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  1. Article ; Online: Development of nitrogen-doped graphene/MOF nanocomposites towards adsorptive removal of Cr(VI) from the wastewater of the Herbert Bickley treatment works

    Madumo, Tshireletso M. / Zikalala, Sithembela A. / Gumbi, Nozipho N. / Mishra, Shivani B. / Ntsendwana, Bulelwa / Nxumalo, Edward N.

    Environmental Nanotechnology, Monitoring & Management. 2023, p.100794-

    2023  , Page(s) 100794–

    Abstract: Industrial effluents laden with Cr(VI) pose considerable health risks to humans and animals if left untreated. Hence, metal-organic framework-5/nitrogen-doped graphene (MOF-5/NGO) nanocomposites were fabricated with increasing NGO loading (0.05, 0.10 and ...

    Abstract Industrial effluents laden with Cr(VI) pose considerable health risks to humans and animals if left untreated. Hence, metal-organic framework-5/nitrogen-doped graphene (MOF-5/NGO) nanocomposites were fabricated with increasing NGO loading (0.05, 0.10 and 0.15 wt. %) to investigate the role of NGO content of the chemical and physical properties of the composites. The FTIR spectra show the nanocomposites be to be rich in surface -OH and -COOH functional groups. Raman spectroscopy confirmed bond formation between the MOF-5 and NGO through downshift of the G- and 2D-bands. XRD showed MOF-5/NGO nanocomposites both the MOF-5 and the NGO to be highly crystalline while thermogravimetric analysis indicated the thermal stabilities of the composites to be enhanced. The SEM micrographs revealed the NGO flakes to be dispersed on the MOF-5 microstructures prior to adsorption and the disappearance of microstructures post adsorption. The as-synthesized nanocomposite exhibited BET surface area in the range 384.55-395.56 m².g⁻¹ which is a significant increase from that of MOF-5 261.00 m².g⁻¹. The optimal conditions for maximum Cr(VI) adsorption were determined to be: pH 2, contact time of 60 min, adsorbent dosage of 6 mg.L⁻¹, initial Cr(VI) concentration of 0.5 mg L⁻¹ and temperature of 30°C. A maximum adsorption efficiency of 46.1% was achieved by the composite MOF-5/NGO (0.05 wt.%) and not significantly compromised by competing metal ions. The Cr(VI) removal on MOF-5/NGO nanocomposites is well described by the Langmuir isotherm, confirming a chemisorption process. In addition, the thermodynamic studies confirmed the adsorption process to be favorable, spontaneous and endothermic. The Cr(VI) removal % on MOF-5/NGO from real water was found to be 52.1%. Therefore, the novel MOF-5/NGO nanocomposite can be applied for efficient Cr(VI) removal from real wastewater due to synergistic surface morphologies between NGO and MOF-5 units characterized by better adsorption capacity not met by pristine materials.
    Keywords Raman spectroscopy ; administrative management ; adsorbents ; adsorption ; endothermy ; graphene ; nanocomposites ; nanotechnology ; pH ; sorption isotherms ; surface area ; temperature ; thermodynamics ; thermogravimetry ; wastewater ; Metal-organic framework-5 ; Nitrogen doped graphene ; Chromium (VI)
    Language English
    Publishing place Elsevier B.V.
    Document type Article ; Online
    Note Pre-press version
    ZDB-ID 2821777-9
    ISSN 2215-1532
    ISSN 2215-1532
    DOI 10.1016/j.enmm.2023.100794
    Database NAL-Catalogue (AGRICOLA)

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  2. Article: A Mini-Review of Nanocellulose-Based Nanofiber Membranes Incorporating Carbon Nanomaterials for Dye Wastewater Treatment

    Moyo, Senelisile / Gumbi, Nozipho N. / De Kock, Lueta A. / Nxumalo, Edward N.

    Environmental nanotechnology, monitoring & management. 2022 June 15,

    2022  

    Abstract: Nanocellulose has over the past decades attracted considerable interest due to its favourable properties compared to the commonly used polymeric materials in the fabrication of wastewater treatment nanofiber membranes. This review presents an overview of ...

    Abstract Nanocellulose has over the past decades attracted considerable interest due to its favourable properties compared to the commonly used polymeric materials in the fabrication of wastewater treatment nanofiber membranes. This review presents an overview of the different types of nanocellulose used in the production of nanofiber membranes, their production routes, and properties, as well as their application in dye wastewater treatment. Traditionally, nanocellulose has been used as an additive in polymeric materials in membrane applications, with better understanding of the properties, characteristics and structure of nanocellulose. Recently, workers shifted towards using nanocellulose as a membrane material instead of an additive. This mini-review first investigates the use of nanocellulose as a sole membrane material to produce membranes normally referred to as nanopapers for use in dye wastewater remediation, its limitations as a membrane material, and the fabrication methods that have been used to produce nanocellulose-based membranes. It has been shown that these nanopapers can be used in both adsorption and filtration processes. Different methods that are used to improve the adsorption and filtration efficiency of pure nanocellulose membranes are also evaluated with a special focus on surface functionalisation and the use of carbon-based nanomaterials in improving the efficiency of nanocellulose-based membranes in wastewater treatment applications particularly in the removal of hazardous dye species. The use of carbon nanotubes and graphene oxide with nanocellulose has been shown to significantly improve the membrane flux, adsorption capacity as well as wet and dry strength of the nanocellulose membranes which consequently leads to enhanced membrane efficiency.
    Keywords administrative management ; adsorption ; carbon nanotubes ; cellulose ; dry strength ; dyes ; filtration ; graphene oxide ; nanofibers ; polymers ; remediation ; wastewater ; wastewater treatment
    Language English
    Dates of publication 2022-0615
    Publishing place Elsevier B.V.
    Document type Article
    Note Pre-press version
    ZDB-ID 2821777-9
    ISSN 2215-1532
    ISSN 2215-1532
    DOI 10.1016/j.enmm.2022.100714
    Database NAL-Catalogue (AGRICOLA)

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  3. Article: Photocatalytic Nanofiber Membranes for the Degradation of Micropollutants and Their Antimicrobial Activity: Recent Advances and Future Prospects.

    Chabalala, Mandla B / Gumbi, Nozipho N / Mamba, Bhekie B / Al-Abri, Mohammed Z / Nxumalo, Edward N

    Membranes

    2021  Volume 11, Issue 9

    Abstract: This review paper systematically evaluates current progress on the development and performance of photocatalytic nanofiber membranes often used in the removal of micropollutants from water systems. It is demonstrated that nanofiber membranes serve as ... ...

    Abstract This review paper systematically evaluates current progress on the development and performance of photocatalytic nanofiber membranes often used in the removal of micropollutants from water systems. It is demonstrated that nanofiber membranes serve as excellent support materials for photocatalytic nanoparticles, leading to nanofiber membranes with enhanced optical properties, as well as improved recovery, recyclability, and reusability. The tremendous performance of photocatalytic membranes is attributed to the photogenerated reactive oxygen species such as hydroxyl radicals, singlet oxygen, and superoxide anion radicals introduced by catalytic nanoparticles such as TiO
    Language English
    Publishing date 2021-08-31
    Publishing country Switzerland
    Document type Journal Article ; Review
    ISSN 2077-0375
    ISSN 2077-0375
    DOI 10.3390/membranes11090678
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Microwave-assisted synthesis of titania-amorphous carbon nanotubes/amorphous nitrogen-doped carbon nanotubes nanohybrids for photocatalytic degradation of textile wastewater.

    Zikalala, Sithembela A / Chabalala, Mandla B / Gumbi, Nozipho N / Coville, Neil J / Mamba, Bhekie B / Mutuma, Bridget K / Nxumalo, Edward N

    RSC advances

    2021  Volume 11, Issue 12, Page(s) 6748–6763

    Abstract: The synthesis of ... ...

    Abstract The synthesis of TiO
    Language English
    Publishing date 2021-02-08
    Publishing country England
    Document type Journal Article
    ISSN 2046-2069
    ISSN (online) 2046-2069
    DOI 10.1039/d0ra08191d
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article: Tailoring the morphology of polyethersulfone/sulfonated polysulfone ultrafiltration membranes for highly efficient separation of oil-in-water emulsions using TiO2 nanoparticles

    Matindi, Christine N / Hu, Mengyang / Kadanyo, Sania / Ly, Quang Viet / Gumbi, Nozipho N / Dlamini, Derrick S / Li, Jiaye / Hu, Yunxia / Cui, Zhenyu / Li, Jianxin

    Journal of membrane science. 2021 Feb. 15, v. 620

    2021  

    Abstract: Polyethersulfone (PES)/sulfonated polysulfone (SPSf)/TiO₂ mixed matrix membranes (MMMs) were fabricated using non-solvent induced phase inversion (NIPS) technique for oil-in-water emulsion separation. The performance of the membrane was tailored by ... ...

    Abstract Polyethersulfone (PES)/sulfonated polysulfone (SPSf)/TiO₂ mixed matrix membranes (MMMs) were fabricated using non-solvent induced phase inversion (NIPS) technique for oil-in-water emulsion separation. The performance of the membrane was tailored by tuning the morphology through the addition of TiO₂ nanoparticles (NPs) (0.05–0.15 wt %) and by varying the polymer concentrations (18–28 wt). The optimum concentration of TiO₂ was found to be 0.075 wt %), where the water permeability and solute rejection trade-off neutralised. In this membrane the polymer concentration was 22 wt %. In terms of performance, the membrane had pure water permeance of 555.2 LMH bar⁻¹, 90% oil rejection and 89.5% permeance recovery rate (PRR) at an initial concentration of 900 ppm. The surface porosity was 13.1%. Molecular dynamic (MD) simulations and spectroscopic analyses proved that the NPs formed hydrogen bonds with the polymer chains. This resulted in two effects with ripple impacts: a) slowed movement of polymer chains or slow solid-liquid phase separation, leading to the MMMs with the thicker top layer and high surface porosity, and b) stable and even distribution of NPs within the framework as observed with elemental mapping. Accordingly, the MMMs obtained desired asymmetric features corresponded to their overall superior performance. In conclusion, small concentrations of TiO₂ NPs can be used to successfully modify morphology and separation performance of membranes used for oil-in-water emulsion filtration.
    Keywords emulsions ; hydrogen ; oils ; permeability ; polymers ; porosity ; separation ; solutes ; spectroscopy ; titanium dioxide ; ultrafiltration
    Language English
    Dates of publication 2021-0215
    Publishing place Elsevier B.V.
    Document type Article
    Note NAL-AP-2-clean
    ZDB-ID 194516-6
    ISSN 0376-7388
    ISSN 0376-7388
    DOI 10.1016/j.memsci.2020.118868
    Database NAL-Catalogue (AGRICOLA)

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    In stock of ZB MED Bonn / Germany

    Z 78/706: Show issues

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  6. Article: Macrovoid-free PES/SPSf/O-MWCNT ultrafiltration membranes with improved mechanical strength, antifouling and antibacterial properties

    Gumbi, Nozipho N / Bhekie B. Mamba / Edward N. Nxumalo / Jianxin Li / Mengyang Hu

    Journal of membrane science. 2018 Nov. 15, v. 566

    2018  

    Abstract: Macrovoid-free polyethersulfone/sulfonated polysulfone (PES/SPSf) ultrafiltration (UF) membranes containing oxidized multi-walled carbon nanotubes (O-MWCNTs) were fabricated via a non-solvent induced phase separation method using H2O and PEG 20 kDa as a ... ...

    Abstract Macrovoid-free polyethersulfone/sulfonated polysulfone (PES/SPSf) ultrafiltration (UF) membranes containing oxidized multi-walled carbon nanotubes (O-MWCNTs) were fabricated via a non-solvent induced phase separation method using H2O and PEG 20 kDa as a non-solvent additives. The results show that the fully sponge-like morphology of the PES/SPSf membranes could be achieved as the content of O-MWCNTs in the casting solutions was increased, due to the formation of strong hydrogen bonds between SPSf, H2O, PEG 20 kDa and O-MWCNTs. Such morphology provided excellent mechanical strength properties with the highest of 4.02 ± 0.08 MPa obtained for the membrane containing 0.1 wt% O-MWCNTs. Microscopic analysis revealed homogenous distribution of O-MWCNTs in the PES/SPSf mixed-matrix membranes. Moreover, pure water flux initially increased from 598 to 713 L/m2 h followed by a decline to 590, 560, 553 and 578 L/m2 h as the content of O-MWCNTs was increased from 0 wt% to 0.005, 0.01, 0.03, 0.05 and 0.1 wt%, respectively. A rejection of > 99.9% for bovine serum albumin (BSA) was achieved by membranes containing 0.05 wt% O-MWCNTs. The water flux recovery ratio of membranes containing O-MWCNTs was found to be higher (> 90%) than that of pristine PES/SPSf (75%) even after the second fouling and cleaning stages. Furthermore, it was found that only 85% of E. coli bacteria were killed by pristine PES/SPSf, compared to 99% by PES/SPSf membrane containing the highest O-MWCNT loading. The fabricated flat-sheet membranes display attractive features for use as UF membranes in the pre-treatment stage of water treatment.
    Keywords antibacterial properties ; artificial membranes ; bovine serum albumin ; carbon nanotubes ; cleaning ; Escherichia coli ; fouling ; hydrogen bonding ; separation ; strength (mechanics) ; ultrafiltration ; water treatment
    Language English
    Dates of publication 2018-1115
    Size p. 288-300.
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 194516-6
    ISSN 0376-7388
    ISSN 0376-7388
    DOI 10.1016/j.memsci.2018.09.009
    Database NAL-Catalogue (AGRICOLA)

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    In stock of ZB MED Bonn / Germany

    Z 78/706: Show issues

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