Experimental study and parametric effects for breaking of butyric acid/water azeotrope using air gap membrane distillation

In this work, the feasibility of air gap membrane distillation for breaking the butyric acid/water azeotrope is examined. The azeotropic mixture was passed through the set up equipped with a porous, hydrophobic PTFE membrane. The effect of various process variables, including feed temperature, feed flow rate, coolant temperature, coolant flow rate, and air gap width on total permeate flux, selectivity of butyric acid, and permeate and retentate concentration has been studied. Furthermore, EDS and FE-SEM were used to investigate how operating time impacts morphology of membrane. The SEM image of membrane was analysed with ImageJ software to determine the pore size distribution. The experimental findings indicate that the total flux increases from 0.54 to 9.81 kg/m2⋅h on increasing the feed temperature from 40°C to 80°C mm at air gap width of 3mm. Total flux decreases from 2.75 to 1.01 kg/m2⋅h on increasing air gap width from 3 to 11 mm at flow rate of 4 l/min. In addition, the total flux decreases from 0.54 to 0.40 kg/m2⋅h when the coolant temperature is increased from 4°C to 20°C for air gap of 3 mm. It was observed that the butyric acid selectivity in the permeate was less than one, indicating the higher butyric acid concentration in retentate relative to permeate.