https://cris.library.msu.ac.zw//handle/11408/302 2026-04-05T04:39:13Z 2026-04-05T04:39:13Z Moyo, Pamela S. Mehlana, Gift Matsinha Leah C. Makhubela Banothile C. E. https://cris.library.msu.ac.zw//handle/11408/6625 2025-07-14T10:11:59Z 2025-01-01T00:00:00Z

Title: Copper-based metal-organic framework: synthesis, characterization and evaluation for the hydrogenation of furfural to furfuryl alcohol Authors: Moyo, Pamela S.; Mehlana, Gift; Matsinha Leah C.; Makhubela Banothile C. E. Abstract: A novel Cu-MOF was synthesized at room temperature from commercially available and inexpensive reagents. The pre-catalyst was characterized using X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, inductively coupled plasma-optical emission spectroscopy, Fourier transform-infrared spectroscopy, powder X-ray diffraction, Brunauer-Emmet-Teller (BET) and scanning electron microscopy-energy dispersive X-ray spectroscopy. The Cu-MOF was characterized as microporous material with BET surface area and pore volume of 7.47 m2/g and 0.27 cm3/g, respectively, and is stable in most solvents. The MOF was evaluated as a heterogeneous catalyst for the hydrogenation of furfural to furfuryl alcohol (FA). Cu-MOF exhibited a high conversion of FF (76%) with selectivity towards FA (100%) at 140 °C, 50 bar for 24 h. The MOF was reused four consecutive times with a loss in catalytic performance. The decrease in catalytic activity could be attributed to the formation of inactive Cu(0) as revealed by HR-TEM and XPS studies. The HR-TEM of spent Cu-MOF showed a uniform particle size diameter of 3.5 nm. This work is significant in providing new strategies for the design and fabrication of highly selective MOF catalysts for the FF upgrading.

2025-01-01T00:00:00Z Moyo, Pamela S. Mehlana, Gift Matsinha Leah C. Makhubela Banothile C. E. Pathak, Ayush Alghamdi, Lana A. Fernández-Catalá, Javier Tricarico, Michele Cazorla-Amorós, Diego Jin-Chong Tan Ángel Berenguer-Murcia Mehlana, Gift Andrew E. H. Wheatley https://cris.library.msu.ac.zw//handle/11408/6624 2025-07-01T13:10:05Z 2025-01-01T00:00:00Z

Title: Understanding metal–organic framework densification: solvent effects and the growth of Colloidal Primary Nanoparticles in Monolithic ZIF-8 Authors: Pathak, Ayush; Alghamdi, Lana A.; Fernández-Catalá, Javier; Tricarico, Michele; Cazorla-Amorós, Diego; Jin-Chong Tan; Ángel Berenguer-Murcia; Mehlana, Gift; Andrew E. H. Wheatley Abstract: To commercialize metal–organic frameworks (MOFs), it is vital they are made easier to handle. There have been many attempts to synthesize them as pellets, tablets, or granules, though they come with innate drawbacks. Only recently have these been overcome, through the advent of self-shaping densified or monolithic MOFs (monoMOFs), which require minimal post-synthetic modification and avoid poor structural integrity, intractability, and pore collapse or blockage. ZIF-8 (zeolitic imidazolate framework-8) has emerged as a prototypical monoMOF in pure and in situ doped forms. Now its formation in solvent mixtures is studied to better understand the early stages of monolith formation and improve the scope of monoliths for hosting solvent-sensitive guests. Solvent-, temperature- and coagulant-dependent control over reaction kinetics induces variations in morphology that are explained by relating the nucleation and growth rates of primary nanocrystallites to the stability of colloidal dispersions during reaction. This yields mesoporous monoZIF-8 with mean pore size 16 nm, SBET >1400 m2 g−1, bulk density 0.76 g cm−3, and resistance to permanent deformation exceeding previous reports. While the study highlights the powerful manipulation of monoMOF characteristics, a new understanding of the growth and stability of primary nanocrystallites has consequences for colloid synthesis generally.

2025-01-01T00:00:00Z Pathak, Ayush Alghamdi, Lana A. Fernández-Catalá, Javier Tricarico, Michele Cazorla-Amorós, Diego Jin-Chong Tan Ángel Berenguer-Murcia Mehlana, Gift Andrew E. H. Wheatley Moyo Praise K. Mehlana Gift Tshuma Piwai Chikukwa Evernice S. Makhubela Banothile C. E. https://cris.library.msu.ac.zw//handle/11408/6608 2025-06-09T13:33:18Z 2025-01-01T00:00:00Z

Title: Closing the loop in the Carbon Cycle: Enzymatic reactions housed in Metal-Organic Frameworks for CO2 conversion to Methanol Authors: Moyo Praise K.; Mehlana Gift; Tshuma Piwai; Chikukwa Evernice S.; Makhubela Banothile C. E. Abstract: The preparation of value-added chemicals from carbon dioxide (CO2) can act as a way of reducing the greenhouse gas from the atmosphere. Industrially significant C1 chemicals like methanol (CH3OH), formic acid (HCOOH), and formaldehyde (HCHO) can be formed from CO2. One sustainable way of achieving this is by connecting the reactions catalyzed by the enzymes formate dehydrogenase (FDH), formaldehyde dehydrogenase (FALDH), and alcohol dehydrogenase (ADH) into a single cascade reaction where CO2 is hydrogenated to CH3OH. For this to be adaptable for industrial use, the enzymes should be immobilized in materials that are extraordinarily protective of the enzymes, inexpensive, stable, and of ultra-large surface area. Metal–organic frameworks (MOFs) meet these criteria and are expected to usher in the much-awaited dispensation of industrial biocatalysis. Unfortunately, little is known about the molecular behaviour of MOF-immobilized FDH, FALDH, and ADH. It is also yet not known which MOFs are most promising for industrial enzyme-immobilization since the field of reticular chemistry is growing exponentially with millions of hypothetical and synthesized MOF structures reported at present. This review initially discusses the properties of the key enzymes required for CO2 hydrogenation to methanol including available cofactor regeneration strategies. Later, the characterization techniques of enzyme-MOF composites and the successes or lack thereof of enzyme-MOF-mediated CO2 conversion to CH3OH and intermediate products are discussed. We also discuss reported multi-enzyme-MOF systems for CO2 conversion cognizant of the fact that at present, these systems are the only chance of housing cascade-type biochemical reactions where strict substrate channelling and operational conditions are required. Finally, we delve into future perspectives.

2025-01-01T00:00:00Z Moyo Praise K. Mehlana Gift Tshuma Piwai Chikukwa Evernice S. Makhubela Banothile C. E. Marko Chigondo Benias Nyamunda Munashe Maposa Knowledge Nyenyayi Delroy Nyadenga Fidelis Chigondo https://cris.library.msu.ac.zw//handle/11408/6361 2024-10-31T07:57:42Z 2024-08-05T00:00:00Z

Title: Histidine-Functionalised Polypyrrole Hybrid Nanocomposite for Adsorption of Toxic Hexavalent Chromium from Water Authors: Marko Chigondo; Benias Nyamunda; Munashe Maposa; Knowledge Nyenyayi; Delroy Nyadenga; Fidelis Chigondo Abstract: Chromium(VI) is one of the most toxic metal ions as it can bioaccumulate and its excessive assimilation may result in anaemia, nervous system failure, kidney damage, cancers of the digestive tract and lungs. In this study a polypyrrole (PPy) modified with histidine (His) by in situ polymerisation technique was investigated for the removal of Cr(VI) from aqueous and characterised by means of Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy/energy dispersive X-ray spectroscopy (FE-SEM/EDS), high resolution-transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS).The influence of solution pH, adsorption time, initial adsorption concentration, temperature and coexisting ions on its adsorption were investigated. The results showed that the optimum adsorption pH was 2.0 with the adsorption being endothermic and chemisorption in nature. Mono-layer adsorption was witnessed as the Langmuir isotherm best described the process with a maximum adsorption capacity 274.73 mg g−1 at 25 °C. Although the removal of Cr(VI) was the primary drive, the reduction of Cr(VI) to Cr(III) during treatment turned out to be very significant to avoid secondary pollution. The adsorption mechanisms were mainly ion exchange, electrostatic attractions, complexation, chelation reactions with protonated histidine sites and reduction. Remarkably, the His-PPy nanocomposite exhibited an exceptional removal for Cr(VI) ions after three cycles of adsorption–desorption (over 99%) suggesting the adsorbent’s exceptional recyclability. The adsorption equilibrium was attained from 60 to 150 min and best described by pseudo-second-order kinetics. The high adsorption efficiency, stability and selectivity makes the His-PPy nanocomposite adsorbent potentially suitable for large-scale Cr(VI) ions removal from water.

2024-08-05T00:00:00Z Marko Chigondo Benias Nyamunda Munashe Maposa Knowledge Nyenyayi Delroy Nyadenga Fidelis Chigondo