Improving Structural Homogeneity, Hydraulic Permeability, and Mechanical Performance of Asymmetric Monophasic Cellulose Acetate/Silica Membranes: Spinodal Decomposition Mix

• Published in: Membranes (Basel) Vol. 13; no. 3; p. 346
• Main Authors: Zare, Fahimeh, Gonçalves, Sérgio B, Faria, Mónica, Gonçalves, Maria Clara
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 17-03-2023; MDPI
• Subjects: Acetic acid; Acetone; Acids; CA/SiO2 membrane; Cellulose; Cellulose acetate; Chemical composition; Decomposition; Ethanol; Founding; Fourier transforms; Homogeneity; Hydraulic permeability; Infrared spectroscopy; integral asymmetric membranes; Mechanical properties; mechanical tensile properties; Membrane permeability; Membranes; Modulus of elasticity; monophasic hybrid membrane; Permeability; Polymerization; Polymers; Scanning electron microscopy; Silica; Silicon dioxide; Solvents; Spinodal decomposition; spinodal decompositions mix; Tensile properties; Tensile tests; Ultrafiltration; Portugal; spinodal decompositions mix; integral asymmetric membranes; hydraulic permeability; mechanical tensile properties; CA/SiO2 membrane; monophasic hybrid membrane
• ISSN: 2077-0375; 2077-0375
• DOI: 10.3390/membranes13030346

In this paper, we propose an optimized protocol to synthesize reproducible, accurate, sustainable integrally skinned monophasic hybrid cellulose acetate/silica membranes for ultrafiltration. Eight different membrane compositions were studied, divided into two series, one and two, each composed of four membranes. The amount of silica increased from 0 wt.% up to 30 wt.% (with increments of 10 wt.%) in each series, while the solvent composition was kept constant within each series (formamide/acetone ratio equals 0.57 wt.% in series one and 0.73 wt.% in series two). The morphology of the membranes was analyzed by scanning electron microscopy and the chemical composition by Fourier transform infrared spectroscopy, in attenuated total reflection mode (FTIR-ATR). Mechanical tensile properties were determined using tensile tests, and a retest trial was performed to assess mechanical properties variability over different membrane batches. The hydraulic permeability of the membranes was evaluated by measuring pure water fluxes following membrane compaction. The membranes in series two produced with a higher formamide/acetone solvent ratio led to thicker membranes with higher hydraulic permeability values (47.2-26.39 kg·h
·m
·bar
) than for the membranes in series one (40.01-19.4 kg·h
·m
·bar
). Results obtained from the FTIR-ATR spectra suggest the presence of micro/nano-silica clusters in the hybrid membranes of series one, also exhibiting higher Young's modulus values than the hybrid membranes in series two.