Experimental and DFT Computational Insights on the Adsorption of Selected Pharmaceuticals of Emerging Concern from Water Systems onto Magnetically Modified Biochar

Authors : Umar YUNUSA, Umaru UMAR, Sulaiman IDRİSS, Abdulrahman IBRAHİM, Tahir ABDULLAHİ

Pages : 1179-1196

Doi:10.18596/jotcsa.900197

View : 10 | Download : 9

Publication Date : 2021-11-30

Article Type : Research Paper

Abstract :This work aimed to fabricate a magnetically modified biochar insert ignore into journalissuearticles values(MBC); through a one-step pyrolysis of Vitex doniana nut at 500 °C and investigate its feasibility for the removal of two pharmaceuticals, namely, amoxicillin insert ignore into journalissuearticles values(AMX); and trimethoprim insert ignore into journalissuearticles values(TMT); from aqueous environment. The textural characteristics, chemical composition and magnetic properties of the MBC were analyzed using Brunauer-Emmett-Teller insert ignore into journalissuearticles values(BET); analysis, scanning electron microscopy insert ignore into journalissuearticles values(SEM);, Fourier Transform Infrared insert ignore into journalissuearticles values(FTIR); spectroscopy, X-ray diffraction insert ignore into journalissuearticles values(XRD); and vibrating sample magnetometer insert ignore into journalissuearticles values(VSM);. The results demonstrated the successful incorporation of the magnetic particles in the biochar matrix. The specific surface area and average pore volume of the MBC were obtained as 108.90 m2/g and 2.98 cm3/g, respectively. The adsorption process was observed to be strongly pH-dependent, and equilibrium was attained within 1 h. The kinetic data favors pseudo-second-order model insert ignore into journalissuearticles values(R2 > 0.999);, implying that the most plausible mechanism for the adsorption was chemisorption. The isothermal data was best fitted by the Langmuir model insert ignore into journalissuearticles values(R2 > 0.985);, signifying that the process was mainly monolayer adsorption on homogeneous surface. The maximum adsorption capacity achieved for AMX and TMT was 41.87 and 55.83 mg/g at 303 K, respectively. The thermodynamic examination highlighted that the adsorption was feasible and accompanied with absorption of heat and increase of entropy for both the adsorbates. Furthermore, the MBC exhibited a good recycling capability such that the adsorption capacity decreases by ~ 25% after reuse for six cycles. Besides, the theoretical results based on density functional theory insert ignore into journalissuearticles values(DFT); calculations demonstrated that the TMT molecules insert ignore into journalissuearticles values(ΔE = 3.762 eV); are more reactive compared to the AMX molecules insert ignore into journalissuearticles values(ΔE = 3.855 eV); which correlates with the experimental observations.
Keywords : Adsorption, Pharmaceuticals, Vitex doniana, Magnetic biochar, DFT calculations