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Overview

Environmental Analytical Chemistry focuses on the chemical analysis of the environment, particularly for pollutants, and explores remediation of polluted environments.

This typically involves the development and optimisation of analytical methods for heavy metal speciation and organic pollutants; the use of nanomaterials for removal and recovery of heavy metals from industrial effluents; and the use of chemical, polymers, biomass and organisms to remediate soils, waters and wastewaters.

Environmental Analytical Chemistry research group

Main Areas of Interest:

  • Environmental research, which uses routine analytical techniques to obtain data to solve environmental problems through chemometric data validation, solution equilibria modelling, and development of predictive models.
  • Analytical services: developing and optimising the new procedures for environmental analysis; routine sample analysis. Study of metals, organic chemicals and their speciation in environmental samples is a specific area of expertise.
Speciation of Inorganic and Organic Pollutants in the Environment

The Environmental Analytical Chemistry research group is especially interested in the transport and fate of pollutants in the environment, and matching this information to potential solutions.

  • Determination and modelling of their mobility, transport, and fate.
  • Elemental analysis of metals and non-metals in various samples using spectro-, electro-, and chromatographic methods.
  • Speciation analysis of heavy metals, inorganic anions, and organic compounds in environmental and industrial samples.
  • Column soil leaching processes (total and sequential), separation and pre-concentration methods such as microwave digestion and/or extraction, Soxhlet, solid phase extraction, membrane based techniques, pressurised hot water extraction, passive samplers BCR sequential extraction.
  • Development and optimisation of analytical procedures.
  • Sampling and samples treatment procedures for environmental monitoring.
  • Modelling of transport and fate of pollutants in the environment with predictive models development.
  • Environmental risk assessment
  • Chemometric data analysis.
  • Development and application of new materials for pollutant extraction and/or remediation.
Analytical Capabilities
  • ICP-MS
  • ICP-OES CCD
  • AAS with graphite furnace and Hydride generation systemCHNS micro analyser
  • Mercury analysers :CVAAS and CVAFS
  • UV/VIS
  • FTIR
  • EcoLab electrochemical system (all electrochemical methods such as voltammetry)
  • Ion selective electrodes (ISE)
  • High performance liquid chromatography with UV, fluorescence and refractive index detector
  • Ion chromatography with conductivity detector
  • Gas chromatography systems with thermal conductivity, flame ionisation, electron capture detector and mass spectrometry detectors.
  • Electrophoresis and Isotachophoresis
  • Membrane and sequential extractions systems, solid phase extraction system, , pressurised hotwater extraction systems
  • Column soils leaching equipment
  • Microwave and UV digestion systems
  • Freeze dryer
  • Incubators
  • Micromill and microsieves
  • Passive samplers for water and air monitoring
  • Classic wet analysis
  • Field measurements laboratory and sampling equipment
  • Scientific modelling computer software (JESS, Geochem. Workbench, Phreeqc2, SolEQ, MinteQ, Teach Me, Stella, StatGraph, Statistica, SAS)
Projects

The Environmental Analytical Chemistry research group is continually involved in the development of new projects as new research frontiers open and analytical needs change. Some recent projects that we have been involved in include:

  • Water-sediments-soil equilibria in permanent and seasonal water systems.
  • Speciation of mercury, chromium, arsenic, selenium, uranium, cyanide.
  • Transport and fate of heavy metals in the environment.
  • Organometallic (Hg, Sn, Pb) compounds speciation.
  • Toxicity of manganese.
  • Speciation and mobility of uranium in the environment.
  • Biological uptake of heavy metals by plants and animals (bioindicators, bioremediation)
  • Humic acids – complexation of metal ions in the environment
  • Chemistry of air particulates.
  • Pesticides determination
  • Fatty acids in biological samples
  • Hydrocarbons in the environment - determination, mobility modelling and removal.
  • Green chemistry, chemical and biological remediation of waters and soils polluted by hydrocarbons and heavy metals (chemcap and biocap)
  • ICP slurry analysis for monitoring of PGMs.
  • Chemometric validation and modelling of environmental data.
  • Column leaching of tailings dumps material as an analytical procedure for heavy metals mobility assessment.
  • Acid mine drainage, determination, modelling of seasonal changes. Geochemical stud.
  • Fate, transport and bioavailability of POPs
  • Seasonal and spatial trends of POPs
Collaborations

The Environmental Analytical Chemistry research group collaborates with other Schools within the University to provide multi-disciplinary Environmental research capabilities.

Internal collaborations include those with: 

  • Geosciences,
  • APES (Biology)
  • Molecular Cell Biology (Biotechnology)
  • Chemical Engineering
  • Medicine
  • Atmosphere & Energy Research Groups

We have also worked with, Lund University (Sweden),Pau University (France), Copernicus Univ. Torun, Poland, the CSIR and NIOH. Other countries where collaboration with our group has been involved include Romania, USA, Czech, and Namibia to name but a few.

Teaching

The development of high-level skills in environmental and analytical research in South Africa is critical as environmental compartments such as water are one of our most precious resources. The Environmental Analytical Chemistry research group is involved in providing courses in: Instrumental methods of analysis (undergraduate, BSc), Environmental Chemistry (undergraduate, BSc), Environmental Chemistry, Environmental modelling, Organic chemical analysis, Problem-solving in analytical chemistry, (postgraduate, BSc Honours), Environmental Chemistry (MSc). The research group has provided training courses with South African police forensics.

Contact Us

Professor Ewa Cukrowska

Ewa.Cukrowska@wits.ac.za

tel: 011 717 6743

Clients

Our clients have included the Anglo Research, Anglo Gold, ESKOM, SASOL, Holcim, Xstrata, SAFIC, NIOH, SPECTRO Analytical Instruments, Swiss Lab., and public. Stakeholders include NRF/ THRIP, DST etc.

Geochemistry

Geochemistry has a focus is on the sedimentary and hydrological processes of wetlands and lakes. The programme collaborates with the Schools of, Animal, Plant and Environmental Sciences (AP&ES), Geosciences, departments in Faculties of Medicine and Engineering and industrial partners.

Contacts

Prof Marc Humphries

Marc.Humphries@wits.ac.za 

Dr Letitia Pillay

Letitia.pillay@wits.ac.za

Overview

Electrochemistry is involved mainly in the study of metal-ligand equilibria by voltammetric and related techniques. Research activities are focused on methodologies, theories, data treatment and refinement and software development.

Metal-Ligand Equilibria

Electrochemical techniques are used and procedures developed to study metal-ligand equilibria and determine stability constants of solution species. Methodologies have been developed to study complex formation under very acidic conditions (below pH 2) by accounting for the diffusion junction potential.

Methodologies to study complex formation at very low concentrations are also being investigated and would have application to a number of fields such as biological and environmental chemistry. The relationship between the solution and solid-state complexes is also of interest, whether it be in growing crystals from solution or precipitates formed.

Of particular interest is the coordination chemistry of bismuth(III). Bi(III) hydrolyses from pH 0 already and precipitates from solution at around pH 2 in the presence of a supporting electrolyte. Thus difficulties in studying complex formation of Bi(III) has left much of this chemistry largely unknown.

The fact that Bi(III) is used in the treatment of peptic ulcers and has shown promise in other medicinal applications indicates the need to develop an understanding of Bi(III) coordination chemistry.

Energy Materialsa

This project involves the study of energy and related materials using cyclic voltammetry and electrochemical impedance spectroscopy (EIS).

  • Typical types of materials to be investigated include mixed metal oxides which have been used in fuel cell, mixed metal oxide functionalised nano-carbon materials with potential applications as photocatalysts and supercapacitors, as well as hybrid perovskite materials that have shown great promise when used in solar cells.
  • EIS is vital for developing an understanding of the mechanisms by which these materials conduct the charged species and the fundamental processes that make these materials ideal for these types of applications.
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