scholarly journals Physico-Chemical Characteristics of Spodumene Concentrate and Its Thermal Transformations

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7423
Author(s):  
Allen Yushark Fosu ◽  
Ndue Kanari ◽  
Danièle Bartier ◽  
Harrison Hodge ◽  
James Vaughan ◽  
...  
Keyword(s):  
Threshold Temperature ◽  
Strong Temperature Dependence ◽  
Order Kinetic ◽  
Sem Images ◽  
Α Phase ◽  
Order Kinetic Model ◽  
Apparent Activation Energies ◽  
Concentrate Particle ◽  
Liberation Analysis ◽  
Increasing Temperature

Spodumene concentrate from the Pilbara region in Western Australia was characterized by X-ray diffraction (XRD), Scanning Electron Microscope Energy Dispersive Spectroscopy (SEM-EDS) and Mineral Liberation Analysis (MLA) to identify and quantify major minerals in the concentrate. Particle diameters ranged from 10 to 200 microns and the degree of liberation of major minerals was found to be more than 90%. The thermal behavior of spodumene and the concentration of its polymorphs were studied by heat treatments in the range of 900 to 1050 °C. All three polymorphs of the mineral (α, γ and β) were identified. Full transformation of the α-phase was achieved at 975 °C and 1000 °C after 240 and 60 min treatments, respectively. SEM images of thermally treated concentrate revealed fracturing of spodumene grains, producing minor cracks initially which became more prominent with increasing temperature. Material disintegration, melting and agglomeration with gangue minerals were also observed at higher temperatures. The metastable γ-phase achieved a peak concentration of 23% after 120 min at 975 °C. We suggest 1050 °C to be the threshold temperature for the process where even a short residence time causes appreciable transformation, however, 1000 °C may be the ideal temperature for processing the concentrate due to the degree of material disintegration and α-phase transformation observed. The application of a first-order kinetic model yields kinetic parameters which fit the experimental data well. The resultant apparent activation energies of 655 and 731 kJ mol−1 obtained for α- and γ-decay, respectively, confirm the strong temperature dependence for the spodumene polymorph transformations.

scholarly journals Development of Biochars Derived from Water Bamboo (Zizania latifolia) Shoot Husks Using Pyrolysis and Ultrasound-Assisted Pyrolysis for the Treatment of Reactive Black 5 (RB5) in Wastewater

Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1615
Author(s):  
Thanh Tam Nguyen ◽  
Hung-Hsiang Chen ◽  
Thi Hien To ◽  
Yu-Chen Chang ◽  
Cheng-Kuo Tsai ◽  
...  
Keyword(s):  
Cost Effective ◽  
Reactive Black 5 ◽  
Order Kinetic ◽  
Sem Images ◽  
Zizania Latifolia ◽  
Surface Areas ◽  
Order Kinetic Model ◽  
Pseudo Second Order ◽  
Ultrasound Assisted ◽  
Green Technique

Adsorbent made by carbonization of biomass under oxygen-limited conditions has become a promising material for wastewater treatment owing to its cost-effective, simple, and eco-friendly processing method. Ultrasound is considered a green technique to modify carbon materials because it uses water as the solvent. In this study, a comparison of Reactive Black 5 (RB5) adsorption capacity between biochar (BC) generated by pyrolysis of water bamboo (Zizania latifolia) husks at 600 °C and ultrasound-assisted biochar (UBC) produced by pyrolysis at 600 °C assisted by ultrasonic irradiation was performed. UBC showed a greater reaction rate and reached about 80% removal efficiency after 4 h, while it took 24 h for BC to reach that level. Scanning electron microscope (SEM) images indicated that the UBC morphology surface was more porous, with the structure of the combination of denser mesopores enhancing physiochemical properties of UBC. By Brunauer, Emmett, and Teller (BET), the specific surface areas of adsorbent materials were analyzed, and the surface areas of BC and UBC were 56.296 m2/g and 141.213 m2/g, respectively. Moreover, the pore volume of UBC was 0.039 cm3/g, which was higher than that of BC at 0.013 cm3/g. The adsorption isotherms and kinetics revealed the better fits of reactions to Langmuir isotherm and pseudo-second-order kinetic model, indicating the inclination towards monolayer adsorption and chemisorption of RB5 on water bamboo husk-based UBC.

scholarly journals Enhanced photocatalytic activity of wool-ball-like TiO2 microspheres on carbon fabric and FTO substrates

2018 ◽  
Vol 38 ◽  
pp. 02014
Author(s):  
Yu Zhang ◽  
Jian Gu ◽  
Mengqi Zhang
Keyword(s):  
Hydrothermal Method ◽  
Order Kinetic ◽  
Carbon Fabric ◽  
Facile Hydrothermal Method ◽  
Sem Images ◽  
First Order ◽  
Good Crystallinity ◽  
Degradation Rate Constant ◽  
Order Kinetic Model ◽  
Pseudo First Order

The wool-ball-like TiO2 microspheres on carbon fabric (TiO2-CF) and FTO substrates (TiO2-FTO) have been synthesized by a facile hydrothermal method in alkali environment, using commercial TiO2 (P25) as precursors. The XRD results indicate that the as-prepared TiO2 have good crystallinity. And the SEM images show that the wool-ball-like TiO2 microspheres with a diameter of 2-3 μm are composed of TiO2 nanowires, which have a diameter of ~50 nm. The photocatalytic behavior of the wool-ball-like TiO2 microspheres, TiO2-CF and TiO2-FTO under ultraviolet light was investigated by a pseudo first-order kinetic model, using methyl orange (MO) as pollutant. The wool-ball-like TiO2 microspheres obtained a degradation rate constant (Kap) of 6.91×10-3 min-1 . The Kap values of TiO2-FTO and TiO2-CF reach 13.97×10-3 min-1 and 11.80×10-3 min-1, which are 2.0 and 1.7 times higher than that of pristine wool-ball-like TiO2 microspheres due to the “sum effect” between TiO2 and substrates. This study offers a facile hydrothermal method to prepare wool-ball-like TiO2 microspheres on CF and FTO substrates, which will improve the recyclability of phtocatalysts and can be extended to other fields.

scholarly journals Bioadsorption characteristics of Pseudomonas aeruginosa PAOI

2014 ◽  
Vol 79 (4) ◽  
pp. 495-508 ◽  
Author(s):  
Anikó Kőnig-Péter ◽  
Béla Kocsis ◽  
Ferenc Kilár ◽  
Tímea Pernyeszi
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Ph Value ◽  
Nonlinear Least Squares ◽  
Equilibration Time ◽  
Order Kinetic ◽  
Experimental Conditions ◽  
Order Kinetic Model ◽  
Pseudo Second Order ◽  
Nonlinear Least Squares Estimation ◽  
Increasing Temperature

Biosorption of Cd(II) and Pb(II) ions from aqueous solution using lyophilized Pseudomonas aeruginosa (PAOI) cells were observed under various experimental conditions. The effect of pH, initial metal concentration, equilibration time and temperature on bioadsorption was investigated. The optimum pH value for Pb(II) adsorption was found to be 5.0, and for Cd(II) 5.0 ? 6.0. The Pb(II) and Cd(II) bioadsorption equilibrium were analyzed by using Freundlich and Langmuir model using nonlinear least-squares estimation. The experimental maximum uptake capacity of Pb(II) and Cd(II) was estimated to be 164 mg g-1 and 113 mg g-1, respectively. For biosorption kinetic study the pseudo second-order kinetic model was applied at various temperatures. The temperature had no significant effect on Pb(II) bioadsorption. In case of Cd(II) bioadsorption the adsorbed amount decreased with increasing temperature.

scholarly journals Adsorption of tricresyl phosphate onto graphene nanomaterials from aqueous solution

2017 ◽  
Vol 76 (6) ◽  
pp. 1565-1573 ◽  
Author(s):  
Jun Liu ◽  
Siying Xia ◽  
Xiaomeng Lü ◽  
Hongxiang Shen
Keyword(s):  
Experimental Data ◽  
Maximum Adsorption Capacity ◽  
Order Kinetic ◽  
Tricresyl Phosphate ◽  
Batch Mode ◽  
Order Kinetic Model ◽  
Endothermic Process ◽  
Langmuir Isotherm Model ◽  
Pseudo Second Order ◽  
Increasing Temperature

Phosphorus flame retardant tricresyl phosphate (TCP) adsorption on graphene nanomaterials from aqueous solutions was explored using batch and column modes. Comparative studies were performed regarding the kinetics and equilibrium of TCP adsorption on graphene oxide (GO) and graphene (G) in batch mode. The adsorption kinetics exhibited a rapid TCP uptake, and experimental data were well described by the pseudo-second-order kinetic model. Adsorption isotherm data of TCP on the two adsorbents displayed an improved TCP removal performance with increasing temperature at pH 5, while experimental data were well described by the Langmuir isotherm model with a maximum adsorption capacity of 87.7 mg·g−1 for G, and 30.7 mg·g−1 for GO) at 303 K. The thermodynamic parameters show that the adsorption reaction is a spontaneous and endothermic process. In addition, dynamic adsorption of TCP in a fixed G column confirmed a faster approach to breakthrough at high flow rate, high influent TCP concentration, and low filling height of adsorbent. Breakthrough data were successfully described by the Thomas and Yoon-Nelson models.

Hydration of Partially Sulfated Lime Particles From Fluidized Bed Combustors

2000 ◽  
Vol 123 (2) ◽  
pp. 173-178 ◽  
Author(s):  
M. F. Couturier ◽  
Y. Volmerange ◽  
F. Steward
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Hydration Reaction ◽  
Order Kinetic ◽  
First Order ◽  
Thermogravimetric Analyzer ◽  
Order Kinetic Model ◽  
Increasing Temperature

The reaction between water and partially sulfated lime particles was studied under isothermal conditions using a microcalorimeter. Experiments were performed with spent sorbent particles from two industrial circulating fluidized bed combustors and with lime particles sulfated in the laboratory using a thermogravimetric analyzer. The rate of hydration of the partially sulfated lime particles was found to be independent of particle size, to increase with increasing temperature, and to decrease with increasing level of sulfation of the particles. A first-order kinetic model is shown to correlate well the effect of time and temperature on the extent of hydration of spent sorbent particles from fluidized bed combustors. The apparent activation energy of the hydration reaction is 45 kJ/mol.

Study on Kinetics and Thermodynamic in Bamboo Charcoal Adsorb Ammonia Nitrogen in Wastewater

2011 ◽  
Vol 356-360 ◽  
pp. 355-359 ◽  
Author(s):  
Wen Hui Wei ◽  
Mei Na Liang ◽  
Zong Qiang Zhu ◽  
Hong Dong Qin ◽  
Yi Nian Zhu
Keyword(s):  
Apparent Rate Constant ◽  
Nitrogen Adsorption ◽  
Ammonia Nitrogen ◽  
Order Kinetic ◽  
Bamboo Charcoal ◽  
Adsorption Experiment ◽  
Order Kinetic Model ◽  
Pseudo Second Order ◽  
Increasing Temperature ◽  
Kinetics And Thermodynamic

The Kinetics and thermodynamic was studied in ammonia nitrogen adsorption experiment using bamboo charcoal. The results showed that the dynamical data fit well with the pseudo-second-order kinetic model. The positive value of ΔH° (42.065 kJ/mol) and the apparent activation energy of the reaction of adsorption (20.67 kJ/mol) indicated that adsorption apparent rate constant increased with increasing temperature.

Decolorization Kinetics and Properties of Triphenodioxazine Reactive Dyes in Sodium Perborate-TAED Bleaching System

2012 ◽  
Vol 550-553 ◽  
pp. 2612-2615
Author(s):  
Jun Zhang ◽  
Yang Zhu
Keyword(s):  
Rate Constant ◽  
Reactive Dye ◽  
Sodium Perborate ◽  
Order Kinetic ◽  
Activated Oxygen ◽  
Order Kinetic Model ◽  
Increasing Temperature ◽  
Kinetics Of ◽  
Poor Stability ◽  
Decolorization Kinetics

The decolorization behaviors of a triphenodioxazine reactive dye (C.I. Reactive Blue 198) in the activated oxygen bleach system containing sodium perborate (PB) and tetra-acetylethylenediamine (TAED) were investigated. The decolorization kinetics of the dye was found to follow the first-order kinetic model and the rate constant of decolorization increased significantly with increasing temperature. The activation energy for decolorizing reaction was 50.41 kJ/mol. The highest rate constant appeared at pH 8. The triphenodioxazine reactive dye showed poor stability to activated oxygen washing.

scholarly journals Adsorptive Separation of Metal Ions with Surface Modified Desmostachya bipinnata

2013 ◽  
Vol 13 (1) ◽  
pp. 101-106 ◽  
Author(s):  
Jagjit Kour ◽  
Puspa Lal Homagai ◽  
Megh Raj Pokhrel ◽  
Kedar Nath Ghimire
Keyword(s):  
Aqueous Solution ◽  
Kinetic Model ◽  
Metal Ions ◽  
Order Kinetic ◽  
Sem Images ◽  
Separation Of Metal Ions ◽  
Adsorptive Separation ◽  
Order Kinetic Model ◽  
Removal Of Metal Ions ◽  
Surface Modified

The biomass of Desmostachy bipannata (Kush, a religious plant of Hindus) was modified for the better adsorption of metal ions from aqueous solution. The FTIR and SEM images were used for the characterization of biomass. The adsorptive separation of metal ions from aqueous solution was studied with equilibrium isotherm and kinetic model. Langmuir adsorption isotherm and pseudo second order kinetic model showed better explanation for the adsorption process. The experimental results suggest that biomass from Kush can be used as an effective biosorbent for the removal of metal ions from aqueous solution. Nepal Journal of Science and Technology Vol. 13, No. 1 (2012) 101-106 DOI: http://dx.doi.org/10.3126/njst.v13i1.7448

scholarly journals Q10 of heterotrophic activity during aerobic decomposition of Utricularia breviscapa and its effect on carbon cycling in a tropical lagoon

2010 ◽  
Vol 70 (2) ◽  
pp. 317-324 ◽  
Author(s):  
MB Cunha-Santino ◽  
I Bianchini Júnior
Keyword(s):  
Dissolved Oxygen ◽  
Temporal Variations ◽  
Summer Temperature ◽  
Order Kinetic ◽  
First Order ◽  
Order Kinetic Model ◽  
Aerobic Decomposition ◽  
Set Up ◽  
Increasing Temperature ◽  
Carbon Concentrations

In this study the Q10 coefficients of heterotrophic activities were measured during aerobic decomposition of Utricularia breviscapa Wright ex Griseb from Óleo lagoon (21° 36' S and 49° 47' W), Luiz Antonio, SP. The bioassays were set up with fragments of U. breviscapa and incubated with lagoon water at distinct temperatures (15.3, 20.8, 25.7 and 30.3 °C). Periodically for 95 days, the concentrations of dissolved oxygen were determined in the bioassays. The results of the temporal variation of dissolved oxygen were fitted to a first-order kinetic model. The stoichiometric relations were calculated on the basis of these fittings. In general, the results allowed us to conclude: i) the oxygen/carbon stoichiometric relations (O/C) varied in function of temperature and time. The temporal variations of the O/C observed in the decomposition of U. breviscapa, suggest that, in the initial phases of the process, low organic carbon concentrations were enough to generate great demands of oxygen, ii) the oxygen consumption coefficients (k d) presented low variation in function of increasing temperature, iii) the increment of the temperature induced a higher consumption of oxygen (COmax) and iv) the simulations indicate that during summer, temperature activates the metabolism of decomposing microbiota.

Oxidation Decoloration Kinetics of C.I. Direct Blue 108 in Activated Oxygen Bleach Systems

2011 ◽  
Vol 332-334 ◽  
pp. 391-394 ◽  
Author(s):  
Yang Zhu ◽  
Ren Cheng Tang
Keyword(s):  
Kinetic Model ◽  
Order Kinetic ◽  
Activated Oxygen ◽  
Direct Blue ◽  
Two Systems ◽  
Order Kinetic Model ◽  
Increasing Temperature ◽  
Kinetics Of ◽  
Decoloration Rate ◽  
Decoloration Kinetics

The decoloration behaviors of C.I. Direct Blue 108 in two activated oxygen bleach systems (PB/TAED and PC/TAED) were investigated. It was found that the decoloration kinetics of the dye in the two systems followed the first-order kinetic model and the rate constants calculated by linear regression increased significantly with increasing temperature. The activation energies for the decoloration in PB/TAED and PC/TAED systems were 63.34 and 58.10 kJ/mol, respectively. Moreover, the highest decoloration rate constant was obtained at pH 9 in the two systems. The kinetic model had not changed with temperature and pH in the two systems.

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