Electrospun quaternized polysulfone from industrial waste: A multi-scale porous architecture for ultra-high performance moisture-swing direct air capture

The urgency of implementing effective Direct Air Capture (DAC) technologies is currently constrained by sorbent limitations in capacity, kinetics, and energy requirements for regeneration, particularly within moisture-swing adsorption (MSA) systems. This report details a novel electrospun quaternized polysulfone (QP-es) sorbent, strategically fabricated from industrial polysulfone waste, thereby integrating circular-economy valorization with exceptional capture performance. While, the dense counterpart in characterized by a dense structure with minimum active surface area (28.5 m 2 g −1 ), the QP-es material is characterized by a multi-scale porous architecture that significantly enhances mass transport. It exhibits a high BET surface area of 587 m 2 g −1 , marking a twenty-fold increase over its dense cast analogue, QP-d. This architectural advantage yields rapid CO 2 uptake, reaching 1.68 mmol g −1 in 10 to 15 min under 400 ppm CO 2 conditions, compared to the slow performance of QP-d, which achieves only 0.63 mmol g −1 in 40 to 50 min. The optimal peak capacity for QP-es is 2.16 mmol g −1 at 20 % relative humidity (RH), exceeding the peak capacity of QP-d (0.8 mmol g −1 ) by 2.7×. Furthermore, QP-es demonstrates robust operational viability through high selectivity for CO 2 over atmospheric bulk gases (CH 4 , H 2 , N 2 , O 2 ) and acidic contaminants (NO 2 , and SO 2 ). Under MSA, the material maintains a substantial working capacity of approximately 1.6 mmol g −1 (swinging between 20 % RH and 100 % RH) and retains 85 % of its original capacity over 140 cycles. The sorbent also regenerates efficiently using temperature-swing adsorption (TSA) at a remarkably low temperature of just 50 °C, thus leading to an overall regeneration energy of ⁓1.98 MJ kg −1 . These findings demonstrate that utilizing electrospinning to engineer multi-scale porosity successfully overcomes internal mass-transfer limitations, offering a scalable, energy-efficient, and durable DAC sorbent optimized for cost-effective moisture-swing operation. Electrospun quaternized polysulfone nanofibers recycle industrial waste into a hierarchically porous membrane that rapidly and selectively captures CO 2 from ambient air under a moisture swing—achieving >2.1 mmol g −1 uptake in ~15 min, robust cyclic stability, and low-temperature regeneration while excluding common atmospheric gases. • Electrospun quaternized polysulfone from waste achieves 587 m 2 g −1 surface area for rapid CO 2 direct air capture. • Multi-scale porous architecture enables CO 2 saturation in 10–15 min vs. 40–50 min for dense analogue at 400 ppm. • Peak capacity reaches 2.16 mmol g −1 at 20 % RH with 95 % active site utilization and high selectivity over air gases. • Moisture-swing operation delivers 1.6 mmol g −1 working capacity with 85 % retention over 140 cycles at ambient temp. • Low-temperature regeneration at 50 °C enables energy-efficient, scalable DAC with circular economy waste valorization.