Philiswa Nomngongo

By Philiswa N. Nomngongo, Tshimangadzo S. Munonde, Anele Mpupa and Nkositetile Raphael Biata

Environmental contamination by trace elements is becoming increasingly important problem worldwide. Trace metals such as cadmium, copper, lead, chromium, and mercury are major environmental pollutants that are predominantly found in areas with high anthropogenic activities. Therefore, there is a need for rapid and reliable tools to assess and monitor the concentration of heavy metal in environmental matrices. A nondestructive, cost-effective, and environmentally friendly procedure based on near-infrared reflectance spectroscopy (NIRS) and chemometric tools has been used as alternative technique for the simultaneous estimation of various heavy metal concentrations in environmental sample. The metal content is estimated by assigning the absorption features of metals associated with molecular vibrations of organic and inorganic functional groups in organic matter, silicates, carbonates, and water at 780–2500 nm in the near-infrared region. This chapter, reviewed the application of NIRS combined with chemometric tools such as multiple linear regression (MLR), principal component regression (PCR), and partial least squares (PLS) regression. The disadvantages and advantages of each chemometric tool are discussed briefly.

Part of the book: Developments in Near-Infrared Spectroscopy

By Azile Nqombolo, Anele Mpupa, Richard M. Moutloali and Philiswa N. Nomngongo

Water contamination by heavy metals, cyanides and dyes is increasing globally and needs to be addressed as this will lead to water scarcity as well as water quality. Different techniques have been used to clean and renew water for human consumption and agricultural purposes but they each have limitations. Among those techniques, membrane technology is promising to solve the issues. Nanotechnology present a great potential in wastewater treatment to improve treatment efficiency of wastewater treatment plants. In addition, nanotechnology supplement water supply through safe use of modern water sources. This chapter reviews recent development in membrane technology for wastewater treatment. Different types of membrane technologies, their properties, mechanisms advantages, limitations and promising solutions have been discussed.

Part of the book: Wastewater and Water Quality

By Anele Mpupa and Philiswa N. Nomngongo

Determination of emerging pollutants such as UV-filters in environmental samples is very important because they have been proven to have harmful effects on human and aquatic life. In this study, a simple, fast and inexpensive method combining solid phase extraction (SPE) and UV spectrophotometry was developed for simultaneous preconcentration and determination of benzophenone and sulisobenzone in wastewater samples. The effect of factors affecting the preconcentration of UV-filters was optimized using univariate and multivariate approach. Under optimized conditions, the limits of detection (LOD), limits of quantification (LOQ) and preconcetration factors were in the range of 0.15–0.28 and 0.50–0.93 μg L−1, 50–55, respectively. The dynamic linear range was up to 250 μg L−1 for benzophenone and sulisobenzone. In addition, the intra- and inter-day precisions were 3.1–3.3 and 4.5–5.2%, respectively. The developed method was successfully applied to determine UV filters in wastewater samples attaining satisfactory recoveries over the range of 99.3–100.7%. The concentration of the target pollutants in wastewater samples ranged from 6.83 to 85.67 μg L−1.

Part of the book: Emerging Pollutants

By Sandile Surprise Gwebu, Philiswa N. Nomngongo and Nobanathi W. Maxakato

Platinum and its alloys are regarded as best nanocatalysts for the electro-oxidation of alcohol fuels especially in acidic conditions. The performance of nanocatalysts for alcohol fuel cells depends greatly on the support material. A good support material should have high surface area to obtain high metal dispersion. It should also bond and interact with the nanocatalysts to improve the activity of the overall electrode. Most importantly, the support material should offer great resistance to corrosion under the harsh fuel cell conditions. In this chapter, the use of carbon nanodots as support materials for Pt-Sn and Pt-TiO2 nanoparticles is discussed. The electrochemical activity of Pt/CNDs, Pt-Sn/CNDs and Pt/CNDs-TiO2 nanocatalysts was studied using cyclic voltammetry (CV) in acidic and alkaline conditions. Chronoamperometry (CA) was used to investigate the long-term stability of the nanocatalysts under the fuel cell environment. Electrochemical results demonstrated that binary Pt nanocatalysts are more active compared to monocatalysts. It was also observed that carbon nanodots are better support materials than carbon black. Blending carbon nanodots with titanium dioxide (a ceramic material) improves the corrosion resistance of the nanocatalyst. Cyclic voltammetry results also proved that alcohol electro-oxidation is enhanced in alkaline conditions.

Part of the book: Nanocatalysts