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Production of rare earth oxides from raw ore in fluidized bed reactor
Adrián Carrillo García,Mohammad Latifi,Said Samih,Jamal Chaouki 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.85 No.-
This study deals with the calcination of a rare earth bearing ore to produce rare earth oxides in afluidizedbed reactor, with the aim of demonstrating the advantage of calcining bigger particles to decomposestable minerals such as monazite by its mineral association within a particle. Rare earth oxides wereproduced by the decomposition of its bearing minerals, bastnäsite and monazite along with the gangues. During the calcination, bastnäsite decomposed at relatively low temperature while monazite reacted CaOat high temperature. The formation of cracks, revealed by BET and SEM analysis, allowed the particle’sdegassing while the size remained constant, thus describing a crackling core behavior. The association of monazite to calcite for bigger particles ( 60 mesh) allowed its decomposition toproduce rare earth oxides with a monazite conversion of 50 %. Also, an extraction process comprised ofcalcination and mild acid leaching enriched the rare earth oxides in the ore by 3.34 and improvedleaching efficiency of the gangues compared to smaller size (enrichment ration of 2.35). Using biggerparticle sizes in the upstream process of a mining industry, i.e. comminution, can also reduce the energyconsumption.
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Asmaa M. Arafa,Afaf E. Abdel-Ghany,Samih I. El-Dahmy,Sahar Abdelaziz,Yassin El-Ayouty,Ashraf S. A. El-Sayed 한국미생물·생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.4
Phenylalanine ammonia-lyase (PAL) catalyzes the reversible deamination of phenylalanine to cinnamic acid and ammonia. Algae have been considered as biofactories for PAL production, however, biochemical characterization of PAL and its potency for myristicin biotransformation into MMDA (3-methoxy-4, 5-methylenedioxyamphetamine) has not been studied yet. Thus, PAL from Anabaena flos-aquae and Spirulina platensis has been purified, comparatively characterized and its affinity to transform myristicin was assessed. The specific activity of purified PAL from S. platensis (73.9 μmol/mg/min) and A. flos-aquae (30.5 μmol/mg/min) was increased by about 2.9 and 2.4 folds by gel-filtration comparing to their corresponding crude enzymes. Under denaturing-PAGE, a single proteineous band with a molecular mass of 64 kDa appeared for A. flos-aquae and S. platensis PAL. The biochemical properties of the purified PAL from both algal isolates were determined comparatively. The optimum temperature of S. platensis and A. flos-aquae PAL for forward or reverse activity was reported at 30oC, while the optimum pH for PAL enzyme isolated from A. flos-aquae was 8.9 for forward and reverse activities, and S. platensis PAL had maximum activities at pH 8.9 and 8 for forward and reverse reactions, respectively. Luckily, the purified PALs have the affinity to hydroaminate the myristicin to MMDA successfully in one step. Furthermore, a successful method for synthesis of MMDA from myristicin in two steps was also established. Gas chromatography-mass spectrometry (GC-MS) analysis was conducted to track the product formation.
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