Browsing by Author "Nyoni, Bothwell"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Adsorption of Mercury by Pterocarpus Anglolensis: Study on Adsorption Isotherms and Kinetics
    (Iranian Institute of Research and Development in Chemical Industries (IRDCI)-ACECR, 2022) Mapombere, Garainesu; Nyoni, Bothwell; Sibali, Linda L.; Chiririwa, Haleden; Seodigeng, Tumisang
    The efficiency of Pterocarpus Anglolensis sawdust, an abundantly available waste product of the timber industry, capacity as an adsorbent for mercury was investigated. A series of batch experiments was carried out with experimental conditions of metal concentration, adsorbent concentration, pH, and contact time being changed. The concentration of the metal ion was deduced using spectrophotometric means. The adsorption efficiency was found to be pH-dependent with pH 4 being the optimum. 90 minutes was found to be the equilibrium time with particle size range 90-124 μm being the most efficient. Maximum adsorption of mercury was evaluated at 80.33 %. The experimental data was best modeled by the Freundlich isotherm and Pseudo second-order kinetic models. The calculated adsorption parameters are Kf = 0.0002 L/mg, bF = 3.0 and k2 = 0.00016 g/μg.min.
  • Thumbnail Image
    Item
    Re-Visting the Electricity-Growth Nexus in South Africa
    (De Gruyter, 2016) Phiri, Andrew; Nyoni, Bothwell
    This research study contributes to the ever-expanding literature by examining multivariate cointegration and causality relationships between electricity consumption, economic growth and other growth determinants for quarterly South African data collected between 1994/Q1 – 2014/Q4. The motivation behind this current research case study becomes apparent when taking into consideration that no previous studies have gone further than bivariate and trivariate analysis in investigating the electricity-growth nexus in South Africa. In conducting our empirical investigation, our obtained empirical results are two-fold in nature. Firstly, we find significant multivariate long-run cointegration relationships between economic growth, electricity consumption and other growth determinants. Secondly, our empirical analysis offers support in favour of the neutrality hypothesis, that is, the notion of no causal effects existing between electricity consumption and economic growth in the long-run. However, we find that exports directly cause electricity consumption whereas economic growth, domestic investment and employment levels causally flow to exports.
  • Thumbnail Image
    Item
    Removal of Chromium and Nickel from Electroplating Wastewater using Magnetite Particulate Adsorbent: (1) Effect of pH, Contact Time and Dosage, (2) Adsorption Isotherms and Kinetics
    (Canadian Center of Science and Education, 2016-02-06) Dube, Donatus; Champaklal, Parekh T.; Nyoni, Bothwell
    Wastewater discharged into municipal sewer systems from electroplating process plants contains a heavy load of metal ions and often requires pre-discharge treatment. Treatment of wastewater to reduce the concentration of metal ions employing an adsorption process has been studied using a wide range of adsorbents. In this work, the concentrations of chromium and nickel ions in wastewater samples from a local electroplating shop were found to be above the limits set out by the Bulawayo City Council, and the Environmental Management Agency, a statutory agency under the Ministry of Environment and Tourism, Government of Zimbabwe. Furthermore, the removal of chromium and nickel ions from the wastewater using magnetite as an adsorbent is studied. Magnetite particulate adsorbent used in this experiment has demonstrated to be an effective adsorbent material. At the optimum process operating pH of 4 – 7 the absorbent was able to achieve removal rates of up to 99% for chromium and 98% for nickel. The adsorption processes for chromium and nickel have been proven to be physical in nature using the Dubinin-Radushkevich isotherm model. Also, the adsorption kinetics data fit well with pseudo second-order kinetic model.