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    Effects of microbubbles and frother types on first-order flotation kinetics of coarse quartz: a Box-Behnken design study
    (Taylor & Francis Ltd, 2024) Abbaker, Ahmed; Aslan, Nevzat; Motasim, Mahmoud
    This study utilised a Box-Behnken experimental design to examine the influence of various frothers (MIBC, 2-Ethylhexanol, alpha-Terpineol, and AF-65), dodecylamine (DDA) collector, and microbubbles on coarse quartz flotation performance. The flotation efficiency was evaluated through two key parameters: maximum recovery (R infinity) and first-order rate constant (k). The findings revealed that microbubbles substantially enhanced flotation kinetics through synergistic interactions, particularly in combination with aliphatic alcohol frothers. The effectiveness of cyclic alcohol and polyglycol-type frothers varied significantly, depending on microbubble presence, frother concentration, and DDA interactions. While 2-Ethylhexanol achieved the highest recovery (97.71%) in conventional flotation without microbubbles, alpha-Terpineol exhibited the most pronounced synergistic effect when combined with microbubbles and DDA, reaching 99.71% recovery. In terms of kinetic performance, AF-65 demonstrated exceptional results in the presence of microbubbles and DDA, achieving the highest rate constant of 2.12 min-1. The effectiveness of the bubble bridging mechanism showed considerable variation across different frother types, with aliphatic alcohols exhibiting notable improvements in the presence of microbubbles, particularly at lower concentrations. Although increased DDA concentrations generally resulted in decreased flotation rates, they enhanced overall recovery - an effect that was further amplified by the presence of microbubbles. Cette & eacute;tude a utilis & eacute; une conception exp & eacute;rimentale de Box-Behnken pour examiner l'influence de divers moussants (MIBC, 2-& eacute;thylhexanol, terpin & eacute;ol-alpha et AF-65), du collecteur dod & eacute;cylamine (DDA) et de microbulles sur les performances de flottation du quartz grossier. On a & eacute;valu & eacute; l'efficacit & eacute; de flottation au moyen de deux param & egrave;tres cl & eacute;s: la r & eacute;cup & eacute;ration maximale (R infinity) et la constante cin & eacute;tique de premier ordre (k). Les r & eacute;sultats ont r & eacute;v & eacute;l & eacute; que les microbulles am & eacute;lioraient consid & eacute;rablement la cin & eacute;tique de flottation par des interactions synergiques, particuli & egrave;rement en combinaison avec des moussants d'alcool aliphatique. L'efficacit & eacute; des moussants de type alcool cyclique et polyglycol variait de mani & egrave;re significative, d & eacute;pendant de la pr & eacute;sence de microbulles, de la concentration du moussant et des interactions du DDA. Tandis que le 2-& eacute;thylhexanol atteignait la r & eacute;cup & eacute;ration la plus & eacute;lev & eacute;e (97.71%) dans la flottation conventionnelle sans microbulles, le terpin & eacute;ol-alpha pr & eacute;sentait l'effet synergique le plus prononc & eacute; lorsque combin & eacute; avec des microbulles et du DDA, atteignant une r & eacute;cup & eacute;ration de 99.71%. En termes de performance cin & eacute;tique, AF-65 a d & eacute;montr & eacute; des r & eacute;sultats exceptionnels en pr & eacute;sence de microbulles et de DDA, atteignant la constante cin & eacute;tique la plus & eacute;lev & eacute;e de 2.12 min-1. L'efficacit & eacute; du m & eacute;canisme de pontage des bulles a montr & eacute; une variation consid & eacute;rable parmi les diff & eacute;rents types de moussants, les alcools aliphatiques pr & eacute;sentant des am & eacute;liorations notables en pr & eacute;sence de microbulles, particuli & egrave;rement & agrave; des concentrations plus faibles. Bien que les concentrations accrues de DDA avaient g & eacute;n & eacute;ralement pour r & eacute;sultat une diminution des taux de flottation, elles am & eacute;lioraient la r & eacute;cup & eacute;ration globale-un effet davantage amplifi & eacute; par la pr & eacute;sence de microbulles.
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    Reaction kinetics of molybdenum dissolution by hydrogen peroxide in acidic and alkaline solutions using tartaric acid and sodium hydroxide: A semi-empirical model with rotating disc method
    (Wiley, 2024) Motasim, Mahmoud; Agacayak, Tevfik; Eker, Yasin Ramazan; Aydogan, Salih; Abbaker, Ahmed
    Molybdenum is an amphoteric metal that dissolves in both acidic and alkaline solutions. This fundamental study explores a sustainable process for the dissolution of molybdenum, focusing on the reaction kinetics in H2O2, H2O2-NaOH, and H2O2-C4H6O6 solutions. A rotating disc method was applied with the Levich's equation. Semi-empirical models with activation energy were developed for the H2O2-NaOH and H2O2-C4H6O6 solutions. The study examined the effects of rotating speed, disc surface area, temperature, H2O2, NaOH, and C4H6O6 concentrations, along with rotating speed, disc surface area, and temperature. Hydrogen peroxide significantly impacted molybdenum dissolution rates across all three solutions. The reaction order of hydrogen peroxide concentration in the H2O2 solution was greater than that of the H2O2-NaOH and H2O2-C4H6O6 solutions. The complex of molybdenum peroxo was formed in H2O2 and H2O2-NaOH solutions but decomposed at a temperature >= 50 degrees C. The activation energies were determined to be 49.90, 43.60, and 41.10 kJ/mol for the H2O2, H2O2-NaOH, and H2O2-C4H6O6 solutions. Molybdenum dissolution in H2O2-NaOH solution. image