In this work, sulfur-functionalized ordered mesoporous carbons were synthesized by activating the soft-templated mesoporous carbons with sulfur bearing salts that simultaneously enhanced the surface area and introduced sulfur functionalities onto the parent carbon surface. XPS analysis showed that sulfur content within the mesoporous carbons were between 8.2% and 12.9%. The sulfur functionalities include C-S, C═S, -COS, and SO. SEM images confirmed the ordered mesoporosity within the material. The BET surface areas of the sulfur-functionalized ordered mesoporous carbons range from 837 to 2865 m/g with total pore volume of 0.71-2.3 cm/g. The carbon with highest sulfur functionality was examined for aqueous phase adsorption of mercury (as HgCl), lead (as Pb(NO)), cadmium (as CdCl), and nickel (as NiCl) ions in both noncompetitive and competitive mode. Under noncompetitive mode and at a pH greater than 7.0 the affinity of sulfur-functionalized carbons toward heavy metals were in the order of Hg > Pb > Cd > Ni. At lower pH, the adsorbent switched its affinity between Pb and Cd. In the noncompetitive mode, Hg and Pb adsorption showed a strong pH dependency whereas Cd and Ni adsorption did not demonstrate a significant influence of pH. The distribution coefficient for noncompetitive adsorption was in the range of 2448-4000 mL/g for Hg, 290-1990 mL/g for Pb, 550-560 mL/g for Cd, and 115-147 for Ni. The kinetics of adsorption suggested a pseudo-second-order model fits better than other models for all the metals. XPS analysis of metal-adsorption carbons suggested that 7-8% of the adsorbed Hg was converted to HgSO, 14% and 2% of Pb was converted to PbSO and PbS/PbO, respectively, and 5% Cd was converted to CdSO. Ni was below the detection limit for XPS. Overall results suggested these carbon materials might be useful for the separation of heavy metals.

In this work, we have measured the adsorption isotherms and calculated the equilibrium selectivity for CO 2 , CH 4 , and N 2 on micro-mesoporous nanographene at three temperatures of 298 K, 278 K, and 263 K and pressures up to 760 Torr. The nanographene sample possesses a particle size range of 50 nm to 250 nm along with a Brunauer−Emmett−Teller (BET) specific surface area of 514 m 2 /g and total pore volume of 3 cm 3 /g. The pore widths varied from 3.5 Å to 8 Å in the microporous region and very large distributed widths within 45 Å to 250 Å in the region of mesoporosity. The calculated equilibrium selectivity of gas separation at 298 K by pressure swing adsorption for CO 2 /N 2 , CO 2 /CH 4 , and CH 4 /N 2 are 55, 8.2, and 6.5, respectively, whereas the adsorption selection parameters for same pair of gases are 540, 101, and 117, respectively. To compare the equilibrium selectivity values with other adsorbents, we have measured the gas adsorption isotherms for CO 2 , CH 4 , and N 2 on Maxsorb (a commercial activated carbon with BET surface area 3200 m 2 /g) and calculated the selectivity values for several adsorbents based on their adsorption isotherms reported in the literature. We have found that equilibrium selectivity for all the gas pairs are higher for graphene compared to Maxsorb. We also found that the equilibrium selectivity for CO 2 /N 2 for graphene is higher than all the carbon-based materials reported so far. The equilibrium selectivity for CO 2 /CH 4 and CH 4 /N 2 in graphene is also higher than the majority of the adsorbents reported in the literature. Our findings suggest that graphene can serve as a potential adsorbent for gas separation purposes.

We have demonstrated the potential of meso- and microporous carbons in controlled release applications and targeted oral drug delivery.