Investigation On Processing Of Chicken Feathers And Other Wastes Into Functional Carbon Materials

White pollution caused by waste plastic has become one of the most serious problems facing mankind. The waste plastic not only has potential harm to the environment, but also is not beneficial for physical and mental health. Recycling of waste plastic or converting to higher value-added products will be help to reduce the environment pressure and save a lot of energy and raw materials. On the other hand, the keratin wastes such as chicken feathers have also become harm to the environment increasingly, and how to deal with these wastes becomes a difficult problem to be solved. Now a general approach which is compatible with these different kinds of waste and converts them to value-added products needs to be developed. Here in this dissertation, supercritical carbon dioxide (scCO2) is used to treat these different types of waste into carbon materials, and their applications in the field of superhydrophobicity and catalysis have been explored.Poultry feathers are renewable, inexpensive and abundantly available. They hold great business potentials if they can be converted to valuable functional materials. Pyrolysis of1g of waste chicken feathers (quills and barbs) in supercritical carbon dioxide (SC-CO2) system at600℃for3h leads to the formation of0.25g well-shaped carbon microspheres(CMS) with diameters of1-5μm and0.26g ammonium bicarbonate ((NH4)HCO3). Reaction temperature plays a critical role in the product formation. Below600℃, no (NH4)HCO3and little carbon product could be generated. The CMS product has very high nitrogen content (12.8wt.%). Using this strategy, ca.30.6wt.%of the nitrogen content in the chicken feathers is transferred to (NH4)HCO3and ca.21.1wt.%is transferred into nitrogen-containing CMS product. Furthermore, we developed a simple coating strategy to prepare super-hydrophobic fabric materials using CMS and annealed CMS products, and the water contact angle can reach153.2±1.7and165.2±2.5°. The biggest advantage of this strategy is that the whole chicken feather (quills and barbs) can be converted to two valuable materials at the same time. Furthermore, other nitrogen-containing materials (such as nylon-6) can also be converted to carbon microspheres and (NH4)HCO3highly efficiently, suggesting the generality of this process.We have also developed a strategy for the catalytic conversion of chicken feather waste to carbon-Ni3S2coaxial nanofibers (Ni3S2@C) which can be further converted to nitrogen doped carbon nanotubes (N-CNTs). Using this strategy, ca.34.0wt.%of the nitrogen content in the chicken feathers is transferred to (NH4)HCO3fertilizer and ca.9.5wt.%is transferred into the outer nitrogen-containing carbon nanotubes. About86.6wt.%S of element in the chicken feathers is converted into Ni3S2, which is beneficial to reduce the emissions of harmful gas, such as H2S or SO2. Both Ni3S2@C and N-CNTs exhibit high catalytic activity and good reusability in reduction of4-nitrophenol (4-NP) to4-aminophenol (4-AP) by NaBH4with the first order rate constant (k) of0.9×10-3s-1and2.1×10-3s-1, respectively. Moreover, the catalyst can be easily recycled by centrifugation and maintain the catalytic activity even after6cycles. The catalytic activity of N-CNTs is better than that of N-doped graphene and comparable to commonly used noble metal catalyst. The N content in N-CNTs reaches as high as6.43wt.%, which is responsible for the excellent catalytic performance. This strategy provides an efficient and low-cost method for the comprehensive utilization of chicken feathers. Moreover, this study provides a new application direction for the N-CNTs materials.3C-SiC nanowires have been synthesized by reaction of Polyethylene terephthalate (PET) waste with SiO2microspheres in a supercritical carbon dioxide system at650℃for3h, followed by vacuum annealing at1500℃for4h. The3C-SiC nanowires are tens of microns in length and30-150nm in diameter. It is found that the reaction forming3C-SiC nanowires take place in the inner of the carbon microspheres generated from PET. Therefore,3C-SiC nanowires are embedded in carbon microsphere. After removing the external superfluous carbons by heating in air, the nanowires appear and can be observed by SEM and TEM.Polyethylene-based waste plastics need hundreds of years to degrade in atmospheric conditions. As such, innovative treatment methods are highly desired. Herein, carbon nanotubes with Ni nanopaticles encapsulation are synthesized using polyethylene waste as carbon source and nickel acetate tetrahydrate as catalyst in supercritical carbon dioxide system at650℃for3h. The carbon nanotubes are tens of microns in length and about100nm in diameter, containing20wt%of Ni nanoparticles with diameter of about100nm. About60.7wt%carbon in the polyethylene waste is converted to carbon nanotubes. The carbon nanotubes with Ni nanopaticles encapsulation display a high catalytic activity for the reduction of4-nitrophenol to4-aminophenol. This not only provides an alternative strategy to treat plastic waste, but also demonstrates a new direction for the applications of the carbonaceous materials generated from the plastic waste.