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Article ; Online: The potential of biochar-photocatalytic nanocomposites for removal of organic micropollutants from wastewater.

Fito, Jemal / Kefeni, Kebede K / Nkambule, Thabo T I

2022 Volume 829, Page(s) 154648

Abstract: Biochar (BC)-photocatalyst nanocomposites have emerged as appealing water and wastewater treatment technology. Such nanocomposite materials benefit from the synergistic effect of adsorption and photocatalysis to attain improved removal of pollutants from ...

Abstract	Biochar (BC)-photocatalyst nanocomposites have emerged as appealing water and wastewater treatment technology. Such nanocomposite materials benefit from the synergistic effect of adsorption and photocatalysis to attain improved removal of pollutants from water and wastewater. Under this review, three BC-based nanocomposite photocatalysts such as BC-TiO
MeSH term(s)	Catalysis ; Charcoal ; Environmental Pollutants ; Nanocomposites/chemistry ; Titanium/chemistry ; Waste Water
Chemical Substances	Environmental Pollutants ; Waste Water ; biochar ; Charcoal (16291-96-6) ; Titanium (D1JT611TNE)
Language	English
Publishing date	2022-03-16
Publishing country	Netherlands
Document type	Journal Article ; Review
ZDB-ID	121506-1
ISSN	1879-1026 ; 0048-9697
ISSN (online)	1879-1026
ISSN	0048-9697
DOI	10.1016/j.scitotenv.2022.154648
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Article: TiO

Madima, Ntakadzeni / Kefeni, Kebede K / Mishra, Shivani B / Mishra, Ajay K

Heliyon

2022 Volume 8, Issue 9, Page(s) e10683

Abstract: In the current study, a direct S-scheme titanium dioxide/graphitic carbon nitride ( ... ...

Abstract	In the current study, a direct S-scheme titanium dioxide/graphitic carbon nitride (TiO
Language	English
Publishing date	2022-09-18
Publishing country	England
Document type	Journal Article
ZDB-ID	2835763-2
ISSN	2405-8440
ISSN	2405-8440
DOI	10.1016/j.heliyon.2022.e10683
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Article: Brewery industrial wastewater treatment through mesocosm horizontal subsurface flow constructed wetland

Angassa, Kenatu / Assefa, Berhanu / Kefeni, Kebede K. / Nkambule, Thabo T. I. / Fito, Jemal

Environment systems & decisions. 2022 June, v. 42, no. 2

2022

Abstract: The brewing industry discharges huge amounts of wastewater, which contains a high concentration of organic and nutrient-rich components. Therefore, this study aimed to evaluate the treatment performance of Horizontal-Subsurface-Flow-Constructed Wetland ... ...

Abstract	The brewing industry discharges huge amounts of wastewater, which contains a high concentration of organic and nutrient-rich components. Therefore, this study aimed to evaluate the treatment performance of Horizontal-Subsurface-Flow-Constructed Wetland Systems (HSSFCWs) for brewery wastewater remediation. A mesocosm HSSFCWs was constructed and the inside of each unit was covered with high-density polyethylene and filled with gravel. The HSSFCWs were planted with Colocasia gigantean, Phragmites karka, and Canna indica while the control treatment unit was left unplanted. The HSSFCWs were operated with a hydraulic loading rate of 21.7 Lm⁻² day⁻¹ and a hydraulic residence time of 7 days. The removal efficiencies of the primary clarifier for COD, BOD₅, and TSS were found to be 65.5%, 67.0%, and 98.0%, respectively. The treatment performances of the HSSFCWs with P. karka, C. gigantean and C. indica were COD 80.3%, 79.0%, and 73.6%; BOD₅ 75.4%, 74.0% and 73.6%; TN 84.0%, 77.0% and 64.0%; TP 71.0%, 69.0% and 63.0%; and PO₄³⁻ 85.7%, 80.0% and 79.0%, respectively. Compared to the other two treatment systems, the species P. karka achieved the best treatment performance in terms of the removal of organic matter and nutrients. In general, it can be concluded that the wetland systems planted with P. karka, C. gigantean, and C. indica have the potential to remove organic matter and nutrients from brewery wastewater. Therefore, this finding is encouraging to scale up this wastewater treatment practice at an industrial level as alternative industrial wastewater remediation.
Keywords	Canna indica ; Colocasia ; Phragmites ; environment ; gravel ; industrial wastewater ; industrial wastewater treatment ; organic matter ; polyethylene ; remediation ; subsurface flow
Language	English
Dates of publication	2022-06
Size	p. 265-275.
Publishing place	Springer US
Document type	Article
ISSN	2194-5403
DOI	10.1007/s10669-022-09849-z
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: TiO2-modified g-C3N4 nanocomposite for photocatalytic degradation of organic dyes in aqueous solution

Madima, Ntakadzeni / Kefeni, Kebede K. / Mishra, Shivani B. / Mishra, Ajay K.

Heliyon. 2022 Sept., v. 8, no. 9 p.e10683-

2022

Abstract: In the current study, a direct S-scheme titanium dioxide/graphitic carbon nitride (TiO₂/g-C₃N₄) heterojunction structure was fabricated via simultaneous calcination of TiO₂ precursors and g-C₃N₄. Guava leaf extract was utilized as a reductant for TiO₂ ... ...

Abstract	In the current study, a direct S-scheme titanium dioxide/graphitic carbon nitride (TiO₂/g-C₃N₄) heterojunction structure was fabricated via simultaneous calcination of TiO₂ precursors and g-C₃N₄. Guava leaf extract was utilized as a reductant for TiO₂ production through a green synthetic method, and g-C₃N₄ was prepared by thermal decomposition of melamine. The pristine and nanocomposite photocatalysts were characterized by XRD, FTIR, BET, TGA, HRTEM, UV-vis DRS, and PL to elucidate their physicochemical properties. The photocatalytic activity of synthesized photocatalysts was examined through the degradation of rhodamine B (RhB) and methylene blue (MB) dyes under simulated solar light irradiation. The nanocomposite exhibited commendable photocatalytic performances with 96% degradation efficiency of RhB attained in 120 min and 95% degradation efficiency of MB achieved in 150 min. The enhanced photocatalytic activities were attributable to visible light-harvesting characteristics and the formation of an S-scheme heterojunction system between two catalysts which promotes interfacial charge separation efficiency and longer charge carrier lifespan. After 4 consecutive cycles, the degradation efficiencies of both RhB and MB remained above 85%. According to the trapping experiments, OH• and O₂•⁻ radicals were critical in the degradation of RhB, while h⁺ and O₂•⁻ radicals were dominant in the degradation of MB. The nanocomposite was also tested for elution of actual water pollutants by combining two dyes, and above 90% degradation efficiencies were achieved for both dyes after 240 min.
Keywords	aqueous solutions ; carbon nitride ; graphene ; guavas ; irradiation ; leaf extracts ; lighting ; longevity ; melamine ; methylene blue ; nanocomposites ; photocatalysis ; photocatalysts ; reducing agents ; rhodamines ; thermal degradation ; titanium dioxide ; Green synthesis ; Photocatalytic degradation ; Nanocomposite ; Radical scavenger
Language	English
Dates of publication	2022-09
Publishing place	Elsevier Ltd
Document type	Article ; Online
Note	Use and reproduction
ZDB-ID	2835763-2
ISSN	2405-8440
ISSN	2405-8440
DOI	10.1016/j.heliyon.2022.e10683
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Article: The potential of biochar-photocatalytic nanocomposites for removal of organic micropollutants from wastewater

Fito, Jemal / Kefeni, Kebede K. / Nkambule, Thabo T.I.

Science of the total environment. 2022 July 10, v. 829

2022

Abstract	Biochar (BC)-photocatalyst nanocomposites have emerged as appealing water and wastewater treatment technology. Such nanocomposite materials benefit from the synergistic effect of adsorption and photocatalysis to attain improved removal of pollutants from water and wastewater. Under this review, three BC-based nanocomposite photocatalysts such as BC-TiO₂, BC-ZnO, and BC-spinel ferrites were considered. These nanocomposites acquire intrinsic properties to improve the practical limitations of the pristine BC and photocatalysts. The BC-based nanocomposites attained high photocatalytic activity, mechanical hardness, thermal stability, chemically non-reactive, magnetically permeable, reduced energy band gaps, improved reusability, and simplified recovery. Moreover, BC-based photocatalytic nanocomposites showed reduced recombination rates of the electron-hole pairs which are desirable for photocatalytic applications. However, the surface areas of the composites are usually smaller than that of the BC but higher than those of the pristine photocatalysts. Practically, the performances of the nanocomposites are much superior to those of the corresponding pristine components. This hybrid treatment technology is an emerging field and its industrial application is still at an early stage of the investigation. Therefore, exploring the full potential and practical applications of this technology is highly encouraging. Hence, this review focused on the critical evaluation of the most recent research on the synthesis, characterization, and photocatalytic treatment efficiency of the BC photocatalyst nanocomposites towards emerging pollutants in the aqueous medium. Moreover, the influence of various sources of BC feedstocks and their limitations on adsorption and photodegradation activities are discussed in detail. Finally, concluding remarks and future research directions are given to assist and shape the exploration of BC-based nanocomposite photocatalysts in water treatment.
Keywords	adsorption ; biochar ; energy ; environment ; feedstocks ; hardness ; industrial applications ; magnetism ; nanocomposites ; photocatalysis ; photocatalysts ; photolysis ; pollutants ; synergism ; thermal stability ; wastewater ; wastewater treatment
Language	English
Dates of publication	2022-0710
Publishing place	Elsevier B.V.
Document type	Article
ZDB-ID	121506-1
ISSN	1879-1026 ; 0048-9697
ISSN (online)	1879-1026
ISSN	0048-9697
DOI	10.1016/j.scitotenv.2022.154648
Database	NAL-Catalogue (AGRICOLA)

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Article: Effect of Zn doping on physico-chemical properties of cobalt ferrite for the photodegradation of amoxicillin and deactivation of E. coli

Mmelesi, Olga K. / Patala, Rapelang / Nkambule, Thabo T.I. / Mamba, Bhekie B. / Kefeni, Kebede K. / Kuvarega, Alex T.

Colloids and surfaces. 2022 Sept. 20, v. 649

2022

Abstract: In this study, ZnₓCo₁₋ₓFe₂O₄ (x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) nanoparticles were synthesized by co-precipitation method. The prepared ZnₓCo₁₋ₓFe₂O₄ NPs were annealed at 500 ⁰C for 3 h. The nanoparticles were characterized using XRD, BET, UV–VIS–DRS ... ...

Abstract	In this study, ZnₓCo₁₋ₓFe₂O₄ (x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) nanoparticles were synthesized by co-precipitation method. The prepared ZnₓCo₁₋ₓFe₂O₄ NPs were annealed at 500 ⁰C for 3 h. The nanoparticles were characterized using XRD, BET, UV–VIS–DRS spectroscopy, PL spectroscopy, FT-IR spectroscopy, Raman spectroscopy, VSM, and XPS. The XRD patterns indicated the formation of cubic inverse/mixed spinel structure of ZnₓCo₁₋ₓFe₂O₄ NPs and the change in structural parameters with increasing Zn concentration. The agglomerated and cubic morphology of the nanoparticles was confirmed by TEM. The magnetic properties such as saturation magnetization (Ms), residual magnetization (Mr), and coercivity (Hc) were calculated from the hysteresis curves. The performance of the obtained nanoparticles was studied on the photodegradation of amoxicillin using visible light irradiation and the deactivation of E. Coli. Zn₀.₄Co₀.₆Fe₂O₄ NPs showed enhanced results such as saturation magnetization (68 emu/g), photodegradation (89%), and bacterial inactivation (11 mm zone of inhibition). The results indicate that Zn₀.₄Co₀.₆Fe₂O₄ is of great potential application value in wastewater remediation.
Keywords	Escherichia coli ; Fourier transform infrared spectroscopy ; Raman spectroscopy ; amoxicillin ; cobalt ; coprecipitation ; ferrimagnetic materials ; hysteresis ; irradiation ; light ; magnetism ; photolysis ; remediation ; wastewater
Language	English
Dates of publication	2022-0920
Publishing place	Elsevier B.V.
Document type	Article
ZDB-ID	1500517-3
ISSN	0927-7757
ISSN	0927-7757
DOI	10.1016/j.colsurfa.2022.129462
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Article ; Online: Magnetite and cobalt ferrite nanoparticles used as seeds for acid mine drainage treatment.

Kefeni, Kebede K / Mamba, Bhekie B / Msagati, Titus A M

Journal of hazardous materials

2017 Volume 333, Page(s) 308–318

Abstract: In this study, magnetite and cobalt ferrite nanoparticles were used as seeds for acid mine drainage (AMD) treatment at pH of 7.05±0.35. Duplicate samples of AMD, one without heating and another with heating at 60°C was treated under continuous stirring ... ...

Abstract	In this study, magnetite and cobalt ferrite nanoparticles were used as seeds for acid mine drainage (AMD) treatment at pH of 7.05±0.35. Duplicate samples of AMD, one without heating and another with heating at 60°C was treated under continuous stirring for 1h. The filtrate analysis results from ICP-OES have shown complete removal of Al, Mg, and Mn, while for Fe, Ni and Zn over 90% removals were recorded. Particularly, settling time has significant effect on the removal of Mg, Ca and Na. The results from SQUID have shown superparamagnetic properties of the synthesised magnetic nanoparticles and ferrite sludge. The recovered nanoparticles from AMD are economically important and reduce the cost of waste disposal.
Language	English
Publishing date	2017-07-05
Publishing country	Netherlands
Document type	Journal Article
ZDB-ID	1491302-1
ISSN	1873-3336 ; 0304-3894
ISSN (online)	1873-3336
ISSN	0304-3894
DOI	10.1016/j.jhazmat.2017.03.054
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Article ; Online: Trace metals, anions and polybromodiphenyl ethers in settled indoor dust and their association.

Kefeni, Kebede K / Okonkwo, Jonathan O

Environmental science and pollution research international

2013 Volume 20, Issue 7, Page(s) 4895–4905

Abstract: Contaminants in settled indoor dust are potentially health hazardous to human. Thus, identification and quantification of toxic chemicals in settled indoor dust is of great concern. In this study, the levels of major anions ([Formula: see text]), trace ... ...

Abstract	Contaminants in settled indoor dust are potentially health hazardous to human. Thus, identification and quantification of toxic chemicals in settled indoor dust is of great concern. In this study, the levels of major anions ([Formula: see text]), trace metals (Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, As and Pb) and polybromodiphenyl ethers (PBDEs) in settled office and home dust were determined and correlations between the contaminants investigated. Depending on the available materials in both microenvironments, the most possible sources were identified. The results showed that the settled office dusts (n = 6 pooled samples from 85 offices) were more contaminated than home dusts (n = 8 homes). For anions, [Formula: see text] and Cl(-) accounted for 87 and 97% of the total office and home dust contaminants, respectively. For trace metals, Fe, Cu, Zn and Mn, accounted for 98% of the contaminants in both office and home dust samples. Fe exhibited the highest percentage of 76.7 and 87.3% in office and home dust samples, respectively. For PBDEs, the mean concentrations detected in office and home dust ranged between 5.8-86.3 and 1.5-20.6 ng g(-1), respectively. The log-transformed correlation between the total concentrations of trace metals and major anions detected in offices and homes was positive for offices and negative for homes with a statistically significant values (r = 0.73, p < 0.01; r = -0.22, p < 0.01, respectively). The daily exposure rates determined for the most hazardous such as As, Cd, Pb and PBDEs congeners, relative to the individual concentrations reported in the literature in settled indoor dust, were found very lower. Therefore, maybe it is possible to expect less potential health risk. Investigation of formation of coordination compounds between trace metals and PBDEs congeners is possible; however, this requires further study.
MeSH term(s)	Air Pollution, Indoor/analysis ; Anions/analysis ; Dust/analysis ; Environmental Exposure/analysis ; Halogenated Diphenyl Ethers/analysis ; Humans ; Metals/analysis ; South Africa
Chemical Substances	Anions ; Dust ; Halogenated Diphenyl Ethers ; Metals ; pentabromodiphenyl ether (7REL09ZX35)
Language	English
Publishing date	2013-01-15
Publishing country	Germany
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	1178791-0
ISSN	1614-7499 ; 0944-1344
ISSN (online)	1614-7499
ISSN	0944-1344
DOI	10.1007/s11356-013-1469-4
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Article ; Online: Spinel ferrite nanoparticles and nanocomposites for biomedical applications and their toxicity.

Kefeni, Kebede K / Msagati, Titus A M / Nkambule, Thabo Ti / Mamba, Bhekie B

Materials science & engineering. C, Materials for biological applications

2019 Volume 107, Page(s) 110314

Abstract: This review focuses on the biomedical applications and toxicity of spinel ferrite nanoparticles (SFNPs) with more emphasis on the recently published work. A critical review is provided on recent advances of SFNPs applications in biomedical areas. The ... ...

Abstract	This review focuses on the biomedical applications and toxicity of spinel ferrite nanoparticles (SFNPs) with more emphasis on the recently published work. A critical review is provided on recent advances of SFNPs applications in biomedical areas. The novelty of SFNPs in addressing the bottleneck problems encountered in the areas of health; in particular, for diagnosis and treatment of tumour cells are well reviewed. Furthermore, research gaps, toxicity of SFNPs and areas which still need more attention are highlighted. Based on the result of this review, the SFNPs have unlimited capacity in cancer treatment, disease diagnosis, magnetic resonance imaging, drug delivery and release. Overall, stepping out of the conventional way of treatment is difficult but also essential in bringing long lasting solution for cancer and other diseases treatment. In fact, the toxicity study and commercialisation of the SFNPs based cancer treatment options are the main challenges and need further study, in order to reduce unforeseen consequences.
MeSH term(s)	Aluminum Oxide/chemistry ; Animals ; Coated Materials, Biocompatible/chemistry ; Coated Materials, Biocompatible/therapeutic use ; Drug Delivery Systems/methods ; Ferric Compounds/chemistry ; Humans ; Hyperthermia, Induced/methods ; Magnesium Oxide/chemistry ; Nanocomposites/chemistry ; Nanocomposites/therapeutic use ; Nanocomposites/toxicity ; Nanoparticles/chemistry ; Nanoparticles/therapeutic use ; Nanoparticles/toxicity ; Neoplasms/diagnosis
Chemical Substances	Coated Materials, Biocompatible ; Ferric Compounds ; spinell ; ferrite (1317-54-0) ; Magnesium Oxide (3A3U0GI71G) ; Aluminum Oxide (LMI26O6933)
Language	English
Publishing date	2019-10-23
Publishing country	Netherlands
Document type	Journal Article ; Review
ZDB-ID	2012160-X
ISSN	1873-0191 ; 0928-4931
ISSN (online)	1873-0191
ISSN	0928-4931
DOI	10.1016/j.msec.2019.110314
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Article ; Online: Analysis of major congeners of polybromobiphenyls and polybromodiphenyl ethers in office dust using high resolution gas chromatography-mass spectrometry.

Kefeni, Kebede K / Okonkwo, Jonathan O

Chemosphere

2012 Volume 87, Issue 9, Page(s) 1070–1075

Abstract: The study focused on analysis of polybromobiphenyls (PBBs) and polybromodiphenyl ethers (PBDEs) congeners in office dust obtained in Pretoria, South Africa. Of the 32 congeners considered for identification, (BB-1, 2, 4, 10, 15, 26, 29, 30, 31, 38, 49, ... ...

Abstract	The study focused on analysis of polybromobiphenyls (PBBs) and polybromodiphenyl ethers (PBDEs) congeners in office dust obtained in Pretoria, South Africa. Of the 32 congeners considered for identification, (BB-1, 2, 4, 10, 15, 26, 29, 30, 31, 38, 49, 80, 103, 153, 155, 209 and BDE-3, 15, 17, 28, 47, 66, 77, 85, 99, 100, 126, 138, 153, 154, 183, 209) only BB-2, 4, 30, 153, 209 and BDE-47, 66, 85, 99, 153 and 209 congeners were detected. The sum of PBBs concentration detected in office dust ranged from <dl-196 ng g(-1) dry weight (dw) with a median and mean of 11.4 and 38.2 ng g(-1), respectively. On the other hand, the sum of PBDEs concentration detected ranged from 21.6 to 578.6 ng g(-1)dw with a median and mean of 162 and 169 ng g(-1)dw, respectively. A Spearman rank correlation between ∑(5)PBBs and ∑(6)PBDEs (r(s)=0.55, p=0.003), indicated a statistical significant positive correlation for the similarity of pollution sources for both compound classes. However, no correlation was observed between the number of electronic materials and summation of concentrations of PBBs and PBDEs congeners detected. Concentrations of PBDEs detected in this study are substantially lower than reported in office dust in developed countries.<br />
MeSH term(s)	Dust/analysis ; Gas Chromatography-Mass Spectrometry/methods ; Halogenated Diphenyl Ethers/analysis ; Occupational Exposure ; Polybrominated Biphenyls/analysis ; South Africa
Chemical Substances	Dust ; Halogenated Diphenyl Ethers ; Polybrominated Biphenyls ; 2,2',4,4'-tetrabromodiphenyl ether (0N97R5X10X)
Language	English
Publishing date	2012-05
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	120089-6
ISSN	1879-1298 ; 0045-6535 ; 0366-7111
ISSN (online)	1879-1298
ISSN	0045-6535 ; 0366-7111
DOI	10.1016/j.chemosphere.2012.02.014
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