Lab
Keneiloe Sikhwivhilu's Lab
Institution: Mintek
Department: Advanced Materials Division
Featured research (4)
Currently, 91% of the world population has access to clean and safe water. Despite this encouraging development exclusion and marginalisation of the poor appear not only to be deepening but also spreading. Low-income communities in urban areas are increasingly grappling with issues of reliability, sufficiency, and affordability of potable water. Attaining SDG 6 and its targets goal is a daunting task for most developing nations and limited evidence provide an intrinsic look at water systems for marginalised urban communities. This study investigates factors influencing household water access, its reliability and affordability among the low-income communities. The study administered a structured questionnaire to 500 households. Findings show persistent high unemployment levels with the majority of the people surviving on less than R 3000 a month. Around 66% of households had access to tap water either inside the house or yard, but the water supply was irregular, and the majority of households were not paying for the water. Household water access and payment for water services were influenced by house type and household size. Other variables such as education, employment, and income were not significant predictors of household's water access. The study observed that income, employment, education, gender, drinking tap water, water interruptions, and satisfaction levels did not have a significant relationship with household water payment for water services. The findings of this study highlight issues that are important and have serious policy implications on water service provision if attainment of Sustainable Development Goal 6.1 is to be realised.
The release of azo dye contaminants from textile industries into the environment is an issue of major concern. Nanoscale zerovalent iron (nZVI) has been extensively studied in the degradation of azo dye pollutants such as methyl orange (MO). In this study, iron was coupled with copper and silver to make trimetallic Fe/Cu/Ag nanoparticles, in order to enhance the degradation of MO and increase reactivity of the catalyst by delaying the rate of oxidation of iron. The synthesis of the trimetallic nanoparticles (Fe/Cu/Ag) was carried out using the sodium borohydride reduction method. The characterization of the particles was performed using XRD, XPS, EDX, and TEM. The analyses confirmed the successful synthesis of the nanoparticles; the TEM images also showed the desired structures and geometry of the nanoscale zerovalent iron particles. The assessment of the nanoparticles in the degradation of methyl orange showed a notable degradation within few minutes into the reaction. The effect of parameters such as nanoparticle dosage, initial MO concentration, and the solution pH on the degradation of MO using the nanoparticles was investigated. Methyl orange degradation efficiency reached 100% within 1 min into the reaction at a low pH, with lower initial MO concentration and higher nanoparticle dosage. The degradation rate of MO using the nanoparticles followed pseudo first-order kinetics and was greatly influenced by the studied parameters. Additionally, LC-MS technique confirmed the degradation of MO within 1 min and that the degradation occurs through the splitting of the azo bond. The Fe/Cu/Ag trimetallic nanoparticles have proven to be an appropriate and efficient alternative for the treatment of dye wastewater.
The impact of worldwide water scarcity, further exacerbated by environmental pollution, necessitates the development of effective water treatment membranes. Herein, we report the synthesis and characterization of nanocomposite membranes containing hyperbranched polyethyleneimine (HPEI) stabilized bi-and trimetallic nanoparticles. These membranes were prepared by blending a pre-grafted Polyethersulfone (PES) powder with the Pd@Fe@HPEI and Pd@FeAg@HPEI nanoparticles followed by phase inversion. The membranes, together with stabilized nanoparticles, were characterized by several analytical techniques, such as attenuated total reflectance-Fourier transform infra-red spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffractometry (XRD), optical contact angle (OCA), scanning electron microscopy (SEM), atomic force microscopy (AFM), and high-resolution transmission electron microscopy (HRTEM). These techniques revealed the elemental composition, zerovalent nature of the nanoparticles, and their small and even size distribution. Surface analysis showed chemical bonding between the polymeric functional groups and the supported nanoparticles. Furthermore, the nanocomposite membranes were found to be hydrophilic. Additionally, the membranes were investigated for swelling (water uptake), porosity, pore size, pure water permeation fluxes, and they indicated a decreased protein adhesion property. As such, the membranes fabricated in this work indicate the required properties for application in water treatment.
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