Contents of silica and extractive substances in rice straw depending on rice varieties were investigated. The samples of amorphous silica were prepared, their microelement composition and morphology were investigated, and the values of true and bulk density were estimated. The porous structure of the samples was studied by the Brunauer-EmmettTeller (BET) method and by water vapour sorption; the specific surface values, as well as the pore diameter and volume, were also determined. Sorption properties of the SiO2 surface were analyzed on a sample of Mn 2+ -ions and the organic dyes brilliant green and methylene blue.
Application of composite catalyst carbon fiber modified with iron/iron oxides for heterogeneous catalytic wet peroxide oxidation of phenol is considered. Aspects of catalytic degradation of hydrogen peroxide resulting in formation of active species for CWPO in the presence of heterogeneous catalysts such as activated carbon and activated carbon with the phase of metal/metal oxides are overviewed. Phenol was degraded mostly by the attack of hydroxyl radicals formed from hydrogen peroxide in presence of iron(II) ions on the catalyst surface and in the bulk solution due to iron leaching. The efficiency of application of heterogeneous catalysts carbon fiber and composite carbon fiber/(iron, iron oxide) is determined by few factors such as pH and ratio of phenol : hydrogen peroxide at initial concentration of phenol of 0.182∙10-3 mol/L. In all experimental runs other parameters were kept constant and samples of solution were being withdrawn at regular intervals of time for the analysis on UV-spectrometer. The removal efficiency of phenol (%) was calculated as ratio of the change in the phenol concentration at reaction time to initial concentration of phenol. It was shown that optimal ratio of phenol: hydrogen peroxide and value of pH exists, at which high efficiency of degradation of organic pollutant is achieved. A solution pH 4 and ratio of phenol:hydrogen peroxide 1:6 appeared as the most favorable reaction conditions for achieving 88 % removal efficiency of phenol. At these conditions composite carbon fiber/(iron, iron oxide) acting as a heterogeneous catalyst in the Fenton-like process, demonstrates the high efficiency of degradation and removing organic pollutant from the water.Forcitation:Artemyanov A.P., Zemskova L.A., Ivanov V.V. Catalytic liquid-phase oxidation of phenol in water media using carbon fiber/(iron, iron oxide) catalyst. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 8. P. 88-95.
Adsorption and catalytic decomposition of 3- and 4-chlorophenols in the presence of hydrogen peroxide were studied for estimation of efficiency of the adsorption and catalytic methods for purification of solutions from chlorophenols related to special group of the priority toxic water pollutants. Activated carbon fiber and fiber modified with iron/iron oxide having highly developed surface and porous structure were used as the adsorbents. It was shown that adsorption of chlorophenols on the initial carbon fiber was higher as compared to the modified one and equaled to 309 mg/g for 3-chlorophenol and 301 mg/g for 4-chlorophenol. The sorption isotherm of 4-chlorophenol on the initial fiber is described by Langmuir equation with constant equals to 0.065 L/mg, while for composite sorbent constant equals to 0.037 L/mg. It was discovered that removal of chlorophenols from aqueous solutions in the processes of catalytic oxidation in the presence of a heterogeneous catalyst was more efficient than that in the adsorption process. Experimental data have been obtained on the dependence of the concentration of 3-and 4-chlorophenols on the time of destruction at specified pH values and the ratios of the pollutant and hydrogen peroxide. With an increase in the 4-chlorophenol: H2O2 ratio from 1:1 to 1:6, the degree of chlorophenol destruction increases from 75% to 88% (pH 3); when the pH changes from 1 to 9, the greatest degree of destruction is 70% (3-CP) and 87% (4-CP) was achieved at pH 3 (chlorophenol: H2O2 1:4). It was shown that in the system chlorophenol / H2O2 / catalyst there are optimal parameters (pH is 3 and chlorophenol : H2O2 ratio is 1:6), which provide the most complete removal of chlorophenol from solution. The results of chromatography-mass spectrometry analysis show that during contact with the modified fiber, the content of 4-CP decreases dramatically and degradation products are formed (for example, maleic acid), which is consistent with the known schemes for the oxidative destruction of chlorophenols.
The influence exerted by the porous structure of fibrous and granulated carbon materials on the nature of the charging process and depth of penetration of the electrochemical process was studied.
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