Wyniki wyszukiwania - Biblioteka Nauki

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

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2013

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tom 22

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nr 1

EN

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

Preliminary investigation into occurrence and removal of arsenic, cadmium, mercury, and zinc in wastewater treatment plants in cape town and stellenbosch

88%

Olujimi O. O. , Fatoki O. S. , Odendaal J. , Daso A. P. , Oputu O.

Polish Journal of Environmental Studies

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2012

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tom 21

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nr 6

EN

The results of metals determination using inductively coupled plasma mass spectrometry (ICP-MS) for wastewater, sludges, freshwater, and sediment from six treatment plants and rivers in Cape Town and Stellenbosch are presented. The possible impacts of waste effluent on the freshwater systems are also assessed. The concentrations of the respective metals can be ranked in the order mercury < cadmium < arsenic < zinc. Occurrence of metals in influent wastewater ranged from 4.04-28.19, 1.64-17.39, 0.64-2.2, and 684.94- 5128.31 μg·l-1 for arsenic, cadmium, mercury and zinc, respectively. Average metal removal efficiency in WWTP is listed as mercury > zinc > cadmium > arsenic, with removal efficiency ranging from 28% for arsenic at Plant B and 90.25% for As at Plant D. Sludges from the six treatment plants exhibited particularly high contents of heavy metals, above the permissible utilization and disposal of sewage sludge guidelines. Metal content of sediment and freshwater samples were also above the acceptable limits for aquatic ecosystems.

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

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2012

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tom 21

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nr 6

EN

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.

4

Coal fly ash supported nZnO for the sorption of triphenyltin chloride

75%

Ayanda O. S. , Fatoki O. S. , Adekola F. A. , Ximba B. J. , Akinsoji O. S. , Petrik L. F.

Archives of Environmental Protection

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2015

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tom Vol. 41, no. 1

59--71

EN

A laboratory study was performed to study the effects of various operating factors, viz. adsorbent dose, contact time, solution pH, stirring speed, initial concentration and temperature on the adsorption of triphenyltin chloride (TPT) onto coal fly ash supported nZnO (CFAZ). The adsorption capacity increases with increase in the adsorbent amount, contact time, pH, stirring speed and initial TPT concentration, and decrease with increase in the solution temperature. The adsorption data have been analyzed by Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) adsorption models to determine the mechanistic parameters associated with the adsorption process while the kinetic data were analyzed by pseudo first-order, pseudo second-order, Elovich, fractional power and intraparticle diffusivity kinetic models. The thermodynamic parameters of the process were also determined. The results of this study show that 0.5 g of CFAZ was able to remove up to 99.60% of TPT from contaminated natural seawater at 60 min contact time, stirring speed of 200 rpm and at a pH of 8. It was also found that the equilibrium and kinetic data fitted better to Freundlich and pseudo second-order models, respectively. It can therefore be concluded that CFAZ can be effectively used for shipyard process wastewater treatment.