Study on Structural Regulation of Phenolic Resin-based Carbon Aerogels and Their Adsorption Performance for Cr(Ⅵ)

Hexavalent chromium (Cr(Ⅵ)) is a highly toxic and carcinogenic heavy metal pollutant, posing serious threats to the environment and human health. The development of efficient and cost-effective adsorbents is crucial for treating Cr(Ⅵ)-containing wastewater. In this study, porous carbon aerogels (CAs) with a three-dimensional network structure were prepared using resorcinol-formaldehyde as precursors and polydiallyldimethylammonium chloride (PDADMAC) as a soft template via sol-gel method, ambient pressure drying, and high-temperature carbonization. The regulation of PDADMAC dosage on the microporous structure of the carbon aerogels was systematically investigated, and their performance as adsorbents for the removal of Cr(Ⅵ) from water, as well as their compressive properties, were thoroughly evaluated. The results demonstrated that by adjusting the amount of PDADMAC, the pore structure of the carbon aerogels could be effectively tailored, achieving a transition from microporous to mesoporous structures. Adsorption experiments revealed that the abundant mesoporous structure provided low-resistance mass transfer channels for Cr(Ⅵ) compounds, resulting in an adsorption capacity of 102.34 mg·g^-1 while maintaining compressive strength up to 7.08 MPa. The adsorption kinetics followed the pseudo-second-order model and the intra-particle diffusion model, which indicated that the process was dominated by chemical adsorption and exhibited multi-stage adsorption characteristics. This study demonstrates the preparation of high-performance carbon aerogels through structural regulation, offering a feasible strategy for the efficient adsorption of heavy metal Cr(Ⅵ).