Project Research
Chemistry research is principally focused in the disciplines of physical, applied, organic and inorganic chemistry.
Specifically, the areas of focus within these are:
- Physical Chemistry
This primarily includes the design and electrochemical interrogation of smart materials for application in targeted drug or controlled ion delivery to candidate biological cells. In addition biocompatible nano-materials are integrated and interdigitated to produce nano bio-, immuno- and genosensors.
- Applied Chemistry
Areas of research include nanoscience and the development of nano-catalysts; brine and fly ash treatment together with acid mine drainage; and zeolite catalysts /adsorbents in waste water treatment.
- Organic Chemistry
This centres on natural product chemistry particularly those derived from medicinal plants, marine organisms and fungal sources. In addition, general organic synthesis and development of new methods for herbal drug standardisation and quality control are also undertaken.
- Inorganic Chemistry
Hetero and homogeneous catalysts are prepared and subsequently examined for applications in fine chemicals, energy and environmental applications.
Current interests lie in the identification and characterisation of natural products using spectroscopic techniques as well as the synthesis of organic molecules lending applications to the pharmaceutical and cosmetic industries.
Current Projects
- Development of a non-lye based hair straightener.
- Conversion of glycerol to value added products in the automotive sector.
Research interests lie mainly in the field of natural product structural studies, directed particularly at indigenous medicinal plants of South Africa. This involves a broad range of common natural products such as flavonoids, alkaloids and terpenoids as well as complex carbohydrates, especially those which are implicated in biological or pharmacological activities. These studies generally involve the use of separation techniques such as solvent extraction and chromatography, as well as spectroscopy, including UV, IR, MS and NMR.
Current Projects:
- Structural investigation of the natural products composition of selected South African seaweeds.
- Chemical studies on complex carbohydrates from myrothamnus flabellifolius.
- Studies of chemical constituents on the aerial parts of pelargonium capitatum.
- Isolation and characterisation of natural products from selected species of the rhus genus.
- The impact duration of storage and seasonal harvesting has on biomarker levels for lessertia frutescens.
Research interests lie mainly in the field of natural product structural studies, directed at nano-architecture in the beneficiation of platinum group metals. Novel consolidated core/shell nanomaterials based on noble metals and semiconductors for hybrid photovoltaic membrane processes in water purification Nanotechnology in water treatment.
Ongoing heterogeneous catalysis research includes development of supported metal catalysts for Friedel-Crafts alkylation as well as the synthesis of low cost, high quality fly ash-based beta zeolite, ZSM-5 and MCM-41 from South African fly ash and application in n-hexane cracking, MTO reaction, etc. Copper(1)-doped Zeolite X produced from fly- ash, as a heterogeneous catalyst for the synthesis of diynes is also being investigated.
Research focused on preventing charge recombination and developing advanced and efficient supported photocatalysts looks at enhancement of the photocatalytic activity of immobilised TiO2 nanocrystal including x-y TiO2 co-doped (x=non metals {S, N, B} and y= metals {Fe, Co, Ni} as well as silver or carbon doped and carbon-nitrogen co-doped nanocrystals supported on porous metal or glass supports for photochemical degradation of organic water pollutants under UV and visible light. Investigating their antimicrobial effects and toxicity on environmental systems is a new direction.
ADVANCED OXIDATION
Studies relating to various advanced oxidation techniques are ongoing for degradation of pharmaceutical compounds in water include dielectric barrier discharge, photo Fenton, cavitations, photocatalysis and combined AOT systems. The generation of free radicals by these AOT systems is being quantified. The degradation of persistent pharmaceuticals in water using free radicals generated by combined advanced oxidation is promising and degradation pathways of Bisphenol A, Nitrophenol, triclocarban, triclosan, various dyes and other persistent compounds are being elucidated. Moreover, new methods for degrading recalcitrant organics are under development and approaches such as dielectric barrier discharges, cavitations, impingement, coupled with nanotechnology are under investigation to provide low cost and scalable techniques to purify contaminated water. Moreover, zero-valent iron nanoparticles are being applied for the removal of nitrates and organics from water. The use of novel antifouling, photocatalytic track-etched nano-filters is also under investigation. Additionally, the research investigates fouling on membranes and regeneration. The ultimate goal is to develop nano structured self regenerating membranes with antifouling properties for the removal of organic pollutants and microbes.
WATER QUALITY
Water quality monitoring is ongoing and the research includes studying radionuclides, toxic metals and organic contaminants in Karoo Aquifers, and from mining or in effluents from waste water treatment plants in the Western Cape.
SEPARATIONS
Apart from the extensive metal adsorption work already performed using zeolites and nano Iron, research is ongoing on fictionalisation of electrospun polymer nanofibers for removal or recovery of metals from aqueous solution including lanthanide ion adsorption. The fibres are also being used for treatment of brine for enhanced evaporation, for radionuclide removal from mining effluents, and rare earth element extractions in hydrometallurgical applications
WASTE REUSE
Electrospinning and functionalisation of chitosan isolated from biomass is ongoing. The fundamental science and technology in the management, application and reuse of coal fly ash has been elucidated. The outputs over the last ten years in this topic have been significant and are ongoing. In the studies undertaken, the topics of waste fly ash from coal combustion and its disposal, management, reuse and beneficial applications have made a significant contribution towards industrial waste management locally and internationally, and the work is cited widely. Treatment of acid mine drainage with fly ash has been shown feasible up to large pilot scale and industry has taken note of the process for low cost mine water purification. A patent has been granted in this topic and large scale pilot trials are in progress.
Many different high purity zeolites have been made from South African fly ash and application of hierarchical zeolites for bio fuel production, for instance offers a green route that saves scarce water resources and lowers the cost of fuel production. Moreover, new hydrothermal synthesis routes and monitoring methods by ultrasound were developed and two patents have been granted in this field.
Apart from the large body of work on reuse of South African coal fly ash waste, recovery of rare earth elements concentrates from fly ash is being studied. The reduction of the level of major components in fly ash by suitable extraction techniques allows preconcentration of more valuable trace elements. Furthermore, the detection and qualification of short-lived and other radionuclides in transformed fly ash products is most necessary. Determination of the leaching of toxic metals and contaminants of emerging concern from repurposed waste products needs elucidation.
Current and ongoing areas of research include:
CATALYSIS:Ongoing heterogeneous catalysis research includes development of supported metal catalysts for Friedel-Crafts alkylation as well as the synthesis of low cost, high quality fly ash-based beta zeolite, ZSM-5 and MCM-41 from South African fly ash and application in n-hexane cracking, MTO reaction, etc. Copper(1)-doped Zeolite X produced from fly- ash, as a heterogeneous catalyst for the synthesis of diynes is also being investigated.
Research focused on preventing charge recombination and developing advanced and efficient supported photocatalysts looks at enhancement of the photocatalytic activity of immobilised TiO2 nanocrystal including x-y TiO2 co-doped (x=non metals {S, N, B} and y= metals {Fe, Co, Ni} as well as silver or carbon doped and carbon-nitrogen co-doped nanocrystals supported on porous metal or glass supports for photochemical degradation of organic water pollutants under UV and visible light. Investigating their antimicrobial effects and toxicity on environmental systems is a new direction.
ADVANCED OXIDATION
Studies relating to various advanced oxidation techniques are ongoing for degradation of pharmaceutical compounds in water include dielectric barrier discharge, photo Fenton, cavitations, photocatalysis and combined AOT systems. The generation of free radicals by these AOT systems is being quantified. The degradation of persistent pharmaceuticals in water using free radicals generated by combined advanced oxidation is promising and degradation pathways of Bisphenol A, Nitrophenol, triclocarban, triclosan, various dyes and other persistent compounds are being elucidated. Moreover, new methods for degrading recalcitrant organics are under development and approaches such as dielectric barrier discharges, cavitations, impingement, coupled with nanotechnology are under investigation to provide low cost and scalable techniques to purify contaminated water. Moreover, zero-valent iron nanoparticles are being applied for the removal of nitrates and organics from water. The use of novel antifouling, photocatalytic track-etched nano-filters is also under investigation. Additionally, the research investigates fouling on membranes and regeneration. The ultimate goal is to develop nano structured self regenerating membranes with antifouling properties for the removal of organic pollutants and microbes.
WATER QUALITY
Water quality monitoring is ongoing and the research includes studying radionuclides, toxic metals and organic contaminants in Karoo Aquifers, and from mining or in effluents from waste water treatment plants in the Western Cape.
SEPARATIONS
Apart from the extensive metal adsorption work already performed using zeolites and nano Iron, research is ongoing on fictionalisation of electrospun polymer nanofibers for removal or recovery of metals from aqueous solution including lanthanide ion adsorption. The fibres are also being used for treatment of brine for enhanced evaporation, for radionuclide removal from mining effluents, and rare earth element extractions in hydrometallurgical applications
WASTE REUSE
Electrospinning and functionalisation of chitosan isolated from biomass is ongoing. The fundamental science and technology in the management, application and reuse of coal fly ash has been elucidated. The outputs over the last ten years in this topic have been significant and are ongoing. In the studies undertaken, the topics of waste fly ash from coal combustion and its disposal, management, reuse and beneficial applications have made a significant contribution towards industrial waste management locally and internationally, and the work is cited widely. Treatment of acid mine drainage with fly ash has been shown feasible up to large pilot scale and industry has taken note of the process for low cost mine water purification. A patent has been granted in this topic and large scale pilot trials are in progress.
Many different high purity zeolites have been made from South African fly ash and application of hierarchical zeolites for bio fuel production, for instance offers a green route that saves scarce water resources and lowers the cost of fuel production. Moreover, new hydrothermal synthesis routes and monitoring methods by ultrasound were developed and two patents have been granted in this field.
Apart from the large body of work on reuse of South African coal fly ash waste, recovery of rare earth elements concentrates from fly ash is being studied. The reduction of the level of major components in fly ash by suitable extraction techniques allows preconcentration of more valuable trace elements. Furthermore, the detection and qualification of short-lived and other radionuclides in transformed fly ash products is most necessary. Determination of the leaching of toxic metals and contaminants of emerging concern from repurposed waste products needs elucidation.
Our research interests involve materials and catalyst preparation. Specific emphases are placed on catalytic materials for fine chemical, energy and environment applications. The current research lies with heterogeneous catalysis and coordination chemistry and entails designs for the synthesis of inorganic and hybrid, organic-inorganic materials for catalysis.
Current Projects:
- Catalysis by supported nano-clusters: zeolite synthesis and surface modifications metal complexes and metal nano-clusters in zeolite cages (ship-in-a-bottle syntheses).
- Catalysis by zeolites and porous silica materials: materials for greenhouse gases removal such as adsorbents for CO2 capture and catalysts for NO removal.
- Catalysis for water treatment using functionalized magnetic nano-particles.
The project involves design, synthesis of inorganic and organometalllic complexes. We also design and prepare nanomaterials. These novel materials are either singly or multiply applied in catalysis and biological studies.
Current Projects:
- Oxidative cleavage of long chain alkenes using ruthenium and rhenium dendrimeric catalysts.
- Fabrication of type I indium-based near-infrared emitting quantum dots for biological imaging applications.
- Synthesis, optical and morphological characterisation of doped PbX/PbS (X = Se, Te) quantum dots for diagnostic studies: a model Study.
- Synthesis, optical and structural characterisation of transition metal-doped-InP/ZnSe quantum dots for diagnostic studies.
- Synthesis and characterisation of yttria-stabilised zirconia (YSZ) hollow fibre supports for palladium based membranes.
An increase in the number of fatalities has been observed in South Africa in the past ten years due to the epidemics of tuberculosis and HIV/Aids. The main contributing factor is genetic polymorphism, resulting in drug toxicity, drug overdose and drug resistance. To eradicate this problem, the SensorLab is intensively involved in the development of sensitive detection methods in the form of nano-biosensors. My interests include the development of drug metabolism biosensors and the synthesis of various conducting polymeric and metallic nanomaterials to facilitate optimum functioning of these sensors.
Current Projects:
- Frequency-modulated haemolytic biosensor for nevirapine.
- Telluric quantum dots biosensor chips for monitoring the metabolism of anti-tuberculosis drugs.
- Palladium selenide and telluride quantum dots electrochemical bio-transducers for the determination of indinavir - a protease inhibitor anti-retroviral drug.
My research interest is in electro-analytical chemistry. We use electrochemical stripping analysis for determining trace amounts of heavy metals, and explore and develop new electrode materials for the electrochemical sensing of organic compounds. In addition, we modify electrodes with molecularly imprinted conducting polymers to improve the selectivity of electrochemical sensors.
Current Projects:
- Investigation of a lead pencil electrode for determination of folic acid by stripping voltammetry.
- Graphene modified metal film electrodes for the determination of trace metals by anodic stripping voltammetry/]
- Pencil-lead electrodes modified with graphene for the determination of trace metals by anodic stripping voltammetry.
- A sensor for detecting ascorbic acid using a glassy carbon electrode modified with molecularly imprinted polypyrrole.
