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1

Sorptive interaction of oxyanions with Iron oxides: A review

100%
Adegoke H. I., Adekola F. A., Fatoki O. S., Ximba B. J.
Polish Journal of Environmental Studies
|
2013
|
tom 22
|
nr 1
Iron oxides are a group of minerals composed of Fe together with O and/or OH. They have high points of zero charge, making them positively charged over most soil pH ranges. Iron oxides also have relatively high surface areas and a high density of surface functional groups for ligand exchange reactions. In recent time, many studies have been undertaken on the use of iron oxides to remove harmful oxyanions such as chromate, arsenate, phosphate, and vanadate, etc., from aqueous solutions and contaminated waters via surface adsorption on the iron oxide surface structure. This review article provides an overview of synthesis methods, characterization, and sorption behaviours of different iron oxides with various oxyanions. The influence of thermodynamic and kinetic parameters on the adsorption process is appraised.
2

Efficient Rhodamine B removal using acid- and alkaline-activated Musa paradisiaca biochar

100%
Adekola F. A., Ayodele S. B., Inyinbor A. A.
Polish Journal of Environmental Studies
|
2019
|
tom 28
|
nr 5
Musa paradisiaca char was subjected to acid and alkaline treatment in order to prepare highly porous and efficient adsorbents. Prepared adsorbents were subjected to various characterizations viz surface morphology using a scanning electron microscopic (SEM), surface functional group using the Fourier transformed infrared spectroscopic (FTIR) analysis, and Brunauer-Emmett-Teller (BET) surface area among others. Adsorbents were subsequently used for the uptake of Rhodamine B (RhB) from aqueous solution, and adsorption data were tested with isothermal and kinetics models. BET surface area of 985 m²/g was obtained for alkaline-treated Musa paradisiaca. SEM revealed large pores on treated biomass and functional groups analysis revealed functional groups suitable for sorption. The prepared adsorbents were found to be effective in the uptake of Rhodamine B, with more than 90% removal in some cases. Maximum adsorption was obtained at pH 4 for both adsorbents. Equilibrium adsorption data fitted best into the Langmuir adsorption isotherm with maximum monolayer adsorption capacity of 7.003 mg/g and 6.878 mg/g for acid-treated biomass and alkaline-treated biomass, respectively. Pseudo second-order kinetics best described the adsorption kinetic data of the two adsorption systems.
3

Development of an analytical method for determining tributyltin and triphenyltin in seawater, sediment, and mussel samples using GC-FPD and GC-MS – TOF

88%
Okoro H. K., Fatoki O. S., Ximba B. J., Adekola F. A., Snyman R. G.
Polish Journal of Environmental Studies
|
2012
|
tom 21
|
nr 6
Analytical methods for speciation of targeted organotin compounds (TBT and TPT) in water samples using SPE cartridge and liquid-liquid extraction has been carried out. Also, sediment analysis using methanolacid digestion and acid-sonication extraction methods also were developed. Different parameters affecting extraction and peak resolution were optimized. Also, three derivatization procedures were optimized. The accuracy of the extraction procedure also was verified on certified reference material (BCR-462) certified for TBT (54±15 μg/kg) and DBT (68±12 μg/kg). Freeze-dried mussel tissue (ERM-CE 477) was certified for TBT (2.20±0.19 mg/kg), DBT (1.54±0.12 mg/kg), and MBT (1.50±0.28 mg/kg). The two certified reference materials were used for recovery experiments. Good recoveries were obtained with methanol-acid digestion. The result was validated by analyzing the real water and sediment samples collected from Cape Town harbor and the compounds were detected in both water and sediment samples. Extraction of water samples with SPE gave better recovery for TPT than TBT. Performance characteristics such as linearity, detection limit (LOD), quantification limit (LOQ), and recovery were determined. Recoveries of TBT and TPT in spiked water using SPE were 65% and 70%, respectively. Quantitative recoveries also were recorded for the certified reference standards of sediments and mussel materials used.
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