Faculty of Engineering, Built Environment and Information Technology
School of Engineering
Department of Chemical Engineering
Selected Highlights from Research Findings
The department has research focus areas in process modelling and control, applied materials, environmental engineering, water utilisation, reaction engineering, biochemical engineering and sustainable process systems engineering. The chairs of Fluoromaterial Science and Process Integration and of Carbon Technology and Materials are associated with the department.
Work on the simulation of chemical engineering processes focused on the stochastic simulation of chemical engineering processes using open-source tools and the Modelica language, an open standard. The aim is to be able to simulate complex chemical engineering systems efficiently, utilising Monte Carlo simulation for stochastic estimates. Contributions were made on the identification and generation of realistic input sequences for stochastic simulation with Markov processes, which provide a simple, yet powerful method for generating realistic input sequences. The techniques for segmenting input signals and identifying model parameters are applicable to a broad range of fields and include novel work on the employment of multi-objective optimisation to signal segmentation and estimation. The most interesting future work suggested by this research is the use of variable-length multi-objective genetic algorithms to segment signals. This framework was extended to interface with external CAPE tools using the CAPE-Open protocols for thermodynamic interfaces.
Contributions were made in Applied Materials to the development of degradable polymers as a contribution to a possible litter reduction strategy through the development of degradation enhancing additives based on nanostructured anionic clays. The idea is to accelerate the natural sunlight mediated degradation pathways of a littered plastic object, for example, shopping bags. The technology was patented locally and licensed to a commercial company. Commercialisation of this new nanotechnology route for controlled lifetime plastics is being investigated. Long-life polypropylene mosquito netting, incorporating up to 0.76% of pyrethroid insecticides in the fibre polymer, was developed with the support of Sasol ChemCity as a contribution to the World Health Organization’s strategy to “roll back malaria”. These polymers were successfully produced on a conventional production-scale fibre spinning machine and the yarn was knitted into nets that showed good efficacy against mosquitoes. Functional polymer additives based on novel intercalation procedures invented for anionic clays are also being explored using surfactant-mediated intercalation of aliphatic carboxylic acids into a commercial layered double hydroxide (LDH).
Fluoromaterials are most useful, but are relatively difficult to manufacture. Contributions to fluoro-based processing were made in support of the development of local resources through the development of a kinetic expression for the pyrolytic decomposition of polytetrafluoroethylene Despite the fact that the thermal decomposition of polytetrafluoroethylene has been extensively studied over the past six decades, some inconsistencies regarding the kinetic parameters, for example, the order of the reaction, remain. A rate law was developed that is applicable to the reaction of granules, and can be used for geometries of arbitrary shape.
Research in environmental engineering contributed to the characterisation of photocatalytical processes for the destruction of troublesome pollutants in water. The required exposure time for complete degradation of single-ring aromatic compounds was reduced to less than two minutes under aerated conditions in a photocatalytic reactor. When applied to the taste odour-causing compounds commonly found in drinking water sources – geosmin and 2-methylisoborneol (MIS) that are produced by blue-green algae (cyanobacteria) – complete degradation was achieved in less than eight minutes. These results indicate a high potential for substituting slower-acting biological processes with photocatalytic and photolytic systems to degrade refractory and hard-to-degrade organic compounds using a cheap source of energy such as sunlight. The use of the cheaper energy source –solar energy – in the treatment of water using photo-oxidation is expected to improve the economic viability of the technology and contribute further in reducing the energy required. Contributions were also made on the use of tubular reverse osmosis for the treatment of solid waste leachate, the development of a defluoridation plant for rural areas, the use microbial interventions for toxic waste minimisation, and in situ bioremediation for the treatment of U(VI) and Cr(VI) from the nuclear and mining industries.
Further contributions to the development of trickle-bed reactors were made by the reaction engineering group regarding the influence of shape on entrainment behaviour and of hydrodynamic multiplicity on axial dispersion. Sustainable process systems engineering contributions were made on water reuse in multicontaminant batch plants, the use of heat, as well as inherent storage to minimise energy usage in batch plants.
Contact person: Prof PL de Vaal.
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