Optimizing membrane synthesis parameters via Taguchi method: An approach to prepare high performance mixed-matrix membranes for carbon capture applications

Mixed-matrix membranes (MMMs) comprising polysulfone (PSF) and zeolite 4A (Z4A) were prepared for carbon capture applications. Membranes of varying compositions were fabricated by solution casting technique. Viscous solutions of dissolved ingredients were cast on a clean glass plate followed by evaporation and drying of prepared membrane. Fabricated composite membranes were subjected to morphological, structural, and permeation analyzes. The morphological results showed a uniform dispersal of zeolite nanoparticles with agglomerates formation at higher nanofiller loadings. The structural analysis corroborated the noninteractive behaviour of organic polymer and inorganic zeolite phases. Permeation results suggested that the fabricated membranes were more permeable to CO₂ gas, which can be described by higher diffusivity and structural affinity for CO₂. Taguchi statistical analysis was employed to optimize carbon capture performance of developed hybrid membranes by carefully controlling the membrane casting parameters such as loading levels of functional nanofiller, sonication time, and drying time of casting solution. The statistical investigation of permeation results suggested the sensitivity of casting parameters on membrane performance in the following manner: zeolite loading > sonication time > drying time. The optimized membrane casting parameters obtained from signal-to-noise ratio analysis performed on Minitab led to synthesis of a composite membrane with both high CO₂/N₂ selectivity and CO₂ permeability. The chosen technique also assisted in justifying the dependence of permeation results on various membrane casting parameters, associating it with the morphological results. The technique also facilitated the optimization of the membrane characteristics and is recommended for future study based on membrane separation processes.