Browsing by Author "Lee, In-Gu"

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Selective extraction of uranium from nitric acid leachate of Minjingu rock phosphate
(2025-04) Kariim, Ishaq; Bakari, Ramadhani; Syed, Muhammad; Park, Ji-Yeon; Lee, In-Gu; Thomas Kivevele
A sample of beneficiated rock phosphate from Minjingu Mine and Fertilizer Plant, Tanzania was analysed by energy-dispersive X-ray fluorescence (ED-XRF) spectroscopy and found to contain 15.8 % and 5.30 × 10−2 % w/w P2O5 and U, respectively. The U content of the same sample was estimated to be 3.70 × 10−2 % w/w when the digested mass was analysed by inductively coupled plasma mass spectrometry (ICP-MS). The rock was leached with three different mineral acids at 65–70 °C. The outlet liquid and solid streams were analysed by ICP-MS and ED-XRF, respectively. Maximum leaching of P2O5 and U occurred with 8.9 M HNO3. Their respective concentrations in the leachate were 6.69 % w/w (99.0 g L−1) and 1.80 × 10−2 % w/w (0.27 g L−1). The leachate also contained 1.90 × 10−2 % w/w (0.28 g L−1) rare earth elements (REEs). Selective extraction of U was attempted employing Di-2-ethyl hexyl phosphoric acid (D2EHPA) and Tri-butyl phosphate (TBP) as co-extractants. A 2-stage cross-current solvent extraction (10 g scale; 30 °C) with 1:6 mol ratio of D2EHPA:TBP (0.14 M total extractant concentration; 1:1 w/w organic/aqueous ratio) gave 81–89 % U extraction without co-extraction of REEs. The extraction of U increased to 95.6 % after four stages of solvent extraction but there was a noticeable co-extraction of Y beyond the first two stages. Production of fertilizers from U-free leachate is environmentally safer and the recovered U, in pure form, can be used for fuel production.
Solvothermal liquefaction of orange peels into biocrude: An experimental investigation of biocrude yield and energy compositional dependency on process variables
(Elsevier, 2024-01) Kariim, Ishaq; Park, Ji-Yeon; Kazmi, Wajahat; Swai, Hulda; Lee, In-Gu; Kivevele, Thomas
The efficient valorization of biomass for energy-derived biocrudes is essential for effective waste management. However, the production of biocrudes with high energy and reduced oxygen contents during the liquefaction process requires further insight. Therefore, the impact of reaction temperature, residence time, and ethanol: acetone on the energy compositions and bioproduct’s yield enhancement were investigated. The biocrudes obtained were characterized using elemental analysis, GC–MS, FTIR, GPC and TGA to understand the effects of process parameters on the biocrudes’ compositions. An improved HHV (38.18 MJ/kg) and lower O/C ratio (0.11) were obtained at 430 °C, 35 min and 50% ethanol with a significant improvement in the enhancement factor, deoxygenation, and percentage hydrogenation of 2.63, 36.88%, and 77.87%, respectively. The presence of ketones, hydrocarbons, phenolics and aromatics of 23.74, 4.28, 37.20 and 17.81% respectively indicate the potential of the obtained biocrude as renewable energy sources upon further upgrading.
Solvothermal liquefaction of orange peels into biocrude: An experimental investigation of biocrude yield and energy compositional dependency on process variables
(Elsevier, 2024-01) Kariim, Ishaq; Park, Ji-Yeon; Kazmi, Wajahat; Swai, Hulda; Lee, In-Gu; Kivevele, Thomas
The efficient valorization of biomass for energy-derived biocrudes is essential for effective waste management. However, the production of biocrudes with high energy and reduced oxygen contents during the liquefaction process requires further insight. Therefore, the impact of reaction temperature, residence time, and ethanol: acetone on the energy compositions and bioproduct’s yield enhancement were investigated. The biocrudes obtained were characterized using elemental analysis, GC–MS, FTIR, GPC and TGA to understand the effects of process parameters on the biocrudes’ compositions. An improved HHV (38.18 MJ/kg) and lower O/C ratio (0.11) were obtained at 430 °C, 35 min and 50% ethanol with a significant improvement in the enhancement factor, deoxygenation, and percentage hydrogenation of 2.63, 36.88%, and 77.87%, respectively. The presence of ketones, hydrocarbons, phenolics and aromatics of 23.74, 4.28, 37.20 and 17.81% respectively indicate the potential of the obtained biocrude as renewable energy sources upon further upgrading.
Solvothermal liquefaction of orange peels into biocrude: An experimental investigation of biocrude yield and energy compositional dependency on process variables
(Elsevier, 2024-01) Kariim, Ishaq; Park, Ji-Yeon; Kazmi, Wajahat; Swai, Hulda; Lee, In-Gu; Kivevele, Thomas
The efficient valorization of biomass for energy-derived biocrudes is essential for effective waste management. However, the production of biocrudes with high energy and reduced oxygen contents during the liquefaction process requires further insight. Therefore, the impact of reaction temperature, residence time, and ethanol: acetone on the energy compositions and bioproduct’s yield enhancement were investigated. The biocrudes obtained were characterized using elemental analysis, GC–MS, FTIR, GPC and TGA to understand the effects of process parameters on the biocrudes’ compositions. An improved HHV (38.18 MJ/kg) and lower O/C ratio (0.11) were obtained at 430 °C, 35 min and 50% ethanol with a significant improvement in the enhancement factor, deoxygenation, and percentage hydrogenation of 2.63, 36.88%, and 77.87%, respectively. The presence of ketones, hydrocarbons, phenolics and aromatics of 23.74, 4.28, 37.20 and 17.81% respectively indicate the potential of the obtained biocrude as renewable energy sources upon further upgrading.