Search

As an emerging carbonaceous material, carbon aerogels (CAs) display a great potential in environmental cleanup. In this study, a macroscopic three-dimensional monolithic cobalt-doped carbon aerogel was developed by co-condensation of graphene oxide sheets and resorcinol-formaldehyde resin in the presence of cobalt ions, followed by lyophilization, carbonization and thermal treatment in air. Cobalt ions were introduced as a polymerization catalyst to bridge the organogel framework, and finally cobalt species were retained as both metallic cobalt and Co 3 O 4 , wrapped by graphitized carbon layers. The material obtained after a thermal treatment in air (CoCA-A) possesses larger BET specific surface area and pore volume, better hydrophilicity and lower leaching of cobalt ions than that without the post-treatment (CoCA). Despite of a lower loading of cobalt content and a larger mass transfer resistance than traditional powder catalysts, CoCA-A can efficiently eliminate organic contaminants by activation of peroxymonosulfate with a low activation energy. CoCA-A can float beneath the surface of aqueous solution and can be taken out completely without any changes in morphology. The monolith is promising to be developed into an alternative water purification technology due to the easily separable feature. [ABSTRACT FROM AUTHOR]

Abstract: Batch sorption experiments were conducted using macroreticular poly(vinyl alcohol) (MR-PVA) beads as a adsorbent to adsorb Pb(II) from both single component system and multi-metal solution in which experimental parameters were studied including solution pH, contact time, adsorbent dose, initial concentration of metal ions and ionic strength. The equilibrium isotherms were determined at pH 6 under constant ionic strength and at different temperatures. The results showed that the maximum adsorption capacity of Pb(II) (213.98mgg−1) with 1gL−1 of adsorbent was observed at 300mgL−1 at an initial pH value of 6.0 under temperature of 288K. Removals of about 60% occurred in 30min, and equilibrium was attained at around 150min. The equilibrium data for the adsorption of Pb(II) on MR-PVA beads was tested with various adsorption isotherm models among which three models were found to be suitable for the Pb(II) adsorption. In addition, the kinetic adsorption fitted well to the pseudo-second-order model and the corresponding rate constants were obtained. Thermodynamic aspects of the adsorption process were also investigated. [Copyright &y& Elsevier]

This work illustrates a simple polymer thermal treatment strategy to develop high-dispersed Fe 2 O 3 /Fe nanoparticles residing in honeycomb-like N-doped graphitic carbon (Fe 2 O 3 /Fe@N-GC). The as-prepared Fe 2 O 3 /Fe@N-GC composites consist of three-dimensional (3D) strutted interconnective graphitic carbon frame, which would not only refrain from restacking and facilitate the charge transfer, but also provide more reaction interface between gas molecules and materials. Benefiting from the synergistic merits of Fe 2 O 3 /Fe, N-doping graphitic carbon, high surface area and unique 3D architectures, the optimal Fe 2 O 3 /Fe@N-GC presents impressive sensitivity and selectivity for NO 2 gas detection at room temperature with the response of 25.48–100 ppm, response time of 2.13 s, recovery time of 11.73 s, detection limit of 10 ppb and as long as 60 days of stability. As a result, the present Fe 2 O 3 /Fe@N-GC composite with an easy fabrication method and high sensitivity, selectivity, stabitliy towards NO 2 at RT would inspire various designs based on the 3D honeycomb structure for more real applications in gas sensors. ga1 • Honeycomb embedded with Fe 2 O 3 /Fe nanoparticles was synthesized by a simple strategy. • Honeycomb provides the pathway for fast electron and target gas diffusion. • The response of optimized Fe 2 O 3 /Fe@N-GC sensor to 100 ppm NO 2 at RT is 25.48. • The sensor maintains a good stability in the whole 60 days. [ABSTRACT FROM AUTHOR]