Separation of binary mixtures by thermostatic sweeping gas membrane distillation: II. Experimental results with aqueous formic acid solutions

Aqueous solutions of formic acid have been experimentally investigated in a modified sweeping gas membrane distillation (SGMD) configuration. A thermostated sweeping gas was used in order to enhance the mass transfer performance. A new tubular module was designed and built for this purpose. The effects of the relevant process parameters on the permeate flux and selectivity have been studied. Experiments with pure water and pure formic acid were used to estimate certain parameters in the model. From these mass transfer coefficients, the fluxes and selectivity for aqueous formic acid mixtures have been calculated using the mathematical model previously described [J. Membr. Sci., 2001, in press]. The model predictions were compared with the experimental data and a good agreement between both flux values were obtained.