E. V. Matveev, A. Gaidar, B. Lapshinov, V. V. Berestov
{"title":"Secondary micro- and nanostructures on the surface of microwave carbonized cotton fibers","authors":"E. V. Matveev, A. Gaidar, B. Lapshinov, V. V. Berestov","doi":"10.30791/0015-3214-2023-6-57-74","DOIUrl":null,"url":null,"abstract":"The method of scanning electron microscopy and X-ray microanalysis was used to study the morphology and surface composition of cotton lint fibers carbonized by microwave radiation and secondary micro- and nanostructures formed on the surface of the fibers in the process of carbonization. The mass of 3 g of cotton lint treated with 5 at. % H3PO4 solution and having a cylindrical form with transverse notches was used as samples for microwave carbonization. It was shown that impurity elements contained in the initial fibers move during microwave carbonization from the central region of the sample to the marginal zones, where they are deposited on the fibers both as continuous phosphorus-containing coatings and as micro- and nanostructures with different morphology and composition. It was found that the most difficult to remove impurities are P and Ca. On the surfaces of notches of microwave carbonized samples, mainly in the central part, there are areas of deep black color characteristic of activated carbon. It is shown that the carbonized fibers of these areas do not contain impurity elements. Significant differences in the morphology of the fiber surface in this area were found. Four characteristic types of fiber surface structure were revealed. In similar areas of samples without notches, carbonized earlier, the fiber surface always contained a small amount of impurity elements (phosphorus ~ 3 – 6 at. %, calcium ~ 1 – 3 at. %), and the fiber structure was fairly uniform. Secondary carbon structures of various morphologies were found on the surfaces of the cuts: monolithic carbon deposits with a hummocky and platelet structure, thin transparent films (presumably, graphene-like structures), carbon nanofibers and nanotubes (straight and curved, diameter 70 – 150 nm and several microns long). A large variety of structures of carbon products and the absence of impurities in them is due to the high heterogeneity of the process conditions in the slit gap, within which microplasma spots, spark and arc discharges arise.","PeriodicalId":366423,"journal":{"name":"Physics and Chemistry of Materials Treatment","volume":"36 21","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Physics and Chemistry of Materials Treatment","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.30791/0015-3214-2023-6-57-74","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
The method of scanning electron microscopy and X-ray microanalysis was used to study the morphology and surface composition of cotton lint fibers carbonized by microwave radiation and secondary micro- and nanostructures formed on the surface of the fibers in the process of carbonization. The mass of 3 g of cotton lint treated with 5 at. % H3PO4 solution and having a cylindrical form with transverse notches was used as samples for microwave carbonization. It was shown that impurity elements contained in the initial fibers move during microwave carbonization from the central region of the sample to the marginal zones, where they are deposited on the fibers both as continuous phosphorus-containing coatings and as micro- and nanostructures with different morphology and composition. It was found that the most difficult to remove impurities are P and Ca. On the surfaces of notches of microwave carbonized samples, mainly in the central part, there are areas of deep black color characteristic of activated carbon. It is shown that the carbonized fibers of these areas do not contain impurity elements. Significant differences in the morphology of the fiber surface in this area were found. Four characteristic types of fiber surface structure were revealed. In similar areas of samples without notches, carbonized earlier, the fiber surface always contained a small amount of impurity elements (phosphorus ~ 3 – 6 at. %, calcium ~ 1 – 3 at. %), and the fiber structure was fairly uniform. Secondary carbon structures of various morphologies were found on the surfaces of the cuts: monolithic carbon deposits with a hummocky and platelet structure, thin transparent films (presumably, graphene-like structures), carbon nanofibers and nanotubes (straight and curved, diameter 70 – 150 nm and several microns long). A large variety of structures of carbon products and the absence of impurities in them is due to the high heterogeneity of the process conditions in the slit gap, within which microplasma spots, spark and arc discharges arise.