the adsorption process of modified activated carbon material 2,modified cellulose material 1,modified cellulose material 2 and modified cellulose material 3 for cobalt is in accordance with the Langmuir isothermal adsorption model,with single-molecular layer adsorption as the dominant factor,all materials conformed to the proposed secondary kinetic model.(4)Modified activated carbon material 1,modified cellulose material 1 and modified cellulose material 3 were stable,with adsorption rates maintained above 75.00 %,elution rates > 90.00 %,recovery rates > 70.00 %,and RSD ≤ 5.00 %.(5)After modification,the surface structure of the functional material becomes rougher,and the specific surface area increases,which is more favorable for the adhesion of cobalt.At the same time,because of hydrogen-bond interaction,van der Waals force,electrostatic attraction,or electrostatic repulsion,the modifier binds to the substrate,and the number of functional groups such as hydroxy,carboxyl,and amino groups increases,which is more conducive to the binding of pollutants.In summary,modified activated carbon material 1,modified cellulose material 1,and modified cellulose material 3 have good adsorption performance and stability and can be used for the enrichment of trace cobalt in natural water bodies and also for adsorption treatment of cobalt in industrial wastewater.The results of the study will provide new materials and methods for the enrichment of trace cobalt in natural water bodies and the treatment of cobalt in water.