Waste lignosulfonate upcycling towards durable and efficient pelletized adsorbents for diluted NH3 adsorption

Lignin is the largest natural reservoir of aromatic compounds while its intricate polymeric structure complicates the reuse of lignin-derived waste. Herein, we report the development of lignin-based NH 3 adsorbents by upcycling sodium lignosulfonate (SLS) from spent paper pulp liquor. The demethylation of SLS was carried out to obtain the demethylated SLS (DSLS) and subsequently the pelletized DSLS@binder adsorbents were prepared using DSLS and three binders. The results indicate that the optimized 95% DSLS@PVA pellets with binder dosage of 5 wt% PVA (polyvinyl alcohol, PVA) exhibit the NH 3 adsorption capacity of 11.5 mmol g −1 , along with remarkable selectivity uptake for NH 3 /N 2 (3573) and NH 3 /CO 2 (1380). Moreover, the 95% DSLS@PVA pellets demonstrate ultra-fast adsorption kinetics (half-capacity uptake time of merely 38 s). Column breakthrough tests showed that the 95% DSLS@PVA pellets achieved NH 3 retention time of 370 min g −1 in a ternary gas mixture of NH 3 /N 2 /CO 2 (1 %/98 %/1%), with a dynamic adsorption capacity of 2.07 mmol g −1 . In addition, the 95% DSLS@PVA has a good balance between mechanical strength and NH 3 uptake cycle performance. This work provides a sustainable strategy for valorizing lignin waste into high-performance NH 3 adsorbents.