Preparation Of Sulfhydryl Modified Cellulose And Its Adsorption Performance For Copper Ion In Water

The continuous advancement of modern industry technology provides convenience for production and life,but produces a large number of detrimental by-products and wastes.These pollutants have brought great harm to the environment,humans and other organisms.The adsorption method which is widely utilized for the removal of heavy metal ions in water has the advantages of economy,high efficiency,wide application range,less secondary pollution,etc.Biopolymer is a kind of natural polymer material with a wide range of sources that with the feature of possessing a certain adsorption capacity,biodegradable,and environmentally friendly,which makes it a powerful candidate for adsorbent.However,due to the limitation of adsorption capacity and chemical stability,it is difficult to be directly used in sewage treatment.The functional groups provide more active sites for complexing with heavy metal ions,thereby the adsorption performance could be improved through the introduce of them.（1）In this paper,αcellulose is used as the raw material,select and optimize the environmental factors such as temperature,time,solvent type and ratio.Under the optimal conditions,the olefin functional group is introduced into the cellulose（Cell-GMA）through the ring opening of the epoxy group of glycidyl methacrylate.Subsequently,hydrogen sulfide was introduced into Cell-GMA,and thiol-modified cellulose（Cell-SH）was prepared by Michael addition,and its ability to remove copper ions in water was studied by batch experiments.The results show that the adsorption of copper ions on Cell-SH is a spontaneous exothermic process.The adsorption isotherm curve follows the Langmuir model,copper ions are uniformly adsorbed on the surface of Cell-SH in the form of a monolayer.At 25°C,p H=6,the maximum adsorption capacity of Cell-SH is 667.878mg·g^-1.At each temperature in the experiment,the concentration of the copper ions solution can be reduced from106.852 mg·L^-1 to less than 0.5 mg·L^-1.Cell-SH has a very fast adsorption rate and follows a pseudo-second-order kinetic model（R²=1）,which mainly adsorbs copper ions in aqueous solution through ion exchange and coordination.Under the coexistence of other divalent metal cations,the removal rate of copper ions by Cell-SH can still be as high as 97.59%.After 6 desorption-adsorption cycles,the removal rate of copper ions in the solution by the adsorbent is reduced to 70.77%.Cell-SH has great potential for removing copper ions from water.（2）Using alkalized cellulose as raw material and GMA as modifier,four kinds of epoxy functionalized cellulose were prepared by coating,alkalization and ring-opening and graft copolymerization.Then use Sodium hydrosulfide hydrate to modify them for the purpose of introduction of thiol groups.The experimental results show that the epoxy functionalized cellulose（C-c-PGMA）obtained by the coating method has a higher epoxy group content.And the epoxy content is about 5.052mmol·g^-1.The adsorption capacity of cellulose（C-c-PGMA-SH）modified by thiol groups on copper ions was studied,and the results show that the adsorption of Cu（II）on C-c-PGMA-SH is a spontaneous exothermic process,and follows the Langmuir model（R²>0.95）and the pseudo-second-order kinetic model（R²>0.999）,indicating that Cu（II）is a single-layer chemical adsorption on the surface of C-c-PGMA-SH.At25℃and p H=6,the maximum adsorption capacity of C-c-PGMA-SH is 281.440mg·g^-1.In the coexistence of other divalent cations,although the removal rate of copper ions by C-c-PGMA-SH is 77.78%,the adsorption capacity can reach 184.322mg·g^-1.After 6 desorption cycles,it still remain a removal rate of more than 90%.