Preparation And Application Of Functionalized Composite Materials Based On Cotton Cellulose

With the rapid development of industry in China,the discharge of large amounts of wastewater has caused serious pollution to the environment,and wastewater treatment has become an urgent problem to be solved.Heavy metals are one of the most important pollutants in wastewater,and Cu²⁺is the most common heavy metal ion in wastewater and poses a serious threat to the ecological environment and human health.In this paper,we used natural polymer material,waste cotton lint,as the substrate,and used two pretreatment methods,dissolution by deep eutectic solvents（DES）and oxidation by sodium periodate（Na IO₄）,respectively,and generated functionalised Fe₃O₄in situ on the surface of the pretreated cotton fibres.Fe₃O₄was generated in situ on the surface of the pretreated cotton fibres,resulting in the preparation of different functionalised adsorbents.The adsorption performance of the different adsorbents on Cu²⁺was investigated and the structural properties of the adsorbents were characterised in detail.The effects of adsorbents at different p H,temperature,initial concentration of Cu²⁺solution,adsorption time and cotton staple species on the adsorption performance of Cu²⁺in wastewater were investigated to obtain the optimum adsorption conditions.Twenty-four different components of ternary DES dissolved cotton fibres were prepared on the basis of binary DES,characterised and analysed by SEM and XRD,and the three that were more effective in modifying the adsorbent material preparation were selected for comparison experiments.These were the outcomes:（1）The adsorption capacity of both materials after DES dissolution and Na IO₄oxidation and then composite synthesis was high for Cu²⁺,with 48.08 mg/g for Fe₃O₄/YCL-Ch Cl/OA and 42.82 mg/g for Fe₃O₄/YCL-Na IO₄,significantly stronger than the unprepared Fe₃O₄/YCL adsorption material.The characterisation analysis showed that the adsorbent Fe₃O₄/YCL-Na IO₄achieved 8.15%loading of Fe compared to 0.19%loading of Fe by Y17 virgin cotton staple,while the adsorbent Fe₃O₄/YCL-Ch Cl/OA achieved 15.3%loading of Fe,which was 1.87 times higher than the loading of Fe by Fe₃O₄/YCL-Na IO₄.（2）The adsorption performance of Fe₃O₄/YCL-Ch Cl/OA on heavy metal ions Cu²⁺ under different adsorption conditions was investigated.The interaction between the adsorbent and the adsorbent mass had a substantial impact on the adsorption capacity and was influenced by p H,temperature,starting solution concentration,and adsorption period.Because all three adsorbents are made of natural cellulose and have essentially identical chemical structures,the impact of various cotton linter kinds on the adsorbent was insignificant.When the solution p H was 6,the temperature was 30℃,the initial concentration of Cu²⁺solution was 1000 mg/L,and the adsorption time was 2 hours,the adsorption capacity of Fe₃O₄/YCL-Ch Cl/OA for Cu²⁺was as high as 48 mg/g.The results of the adsorption isotherm experiments demonstrated that the Freundlich isotherm model accurately described the adsorption of the heavy metal ions Cu²⁺by Fe₃O₄/YCL-Ch Cl/OA,and that this process involved many layers.The results of the tests on adsorption kinetics demonstrated that the adsorption of Cu²⁺on Fe₃O₄/YCL-Ch Cl/OA followed the Pesudo-second-order model and was a composite adsorption involving both chemisorption and physical adsorption.（3）On the basis of binary deep eutectic solvent,24 groups of ternary deep eutectic solvent were created,and dissolution tests were conducted,because the various deep eutectic solvent components have a significant impact on the adsorption performance of cotton linter.Three groups of ternary deep eutectic solvent（Fe₃O₄/YCL-Ch Cl/OA/4HBA,Fe₃O₄/YCL-Ch Cl/OA/EG and Fe₃O₄/YCL-Ch Cl/OA/MA）were chosen from the range of crystallinity and hydroxyl group variations through characterisation study.The results of the adsorption studies with the three sets of ternary deep eutectic solvent were compared with Fe₃O₄/YCL-Ch Cl/OA.The adsorption quantities of Fe₃O₄/YCL-Ch Cl/OA/4HBA reached 54.65 mg/g,Fe₃O₄/YCL-Ch Cl/OA/EG reached 33.38 mg/g,and Fe₃O₄/YCL Fe₃O₄/YCL-Ch Cl/OA/MA attracted 48.28 mg/g of adsorption.This suggests that adding the right quantity of p-hydroxybenzoic acid to the DES solvent species can enhance the number of hydroxyl structural groups,which improves the adsorption effect of the adsorbent on Cu²⁺.The best adsorption effect of Fe₃O₄/YCL-Ch Cl/OA/4HBA on Cu²⁺.