The effects of dissolved solids on the vapor-liquid equilibrium of DMS in black liquor

Abstract

Researchers determined activity coefficients for use in vapor-liquid equilibrium (VLE) calculations using a headspace gas chromatographic method for dimethyl sulfide (DMS) in water, kraft pulp mill black liquor, and sodium salts and alkali lignin mixtures up to 6 wt%, for temperatures of 20°C to 90°C. Experimental data were regressed to determine DMS-water binary parameters for the nonrandom two-liquid (NRTL) equation. The effects of electrolytes were studied, and a strong correlation was observed between the activity coefficient and the sodium cation content of the solution. This suggested that the shift in vapor-liquid equilibrium in black liquor could be modeled based solely on the sodium concentration. Sodium salts solutions data were regressed to determine binary parameters for the eNRTL equation, an extended form of the NRTL equation used to describe electrolyte effects. We found that the eNRTL equation could be used to accurately predict activity coefficients of DMS in black liquor.