Kinetic of Self-Reducing Mixtures of Iron Ore and Biomass of Elephant Grass

2016 ◽  
Vol 869 ◽  
pp. 1007-1012 ◽  
Author(s):  
E.P. Rocha ◽  
José Adilson de Castro ◽  
Flavia de Paula Vitoretti ◽  
F.V. Junior
Keyword(s):  
Reaction Mechanisms ◽  
Iron Ore ◽  
Arrhenius Plot ◽  
Order Kinetic ◽  
Elephant Grass ◽  
First Order ◽  
Fraction Versus ◽  
Dsc Method ◽  
Pellet Feed ◽  
Good Agreement

In this work, kinetic runs of self-reducing mixtures composed by pellet feed, BOF dust and biomass of elephant grass were performed using TGA-DSC method, for the temperatures, 900, 950, 1000, 1050 and 1100°C, and carbon percentages (15, 20 and 30% of carbon). The converted fraction versus time was calculated, and the different regions of the reactions progress were selected to analyze the reactions kinetics that occur in the mixture (devolatilization of biomass, Boudouard and sequence of reduction reactions). The kinetic behavior for the different steps showed good agreement with the first-order kinetic law. Using Arrhenius plot, was possible to estimate the apparent activation energy values obtained for the reaction mechanisms corresponding to Fe3O4→FeO and FeO→Fe. The kinetic constants for the 1100°C temperature and mixture containing 30% of carbon were the higher values: 0.0037 s-1 for the reaction Fe3O4 → FeO and 0.0258 s-1 for the mechanism FeO →Fe.

The thermal decompositions of 2-methyl-2-phenoxypropane

1981 ◽  
Vol 34 (2) ◽  
pp. 343 ◽  
Author(s):  
NJ Daly ◽  
SA Robertson ◽  
LP Steele
Keyword(s):  
Gas Phase ◽  
Reaction Mechanisms ◽  
Arrhenius Equation ◽  
Chain Process ◽  
Quadrupole Mass ◽  
Radical Chain ◽  
Thermal Reactions ◽  
First Order ◽  
Radical Chain Process ◽  
Good Agreement

The thermal reactions of 2-methyl-2-phenoxypropane have been studied in gas phase over the range 600-670 K by quadrupole mass spectrometry and pressure studies. The reaction is shown to be a homogeneous first-order elimination of phenol and 2-methylpropene which is described by the Arrhenius equation k = 1014.10�0.12exp[(-210.46�1.36)/RT] s-1 Possible reaction mechanisms are considered and the reaction is found to be a unimolecular elimination rather than a radical chain process initiated by homolysis to phenoxy and 1,1-dimethylethyl radicals. Evidence for the rearrangement to 4-t-butylphenol previously proposed has been carefully sought and it is concluded that the process does not occur in the gas phase. The A-factor observed for the reaction is in good agreement with that calculated for the four-centred transition state proposed for elimination of 2-methylpropene from alkoxypropanes.

scholarly journals Removal of Ibuprofen From Synthetic Wastewater Using Photocatalytic Method in the Presence of Feo Photocatalyst Supported on Modified Iranian Clinoptilolite

2021 ◽  
Author(s):  
Majid Mohadesi ◽  
Ashkan Gouran ◽  
Kiarash Seifi
Keyword(s):  
Iron Oxide ◽  
Synthetic Wastewater ◽  
Process Time ◽  
Order Kinetic ◽  
Optimal Conditions ◽  
Initial Concentration ◽  
First Order ◽  
Order Kinetic Model ◽  
Ft Ir ◽  
Good Agreement

Abstract This study investigated the removal of an organic drug called ibuprofen from the wastewater containing this drug. Iron oxide supported on modified Iranian clinoptilolite was used as the photocatalyst in the presence of the light of a solar lamp. XRD, SEM, EDAX and FT-IR analyses were performed to detect the prepared photocatalyst. The results of photocatalytic identification analyses proved the suitable loading of iron oxide supported on modified Iranian clinoptilolite. This study investigated the effect of initial concentration of ibuprofen (5–25 mg/L), photocatalyst concentration (100–300 mg/L), and process time (10–240 min) on the removal from ibuprofen from wastewater containing this drug. The experiments were performed in a setup in the presence of a solar lamp with a flux of 300 W/m2. The results indicated that with the initial ibuprofen concentration of 25 mg/L, photocatalyst concentration of 300 mg/L, and time of 210 min, the highest percentage of ibuprofen removal was 99.80%. Kinetic modeling was then performed using the Langmuir-Hinshelwood model, and a quasi-first-order kinetic model showed a good agreement with the results obtained. Finally, the recovery of the photocatalyst was investigated and the results showed that under optimal conditions about 91% of ibuprofen was removed after five re-uses of the photocatalyst.

scholarly journals Sorptive behaviour of chromium on polyethylene microbeads in artificial seawater

2018 ◽  
Vol 250 ◽  
pp. 06001 ◽  
Author(s):  
Nur Farhan Zon ◽  
Ammar Iskendar ◽  
Shamila Azman ◽  
Shazani Sarijan ◽  
Razali Ismail
Keyword(s):  
Potential Role ◽  
Adsorption Process ◽  
Artificial Seawater ◽  
Order Kinetic ◽  
Heavy Metal Adsorption ◽  
First Order ◽  
Pseudo First Order ◽  
Aquatic Food ◽  
Good Agreement

This study investigates the interactions between chromium (Cr) and microplastic under controlled laboratory conditions using low density polyethylene microbeads as plastic particles. Chromium was added to suspensions of in artificial seawater to investigate heavy metal adsorption on microbeads surface. Polyethylene microbeads proved to have affinity in providing surface area for chromium. It served as an effective sorption surface thus lowering amounts of chromium in seawater through adsorption process. The best percentage of heavy metals adsorbed to microbeads and adsorption capacity was 1.7 µg/g and 8.5 % at 1.0 µg/mL respectively. The maximum adsorption was monitored for 180 hours. Kinetic study was performed and fitted well in pseudo-first-order kinetic. In term of isotherm, dataset was in good agreement with both Langmuir and Freundlich with correlation at 0.977 and 0.9606 respectively. Adsorption of chromium to polyethylene microbeads had important implications for the potential role of microplastics, in this case microbeadschromium contaminated act as a quantified link in aquatic food webs.

scholarly journals Frustrated Lewis Pair Stabilized Phosphoryl Nitride (NPO), a Mono Phosphorus Analogue of Nitrous Oxide (N2O)

2021 ◽  
Author(s):  
André Eckhardt ◽  
Martin-Louis Riu ◽  
Peter Müller ◽  
Christopher Cummins
Keyword(s):  
Nitrous Oxide ◽  
Half Life ◽  
Negative Charge ◽  
Activation Enthalpy ◽  
Activation Entropy ◽  
Order Kinetic ◽  
Reactive Intermediate ◽  
First Order ◽  
Frustrated Lewis Pair ◽  
Good Agreement

Phosphoryl nitride (NPO) is a highly reactive intermediate, and its chemistry has only been explored under matrix isolation conditions so far. Here we report the synthesis of an anthracene (A) and phosphoryl azide-based molecule (N3P(O)A) that acts as a molecular synthon of NPO. Experimentally, N3P(O)A dissociates thermally with a first order kinetic half-life that is associated with an activation enthalpy of ΔH⧧ = 27.5 ± 0.3 kcal mol–1 and an activation entropy of ΔS⧧ = 10.6 ± 0.3 cal mol–1 K–1 that are in good agreement with calculated DLPNO-CCSD(T)/cc-pVTZ//PBE0-D3(BJ)/cc-pVTZ energies. In solution N3P(O)A undergoes Staudinger reactivity with tricyclohexylphosphine (PCy3) and subsequent complexation with tris(pentafluorophenyl)borane (B(C6F5)3, BCF) to form Cy3P-NP(A)O-B(C6F5)3. Anthracene is cleaved off photochemically to form the frustrated Lewis pair (FLP) stabilized NPO complex Cy3P⊕-N=P-O-B⊖(C6F5)3. Intrinsic Bond Orbital (IBO) analysis suggests that the adduct is zwitterionic, with a positive and negative charge localized on the complexing Cy3P and BCF, respectively.

Synthesis Pathway of Dioxins in Iron Ore Sintering Process

2011 ◽  
Vol 194-196 ◽  
pp. 71-74 ◽  
Author(s):  
Hong Ming Long ◽  
Jia Xin Li ◽  
Ping Wang ◽  
Ru Fei Wei
Keyword(s):  
Iron Ore ◽  
De Novo ◽  
Order Kinetic ◽  
Phase Reaction ◽  
Sintering Process ◽  
First Order ◽  
Iron Ore Sintering ◽  
Order Kinetic Model ◽  
Iron Ore Sintering Process ◽  
Ore Sintering

Dioxins are a kind of extremely toxic and Persistent Organic Pollutants (POPs). Sintering process has become one of the most dominant unintentional discharge sources. The dioxins synthesis pathway and mechanism being described, related research indicate that: in the low temperature sector (200-500ºС), chlorobenzene and chlorphenol are the representation precursors of dioxin’s precursor catalytic reaction, the dioxins formed in this temperature sector cased by the “de novo” under catalyst (like Cu2+) on the surface of smoke particles; high-temperature gas phase reaction mechanism of dioxins satisfied the first-order kinetic model, the formation of gas related with suitable precursors, it is the result of chlorinated precursors’ pyrolytic rearrangement like chlorobenzene and chlorophenol in the temperature sector 500-800ºС in the gas.

Photodegradation of some Furocoumarins in Ethanol under UV Irradiation

2016 ◽  
Vol 683 ◽  
pp. 402-405
Author(s):  
Natalya G. Bryantseva ◽  
Olga N. Tchaikovskaya ◽  
Vlada S. Kraiukhina ◽  
Maria Gómez ◽  
Jose Luis Gómez
Keyword(s):  
Experimental Data ◽  
Mass Transfer ◽  
Kinetic Model ◽  
Kinetic Parameter ◽  
Bulk Solution ◽  
Order Kinetic ◽  
First Order ◽  
Operational Variables ◽  
Pseudo First Order ◽  
Good Agreement

Photodegradation of 5-Methoxypsoralen (5-MOP), 4', 5'-dimethyl-3,4-cyclogeksilpsoralen (KC5) and 4'-methyl-3,4 cycloheptylpsoralen (KC4) has been carried out in an XeBr exilamps, both in the presence of H2O2, and a kinetic model, which explains the dependence of the pseudo-first order kinetic parameter on the substrate concentration and other operational variables, has been developed. In the development of the model, mass transfer of 5-MOP, KC5 and KC4from the bulk solution to the wall of the vessel was assumed as the step determining the rate of the photodegradation process, which successfully explains some singularities observed in the experimental results.By fitting the experimental data to the model, a detailed study of the influence of all operational variables on the pseudo-first order kinetic parameter has been done, in good agreement with the model hypotheses.

Leaching Kinetics of Atrazine and Inorganic Chemicals in Tilled and Orchard Soils

2014 ◽  
Vol 28 (2) ◽  
pp. 231-237 ◽  
Author(s):  
Lech W. Szajdak ◽  
Jerzy Lipiec ◽  
Anna Siczek ◽  
Artur Nosalewicz ◽  
Urszula Majewska
Keyword(s):  
Reaction Rate ◽  
Inorganic Compounds ◽  
Model Performance ◽  
Order Reaction ◽  
First Order Reaction ◽  
Order Kinetic ◽  
Time Data ◽  
First Order ◽  
Concentration Changes ◽  
Reaction Constants

Abstract The aim of this study was to verify first-order kinetic reaction rate model performance in predicting of leaching of atrazine and inorganic compounds (K+1, Fe+3, Mg+2, Mn+2, NH4 +, NO3 - and PO4 -3) from tilled and orchard silty loam soils. This model provided an excellent fit to the experimental concentration changes of the compounds vs. time data during leaching. Calculated values of the first-order reaction rate constants for the changes of all chemicals were from 3.8 to 19.0 times higher in orchard than in tilled soil. Higher first-order reaction constants for orchard than tilled soil correspond with both higher total porosity and contribution of biological pores in the former. The first order reaction constants for the leaching of chemical compounds enables prediction of the actual compound concentration and the interactions between compound and soil as affected by management system. The study demonstrates the effectiveness of simultaneous chemical and physical analyses as a tool for the understanding of leaching in variously managed soils.

Utilisation of Biomass and Hybrid Biochar from Elephant Grass and Low Density Polyethylene for the Competitive Adsorption of Pb(II), Cu(II), Fe(II) and Zn(II) from Aqueous Media

2020 ◽  
Vol 13 ◽  
Author(s):  
Joshua O. Ighalo ◽  
Lois T. Arowoyele ◽  
Samuel Ogunniyi ◽  
Comfort A. Adeyanju ◽  
Folasade M. Oladipo-Emmanuel ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Removal Efficiency ◽  
Contact Time ◽  
Competitive Adsorption ◽  
Adsorption Process ◽  
Aqueous Media ◽  
Polluted Water ◽  
Batch Adsorption ◽  
Order Kinetic ◽  
Elephant Grass

Background: The presence of pollutants in polluted water is not singularized hence pollutant species are constantly in competition for active sites during the adsorption process. A key advantage of competitive adsorption studies is that it informs on the adsorbent performance in real water treatment applications. Objective: This study aims to investigate the competitive adsorption of Pb(II), Cu(II), Fe(II) and Zn(II) using elephant grass (Pennisetum purpureum) biochar and hybrid biochar from LDPE. Method: The produced biochar was characterised by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). The effect of adsorption parameters, equilibrium isotherm modelling and parametric studies were conducted based on data from the batch adsorption experiments. Results: For both adsorbents, the removal efficiency was >99% over the domain of the entire investigation for dosage and contact time suggesting that they are very efficient for removing multiple heavy metals from aqueous media. It was observed that removal efficiency was optimal at 2 g/l dosage and contact time of 20 minutes for both adsorbent types. The Elovich isotherm and the pseudo-second order kinetic models were best-fit for the competitive adsorption process. Conclusion: The study was able to successfully reveal that biomass biochar from elephant grass and hybrid biochar from LDPE can be used as effective adsorbent material for the removal of heavy metals from aqueous media. This study bears a positive implication for environmental protection and solid waste management.

scholarly journals Enhancing methane production from the invasive macroalga Rugulopteryx okamurae through anaerobic co-digestion with olive mill solid waste: process performance and kinetic analysis

2021 ◽  
Author(s):  
D. de la Lama-Calvente ◽  
M. J. Fernández-Rodríguez ◽  
J. Llanos ◽  
J. M. Mancilla-Leytón ◽  
R. Borja
Keyword(s):  
Anaerobic Digestion ◽  
Solid Waste ◽  
Methane Production ◽  
Methane Yield ◽  
Specific Rate ◽  
Order Kinetic ◽  
Two Phase ◽  
First Order ◽  
Olive Mill Solid Waste ◽  
Olive Mill

AbstractThe biomass valorisation of the invasive brown alga Rugulopteryx okamurae (Dictyotales, Phaeophyceae) is key to curbing the expansion of this invasive macroalga which is generating tonnes of biomass on southern Spain beaches. As a feasible alternative for the biomass management, anaerobic co-digestion is proposed in this study. Although the anaerobic digestion of macroalgae barely produced 177 mL of CH4 g−1 VS, the co-digestion with a C-rich substrate, such as the olive mill solid waste (OMSW, the main waste derived from the two-phase olive oil manufacturing process), improved the anaerobic digestion process. The mixture improved not only the methane yield, but also its biodegradability. The highest biodegradability was found in the mixture 1 R. okamurae—1 OMSW, which improved the biodegradability of the macroalgae by 12.9% and 38.1% for the OMSW. The highest methane yield was observed for the mixture 1 R. okamurae—3 OMSW, improving the methane production of macroalgae alone by 157% and the OMSW methane production by 8.6%. Two mathematical models were used to fit the experimental data of methane production time with the aim of assessing the processes and obtaining the kinetic constants of the anaerobic co-digestion of different combination of R. okamurae and OMSW and both substrates independently. First-order kinetic and the transference function models allowed for appropriately fitting the experimental results of methane production with digestion time. The specific rate constant, k (first-order model) for the mixture 1 R. okamurae- 1.5 OMSW, was 5.1 and 1.3 times higher than that obtained for the mono-digestion of single OMSW and the macroalga, respectively. In the same way, the transference function model revealed that the maximum methane production rate (Rmax) was also found for the mixture 1 R. okamurae—1.5 OMSW (30.4 mL CH4 g−1 VS day−1), which was 1.6 and 2.2 times higher than the corresponding to the mono-digestions of the single OMSW and sole R. okamurae (18.9 and 13.6 mL CH4 g−1 VS day−1), respectively.

MODELLING NITROGEN PROCESSES IN SOIL: MATHEMATICAL DEVELOPMENT AND RELATIONSHIPS

1976 ◽  
Vol 56 (2) ◽  
pp. 71-78 ◽  
Author(s):  
D. R. CAMERON ◽  
C. G. KOWALENKO
Keyword(s):  
Time Dependent ◽  
Rate Coefficients ◽  
Nitrification Rate ◽  
Order Kinetic ◽  
Nitrogen Flow ◽  
First Order ◽  
Interaction Term ◽  
Flow Pathways ◽  
Adsorption Desorption ◽  
Temperature Water

A small subsystem model was developed to simulate the major nitrogen flow pathways in an unsaturated soil treated with ammonium sulphate. A nonlinear Freundlich equilibrium model and a Langmuir kinetic model were used to describe mathematically the adsorption–desorption of soluble NH4+ to the exchangeable and clay-fixed phases, respectively. Time dependent, microbial mediated first-order kinetic models were used to quantify the ammonification and nitrification processes. The subsystem model was then used as a research tool to derive ammonification and nitrification rate coefficients for a preceding incubation experiment conducted using different soil moisture contents and temperatures. The model yields reasonably good fits to the observed data. A subsequent regression analysis relating the coefficients to temperature and moisture pointed out the importance of the temperature–water content interaction term in quantifying microbial mediated processes.

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