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Browsing Articles by Author "Gitari, Wilson M."

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    Defluoridation of groundwater using diatomaceous earth : optimization of adsorption conditions, kinetics and leached metals risk assessment
    (Taylor and Francis, 2015-08-27) Izuagie, Anthony A.; Gitari, Wilson M.; Gumbo, Jabulani R.
    In Sub-Saharan Africa, many rural communities depend on boreholes as the most appropriate source of water supply. Sadly, water from some of the boreholes contains fluoride above the WHO guideline of 1.5 mg/L. Hence, defluoridation is necessary. The aim of this study is to investigate the fluoride uptake capacity of diatomaceous earth (DE), a natural resource at optimized conditions by batch method. X-ray fluorescence analysis showed that the major component is silica (83.1%), while Al2O3 is the main minor component. XRD shows it is an amorphous material. For 8 mg/L fluoride spiked water, the highest per cent fluoride removal at optimum adsorption conditions (contact time: 30 min, adsorbent dosage: 8 g/L, pH 2, temperature: 298 K and shaking speed: 200 rpm) was between 23.4 and 25.6%. PO3 4 in tested field water was observed to reduce the fluoride uptake capacity of fluoride. The sorption data fitted better into Freundlich isotherm than Langmuir isotherm. Fluoride sorption process was found to be a second-order kinetic. Inductively coupled plasma-mass spectrometer analysis of treated water revealed that metal and non-metal species were released at trace levels. Modification of DE would be necessary to enhance the fluoride adsorption capacity
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    Synthesis and performance evaluation of AI/Fe oxide coated diatomaceous in groundwater defluoridation : towards fluoris mitigation
    (Taylor and Francis, 2016-05-24) Izuagie, Anthony A.; Gitari, Wilson M.; Gumbo, Jabulani R.
    The quest to reduce fluoride in groundwater to WHO acceptable limit of 1.5 mg/L to prevent diseases such as teeth mottling and skeletal fluorosis was the motivation for this study. Al/Fe oxide-modified diatomaceous earth was prepared and its defluoridation potential evaluated by batch method. The sorbent with pHpzc 6.0 § 0.2 is very reactive. The maximum 82.3% fluoride removal attained in 50 min using a dosage of 0.3 g/100 mL in 10 mg/L fluoride was almost attained within 5 min contact time; 81.3% being the percent fluoride removal at 5 min contact time. The sorbent has a usage advantage of not requiring solution pH adjustment before it can exhibit its fluoride removal potential. A substantial amount of fluoride (93.1%) was removed from solution when a sorbent dosage of 0.6 g/100 mL was contacted with 10 mg/L fluoride solution for 50 min at a mixing rate of 200 rpm. The optimum adsorption capacity of the adsorbent was 7.633 mg/g using a solution containing initially 100 mg/L fluoride. The equilibrium pH of the suspensions ranged between 6.77 and 8.26 for 10 and 100 mg/L fluoride solutions respectively. Contacting the sorbent at a dosage of 0.6 g/100 mL with field water containing 5.53 mg/L at 200 rpm for 50 min reduced the fluoride content to 0.928 mg/L—a value below the upper limit of WHO guideline of 1.5 mg/L fluoride in drinking water. The sorption data fitted to both Langmuir and Freundlich isotherms but better with the former. The sorption data obeyed only the pseudo-second-order kinetic, which implies that fluoride was chemisorbed