Modelling and optimization of critical parameters by hybrid RSM-GA for the separation of BSA using a tubular configured MFI-type zeolite microfiltration membrane

Abstract

This paper deals with the fabrication of a MFI-type zeolite membrane via an in situ hydrothermal synthesis technique on a low cost porous tubular ceramic substrate. To formulate the zeolite layer on the porous substrate, the hydrothermal solution was prepared using silicate solutions. The MFI zeolite (as synthesized and calcined) was characterized by X-ray diffraction (XRD), thermogravimetry (TG) and Fourier transform infrared spectroscopy (FTIR) analysis. The fabricated ceramic substrate as well as the zeolite membrane was characterized by field emission scanning electron microscopy (FESEM), porosity and water permeability measurements. The porosity, mean pore size and water permeability of the zeolite membrane were evaluated to be 51%, 0.272 μm and 4.43 × 10⁻⁷ m³ m⁻² s⁻¹ kPa⁻¹, respectively. The separation efficiency of the membrane in terms of permeate flux and rejection was studied with BSA as a model protein. Three operating parameters, BSA concentration (100–500 ppm), pH (2–4) and applied pressure (68.94–275.79 kPa), were optimized for the better separation efficiency of the membrane using response surface methodology (RSM) followed by a bi-objective genetic algorithm (GA). The non-linear models predicted by RSM were further optimized by a GA. The appropriate optimum conditions were obtained as a BSA concentration of 100 ppm, solution pH of 2 and applied pressure of 275.79 kPa. These predicted conditions were experimentally validated and a higher permeate flux and rejection of BSA were obtained as 4.63 × 10⁻⁵ m s⁻¹ and 81.98%, respectively. Further, the separation efficiency of prepared membrane was compared with other membranes used for BSA separation stated in the literature.