Plasma treatment for enhancement of the sorption capacity of carbon fabric

In this work we carried out an experimental investigation into enhancement of the sorption capacity of carbon fabric using plasma treatment methods. Carbon fabric is based on viscose fiber and is hydrophobic by nature. Enhancement of the fabric sorption capacity is required for its application in medicine. For this purpose, two plasma treatment methods were considered, i.e. atmospheric nonequilibrium radiofrequency (RF) discharge and a vacuum RF plasma source with an external magnetic field. Samples treated by atmospheric discharge demonstrated aging effects during the first week after treatment. The sorption capacity of samples treated by the RF plasma source was stable over the same period and reached values as high as 0.95. Parameters of the beam created by the vacuum RF plasma source were analyzed and dependences of the fabric sorption capacity and specific surface area on plasma treatment time were investigated. We found that sorption capacity reached its maximum value after 30 min of treatment and did not change significantly if processing was continued, while the specific surface area reached its maximum after 3 min of treatment and quickly decreased after that. It was found that the micropore structure of the fabric remained almost the same during plasma treatment. The volume of mesopores in a unit of the fabric mass (specific volume) doubled during the first 5 min of treatment and returned to initial values after 30 min of treatment. The sorption capacity continued to increase even when the specific surface area decreased after reaching its peak value. This indicates the important role of surface functional groups formed on carbon fibers during plasma treatment. This is consistent with the results of x-ray photoelectron spectroscopy analysis showing changes in surface oxidation during plasma treatment.