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1

Synthesis of a New Random Copolymer Based on Glycidyl Nitrate and Tetrahydrofuran : A Thermal, Kinetic, and Theoretical Study

Alizadeh Milad, Bayat Yadollah

Central European Journal of Energetic Materials

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2024

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Vol. 21, no. 1

5--21

EN

Today, polymeric binders are regarded as playing a crucial role in solid propellants. Therefore, research aimed at improving the performance of the binder is particularly important. In this study, a new energetic random copolymer of glycidyl nitrate (GN) and tetrahydrofuran (THF), poly (THF-ran-GN) (Mn = 1561 g mol⁻¹) was synthesized using the cationic ring-opening polymerization process. The chemical structure of the prepared copolymers was characterized utilizing FT-IR, ¹H NMR and ¹³C NMR spectroscopic techniques. The thermal properties of the copolymers and their molecular weights were investigated by thermogravimetric analysis (TGA), differential thermal analysis (DTA), differential scanning calorimetry (DSC) and gel permeation chromatography (GPC). The results showed that the glass transition temperatures (Tg) of the synthesized copolymers (Tg= -59 °C) were lower than those of pure PGN (Tg= -32 °C). Therefore, copolymerization led to a decrease in the Tg temperature. The kinetic parameters of the DSC were determined in the non-isothermal framework described by Kissinger. The electronic structure of the copolymers was also simulated with the Gaussian 09 program package in order to investigate the optoelectronic properties of the copolymers based on time dependent density functional theory (TD-DFT) computations. In addition, the existence of three peaks featuring significant excitations associated with electron transition in frontier orbitals was demonstrated. The results showed that the new synthesized random copolymer has energetic properties.

2

Adsorption behaviour of As(III) onto synthetic iron-based minerals: a comparative study of akaganeite, goethite and magnetite

Ulatowska Justyna.

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 2

art. no. 144818

EN

The present study compares the adsorption capacity of iron-based minerals in removing As(III) from aqueous solutions. The work contains the results of studies carried out on a laboratory scale. The synthetic material was used in three forms as akaganeite, goethite and magnetite. To characterise the minerals before and after adsorption of As(III), specific surface area, particle size distribution, density, and zeta potential were determined. Additionally, digital and optical micrographs, SEM, and FTIR analyses were performed. In the experimental part, the influence of the main parameters on the adsorption efficiency was investigated (pH, initial concentration, contact time, and amount of adsorbent). Adsorption isotherms were fitted by Freundlich, Langmuir, and DubininRadushkevich models. Pseudo-first-order (PFO), pseudo-second-order (PSO), and intraparticle diffusion (IPD) models were used to fit the kinetics data. Linear regression was used to estimate the parameters of isotherm and kinetic models. FTIR measurements gave helpful information on the synthesised minerals and the As(III) removal process. Results show that As(III) adsorption is related to the iron-based adsorbents, and adsorption efficiency increases in the following order: goethite < magnetite < akaganeite.

3

Effect of Alkali-NaOH Pretreatment on Methane Production from Anaerobic Digestion of Date Palm Waste

Lahboubi Nabila, Karouach Fadoua, Bakraoui Mohammed, El Gnaoui Yasser, Essamri Azzouz, El Bari Hassan

Ecological Engineering & Environmental Technology

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2022

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Vol. 23, iss. 2

78--89

EN

Anaerobic digestion of the date palm empty fruit bunch is a promising technology for both solid waste management and biogas production. The date palm empty fruit bunch is a lignocellulosic waste that takes more time for degradation and has a low biodegradability, thus pretreatment is needed to improve anaerobic biodegradation. In this study, the substrate was pretreated with different ratios of alkali-NaOH: 6, 18 and 30% (w/w) (ratio weight of NaOH / weight of Volatile Solid) for 10 min at room temperature to evaluate the effect of high alkali concentration on the methane potential and biodegradability. The experiment was conducted in a 5 L batch reactor under mesophilic conditions (37 °C). The methane potential of the untreated substrate was 98.5 N mL/gVS. The best methane potential improvement of 104% was achieved in the treatment of 18% (w/w) (204 N mL/gVS) with a biodegradability of 50%. Besides, two kinetic models were used to fit the experimental methane potentials and to explore process parameters (Modified Gompertz and Transference function). The best fit for predicting the parameters of methane production was observed for the 18% (w/w) pretreatment using the transference function, with a maximum methane production rate of 5 N mL/gVS.d.

4

Kinetic Study on the Preparation of Aluminum Fluoride Based on Fluosilicic Acid

Chen Gaoxiang, Yang Xingdong, Qu Jiyan, Luo Jianhong, Zhang Zhiye, Sun Lan

Polish Journal of Chemical Technology

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2021

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Vol. 23, nr 3

10--16

EN

Reasonable mathematical derivation and mechanism model in the process of producing aluminum fluoride by fluosilicic acid is the key to the industrial treatment of fluorine resources in the tail gas of phosphate ore. In this work, aluminum fluoride was generated directly by fluosilicic acid to extract fl uorine from the tail gas of phosphate rock. The uncreated-core model dominated by interfacial reaction and the uncreated-core model dominated by internal diffusion-reaction were then respectively utilized to describe the reaction kinetics of the generation of aluminum fluoride. The result showed that the uncreated-core model was dominated by interface reaction and internal diffusion, the apparent reaction order n = 1, and the activation energy Ea = 30.8632 kJ . mol–1. Product characterization and kinetic analysis were employed to deduce the reaction mechanism of preparing aluminum fluoride. The theoretical basis for the low-cost recycling of fluorine resources in the tail gas of industrial phosphate ore was provided in this work.

5

Studies on the Effect of a Covalently Bonded PGN Based Reactive Plasticizer on the Thermal Decomposition Behaviour of Glycidyl Azide Polymer

Bodaghi Asghar, Shahidzadeh Mansour

Central European Journal of Energetic Materials

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2019

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Vol. 16, no. 2

259--280

EN

Plasticizers are one of the additives that are added to polymers to increase the plasticity or decrease the viscosity of the material. Here, we have synthesized and characterized a new PGN-based reactive energetic plasticizer that has an oligomeric structure. The reactive energetic plasticizer can be grafted onto glycidyl azide polymer via a Cu-free Huisgen azide-alkyne 1,3-dipolar cycloaddition. The effect of the covalently bonded PGN-based plasticizer on the thermal properties of GAP-g-PGN copolymer has been investigated through thermogravimetric analysis and differential scanning calorimetry. The results indicate that the glass transition temperature of the prepolymer is decreased from –47.8 to –50.7 °C. Also, the kinetics of the thermal behaviour of GAP-g-PGN copolymer was determined by the application of the Kissinger and FWO kinetic models. The activation energies calculated by the Kissinger method were 165 and 188 kJ/mol for peak 1 and peak 2, respectively. Furthermore, the critical temperature (Tb) of thermal explosion for this energetic copolymer was estimated to be 182 °C.

6

Synthesis and Kinetic Study of a PCL-GAP-PCL Tri-block Copolymer

Chizari M., Bayat Y.

Central European Journal of Energetic Materials

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2018

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Vol. 15, no. 2

243--257

EN

An energetic tri-block copolymer PCL-GAP-PCL (Mn = 1794) was synthesized by a ring-opening polymerization of ε-caprolactone with glycidyl azide polymer (GAP) of low molecular weight (Mn = 1006 g/mol) as initiator, in the presence of dibutyltin dilaurate (DBTDL) as catalyst, at 100 °C in the absence of solvent. The products obtained in high yield were characterized by FTIR, gel permeation chromatography (GPC), and 1H and 13C NMR spectroscopy. Thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) were used to study the thermal behaviour of the polymers. An advanced isoconversional method has been applied for kinetic analysis. The activation energy, calculated by the Flynn-Wall-Ozawa (FWO) and Kissinger methods, and thermal analysis revealed that the tri-block copolymer has greater thermal stability than homopolymer GAP. The results of the activation energies from the Kissinger method for the first and second steps were 180.3 kJ·mol−1 and 209.8 kJ·mol−1, respectively. Furthermore, for the copolymer, the activation energy versus the level of conversion was calculated by the FWO method. The glass transition temperature (Tg) for GAP was influenced by the PCL blocks; as a result the copolymer (Tg = −64 °C) showed better thermal properties than homopolymer GAP (Tg = −48 °C).

7

Cementacja miedzi z zastosowaniem cynku, zelaza i aluminium z kwasnych roztworow siarczanowych. Kinetyka procesu i morfologia osadow wycementowanej miedzi

Gumowska W., Maruta M.

Rudy i Metale Nieżelazne Recykling

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2017

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R. 62, nr 1

8--18

PL

Zastosowano metodę cementacji do odzysku miedzi z roztworów odpadowych o niskiej zawartości miedzi. Cementacja jest samorzutnym procesem elektrochemicznym, w trakcie którego jony metalu bardziej szlachetnego osadzają się na powierzchni metalu mniej szlachetnego, a metal mniej szlachetny ulega roztwarzaniu. Miedź wytrąca się najczęściej za pomocą metalicznego żelaza, cynku lub aluminium. Określono wpływ składu elektrolitu oraz rodzaju metalu wytrącającego (Zn, Fe, AL), na kinetykę procesu cementacji miedzi oraz morfologię powsta¬jącego osadu miedzi. Stosowano elektrolity siarczanowe (CuSOĄ i H2S0J o różnym stężeniu jonów Cu2* (2,5-7,5 g/dm3) lub H2S0t (1,25-5,0 g/dm3). Liniowy przebieg zależności In CCul, - f(t) wskazuje, że proces cementacji miedzi cynkiem, żelazem i aluminium, przebiega w obszarze kontroli dyfuzyjnej. Osady miedzi otrzymanej w wyniku cementacji cynkiem lub żelazem, mają postać zbitych, gąbczastych aglomeratów o przypadkowym kształcie. Morfologia osadów uzyskanych podczas cementacji miedzi przez aluminium, zależy od składu elektrolitu. W elektrolicie zawierającym wyłącznie aniony S0t2', uzyskuje się miedź w postaci dużych kryształów o budowie dendrytycznej podczas gdy w elektrolicie zawierającym dodatkowo jony Cl', kryształy miedzi są znacznie mniejsze, o budowie krystalograficznej odpowiadającej strukturze RSC(A 1).

EN

Cementation method was used for the recovery of copper from waste solutions with low concentration of metal ions. Cementation is a spontaneous electrochemical process of deposition of more noble metal on the surface of the less noble metal accompanied by simultaneous dissolution of the less noble metal. Copper is precipitated usually using metallic iron, zinc or aluminum. The influence of the electrolyte composition and the nature of the metal (Zn, Fe, Alj on the kinetics of copper cementation and morphology of the final copper product was investigated. Sulphate electrolytes (CuS04 and H2S0J of various concentrations of Cu2* ions (2.5-7.5 g/dm3) or H-SO^ (1.25-5.0 g/dm3) were used. Linear dependence ofIn Cc „ = f(t) indicates that copper cementation with zinc, iron and aluminum occurs under diffusion control. Copper deposits obtained during cementation with zinc or iron form the spongy agglomerates of fine Cu particles. The morphology of the copper deposits obtained during cementation with aluminum, depends on the composition of the electrolyte. Large copper crystals with dendritic structure are obtained from the electrolyte containing only SO/' anions, while additional presence of CF, ions allows to produce much smaller copper crystals with the FCC(A 1) crystallographic structure.

8

Badania kinetyki zgazowania węgla kamiennego parą wodną w warunkach podwyższonego ciśnienia

Porada S., Rozwadowski A.

Przemysł Chemiczny

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2014

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T. 93, nr 3

384-387

PL

Zbadano szybkość wydzielania się gazowych produktów zgazowania węgla kamiennego parą wodną pod ciśnieniem 2 MPa. Obliczono parametry kinetyczne reakcji tworzenia się wodoru i tlenku węgla(II), wydajności głównych produktów gazowych procesu oraz stopień konwersji pierwiastka C w węglu.

EN

Bituminous coal was gasified with steam at 800–1000°C and under 2 MPa to study the reaction course. Kinetic parameters of H₂ and CO formation, yield of the gas products and the degree of C conversion during the gasification of coal were calcd.

9

Removal of phenol from wastewater using activated waste tea leaves

Mohsin K., Anwar R. S., Nadeem F., Amir Y., Syed W. A.

Polish Journal of Chemical Technology

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2013

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Vol. 15, nr 2

1--6

EN

This investigation enumerates the treatment of phenol contaminated synthetic wastewater by Activated Waste Tea Leaves (AWTL). Phosphoric acid was used for the modification of waste tea leaves. The effects of initial pH, biosorbent dose, contact time, and initial phenol concentration were studied on the phenol uptake from the synthetic solution. Kinetic modelling was performed using pseudo 1st and 2nd order kinetics. The Langmuir and Freundlich’s Models were employed to interpret the AWTL behaviour at various mass transfer gradients. The results show that the optimum values for pH, biosorbent dose and contact time were 2.2 g/L and 180 minutes, respectively. Pseudo 2nd order kinetic and the Langmuir’s Models best described the kinetic and equilibrium behaviours, respectively.

10

Photocatalytic degradation of an organic dye in some aqueous buffer solutions using nano titanium dioxide: A kinetic study

Montazerozohori M., Nasr-Esfahani M., Joohari S.

Environment Protection Engineering

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2012

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Vol. 38, nr 3

45--55

EN

Photocatalytic degradation of an organic dye, emerald green, on nano titanium dioxide (anatase 99.5%) at basic buffer pH of 7, 8 and 9 has been investigated. The effects of various operating parameters such as initial concentration of dye, catalyst dosage, bufferic pH and irradiation time on photocatalytic degradation have been studied in a photoreactor cell containing high pressure mercury lamp to obtain the optimum conditions. COD removal was found to be 65-71% confirming considerable mineralization. The photodegradation of the dye obeyed a pseudo-first order kinetics according to the Langmuir-Hinshelwood model at all used buffer pH. The observed rate constants (Kobs) of photocatalytic degradation were 3.3 ×10-2 min-1, 7.09 × 10-2 min-1 and 1.32 × 10-1 min-1 at buffer pH of 7-9 respectively. Furthermore, the Langmuir-Hinshelwood rate constants, kr and adsorption constants, KA are reported for current process at various buffer pH.

11

Mechanistic and Kinetic Study of Free Radical Polymerization Photoinitiated by Xanthene Dye-n-Phenylglycine Derivatives Photoredox Pairs

Kucybała Z., Pietrzak M., Osmańska K., Pączkowski J.

Polish Journal of Chemistry

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2005

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Vol. 79 / nr 5

851-866

EN

The mechanistic and free radical photopolymerization kinetic studies for the selected xanthene dyes in the presence of N-phenylglycine derivatives are described. The examined transient phenomena, using nanosecond laser flash photolysis, confirm that the oxidation of N-phenylglycine derivatives is a one electron transfer process. The laser flash measurements as well as the steady-state experiments allowed to establish the structure of a free radical, which in ethyl acetate-DMF (9:1) solution, is mostly formed after the electron transfer, e.g. N-phenylglycine _-aminoalkyl radical (Ph-NH-C _ (H)-COOH). However, a careful analysis of the photolysis products indicates another path of secondary reactions that includes the decarboxylation of N-phenylglycine N-centered radical cation, yielding Ph-NH-CH2 radical. The measured electron transfer rates oscillate from 0.23_108 to 35.9_108M-1 s-1 that, in turn, suggests the possibility that the electron transfer process might control the rate of photoinitiated polymerization. The comparison of the rates of xanthene dye triplet state quenching and the measured rates of polymerization shows, however, that there is no correlation between these two variables. This observation permits to conclude that the rate of photopolymerization is probably controlled by the secondary processes such as: (i) the rate of proton transfer reaction between N-phenylglycine radical cation and xanthene dye radical anion, (ii) the participation of decarboxylation process in the secondary reactions and (iii) the reactivity of the free radicals obtained after electron transfer.

12

The kinetics study of the photodegradation of chlorophenols in aquatic environment

Czaplicka M.

Polish Journal of Chemical Technology

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2005

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Vol. 7, nr 1

8-12

EN

The rates of photolysis degradation of 3-chlorophenol, 2,4-dichlorophenol, pentachlorophenol in an aqueous solution were determined. The results obtained show that under the experiments conditions, the rate constants decreased in the PCP > 2,4-DCP> 3-CP order. The quantum yields of the photolysis for the selected chlorophenols at 254 nm were also studied. The kinetic curves, the reaction rate and the rate constant reaction of the photodegradation of chlorophenols were presented. The main photodegradation pathways and primary products were identified.