Cellulose Acetate Membranes from Sisal Fiber Applied for Furfural Recovery

Membrane separation is an effective method for recovering biomass in biorefineries. Cellulose acetate (CA) membranes exhibit excellent separation capabilities and high selectivity. The use of lignocellulosic materials, such as sisal fiber, for the production of CA membranes represents a unique opportunity in this context. This study aimed to develop sisal fiber-derived CA membranes under optimized synthesis conditions for the efficient removal of furfural from lignocellulosic hydrolysates. The biomass was subjected to chemical treatments (organosolv and dilute acid) to isolate the cellulose. An experimental design approach was used to determine the optimal conditions for cellulose recovery, yielding a product containing 2.4% residual impurities. This cellulose was subsequently acetylated to produce CA, a conversion confirmed by spectroscopic analysis. CA and CA/PEG-400 membranes (incorporating poly-(ethylene glycol) 400 into their composition) were synthesized using the phase inversion method. All membranes exhibited a porous, asymmetric structure. Membranes containing PEG-400 within the polymer matrix displayed a higher porosity percentage, lower permeate flux, and higher furfural recovery. The inclusion of PEG-400 resulted in a membrane with a smoother surface and smaller poresfindings corroborated by scanning electron microscopy data. The experimental condition involving the lowest synthesis temperature (5 °C) and the presence of PEG-400 yielded the highest furfural retention, reaching 92%.