MODIFIED CARBON FIBER. USING THEM TO REMOVE METAL AND ORGANIC IMPURITIES FROM AQUATIC ENVIRONMENTS

The adsorption properties of activated and graphitized carbon fibers to heavy metal ions, phenols and anilines have been studied. It is shown that carbon fibers, modified by oxidation with concentrated nitric and sulfuric acids, quantitatively extract ions of heavy metals from water. The distribution and selectivity coefficients of adsorption of heavy metal ions on an activated carbon fiber and its oxidized samples are calculated, and selectivity series of adsorption are presented. Preliminary treatment of carbon fibers with organic reagents containing heteroatoms-donors of activity and selectivity was carried out. Preliminary application of urea to the surface of the carbon fiber, reduces the time of establishment of adsorption equilibrium from 1.5 - 2 h to 40 min, and increases the recovery of bismuth to 64%. Modification of the carbon fiber with thiourea allows quantitatively (99%) to recover bismuth from water in 20 min. The degree of extraction of tin by modified thiourea fiber increases by 14% and reaches 53%. Molybdenum (VI) and mercury (II) are recovered by activated carbon fiber modified with a 15% solution of thiourea by 80% and 99%, respectively. Modification of the surface of activated and graphitized carbon fibers with C60 fullerenes increases the adsorption capacity of the activated carbon fiber to cadmium ions to 69%, and of graphitized carbon fiber to 64%. From the Langmuir equation rectified in the coordinates of the adsorption isotherms of organic and inorganic adsorbates, the monolayer capacitances and the sorption equilibrium constants are calculated. Static exchange capacities of carbon adsorbents for ions of heavy metals vary in the range from 2.8 to 23.0 mg/g. The adsorption equilibrium constants range from 0.1·103 to 9.0·103. It is shown that the adsorption of phenols and anilines depends on the mutual arrangement of the functional groups in the adsorbate molecules. The adsorption equilibrium constants of para-substituted derivatives of phenol and aniline are somewhat lower than those of meta- and ortho-derivatives, the functional groups of which are bound by intramolecular hydrogen bonds and can’t participate fully in adsorption.