Browsing by Author "Chakawa, D.P."

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    Investigating the feasibility of using agricultural waste as an adsorbent of gold ions in small scale gold processing plants.
    (2019) Tapfuma, A.; Chakawa, D.P.; Moyo, L.B.; Hlabangana, N.;; Danha, G.; Muzenda, E.
    The recovery of precious metals like gold is increasing each day due to its high market prices along with diverse applications. Bio-sorption represents a biotechnological innovation as well as a cost effective and excellent tool for recovery of precious metals from aqueous solutions. This study offers an overview of a recent scenario of bio-sorption studies carried out on the use of some promising bio-sorbents which could serve as an economical means for recovering gold for small scale gold processing plants. Results show that activated carbon (control) has the highest adsorption efficiency since it contains more active site on the carbon molecules. The activated maize corn cob had the highest adsorption efficiency (77.09%) compared to all other agricultural adsorbents. Banana peels showed a significant adsorption efficiency of 56.87%.
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    The novel use of calcium sulphate dihydrate as a bleaching agent for pre-processing beef tallow in the soap manufacturing process
    (Elsevier, 2019) Chakawa, D.P.; Nkala, M.; Hlabangana, N.; Muzenda, E.
    In this article we investigate the use of CaSO4.2H2O as an effective bleaching agent for pre-processing of beef tallow destined for use in the soap manufacturing process before storage. The use of CaSO4.2H2O in this particular novel application has never been demonstrated before. Five respective 100 g beef tallow samples were bleached by agitation using a speed of 120 rpm for 30 minutes at different CaSO4.2H2O weight fractions. The different weight fractions used were 1, 2, 3, 5 and 10 wt. %. After bleaching at a constant melt temperature of 90°C, the respective slurries were filtered and analyzed for red and yellow colors respectively as well as for % ffa. The results indicated an increase in red color bleachability from 0 to 68.75 wt. % with an increase in wt. % CaSO4.2H2O from 1 to 10wt%. Yellow color bleachability also increased from 23.65 to 93 % with increase in wt. % of CaSO4.2H2O from 1 to 10 wt. %. The results demonstrate that CaSO4.2H2O is an effective beef tallow bleaching agent for adsorbing red color, brown color and yellow chlorophyll type contaminants that are present in beef tallow.
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    The use of calcium sulphate dihydrate (CaSO4. 2H2O) as a bleaching agent for crude soya bean vegetable oil.
    (Elsevier, 2019) Chakawa, D.P.; Nkala, M.; Hlabangana, N.; Muzenda, E.
    The use of calcium sulphate dihydrate (CaSO4.2H2O) as a bleaching agent during the refining of crude soya bean vegetable oil was investigated. Different weight ratios of CaSO4.2H2O bleaching agent relative to crude oil (2, 4, 5, 10, 20 and 30 wt. %) were prepared. One sample of raw crude without any bleaching agent added was isolated as a control. Each of the 7 crude oil samples were preheated at a temperature range of 80ºC - 120ºC.The different weight compositions of CaSO4.2H2O were added and the respective slurries agitated for 30minutes.The agitated slurry was then filtered. The experimental results for red color were recorded and % free fatty acids (ffa) and % bleachability were calculated. The results indicated that there was decrease in red color of crude oil from 14R-4.3R with increase in weight ratio of bleaching agent. There was also an increase in red color bleachability from 24.285 % - 60.714% with increase in weight ratio. % ffa and solid nonfat (SNF) remained constant at 0.56% and nil respectively. The results indicate that calcium sulphate dihydrate (CaSO4.2H2O) is an effective bleaching agent in bleaching of crude soya bean vegetable oil.