Ntalane Sello Seroka

By Ntalane S. Seroka, Raymond Taziwa and Lindiwe Khotseng

South Africa produces approximately 7 million tons of sugarcane bagasse annually as an agricultural residue, which is treated as waste and its disposal is known to have negative impacts on the environment. To lessen reliance on petroleum and polymers, consideration is given on use of sugarcane bagasse ash as substitute materials for the development of fillers for rubber and other large-scale commodity polymers. This work reports on the mechanical, physiochemical, and structural properties of sugarcane bagasse ash to define the compatibility with the specific polymers that will pave way to the engineering of composites to utilize the potential benefits of these residue-derived fillers. The structural and morphological properties of the untreated and treated sugarcane bagasse ash were performed using XRD, FTIR, and SEM-EDX, respectively. The obtained results confirmed the successful treatment of the sugarcane bagasse ash. The study was successful in showing that sugarcane bagasse ash as potential filler in rubber polymer matrix is a natural resource of silica, which is sustainable and cost-effective, thus should be harnessed for industrial purposes in South Africa.

Part of the book: Application and Characterization of Rubber Materials

By Adebare Nurudeen Adewunmi, Ntalane Sello Seroka, Su Huaneng and Khotseng Lindiwe Eudora

In this work, heat-treated PtRu metal alloys based on multi-walled carbon nanotubes (MWCNT) were synthesized using modified polyol approach for methanol oxidation reaction (MOR) in acidic conditions at 2500, 3500, and 4500 C. The catalysts physical and electrochemical properties were investigated. The High Resolution Transmission Electron Microscopy (HR-TEM) was used to determine the shape, particle size, and particle size distribution of the catalysts, where spherical and agglomerated PtRu nanoparticles with narrow particle size distribution were observed with particle sizes ranging from 0.600 to 1.005 nm. Their crystalline sizes were assessed using the XRD with catalysts presenting a face-centered crystal structure, which is typical of platinum structures with crystalline sizes ranging from 0.500 to 1.180 nm. Energy-Dispersive Spectroscopy, (EDS), was used to identify the elements. Cyclic voltammetry (CV) was used to determine the electroactive surface area (ECSA) and MOR of the electrocatalysts, whereas electrochemical impedance spectrometry (EIS) and chronoamperometry (CA) were used to study their electro-kinetics and stability towards MOR, respectively. PtRu/MWCNT electrocatalysts alloyed at 450°C showed better electroactivity and kinetics as compared to other catalysts, evident from the highest current density of 19.872 mA/cm2 and lowest charge transfer resistance of 0.151 kΩ from CA and EIS, respectively.

Part of the book: Ruthenium

By Ntalane Sello Seroka and Lindiwe Khotseng

Silica molecules present in commercial objects can pose a hazard to human health, which is why the environmentally friendly synthesis of silica has been intensively researched in the recent decades. This chapter describes the synthesis of silica from sugarcane bagasse waste and its physical and chemical properties for potential use in eco-friendly applications. Sugarcane bagasse was burned to produce ash, which was then calcined in a 700°C kiln before being treated with citric acid to remove silica from the ash. X-ray fluorescence (XRF) analysis showed that after the acid treatment, 78–79% of the silica was produced and strong peaks were observed in the X-ray diffraction spectra (XRD) at 2Ɵ = 28 (degree) and an average diameter of 28 nm for 1-HDTA and 30 nm for TPAH, determined by the Scherrer equation. Fourier transform infrared spectroscopy (FTIR) spectra also confirms the presence of synthesized silica. In addition, the shape of the particles was analyzed by TEM and SEM images and it is found that synthesized silica had a spongy shape with irregular sizes ranging from 25 to 50 nm. Overall, the studies show that organic bases are capable of synthesizing silica with application-specific properties from agricultural waste using green chemistry.

Part of the book: Advances in Green Chemistry