Study On Preparation Of PAN Functional Fiber Membrane And Adsorption Properties

The rapid development of industrialization has not only brought economic benefits,but also brought many drawbacks to be solved,such as the water environment pollution and damage caused by heavy metal ions and dye molecules.Heavy metals and dyes that are carried into natural world with the water pollution can greatly affect the growth and metabolism of plants and animals.Furthermore,when get into human bodies through food chain,they can induce various diseases.Therefore,it is particularly important to remove heavy metal ions and dye molecules in aqueous solution.Among the numerous removal methods,adsorption method has become a popular way due to its advantages of low cost and easy operation.In this paper,polyacrylonitrile?PAN?was chosen as the matrix,three different kinds of fiber membranes as adsorbents were prepared by using electrospinning technology and chemical methods.Then the adsorption behaviors of copper ions,methylene blue?MB?and amido black?AB?in aqueous solution by these membranes were studied systematically.The specific research content is as follows:?1?Preparation of PAN-based chelating fiber membrane and its adsorption properties for copper ions.PAN fiber membranes were prepared by electrospinning technology.The fiber membranes were the first time to be treated as follows.Firstly,partial hydrolysis of PAN fiber membranes were carried on by sodium hydroxide,then further amination treatment of partial hydrolyzed PAN fiber membranes were conducted by polyethyleneimine.After both processes,the chelating fiber membranes named APAN were successfully prepared,and its adsorption behavior of copper ions in aqueous solution was investigated systematically.Scanning electron microscopy?SEM?analysis showed that the functionalized fibers had an obvious folded surface,which indicated there were substance attachment on the surface of the fiber.Fourier transform infrared?FTIR?analysis demonstrated there was a stretching vibration peak of H-C=N bond near 1680 cm^-1.Elemental analysis?EA?indicated that the content of N element in fiber membrane increased by 2.54%.All the analysis above verified the successful preparation of APAN fiber membrane.Adsorption experiments showed that the adsorption behavior on copper ions by APAN fiber membrane was in accordance with Langmuir and Pseudo-second-order kinetic model.The maximum adsorption capacity was 149.8 mg·g^-1 at room temperature,pH 6 and adsorption time60 min.?2?Enhanced adsorption performance of PAN fiber membrane enabled by dye capture of?-cyclodextrin.?-CD/PAN composite fiber membranes were prepared through eletrospinning technology using PAN and?-cyclodextrin??-CD?powder.The effects of different?-CD ratios on the physical properties of polymer solutions and changes of the micro structures of fiber membranes were studied,at the same time,the adsorption behavior of MB in aqueous solution by composite fiber membrane was discussed.Physical property data indicated that the addition of?-CD made electrical conductivity and viscosity of spinning solution reach a suitable range,which enhanced the spinning property.SEM analysis demonstrated that?-CD greatly improved the micro morphology of PAN fibers,a small number of beaded structures on PAN fibers no longer existed,meanwhile,the average diameter of composite fibers increased with the addition amount of?-CD.The analysis of FTIR also showed the composite fiber membranes were obtained successfully.Adsorption experiments showed that the adsorption capacity of MB on composite fiber membrane was higher than that on pure PAN fiber membrane,and the adsorption process by composite fiber membrane fitted well in Langmuir and Pseudo-second-order kinetic model.As pH was 7,adsorption time was 40 min,the maximum adsorption capacity was 20.66 mg·g^-1 at room temperature.?3?Preparation of PAN-based anion exchange fiber membrane and its adsorption performance for AB.This part,the?-CD/PAN composite fiber membranes were chosen as matrix,then further chemical treated with triethylenetetramine?TETA?,so as to obtain the amino containing TETA-?-CD/PAN anion exchange fiber membrane.The adsorption behavior of AB in aqueous solution by the anion exchange fiber membrane was considered systematically.FTIR analysis illustrated that the tensile vibration absorption peaks of N-C=N and-NH₂ appeared near 1690 cm^-1 and 1630 cm^-1,which indicated that the TETA-?-CD/PAN fiber membranes were successfully prepared.Adsorption experiments showed that the adsorption behavior on AB by TETA-?-CD/PAN conformed to Langmuir and Pseudo-second-order kinetic model,and the maximum removal rate reached 93.6%at room temperature,pH 1 and adsorption time 30 min.