No abstract

No abstract

No abstract

Nanofiltration (NF) was investigated for the recovery of platform chemicals, specifically, succinic acid, from high-strength bioethanol waste (dunder). Conventional methods focusing on chemical precipitation entail poor selectivity in complex matrices and are inherently expensive owing to the consumption of large volumes of chemicals and the generation of excess byproduct sludge. For these reasons, three commercially available NF membranes with varying molecular weight cut-off were screened in a dead-end configuration to benchmark transmission behavior at different solution chemistries including pH, feed pressure, concentration, and ionic strength prior to filtration with the industrial effluent. Examination of behavior with model solutions only reveals that both NF270 and NTR-7450 membranes exhibit a succinic acid permeation above 80% irrespective of pH and solute concentration, while the addition of inorganic salts, in particular, divalent species, lowered the transmission of succinic acid with all membranes, in particular, NF90. Measurements of the surface charge (zeta potential) before and after filtration of the industrial effluent indicate a shift toward more positive values for the polyamide membranes (NF90 and NF270) within the pH range of 2−10. This change in surface charge was attributed to the formation of complexes between humic compounds and divalent cations present in elevated concentrations. Considerable fouling was observed for all membranes with the mean permeate flux around 2 L/m 2 h at 5 bar for the NF270 and NTR-7450 membranes; however, findings from deionized water rinsing suggest that the majority of foulants reside within the reversible fouling layer. Finally, size exclusion chromatography (liquid chromatography−organic carbon detection) findings highlight substantial (>70%) rejection of biopolymers, humics, building blocks, and low-molecular-weight neutral species following filtration with all membranes. Overall, this work demonstrates the merits and potential of nanofiltration in the recovery of high-value organic acids from concentrated bioethanol waste.

No abstract