Excess amount of potassium permanganate has often been used in-situ for chemical oxidation of contaminated sites. The consequences are not limited to secondary contamination and cost but also inefficient remediation. Encapsulation of permanganate using PMMA enables controlled dissolution of the oxidant and aids long-term processes. This paper focuses on the oxidant release efficiency from polymer matrix and analysis of data using existing models for glassy polymers. The efficiency profile obtained using mass ratios of 2:1, 4:1, and 8:1 of PMMA to KMnO 4 showed a decrease in the extent of release with increasing mass ratio with 79%, 55.35% and 33.59% respectively. Patches were noticed on the surfaces of PMMA after the release of KMnO 4 , these were attributed to crevices created by the non-fickian diffusion of the oxidant.
This paper discusses the toxicity and mobility of chromium species. And it presents the extent and kinetics of reductive remediation of hexavalent chromium, Cr + using ferrous ion, Fe 2+ . Molar ratios of 1:3 and 1:6 of Cr (VI) to Fe (II) were used. Integral method of data analysis showed reaction followed second-order kinetics with R square values near unity. Reaction was initially fast but with a rapid precipitation attributed to Cr (III)-Fe (III) in previous studies. This colloidal precipitate ultimately stops the reaction, which explains while conversion efficiency increases with increased molar ratio of Cr (VI) to Fe (II). The impact of pH was investigated by adjusting the Cr (VI)-Fe (II) medium to pH 2.78, 5.24, 7.00, 9.00 and 11.96 using predetermined drops of acid or base. Reaction was more rapid under alkaline conditions with higher extent of degradation consistent with previous research. In soil system, mass transfer limitation was hardly noticed as high extent of reduction was recorded relative to aqueous phase. The high solubility of Cr (VI) aided the release into the aqueous media for reduction by ferrous sulfate.
The chemical mechanism for the production of ( 2 -2 ) emission observed in reactive hydrocarbon instruments is demonstrated for the prototype olefin, ethylene. The mechanism is studied in a discharge-flow tube reactor at 1 torr total pressure, and the data are consistent with the mechanism CHO* + 0 -» ( 2 ) + CO, where CHO* is either electronically or vibrationally excited CHO. This mechanism will be operative in all reactive hydrocarbon-oxygen atom systems, and it produces a rotationally cold ( 2 ). A reactive hydrocarbon analyzer (RHA) is constructed to observe emission from paraffins, lower olefins, and benzene, and the emission correlates well with the group reactivity scale of Dimitriades and also with the rate constants for the rate-determining step in the proposed kinetic mechanism. Our RHA has an ultimate sensitivity of better than 6 ppb ethylene equivalent concentration at 4.5 torr total pressure and a linear response to at least 1000 ppm.
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