Diekola Yahya’s scientific contributions

In this present study, a facile, sustainable, eco-friendly, and low-cost material was developed using synthesized graphene-oxide (SGO) incorporated with zinc oxide (SGO/ZnO) and its adsorptive performance was compared with commercial graphene oxide (CGO) and synthesized graphene-oxide (SGO) for the removal of fluoride ion from aqueous environment. The materials were characterized using techniques such as Fourier transform spectroscopy (FTIR), Scanning electron microscopy coupled with energy dispersive X-Ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), Zeta potentiometer, Brunauer-Emmett-Teller (BET) measurement, Transmission Electron Microscopy (TEM). The SEM analysis confirmed the existence of a spherical structure, smooth and agglomerated white particle in between the wrinkled GO sheet, demonstrating a successful synthesis of SGO/ZnO composite. The EDX analysis revealed the presence of carbon, zinc, and oxygen with no impurities. The successful incorporation of ZnO on SGO yielded a BET surface of 123 m 2 /g for SGO/ZnO, which is far greater than that of the separate SGO and ZnO with surface areas of 19 m 2 /g and 76 m 2 /g respectively. The batch studies revealed that the removal of fluoride ion by CGO, SGO, and SGO/ZnO was 89.4 %, 94.8 %, and 99.2 %. Also, the jovanovic isotherm model fitted well to the fluoride ion adsorption onto CGO, SGO, and SGO/ZnO suggesting a monolayer adsorption with mechanical contact possibility. The estimated adsorption capacities (Q max) were 105.64, 116.37, and 188.60 mg/g for CGO, SGO, and SGO/ZnO, respectively. In addition, the adsorption kinetics study showed that the pseudo-second-order kinetic model suits the adsorption model, indicating the presence of an ionic interaction between the adsorbent functional groups and the fluoride ion. The adsorption thermody-namic analysis indicates that the adsorption process was spontaneous, endothermic, with strong affinity between the adsorbate and adsorbents. Furthermore, the regenerability and reusability analysis showed that about 39.5 %, 49.9 %, and 70.6 % of fluoride ion on CGO, SGO, and SGO/ZnO was removed after fifth desorption-adsorption cycles, suggesting that the SGO/ZnO was more stable. The interaction mechanism between SGO/ ZnO and fluoride ion was governed primarily by pore-filling, hydrogen bonding, electrostatic attraction, and physical adsorption.

Abstract In this study, stem bark eucalyptus was subjected to pyrolysis modification to produce modified biochar. The modified biochar (MSBEB) was characterized using Fourier transform infrared Spectroscopy (FTIR), Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray Diffraction (XRD), and Brunauer-Emmett-Teller (BET) techniques. The impact of adsorption process variables such as temperature, adsorbent dosage, pH and contact time on the metals ion removal efficiency were investigated. The optimum conditions for maximum removal of Cr(VI) and Pb(II) ions were determined as 45.20 °C, 0.12 g/L, and 120.5 min through optimization process. The excellent performance of the modified biochar can be attributed to its porous structure, surface area, surface chemistry and crystallinity as supported by SEM, BET, FTIR and XRD analysis. However, based on the high correlation coefficient (R 2), low values of chi square (χ 2) and sum of square error (SSE), the Freundlich isotherm and Pseudo-second order kinetics provided the best fit, suggesting chemisorption as the dominant mechanism. Thermodynamic analysis indicated an endothermic, spontaneous, and feasible reaction.