scholarly journals Reaction Kinetics of Iron Oxides in Ok Tedi Magnetite Skarn Ore

2020 ◽  
pp. 1-13
Author(s):  
Mary Kama ◽  
Kaul Gena ◽  
Tindi Seje Nuru
Keyword(s):  
Reaction Kinetics ◽  
Papua New Guinea ◽  
Iron Reduction ◽  
New Guinea ◽  
Reaction Rate Constant ◽  
Close Monitoring ◽  
Significant Difference ◽  
Different Temperatures ◽  
C 30 ◽  
Kinetics Of

Magnetic skarn ore (MSO) is one of the major copper bearing ore extracted by the Ok Tedi Copper Mine in Papua New Guinea (PNG). Copper minerals are recovered by flotation while the iron not associated with copper are discarded as tailings. The objective of this investigation was to determine the iron ore reduction kinetics for the Ok Tedi MSO and ascertain if it can be processed to produce sponge iron for a mini steel plant in Papua New Guinea. SEM-EDAX analyses of the Ok Tedi MSO indicated 10.1% C, 30% O, 0.6% Mg, 1.1% Si, 21.1% S, 0.8% Ca and 36.2 % Fe. Most of the iron is in sulfide form. Both naturally occurring and roasted sinters of Ok Tedi MSO samples of different particle sizes were reduced by charcoal carbon at three different temperatures and seven different reduction times. Analyses of the reduced products indicated a metallic iron content of more than 65 wt. % on average. Results showed that there was no significant difference in reduction between fluxed and control materials. Only a slight increase in kinetics with reduced particle size, hence the reaction rate constant (K) did not vary much within the temperatures investigated. Reaction kinetics increases with increasing reduction time at 900°C. Therefore, more iron reduction is observed with particles of 106 µm size. In addition, the results also confirmed that the reduction energy used was higher at 800°C and lower at 1000°C. In conclusion, iron reduction can be improved but close monitoring of temperature and reduction times are essential to determine the reaction kinetics of the Ok Tedi MSO.

scholarly journals Degradation Kinetics of Anthocyanins in Shalgam Beverage

2019 ◽  
Vol 7 (2) ◽  
pp. 282
Author(s):  
Adnan Bozdoğan ◽  
Kurban Yaşar
Keyword(s):  
Activation Energy ◽  
Reaction Kinetics ◽  
Half Life ◽  
Degradation Kinetics ◽  
Production Method ◽  
Order Reaction ◽  
Different Temperatures ◽  
Traditional Production ◽  
Effects Of Temperature ◽  
Kinetics Of

This research was performed to elucidate the effects of temperature on the degradation kinetics of anthocyanins in shalgam beverage. Shalgam beverage was produced according to traditional production method. Then, it was kept at three different temperatures (65°C, 75°C, and 85°C) for 12 hours, and the relevant quantities of anthocyanins were determined thereafter. The research revealed that degradation of the anthocyanins was well described with a 1st-order reaction kinetics model and the R2 values varied in the range of 0.9059-0.9715. Activation energy of the reaction was determined to be 48537 Joule/mole. The half-lives of anthocyanins at 65°C and 75° C, and 85°C were found to be 138.63, 136.72, and 51.57, respectively. Compared the half-life periods at different temperatures, anthocyanins were found to be more resistant at 65°C and 75°C than at 85°C.

scholarly journals Gut microbiota composition in obese and non-obese adult relatives from the highlands of Papua New Guinea

2020 ◽  
Vol 367 (19) ◽  
Author(s):  
Marinjho E Jonduo ◽  
Lorry Wawae ◽  
Geraldine Masiria ◽  
Wataru Suda ◽  
Masahira Hattori ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Papua New Guinea ◽  
Urban Areas ◽  
New Guinea ◽  
Operational Taxonomic Unit ◽  
Rrna Gene ◽  
Rural And Urban Areas ◽  
Resource Limited ◽  
Rural And Urban ◽  
Significant Difference

ABSTRACT Obesity is a condition that results from an imbalance between energy intake and expenditure. Recently, obesity has been linked to differences in the composition of gut microbiota. To examine this association in Papua New Guinea (PNG) highlanders, fecal samples were collected from 18 adults; nine obese participants were paired with their non-obese relative. Amplification of the 16S rRNA gene targeting the V1–V2 region was performed on DNA extracts for each participant, with high-quality sequences selected and used for operational taxonomic unit clustering. The data showed Firmicutes and Bacteroidetes were the two dominant phyla, while at genus level Prevotella was the most dominant genus in all of the samples. Nonetheless, statistical evaluation of potential association between nutritional status and bacterial abundance at both phyla and genus levels showed no significant difference. Further studies, ideally in both rural and urban areas, are needed to evaluate the role of the gut microbiome in the occurrence of obesity in PNG and other resource-limited settings.

scholarly journals Thermodynamics of copper desorption from soils as affected by citrate and succinate

2008 ◽  
Vol 2 (No. 4) ◽  
pp. 135-140 ◽  
Author(s):  
E.A. Elkhatib ◽  
A.M. Mahdy ◽  
N.H. Barakat
Keyword(s):  
Contaminated Soils ◽  
Reaction Rate Constant ◽  
Organic Ligands ◽  
Order Kinetic ◽  
First Order ◽  
Dissolved Organics ◽  
Different Temperatures ◽  
Energy Consuming ◽  
Delta G ◽  
Kinetics Of

Desorption of Cu and low molecular weight dissolved organics are the primary factors that impact fate and transport of Cu in soils. To improve predictions of the toxicity and threat from Cu contaminated soil, it is critical that time-dependent desorption behaviour be understood. In this paper, the effect of organic ligands citrate and succinate on the kinetics of Cu desorption from contaminated soils varying widely in soil characteristics was investigated at three different temperatures. The results showed that the first order equation adequately described the kinetics of Cu desorption from clay and sandy soils under isothermal conditions. The reaction rate constant (k<sub>d</sub>) values of the first order kinetic equation for Cu desorption increased consistently with temperature, indicating faster release of Cu at higher temperatures. The Cu desorption rate from the studied soils at all three temperatures was as follows: citric &gt; succinic. The E<sub>a</sub>values indicates that Cu desorption from the studied soils in the presence of two organic ligands is a diffusion controlled reaction. The negative values of &Delta;H* suggest that the desorption reactions are not energy consuming process. The higher negative values of (&Delta;H*) for Cu desorption from the studied soils in the presence of succinic ligand indicate that the heat energy required to overcome the Cu desorption barrier was greater than that for Cu desorption in the presence of citric ligand. Computation of the free energy of activation (&Delta;G*) yielded values ranging for 87 to 87.9 kJ/mol. The largest value represents &Delta;G* for Cu desorption for clay soil in the presence of succinic acid while the lowest value represents &Delta;G* for Cu desorption for sandy soil in the presence of citric acid. The information in this study is quite necessary to construct full functioning models that will help scientists to better understand mobility and bioavailability of metals in soils.

scholarly journals Kinetics of Thermal Degradation of Recycled Polyvinyl Chloride Resin

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
I. M. Alwaan
Keyword(s):  
Thermal Degradation ◽  
Polyvinyl Chloride ◽  
Reaction Rate ◽  
Reaction Rate Constant ◽  
Rate Of Reaction ◽  
Different Temperatures ◽  
Zero Order Reaction ◽  
Enthalpy And Entropy ◽  
Kinetics Of ◽  
Entropy Of Reaction

The goal of this study is to find the effect of time and temperature on the thermal degradation of recycled polyvinyl chloride (PVC) resin. The isothermal rate of reaction(r)of recycled PVC resin was investigated at the following temperatures to: 100, 110, 120, 130, and 140°C at period of times ranging from 10 to 50 min. The result shows that the rate of reaction(r)of recycled PVC increases with increasing temperatures. The reaction rate constant(K)for temperatures ranging from 100 to 140°C was doubled from 0.028–0.056 mol·L−1·S−1. The process was found to be zero order reaction at all range of temperatures 100–140°C. The activation energy of the thermal weight loss was calculated at different temperatures(E/R = 2739.5°K). The average enthalpy and entropy of reaction at temperature of 298°K were determined.

scholarly journals Reaction Kinetics of Carbon Dioxide in Aqueous Diethanolamine Solutions Using the Stopped-Flow Technique

2012 ◽  
Vol 19 (1) ◽  
pp. 55-66 ◽  
Author(s):  
Marta Siemieniec ◽  
Hanna Kierzkowska-Pawlak ◽  
Andrzej Chacuk
Keyword(s):  
Carbon Dioxide ◽  
Reaction Kinetics ◽  
Rate Constants ◽  
Reaction Rate ◽  
Reaction Rate Constant ◽  
Stopped Flow ◽  
First Order ◽  
Pseudo First Order ◽  
Kinetics Of ◽  
Good Agreement

Reaction Kinetics of Carbon Dioxide in Aqueous Diethanolamine Solutions Using the Stopped-Flow Technique The pseudo-first-order rate constants (kOV) for the reactions between CO2 and diethanolamine have been studied using the stopped-flow technique in an aqueous solution at 293, 298, 303 and 313 K. The amine concentrations ranged from 167 to 500 mol·m-3. The overall reaction rate constant was found to increase with amine concentration and temperature. Both the zwitterion and termolecular mechanisms were applied to correlate the experimentally obtained rate constants. The values of SSE quality index showed a good agreement between the experimental data and the corresponding fit by the use of both mechanisms.

scholarly journals Effect of pH and concentration on the chemical stability and reaction kinetics of thiamine mononitrate and thiamine chloride hydrochloride in solution

BMC Chemistry ◽  
2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Adrienne L. Voelker ◽  
Lynne S. Taylor ◽  
Lisa J. Mauer
Keyword(s):  
Reaction Kinetics ◽  
High Performance ◽  
Degradation Kinetics ◽  
Degradation Pathway ◽  
Reaction Rate Constant ◽  
Solution Ph ◽  
Kinetics Of Degradation ◽  
One Year ◽  
Kinetics Of ◽  
Over Time

AbstractThiamine (vitamin B1) is an essential micronutrient in the human diet, found both naturally and as a fortification ingredient in many foods and supplements. However, it is susceptible to degradation due to heat, light, alkaline pH, and sulfites, among effects from other food matrix components, and its degradation has both nutritional and sensory implications as in foods. Thiamine storage stability in solution was monitored over time to determine the effect of solution pH and thiamine concentration on reaction kinetics of degradation without the use of buffers, which are known to affect thiamine stability independent of pH. The study directly compared thiamine stability in solutions prepared with different pHs (3 or 6), concentrations (1 or 20 mg/mL), and counterion in solution (NO3−, Cl−, or both), including both commercially available salt forms of thiamine (thiamine mononitrate and thiamine chloride hydrochloride). Solutions were stored at 25, 40, 60, and 80 °C for up to one year, and degradation was quantified by high-performance liquid chromatography (HPLC) over time, which was then used to calculate degradation kinetics. Thiamine was significantly more stable in pH 3 than in pH 6 solutions. In pH 6 solutions, stability was dependent on initial thiamine concentration, with the 20 mg/mL thiamine salt solutions having an increased reaction rate constant (kobs) compared to the 1 mg/mL solutions. In pH 3 solutions, kobs was not dependent on initial concentration, attributed to differences in degradation pathway dependent on pH. Activation energies of degradation (Ea) were higher in pH 3 solutions (21–27 kcal/mol) than in pH 6 solutions (18–21 kcal/mol), indicating a difference in stability and degradation pathway due to pH. The fundamental reaction kinetics of thiamine reported in this study provide a basis for understanding thiamine stability and therefore improving thiamine delivery in many foods containing both natural and fortified thiamine.

Simulation Studies on Transformation of Mercury during Combustion Process

2015 ◽  
Vol 1092-1093 ◽  
pp. 912-916
Author(s):  
Jian Yi Lu ◽  
Jie Gao ◽  
Cheng Long Meng
Keyword(s):  
Combustion Process ◽  
Reaction Rate Constant ◽  
Transformation Mechanism ◽  
Exponential Factor ◽  
Homogeneous Oxidation ◽  
Constant Change ◽  
Different Temperatures ◽  
Oxidation Model ◽  
Reaction Activation Energy ◽  
Kinetics Of

Mercury is one of important trace heavy metal elements and about 1/3 of mercury in the air comes from emissions of coal-fired flue gas. In this study, we simulated mercury’s 4 important reactions of the oxidation kinetics mechanism and got every reactions’ rate variations; meanwhile we studied the kinetics of four reactions and got the reacting paths, five pre-exponential factor in different temperatures, reaction activation energy change and reaction rate constant change, a relatively comprehensive homogeneous oxidation model established. Through the above simulation study, the kinetics and thermodynamics parameters of 4 primitive reactions are obtained, having a great benefit for understanding the transformation mechanism of mercury in the process of coal combustion.

5-hydroxymethyl furfural formation and reaction kinetics of different pekmez samples: effect of temperature and storage

2012 ◽  
Vol 8 (4) ◽  
Author(s):  
Rasim Alper Oral ◽  
Mahmut Dogan ◽  
Kemal Sarioglu ◽  
Ömer Said Toker
Keyword(s):  
Reaction Kinetics ◽  
Arrhenius Equation ◽  
Storage Period ◽  
Effect Of Temperature ◽  
Temperature Changes ◽  
Juniperus Communis ◽  
Hydroxymethyl Furfural ◽  
Different Temperatures ◽  
And Storage ◽  
Kinetics Of

Abstract Pekmez (molasses) is a traditional food commonly produced from grape and other kind of fruit juices by evaporation processes. In this study, 5-Hydroxymethylfurfural (HMF) level of various pekmez samples was investigated during storage at different temperatures. HMF content of apricot, mulberry, carob, grape, Juniperus communis pekmez changed from 133.0 ppm to 1060.5 ppm, from 88.2 to 1921.5 ppm, from 11.1 to 1153.6 ppm, from 75.5 to 2077.0 ppm, from 19.9 to 280.1 ppm throughout eight months storage period, respectively. Samples of pekmez from the Juniperus communis had the minimum k values for each temperature that means HMF formation in these samples were slower than other pekmez types. The kinetic data analysis for HMF formation during storage was performed and an Arrhenius equation was used to determine the effect of temperature on reaction kinetics of 5-HMF formation in pekmez samples. Ea values were found between 10.58–37.73 (kcal/mol). Apricot pekmez was found as the least sensitive sample to HMF formation resulted from temperature changes.

Non-Isothermal Curing Kinetics of a Modified Benzoxazine Resin System Suitable for Hot-Melt Prepreg Preparation

2017 ◽  
Vol 266 ◽  
pp. 128-134 ◽  
Author(s):  
Meng Jin Fan ◽  
Yu Zhou ◽  
Yi Hao Luan ◽  
Qian Zang ◽  
Dong Xia Zhang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Cure Kinetics ◽  
Curing Kinetics ◽  
Curing Temperature ◽  
Resin System ◽  
Average Value ◽  
Significant Difference ◽  
Different Temperatures ◽  
Kinetics Of ◽  
Hot Melt

Non-isothermal DSC was used to study the cure kinetics of a flame-retardant benzoxazine resin system (BZ501-1) suitable for hot-melt prepreg preparation. The variation of activation energy with conversion for BZ501-1 system was investigated by using Flynn-Wall-Ozawa method, and the average value of activation energy obtained from this method was 100.5 kJ/mol. After that, the model function that depends on the reaction mechanism for the non-isothermal cure of BZ501-1 system was determined by Málek method, and the result showed that Šesták-Berggren model can generally simulate well the reaction rate. Finally, the isothermal curing behavior of BZ501-1 at 200 °C was predicted by using the obtained rate equation, and the result showed that there was no significant difference between the experiment conversions and the predicted ones. The predicted results at different temperatures indicated that the curing rate increased gradually with increasing the curing temperature.

Sign in / Sign up

Export Citation Format

Share Document