Comparative study on Perfluoro(2-methyl-3-oxahexanoic) acid removal by quaternary ammonium functionalized silica gel and granular activated carbon from batch and column experiments and molecular simulation-based interpretation

Adsorption Application of Choline Chloride Modified MIL-101 (Cr) in Carbon Capture and Storage

This study developed a new way of designing choline chloride-modified MOF-based materials with advanced gas adsorption properties. To design better carbon capture materials, MIL-101 (Cr) was prepared using the hydrothermal method, and then was modified with different concentrations of choline chloride in a one-step method to enhance its CO2 adsorption capacity. The characterization and experimental results indicated that the modified ChCl-MIL-101(Cr) significantly enhanced the adsorption capacity for CO2. Specifically, the 0.075-ChCl-MIL-101(Cr) showed a 61.191% increase in adsorption capacity compared to that of the raw material. Moreover, the regenerated adsorption loss rate of the modified material was below 4%, proving the permanence of the material synthesis. Simulating isotherms using Langmuir and Freundlich equations revealed the non-uniformity of surface bonding.

Predicting full-scale performance of adsorbents for per- and polyfluoroalkyl substances adsorption: The role of rapid small-scale column tests

Per- and polyfluoroalkyl substances (PFAS) pose persistent environmental and health challenges, requiring the development of effective removal strategies. Rapid Small-Scale Column Tests (RSSCTs) provide a cost-effective approach to evaluating the performance of adsorbents for PFAS removal. Current literature emphasized that the chain length of PFAS tails and the functional groups of PFAS heads play a crucial role in breakthrough behavior, with shorter chains and carboxylate PFAS leading to earlier breakthroughs. Besides, resin-based adsorbents outperform their carbon-based adsorbents counterparts, treating more bed volumes before breakthrough occurs. Furthermore, it is important to note that Proportional Diffusivity (PD)-RSSCTs scaling approach can tend to overestimate full-scale adsorber performance, while Constant Diffusivity (CD)-RSSCTs model can align more closely with pilot-scale application. These findings emphasize the necessity of considering various factors when designing and interpreting RSSCT experiments to achieve effective PFAS removal. Lastly, the presence of existing organic matters in water has a detrimental effect on PFAS adsorption, thus hastening breakthroughs. Overall, the present review study addresses: (i) a summary of PFAS removal on resin- and carbon-based adsorbents using RSSCTs, (ii) a description of the breakthrough curve models, (iii) an in-depth discussion of the PFAS interactions with carbon- and resin-based adsorbents, and (iv) an evaluation of the impact of variables on the PFAS adsorption in RSSCTs. As a result, this literature review identifies future research needs and challenges regarding the adsorption of PFAS by resin- and carbon-based adsorbents in fixed-bed column processes.