Rapid, Accurate Measurement of the Oil and Water Contents of Oil Sludge Using Low-Field NMR

Abstract

Rapid, accurate measurement of the oil and water contents of oil sludge is vital to determine technological solutions for the treatment of that oil sludge. Low-field 1H NMR as a rapid noninvasive method was used in this study. Carr–Purcell–Meiboom–Gill (CPMG) experiments were conducted to construct the transverse relaxation time (T2) distribution curves. The instrument’s ability to quantify oil sludge’s water and oil contents was verified. MnCl2·4H2O was added to the oil sludge to separate the oil and water signals. For calibration curve construction, excellent results were achieved, with correlation coefficients of 0.9996 and 0.987 for regressions between the mass and the relative peak area in the T2 distribution curve for oil and water separately. Good correlation of R2 = 0.998 was achieved between low-field NMR and azeotropic distillation for both water and oil along with standard deviations of 2.67% and 2.61% for the calibration curve method, or standard deviations of 2.81% and 1.88% for water and oil, with more or less similar correlation coefficients, after correction for the amplitude indices of both the water and the oil.