Study On Preparation Of Amino-Functionalized Cellulose Adsorption Materials And Its Adsorption Performance

As a common pollutant in water,heavy metal ions have the characteristics of easy enrichment and non-degradable.Adsorption method is a common method for removing heavy metal ions.It is simple and has high removal efficiency,but its application is limited due to the cumbersome preparation,high cost,and difficulty in recycling.Cellulose is a natural polymer material,it has high chemical stability,low cost,and is biodegradable without toxicity.Cellulose molecules contain multiple hydroxyl groups,making it easy to be modified and treated.It is a good base material for preparing adsorption materials.Select cigarette factory paper and cellulose nanofibers（CE）,use these cellulosic rich materials as the modified matrix for preparing adsorption materials.Through the directed oxidation of cellulose by sodium periodate,the secondary hydroxyl group on the cellulose molecule was converted to an aldehyde group.After a Schiff Base reaction between the amino group and the aldehyde group,polyethylene imine molecules rich in primary and secondary amino groups were grafted onto the oxidized cellulose molecule,thereby preparing amino loaded paper（APA）and amino loaded nanofibers（ACE）.The purpose of removing heavy metal ions from water is achieved through the chelation between amino groups and heavy metal ions.（1）Preparation of paper fiber adsorption materials and testing of their adsorption performance for heavy metal ions:The successful preparation of paper adsorption materials was authenticated by FT-IR,XPS,SEM,and other characterization methods.The factors influencing the preparation of paper adsorption materials were discussed,and the optimal preparation conditions for paper adsorption materials were obtained.The effects of pH value,amount of adsorbent added,inorganic salt solute,and binary system on the adsorption performance of the adsorption material during the adsorption process were explored.It was found that the optimal adsorption performance for Cu（Ⅱ）and Pb（Ⅱ）was obtained at pH values of 5.5 and 4.5,and the salt promoting effect of inorganic salt on heavy metal ions was Na Cl>Mg Cl₂>Na₂SO₄.Cu（Ⅱ）and Pb（Ⅱ）in the binary heavy metal ion system were easier to be adsorbed than Cd（Ⅱ）.The adsorption process of heavy metal ions satisfies the pseudo-second-order kinetic model and the Langmuir isotherm adsorption model,the adsorption occurs in monolayer coverage.The Langmuir isotherm adsorption model has a maximum adsorption capacity of 251.62 mg/g,268.62 mg/g,and 73.24 mg/g for Cu（Ⅱ）,Pb（Ⅱ）,and Cd（Ⅱ）ions.The reusability of the adsorbent material was discussed,it was found that after four adsorption-desorption cycles,the adsorption capacity of the paper adsorbent material remained above 70%.（2）Preparation of cellulose nanofiber adsorption materials and testing of their adsorption properties for heavy metal ions:In this study,the preparation process of nanofibers was first optimized.The effect of the solvent solute ratio of the spinning solution on the morphology and structure of the nanofibers was explored.It was found that when the total mass concentration of the electrospinning solution solute was 21%,the nanofibers with relatively uniform size could be obtained.It was found that when the total mass concentration of the solute in the electrospinning solution was 21%,the nanofibers with relatively uniform size could be obtained.When the mass ratio of cellulose acetate to polyvinylpyrrolidone is 17:4,the composite nanofibers prepared are more suitable for nano size,and after water bath and hydrolysis,the specific surface area of the cellulose nanofibers reaches 5.80 m²/g.The influencing factors in the preparation of nanofiber adsorption materials were discussed,and the optimal preparation conditions were summarized.The factors affecting the adsorption process were explored.The adsorption process of nanofiber adsorption materials for Cu（Ⅱ）,Pb（Ⅱ）,and Cd（Ⅱ）conforms to the pseudo-second-order kinetic model and Langmuir isotherm adsorption model.After four adsorption-desorption cycles,the adsorption capacity of Cu（Ⅱ）,Pb（Ⅱ）,and Cd（Ⅱ）on nanofiber adsorption materials can still reach 73.21 mg/g,77.81 mg/g,and 39.49 mg/g.