Synthesis, physical properties, and carbon dioxide uptake of new metal-sulfamethoxazole complexes

Abstract

Considerable research is currently being undertaken to reduce atmospheric CO2 levels, and a promising approach is capturing and storing the gas using adsorbents. In this regard, the synthesis and investigation of the potential use of new materials as CO2 storage media has attracted attention from both industry and academia. Metal-organic frameworks have a range of unique chemical and physical properties with many applications. Reported here is the synthesis of three new sulfamethoxazole-metal complexes and their use as models for investigation of the influence of the metal on their ability to absorb CO2. A new Schiff base was first synthesized, in 89 % yield, from the condensation of sulfamethoxazole and 4-(dimethylamino)benzaldehyde under acidic conditions. The reaction of the Schiff base with metal (nickel, copper, and cobalt) chlorides in ethanol under reflux gave the corresponding sulfamethoxazole-metal complexes in 71–80 % yield. Several experiments were conducted to assess the uptake of CO2 under different conditions. The complexes have low surface areas (1.36–5.82 m2/g) and average pore volume and diameters of 0.008–0.018 cm3/g and 2.17–4.08 nm, respectively. They showed some ability to adsorb CO2 (323 K and 40 bars), and the storage capacity was 11.2–26.1 cm3/gm. The cobalt-containing complex had the highest CO2 storage capability (26.1 cm3/g) due to its relatively high surface area (5.82 m2/g), pore volume (0.018 cm3/g), pore diameter (4.08 nm), and surface roughness (11.6) compared to the nickel and copper complexes.