Study On Hydroxylation Modification Of Cotton Fiber And Itsadsorption Of Heavy Metal Ions

As people pay more and more attention to environmental protection,people pay more and more attention to wastewater treatment technology.Biosorption method has attracted much attention because of its advantages of low production cost,abundant sources and good removal effect.Cellulose is a macromolecule polysaccharide composed of glucose and a natural polymer synthesized by photosynthesis,is a natural resource with huge reserves,insoluble in water and general organic solvents,can be completely recycled.Cellulose is rich in functional groups,easy to chemical modification,and biological compatibility and safety and other advantages,is the nature of human precious wealth.At present,the proportion of cellulose used by human is less than 10%,resulting in the waste of resources.Hydroxy-terminated hyperbranched polymer(HBP-OH)is a highly branched polymer whose end group is composed of many hydroxyl groups,is easily soluble in water and other common solvents,and has high reactivity.In addition,hydroxyl terminated hyperbranched polymer is simple to prepare,low cost,and has a good application prospect.In this thesis,cotton fibers were epoxided with epichlorohydrin and oxidized by sodium periodate bisaldehyde,and then graft with epichlorohydrin as crosslinking agent,graft with acetaldehyde,and optimize the grafting process of ?-CD and HBP-OH,The adsorbent materials were characterized by FT-IR,SEM,XRD,XPS,etc.The adsorption experiments of heavy metals(Pb2+,Cd2+,Cu2+)showed that the prepared cotton fiber adsorbent had higher adsorption capacity than the original cotton fiber.The maximum adsorption capacities of raw cotton for Pb2+,Cd2+ and Cu2+are 2.7mg/g,2.3mg/g and 1.2mg/g,respectively.The maximum adsorption capacities of cotton fiber adsorbent for Pb2+,Cd2+ and Cu2+ are 54.3mg/g,46.5mg/g and 13.8mg/g,respectively.The adsorbent prepared is 8-20 times the adsorption capacity of raw cotton fibers.The influence of epoxidation temperature,amount of ?-CD,grafting time,concentration of sodium periodate,concentration of HBP-OH,adsorption time and adsorbent dosage on the adsorption effect was also discussed.The adsorption kinetics and isotherm model are also used to fit the experimental results.The results show that the quasi-secondary adsorption kinetics model has a good fitting effect on heavy metal ions.