Response surface optimization of polyethersulfone biocomposite membranes reinforced with pineapple crown leaf-derived microcrystalline cellulose for dye wastewater treatment

Textile dye effluents contain persistent dye pollutants that require separation processes capable of balancing permeability, selectivity, and reusability. Although cellulose-based fillers have been explored for polymeric membranes, limited information is available on response-surface optimization of polyethersulfone (PES) membranes using microcrystalline cellulose (MCC) isolated from pineapple-crown-leaf agricultural waste for methylene blue (MB) removal. In this study, PES/MCC biocomposite membranes were fabricated by non-solvent-induced phase inversion using dimethyl sulfoxide (DMSO) as solvent. A central composite design within response surface methodology (RSM-CCD) was applied to optimize PES concentration (20–25%) and MCC loading (0.1–0.5%) using water flux, MB flux, and MB rejection as responses. Filtration was performed at 1 bar using 10 mg/L MB solution at pH 7. The selected formulation (22.45% PES and 0.50% MCC) achieved a water flux of 4 L·m⁻²·h⁻¹, MB flux of 2 L·m⁻² ·h⁻¹, and 96% MB rejection. Compared with pure PES membrane, the optimized PES/MCC membrane increased water flux by approximately 91% while retaining high rejection, although rejection was slightly lower than that of pure PES membrane. SEM, FTIR, porosity, water uptake, and mechanical tests indicated that MCC promoted a more porous and hydrophilic membrane structure and acted as a reinforcing filler. The membrane showed flux recovery ratios (FRR) of 94% in the first cleaning cycle and 68% after five cleaning cycles with NaOCl and citric acid. These results show that waste-derived MCC can be used as a functional PES membrane additive when permeability-selectivity trade-offs are explicitly optimized.