Supplementary Figures and Tables from Efficient removal of tetracycline with KOH-activated graphene from aqueous solution

Activated graphene absorbents with high specific surface area (SSA) were prepared by an easy KOH-activated method, and were applied in absorbing antibiotics, such as tetracycline (TC). After activation, many micropores were introduced to graphene oxide sheets, leading to higher SSA and many new oxygen-containing functional groups, which gave KOH-activated graphene excellent adsorption capacity (approx. 532.59 mg g⁻¹) of TC. Further study on the adsorption mechanism showed that the Langmuir isotherm model and the pseudo-second-order kinetic model fitted with experiment data. To further understand the adsorption process, the effects of solid–liquid ratio, pH, ionic strength and coexisting ions were also investigated. The results revealed that, compared with pH and ionic strength, solid–liquid ratio and coexisting ions (Cu²⁺, CrO₄²⁻) had more significant influence over the adsorption performance. The findings provide guidance for application of KOH-activated graphene as a promising alternative adsorbent for antibiotics removal from aqueous solutions

Comparative Study of Graphene Hydrogels and Aerogels Reveals the Important Role of Buried Water in Pollutant Adsorption

Water as the universal solvent has well-demonstrated its ability to dissolve many substances, but buried water inside different nanoporous materials always exhibits some unusual behaviors. Herein, 3D porous graphene hydrogel (GH) is developed as a super-adsorbent to remove different pollutants (antibiotics, dyes, and heavy ions) for water purification. Due to its highly porous structure and high content of water, GH also demonstrated its super adsorption capacity for adsorbing and removing different pollutants (antibiotics, dyes, and heavy ions) as compared to conventional graphene aerogel (GA). More fundamentally, the buried-water enhanced adsorption mechanism was proposed and demonstrated, such that buried water in GH plays the combinatorial roles as (1) supporting media, (2) transport nanochannels, and (3) hydrogen bondings in promoting pollutant adsorption. In parallel, molecular dynamics simulations further confirm that buried water in GH has the stronger interaction with pollutants via hydrogen bonds than other buried alcohols. GH integrates the merit of both graphene (e.g., fine chemical resistance and excellent mechanical property) and hydrogel (e.g., high water content, porous structure, and simple solution-based processability and scalability), giving it promising potential for environmental applications