Hierarchical porous carbon derived from waste cotton linter for high-performance capacitive deionization

In this study, a series of hierarchical porous carbons (HPCs) were prepared from waste cotton linter via activation with zinc carbonate basic, and their structure-performance relationships were systematically explored in the context of CDI. The results demonstrate that the introduction of Zn salt effectively tailored the pore architecture and surface chemistry of the carbon materials, leading to the formation of hierarchical structures with interconnected micro-, meso-, and macropores. Among the samples, HPC3 exhibited the highest BET surface area (1298 m²/g), outstanding electrochemical performance with a specific capacitance of 111.7 F/g, and a superior SAC of 19.2 mg/g in 1000 mg/L NaCl solution, surpassing that of commercial activated carbon. Post-reaction XPS and TEM analyses confirmed the material’s structural integrity and regeneration capability during cycling. These findings highlight the critical role of pore structure and surface functionalities in enhancing CDI performance and offer new insights into the high-value utilization of biomass wastes for advanced water treatment applications. • Porous carbon was sustainably synthesized from biomass waste via Zn salt activation. • Hierarchical porosity and redox sites enable dual EDL and pseudocapacitive behavior. • HPC3 exhibit high surface area (1298 m²/g) and excellent capacitance (111.7 F/g). • Outstanding CDI performance with a high SAC of 19.2 mg/g in 1000 mg/L NaCl solution.