Preparation And Properties Research Of Lignin-phenol-formaldehyde Based Macroporous Activated Carbon Fiber

Lignin is the second largest nature macromolecular material only inferior to cellulose in amount.There is much lignin obtained from the black liquor of the pulp industry.If you don't recycle it,not only the renewable resource would be wasted,but it would also pollute the environment.So scientists are working hard to explore the new usages of lignin.Lignin's structure is very complicate.There are such groups as phenyl,phenolic hydroxyl,aliphatic hydroxyl,carbonyl,carboxyl, methoxyl,conjugated double bond,et al.,in their structure which make it can react with many substances.Lignin can be got from different kinds of trees and different methods. So the basic properties of lignin were discussed in detail in this paper first, such as particle diameter,structure,shape,glass transition temperature, surface properties and dissolution behavior in acid-base solutions.In this work,the resin was synthesized by lignin,phenol and formaldehyde with different proportion.Thermal gravimetric(TG) analysis/differential thermogravimetry(DTG) were applied to investigate the affect of lignin content on the thermal performance of precursor fiber. The TG results showed that lignin had a protection effect thereby improved the thermal stability of precursor fiber.Lignin phenol formaldehyde(LPF) resin-based macroporous activated carbon fiber was prepared by the means of wet-spinning,coagulation, pre-oxidation and carbonization.A group of activated carbon fibers with different lignin contents namely 0%,8%,14%and 20%were prepared to study the relationship between lignin content and the structure & properties of carbon fiber.The spectra fourier transform infrared(FT-IR) and scanning electron microscope(SEM) pictures indicated that phenol, formaldehyde and lignin formed a homogeneous copolymer.Based on the TG,elemental analysis and SEM results,the mechanisms of carbonization and activation were analyzed and discussed.In the progress of activation, lignin played the role of pore size controller which made the diameters of pores in carbon fiber appropriate and in a narrower distribution. Compared with the preparation steps of normal activated carbon fiber,the mechanism for the formation of macro-pores was proposed.The stress controlled rheometer was used to analyze the static viscosity of spinning raw material(LPF resin).The spinnability of the LPF resin was studied by discussing the outlook of activated carbon fiber and the determination of coagulation bath.To study the adsorption property of this macroporous activated carbon fibers,small molecular(methylene blue trihydrate) and macromolecular(proteins) were considered.The results showed that macroporous activated carbon fiber has a more satisfactory performance on adopting macromolecular than small molecular according to its structure characteristic.