Carbon Fibers Obtained from Flax and Their Adsorption Performance in the Removal of Cu(II) and Co(II) from Aqueous Solutions

The systematic studies on oxidation of carbon fibers with nitric acid are presented. The carbon fibers were synthesized from the low-cost and natural stock (flax fibers) via the controlled carbonization. The non-oxidized and surface oxidized carbon fibers were thoroughly characterized by means of electron microscopy, FT-IR spectroscopy, thermogravimetry, point of zero charge determination, Boehm titration and nitrogen adsorption at 77K. The second part of this work was focused on the evaluation of adsorption properties of oxidized carbon fibers and their potential in the removal of copper(II) and cobalt(II) ions from aqueous solutions. The obtained results bring a conclusion that the concentration of nitric acid is a key parameter which drives the content of oxygen surface groups, thermal stability and adsorption performance of carbon fibers. The obtained oxidized carbon fibers were found to be prospective adsorbents of Cu-II and Co-II from aqueous solutions.