Effect of parameter variation on the coordination of 5-amino benzene-1, 3-dicarboxylic acid under the solvothermal technique for catalytic adsorption

Abstract

The solvothermal synthesis of metal-organic frameworks (MOFs) has shown to be very effective for the formation of well-crystalline MOFs due to the presence of polar organic solvents to aid solute solubility under high temperatures and pressure. 5-Aminobenzene-1, 3-dicarboxylic acid as a linker for the synthesis of metal-organic frameworks has been identified to have rich coordination properties due to the presence of carboxylic and amino groups in its structure. In this study, two metal-organic frameworks were synthesized using 5-Aminobenzene-1, 3-dicarboxylic acid and copper (II) nitrate trihydrate under two different conditions using the solvothermal technique. The MOFs were characterized to assess the diversity in their structural formation. Characterization confirmed different MOFs, Cu-5abdc and Cu-5abdc-NH₂ formed based on the evaluation of their functional group and bond formations, crystalline phases, morphology as well as thermal stability. The presence of double peaks with bands at 3243 cm⁻¹ and 3120 cm⁻¹ indicated the presence of the primary amine (NH₂) group in Cu-5abdc-NH₂. Both MOFs had some similar crystalline peaks which matched copper oxide (CuO) crystal and other different peak patterns. The MOFs were both stable and could only decompose above 200 °C. However, Cu-5abdc-NH₂ was observed to be more stable in comparison with Cu-5abdc due to a broad study decomposition observed. The Cu-5abdc-NH₂ also showed a more catalytic adsorption activity for the conversion and removal of Hillanthine B. The pseudo-second-order kinetic reaction rate favoured the adsorption of HB by the MOFs. The adsorption of HB on Cu-5abdc and Cu-5abdc-NH₂ both fit the Freundlich model better than the Langmuir model due to the R² values observed.