Applied Chemistry Publications

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Applied Chemistry Publications

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    Biofuel Policy as a Key Driver for Sustainable Development in the Biofuel Sector: The Missing Ingredient in Zimbabwe’s Biofuel Pursuit
    (Canadian Center of Science and Education, 2013-12-14) Moyo, P.; Moyo, M.; Dube, D.; Rusinga, O.
    As global warming continues to be a challenge, there is urgency to look into fossil fuel alternatives for sustainable energy supplies which have also been hastened by the volatility of crude oil prices and the fact that fossil fuel depletion is clearly in sight. Zimbabwe has not been spared of the negative effects of climate change which have affected both the food and energy sectors. This has proved to be a major challenge for the sustainable development of the country’s economy. In an effort to be energy independent, the country has for over decades looked into the prospect of utilising its vast biomass resources to produce biofuels. These programmes have been met with a number of challenges which has seen most such projects not succeeding. The current paper gives a narration of the history of biofuel programmes in Zimbabwe looking at their driving factors and reasons that led to their collapses. Lack of a national biofuel policy is identified as the major factor that has been the missing link in the past and must be addressed. The paper goes further to call for the crafting of a National Biofuel Policy for Zimbabwe highlighting the major thematic issues it would need to cover. An implementation plan for the programme has been proposed
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    Adsorption of Lead and Copper by Carbon Black and Sodium Bentonite Composite Material.
    (Chemic Publishing Company, 2017-10-30) Chiririwa, H.; Matthews, T.; Nyoni, B; Majoni, Stephen; Naidoo, E.B
    The efficiency of using a composite of carbon black and sodium bentonite in treating drinking water contaminated with lead and copper ions was analyzed. The effects of pH, contact time, concentration and adsorbent dosage using an adsorbent composite of 20 % sodium bentonite and 80 % carbon black were studied. The adsorption data was analyzed with respect to Langmuir, Freundlich and Temkin isotherms. The data fits well with the Langmuir isotherm model with high coefficients of determination for both metal ions adsorption. The adsorption kinetics follows a pseudo second-order model for both metal ions. The maximum metal ion uptake (qmax) of composite adsorbent is 7.69 and 0.80 mg/g for lead and copper, respectively.
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    Thermal degradation kinetic study of polystyrene/organophosphate composite
    (Elsevier, 2018) Majoni, Stephen; Chaparadza, Allen
    A polystyrene/bis (2, 4-dicumylphenyl) pentaerythritol diphosphate (DPP) composite (PS-DPP) with a DPP loading of 10% (w/w) was prepared by the melt-compounding method. Results indicated that DPP had a thermal destabilization effect at temperatures below 380 °C. A comparative degradation kinetic analysis was performed employing the Kissinger method and the isoconversional methods of Friedman, Starink and Advanced Isoconversional Method (AICM). Variation of activation energy with extent of conversion (α) results from all the isoconversional methods showed that activation energy did not vary significantly with α for both pure PS and PS-DPP. Activation energies obtained from the Starink method above 380 °C were very close to those obtained from AICM consistent with activation energy values not varying significantly with α. The y(α) master plots and the Friedman methods where used to identify the reaction model and calculate the frequency factor respectively. The Sestak-Berggren model was identified as the most appropriate model to describe the thermal degradation of both PS and PS-DPP. The overall results indicates that activation energies of the composite were not significantly higher than those of pure PS at low conversion (α < 0.2) where DPP had a destabilizing effect but became higher when DPP had a stabilization effect.
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    Effectiveness of Biopolymer-Bentonite Clay Composites in Wastewater Treatment
    (2018) Mupasi, N.M; Dube, Donatus; Chiririwa, H; Naidoo, E.B
    The feasibility of employing wood-bentonite clay composite material as a low-cost and effective adsorbent for removal of cations from wastewater has been investigated. The wood-bentonite clay composites were prepared by a solution intercalation method. Results showed that the percentage adsorption of Pb 2+ , Mg 2+ and Ca 2+ from the effluent water was 88.46, 81.12 and 95.76 % respectively, using 10 g/L of the adsorbent. The desorbed wood-bentonite clay composites could be reused for adsorption of the cations.
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    Controlled Release Kinetics in Hydroxy Double Salts: Effect of Host Anion Structure
    (Hindawi Publishing Corporation, 2014-01-16) Majoni, Stephen; Hossenlopp, Jeanne M.
    Nanodimensional layered metal hydroxides such as layered double hydroxides (LDHs) and hydroxy double salts (HDSs) can undergo anion exchange reactions releasing intercalated anions. Because of this, these metal hydroxides have found applications in controlled release delivery of bioactive species such as drugs and pesticides. In this work, isomers of hydroxycinnamate were used as model compounds to systematically explore the effects of anion structure on the rate and extent of anion release in HDSs. Following intercalation and subsequent release of the isomers, it has been demonstrated that the nature and position of substituent groups on intercalated anions have profound effects on the rate and extent of release.The extent of release was correlated with the magnitude of dipole moments while the rate of reaction showed strong dependence on the extent of hydrogen bonding within the layers.The orthoisomer showed a more sustained and complete release as compared to the other isomers.