Homogeneous production of hydroperoxides concentrate has been simulated via multivariate calibration of yield data, obtained during an earlier study [Naqvi and Khan Ind. Eng. Chem. Res. 2009, 48, 5642] made on the air oxidation of diluted gas oils in the presence of chemically generated redox couple Co(III)/Co(II). Principal component analysis has been applied to abstract dynamic hydroperoxides yield data that provides the basis for the simulation. A novel chemometric technique, inverse nonlinear principal component regression, has been introduced to simulate experimental yield profiles with exceptional accuracy (R 2 ) 0.9841). Simulated yield profiles have then been subjected to Levenberg-Marquardt method in order to estimate the rate constants for formation and decomposition of hydroperoxides. These estimations have permitted the development of two reasonably accurate multivariate global models that relate the specific rates, for formation (R 2 ) 0.8873) and decomposition (R 2 ) 0.9504) of hydroperoxides, to process and composition variables. Construction of such models allows the specific rates to be optimized so that the reactor could be operated at an oil conversion (up to ≈5%) that is almost proportional to the yield of hydroperoxides ensuring selectivity ≈88%.

Raw magnesite is slightly porous but its porosity could be increased on heating at and above 500 ı C. Its adsorption characteristics were investigated for various activation temperatures, times and particle sizes. Maximum adsorption capacity was found for 100-230-mesh magnesite particles activated at 500 ı C for 2 h. This has produced low color index re-refined oil. One of the economical features is the reproducibility of the results after regeneration of the spent magnesite samples. An excellent feature of the adsorbent is the efficient removal capability of aromatics especially PAH, which is supported by UV and FTIR studies of oils.

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Central composite design methodology has been employed to model the sludge yield data obtained during liquid-liquid extractive rerefining of spent lubricants using an alcohol (1-butanol) and a ketone (methyl ethyl ketone) as prospective solvents. The study has resulted in two reasonably accurate multivariate process models that relate the sludge yield (R 2 = 0.9065 and 0.9072 for alcohol and ketone, resp.) to process variables (settling time t, operating temperature T, and oil to solvent ratio r). Construction of such models has allowed the maximization of the sludge yield (more than 8% and 3% in case of alcohol and ketone, resp.) so that the extraction of useable oil components from spent lubricants can economically be performed under extremely mild conditions (t = 16.7 h, T = 10°C, and r = 2) and fairly moderate conditions (t = 26.6 h, T = 10°C, and r = 5) established for the alcohol and ketone correspondingly. Based on these performance parameters alcohol appears to be superior over ketone for this extraction process. Additionally extractive treatment results in oil stocks with lesser quantity of environmentally hazardous polyaromatic hydrocarbons that are largely left in the separated sludge.

Indigenous diaspore is a high density hard mineral. It becomes harder on heating up to 550 o C. The dispore has been characterized thermally by thermal gravimetric analysis and x-ray diffraction. Results show that the indigenous mineral increases its density after heating at various temperatures for 1 hour. Increase in density points out the increase in hardness due to the formation of a more crystalline compact material corundum using as abrasive.