ABSTRACT
Carbonaceous material (brown coal) modified by pyrolysis, activation, and enrichment in nitrogen, with two different factor reagents, have been used as adsorbent of phenol from liquid phase. Changes in the phenol content in the test solutions were monitored after subsequent intervals of adsorption with selected adsorbents prepared from organic materials. Significant effect of nitrogen present in the adsorbent material on its adsorption capacity was noted. Sorption capacity of these selected materials was found to depend on the time of use, their surface area, and pore distribution. A conformation to the most well-known adsorption isotherm models, Langmuir, and Freundlich ones, confirms the formation of mono- and heterolayer solute (phenol) coverage on the surface of the adsorbent applied herein. The materials proposed as adsorbents of the aqueous solution contaminants were proved effective, which means that the waste materials considered are promising activated carbon precursors for liquid phase adsorbents for the environmental protection.
Subject(s)
Charcoal/chemistry , Nitrogen/chemistry , Phenols/chemistry , Water Pollutants, Chemical/chemistry , Adsorption , Algorithms , Conservation of Natural Resources/methods , Kinetics , Models, Chemical , Phenols/isolation & purification , Phenols/pharmacokinetics , Reproducibility of Results , Surface Properties , Thermodynamics , Water Pollutants, Chemical/isolation & purification , Water Pollutants, Chemical/pharmacokinetics , Water Purification/methodsABSTRACT
The effects of ionizing radiation generated by a beam of electrons, in that doses varied from 25-800 kGy, on the physico-chemical properties of sulfamethoxazole (SMX) in solid state have been studied at room temperature and in the air atmosphere. The changes appearing after the irradiation were detected and evaluated by the spectroscopic methods (UV, IR, MS, EPR), chromatography (TLC and HPLC) and SEM, XRD and DSC. Already the lowest dose of 25 kGy was found to change the color of SMX from white to pale cream; such change became more intense with our increasing the irradiation dose. Products of radiodegradation and decreases in the drug content were detected by TLC and HPLC only after irradiation with 400 kGy. Since the SMX radiolysis products (sulfanilamide and sulfanilic acid) are colorless compounds, it is supposed that the color results from trapping of free radicals in the crystal lattice; the concentration of free radicals was 1.04 × 10(15) spin/g. Our results indicate that the radiolysis of SMX in the solid state caused by e-beams involves breaking of the S-N and N-C bonds. The mean radiolytic yield of this process is G((-SMX)) = 1.89 × 10(-7) mol/J, whereas the yield of formation of the two products of radiolysis is close and equal to 2.18 × 10(-8) mol/J (sulfanilamide) and 2.13 × 10(-8) mol/J (sulfanilic acid).
