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Three adsorbents based on the metal–organic frameworks (MOFs), viz.; MIL-88(Fe), NH2-MIL-88(Fe), and mixed-MIL-88(Fe) were synthesized using a microwave-assisted solvothermal technique.

Recently, pharmaceutical pollutants in water have emerged as a global concern as they give threat to human health and the environment. In this study, graphene nanoplatelets (GNPs) were used to efficiently remove antibiotics sulfamethoxazole (SMX) and analgesic acetaminophen (ACM) as pharmaceutical pollutants from water by an adsorption process. GNPs; C750, C300, M15 and M5 were characterized by high-resolution transmission electron microscopy, Raman spectroscopy, X-ray diffraction and Brunauer–Emmett–Teller. The effects of several parameters viz. solution pH, adsorbent amount, initial concentration and contact time were studied. The parameters were optimized by a batch adsorption process and the maximum removal efficiency for both pharmaceuticals was 99%. The adsorption kinetics and isotherms models were employed, and the experimental data were best analysed with pseudo-second kinetic and Langmuir isotherm with maximum adsorption capacity (Q m ) of 210.08 mg g −1 for SMX and 56.21 mg g −1 for ACM. A regeneration study was applied using different eluents; 5% ethanol-deionized water 0.005 M NaOH and HCl. GNP C300 was able to remove most of both pollutants from environmental water samples. Molecular docking was used to simulate the adsorption mechanism of GNP C300 towards SMX and ACM with a free binding energy of −7.54 kcal mol −1 and −5.29 kcal mol −1 , respectively, which revealed adsorption occurred spontaneously.

Density functional calculations were performed on the metal complexes formed during the synthesis of barium zirconate (BZY). This compound has been synthesized previously, but the molecular interactions present during the formation of the ligand-metal complexes are unknown. In this study, calculations were carried out to determine the preferred coordination sites for the metal complexes. The cations Ba 2+ , Y 3+ , and Zr 4+ were modeled to interact with two deprotonated chelating agents (citric acid [CA] and ethylenediaminetetraacetic acid [EDTA]) at strategic positions. Density functional theory (DFT) at the B3LYP level of theory with basis set 6-31G* and Universal Gaussian Basis Set (UGBS) was used. The relevant geometries, binding energies, and charge distributions of the complexes are reported. It was found that both CA and EDTA can bind the metal cations investigated in this study. Metal cations prefer to form bonds at the electron-rich sites of the chelating agents. Of the three metal cations considered, Zr 4+ was found to possess the strongest bonds to deprotonated CA and EDTA, followed by Y 3+ and then Ba 2+ .

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