Iterative Slope and Intercept Method for Diffusion Estimation in Binary Liquids

ABSTRACT

A new geometrical method for diffusion estimation in binary liquids is derived and validated. It incorporates the slope and intercept approach into the integral representation for diffusion. The method significantly improves the existing slope and intercept methods for estimation of the concentration dependent diffusion coefficients. It produces much more accurate diffusion estimations for non-constant diffusion. The slope and intercepts are calculated using the derivative approximation for deterministic concentration data, or the spline linear regression for measurement data containing noise. The verification of the proposed method is performed either by comparing estimated and known diffusion coefficients, or measured and calculated concentration profiles. The sensitivity analysis conducted with respect to the Matano interface position showed that for incorrect Matano interface values the diffusion are significantly overestimated or underestimated. The proposed iterative slope and intercept (ISI) method is applied for the toluene-bitumen binary liquid system with concentration profiles obtained using X-ray Computer Assisted Tomography.

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