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Research Publications (Applied Sciences)

Permanent URI for this collectionhttp://ir-dev.dut.ac.za/handle/10321/213

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Author: search.filters.author.Kumar, Ashwani

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    Development of activated carbon by bio waste material for application in supercapacitor electrodes
    (Elsevier BV, 2023-03) Devi, Raman; Kumar, Vinay; Kumar, Sunil; Kumar Sisodiya, Avnish; Kumar Mishra, Ajay; Jatrana, Anushree; Kumar, Ashwani; Singh, Paul
    Green nanotechnology is now emerging to address society's global sustainability issues by recycling numerous industrial and bio-wastes to produce functional carbonaceous nanomaterials like biochar, 2D graphene, graphene oxide, carbon nanotube (CNT), activated carbon (AC), etc. In this study, we have synthesized AC via the hydrothermal decomposition approach of the walnut shell under high temperature and pressure in a hydrothermal autoclave at temperature ranges from 200 to 250 ℃. The synthesized AC has a high specific surface area of 408.8 m2/g. It has an excellent specific capacitance of 204F/g at 1 A/g of current density with good cyclability up to 10,000 cycles.
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    Microbial production of phytases for combating environmental phosphate pollution and other diverse applications
    (Taylor and Fancis Online, 2016) Kumar, Ashwani; Chanderman, Ashira; Makolomakwa, Melvin; Perumal, Kugen; Singh, Suren
    Concerns of phosphorus pollution and its impact on environments have driven the biotechnological development of phytases. Phosphoric acid, inositol phosphate, or inositols are produced after hydrolysis of phosphate from phytate, initiated by phytase. Research over the last two decades on microbial phytases has deepened our understanding of their production, optimization, and characterization. Despite the wide availability of phytase producing microorganisms, only a few have been commercially exploited. The current high cost of phytases, inability to withstand high temperatures (>85 C), a limited pH range, and poor storage stability are a major bottleneck in the commercialization of phytases. The development of novel phytases with optimal properties for various applications is a major research challenge. In this paper, recent advances in microbial phytase production, application of tools to optimize higher enzyme production, and characterization of phytases along with potential biotechnological applications are reviewed. Additionally the development of phytase assay methods and functions of phytate and phytate degradation products are discussed.
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    Biodegradation of glycerol using bacterial isolates from soil under aerobic conditions
    (Taylor and Francis, 2014) Raghunandan, Kerisha; Mchunu, Siphesihle; Kumar, Ashwani; Kumar, Kuttanpillai Santhosh; Govender, Algasan; Permaul, Kugen; Singh, Suren
    Glycerol, a non-biodegradable by-product during biodiesel production is a major concern to the emerging biodiesel industry. Many microbes in natural environments have the ability to utilize glycerol as a sole carbon and energy source. The focus of this study was to screen for microorganisms from soil, capable of glycerol utilization and its conversion to value added products such as ethanol and 1,3-propanediol (1,3-PDO). Twelve bacterial isolates were screened for glycerol utilization ability in shake flask fermentations using M9 media supplemented with analytical grade glycerol (30 g/L) at various pH values (6, 7 and 8) and temperatures (30◦C, 35◦Cand 40◦C). Among these, six bacterial isolates (SM1, SM3, SM4, SM5, SM7 and SM8) with high glycerol degradation efficiency (>80%) were selected for further analysis. Highest level of 1,3-PDO production (15 g/L) was observed with isolate SM7 at pH 7 and 30◦C, while superior ethanol production (14 g/L) was achieved by isolate SM9 at pH 8 and 35◦C, at a glycerol concentration of 30 g/L. The selected strains were further evaluated for their bioconversion efficiency at elevated glycerol concentrations (50–110 g/L). Maximum 1,3-PDO production (46 g/L and 35 g/L) was achieved at a glycerol concentration of 70 g/L by isolates SM4 and SM7 respectively, with high glycerol degradation efficiency (>90). Three isolates (SM4, SM5 and SM7) also showed greater glycerol tolerance (up to 110 g/L). The isolates SM4 and SM7 were identified as Klebsiella pneumoniae and SM5 as Enterobacter aerogenes by 16S rDNA analysis. These novel isolates with greater glycerol tolerance could be used for the biodegradation of glycerol waste generated from the biodiesel industry into value-added commercial products.