GRAFTING METHOD OF FLUORINATED COMPOUNDS TO CELLULOSE AND CELLULOSE ACETATE: CHARACTERIZATION AND BIODEGRADATION STUDY

Cellulose (Cell) and cellulose acetate (CA) are attractive durable materials; they can acquire various properties through modification in order to obtain valuable industrial products. First, a series of novel fluorinated cellulose carbamate and fluorinated CA carbamate have been synthesized. The introduction of fluoro-groups onto cellulose and CA chain backbone was achieved by the one-pot grafting method using diisocyanate as a coupling agent, which can be considered as a green procedure. The compounds prepared were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), X-ray diffractometry (XRD), thermogravimetric analysis (TGA) and differential thermogravimetry (DTG) measurements. The results obtained from these analytical techniques confirm that modification occurs successfully. Second, the solubility behavior and biodegradation process of these new fluorinated materials have been studied. The results show that these new materials exhibit better solubility compared to cellulose, but this solubility decreases compared to that of CA. The phenomenon of biodegradation was studied using two methods, the rate of biodegradability was determined. The results of this part show that the biodegradation of fluorinated materials decreases compared to that of the starting materials. These novel materials are biodegradable, can substitute currently used industrial non-biodegradable products and be promising agents for several uses, such as bioplastics, drug carriers, etc. A sustainable development and an increased use of green chemistry principles are among the essential objectives of this work.

Preparation and Characterization of Functionalized Cellulose Nanomaterials (CNMs) for Pb(II) Ions Removal from Wastewater

Due to their remarkable properties, cellulose nanomaterials are emerging materials for wastewater (WW) treatment. In this study, both pristine cellulose nanomaterial (CNM) and sodium periodate modified cellulose nanomaterial (NaIO4-CNM) were prepared from the stem of the Erythrina brucei plant for the removal of Pb(II) ions from WW. As-prepared CNMs were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscope (SEM), and thermogravimetric analysis with differential thermogravimetry (TGA-DTG) analysis. The as-prepared and characterized CNMs were tested for the removal of Pb(II) ions from secondary run-off wastewater (SERWW). Langmuir and Freundlich adsorption isotherms were certainly fixed to a maximum Pb(II) ions uptake capability (Qmax) of 91.74 and 384.62 mg g−1 by CNM and NaIO4-CNM adsorbents, respectively. The pseudo-second-order (PSO) kinetics model was well fitted to the uptake process. Results revealed that the percentage removal (%R) of Pb(II) ions was decreased by the presence of nitrogen and organic matter, but not affected by the presence of phosphorous in SERWW. Due to its high efficiency, NaIO4-CNM was selected for the regeneration study. The regeneration study was conducted after desorption of Pb(II) ions from the adsorbent by the addition of HCl, and the regenerated sorbent was reused as an adsorbent for at least 13 successive cycles. The results indicated excellent recycling capabilities, and the adsorbent was used as adsorbing material for the removal of Pb(II) ions from SERWW after 13 successive cycles without significant efficient loss.

Thermogravimetric Study of Refuse Derived Fuel Produced from Municipal Solid Waste of Kazakhstan

Efficient waste management, including proper utilization of municipal solid waste (MSW), is imperative for a sustainable future. Among several management options, pyrolysis and combustion of MSW has regained interest because of improved combustion techniques. This work aims to investigate the thermal conversion and combustion characteristics of refuse derived solid fuel (RDF) samples and its individual compounds collected from Nur-Sultan’s MSW landfills. The waste-derived solid RDF samples originally consist of textile, mixed paper, and mixed plastic. In particular, the samples, including RDF and its three constituent components, were analyzed in the temperature range of 25 to 900 °C, at three different heating rates, by thermogravimetric method. The gross calorific value for RDF derived from Nur-Sultan’s MSW was determined to be 23.4 MJ/kg. The weight loss rates of the samples, differential thermogravimetry (DTG), and kinetic analysis were compared between individual RDF components and for the mixed RDF. Combustion kinetics models were calculated using Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), and Friedman methods. The results revealed that first decomposition of RDF samples was observed at the range of 180–370 °C. Moreover, the activation energy for conversion of RDF was observed to be the highest among the constituent components and gradually decreased from 370 to 140 kJ/kmol.

Mineralogical characterization and evaluation of chromite ore in Grevena and Kozani Vourinos massif, Western Macedonia, Greece

Purpose. Chromite samples from Aetoraches mine area in the southern part of the Vourinos complex in Western Macedonia, Greece were examined from mineralogical-geochemical perspective. Methods. Χ-ray Diffraction (XRD) mineral phase analysis, elemental Scanning Electron Microscopy coupled with Energy Dispersive Spectroscopy (SEM-EDS) analysis and Thermogravimetry/Differential Thermogravimetry (TG/DTG) were carried out. Findings. The XRD results showed that all the samples contain mainly magnesium- and aluminum-chromite (“aluminum-picrochromite”) phases, along with forsterite (magnesian olivine), serpentine and chlorite occurrences. Based on the SEM-EDS results, the computed average chemical formula indicative of this specific chromite type is: (Fe0.4 Mg0.6) (Cr1.6 Al0.4/)O4. The TG-DTG weight losses found to be in the range of 4.4-14.36%, at temperatures between 600 and 750°C, indicated the presence of the hydroxyl-rich silicate minerals, serpentinite and chlorite, in agreement to the Loss of Ignition (LOI) results. The mineral phases detected in the present analyses appear in the dunite/diorite/harzburgite/peridotite main rocks of the ophiolitic complex that hosts the chromite ore. Originality.In the current research, an original characterization, via thorough elemental, phase and thermal analysis, is carried out aiming to enlighten the geochemistry aspects of the Vourinos chromite complex, Region of Western Macedonia, Greece, particularly of easily accessible and exploitable chromite deposits of the Aetoraches mine area. Practical implications. The chromite mineral, and especially the metallurgical type, is of substantial importance in metal industry. In that sense, the findings of the present investigation of chromite purity and mineral structure is a prerequisite for future exploitation of the Aetoraches chromite deposits in particular and broadly for the ongoing exploitation of chromite ore in the Vourinos complex, situated in Region of Western Macedonia, Greece, an area with high unemployment and rather slow economic growth. Keywords: chromite ore, Vourinos massif, Aetoraches mine area, mineralogical characterization, geochemistry, XRD, SEM-EDS, TG/DTG

Supramolecular Triblock Copolymers Through the Formation of Hydrogen Bonds: Synthesis, Characterization, Association Effects in Solvents of Different Polarity

Anionic polymerization techniques were employed for the synthesis of linear polystyrene (PS) and block copolymer of PS and polyisoprene (PI) PS-b-PI bearing end hydroxyl groups. Following suitable organic chemistry transformation, the –OH end groups were converted to moieties able to form complementary hydrogen bonds including 2,6-diaminopurine, Dap, thymine, Thy, and the so-called Hamilton receptor, Ham. The formation of hydrogen bonds was examined between the polymers PS-Dap and PS-b-PI-Thy, along with the polymers PS-Ham and PS-b-PI-Thy. The conditions under which supramolecular triblock copolymers are formed and the possibility to form aggregates were examined both in solution and in the solid state using a variety of techniques such as 1H-NMR spectroscopy, size exclusion chromatography (SEC), dilute solution viscometry, dynamic light scattering (DLS), thermogravimetric analysis (TGA), differential thermogravimetry (DTG), and differential scanning calorimetry (DSC).

Technology and Properties of Chondroitin Sulfate from Marine Hydrobionts

Chondroitin sulfate was isolated from the cartilage tissue of salmon (Salmo salar), northern skate (Raja hyperborean) and black-shark (Galeus melastomus). The polysaccharide content is from 67.1% to 82.2% in the samples. FTIR spectra of the obtained samples contain peaks at wave numbers characteristic of chondroitin sulfates (1550, 1350–1300, 1160–1120 и 822 cм–1). The thermal properties of chondroitin sulfates were studied by differential thermogravimetry. It was shown that the weight loss of the samples in the temperature range of 40–600ºC occurs in several stages. At the first stage, desorption of physically bound water occurs to a temperature of 150–200ºC, which can be explained by the difficulty in breaking hydrogen bonds between water molecules and the polar functional groups of chondroitin sulfate. Thermal decomposition of the bulk of chondroitin sulfate samples is observed at temperatures from 230–530ºC. The presence of peaks on the TGA curves in the temperature range 236–330ºC is associated with the release of sulfate groups and carboxylic acids (thermal destruction of uronic acid and pyranose units). When samples are heated above 350–400ºC, thermal oxidative degradation of residual carbon and sulfur compounds develops. The mass loss rates in each region were determined and the activation energies of each event were calculated. The nature of the cartilage tissue from which chondroitin sulfate is isolated affects the rate of destruction. Thus, in the temperature range 236–244ºC, the lowest destruction rate is observed for samples of chondroitin sulfate from salmon cartilage.

Структурные фазовые переходы в alpha-титане, содержащем неметаллические микропримеси

Using differential scanning calorimetry (DSC), differential thermogravimetry (DTG), mass spectrometry and x- ray diffraction (XRD) analysis, structural phase transitions in alpha-titanium powder containing non-metallic micro-impurities at elevated temperatures were studied. Microstructural and energy characteristics of these transitions are determined.

Studies on Combustion Characteristics of Density by Density Analyzed Coal

This work presents the effect of specific gravity of coal on its combustion characteristics. Coals with different specific gravity fractions represented by the arithmetic mean specific gravity (MSG) in the range of 1.35 to 2.0 were prepared by sink–float based density separation from run-of-mine (ROM) coal. The characterization of coal with different MSG was done using proximate, ultimate, and gross calorific value (GCV) analysis. Thermogravimetric analysis and differential thermogravimetry (TGA-DTG) studies of coals with different MSG were carried out in oxygen atmosphere to analyze their combustion characteristics. Various burning profile parameters (Ti, Tp, Tf, DTGmax) were assessed to identify the impacts of MSG of coals on their combustion characteristics. Further, different combustion indices (Di, Df, S, Hf) were evaluated to get the insights of combustion. Based on the experimental results, it was observed that, with an increase in coal MSG from 1.35 to 2.0, GCV decreased from 7426 to 3625 kcal/kg, Ti varied from 355 to 412 °C, Tp varied between 466 and 487 °C, and DTGmax decreased from 6.73 to 4.83 wt%/min. The result signifies that with an increase in MSG of coal, its combustion properties weaken. The activation energy for combustion varied between 93 and 119 kJ/mol. Based on the present analysis, it may be observed that lower MSG coals have enhanced combustion characteristics than higher MSG coals.

Macromolecular Brushes Based on Poly(L-Lactide) and Poly(ε-Caprolactone) Single and Double Macromonomers via ROMP. Synthesis, Characterization and Thermal Properties

Single and double poly(L-lactide) (PLLA) and poly(ε-caprolactone) (PCL) macromonomers having a norbornenyl polymerizable group were prepared by conventional Ring Opening Polymerization (ROP). These macromonomers were further subjected to ring opening metathesis polymerization (ROMP) reactions in order to produce double polymer brushes consisting of PLLA or PCL side chains on a polynorbornene (PNBE) backbone. Statistical or block ring opening metathesis copolymerization of the PLLA and PCL macromonomers afforded the corresponding random and block double brushes. Sequential ROMP of the single PLLA, PCL and PLLA macromonomers resulted in the synthesis of the corresponding triblock copolymer brush. The molecular characteristics of the macromolecular brushes were obtained by 1H-NMR spectroscopy and Size Exclusion Chromatography. The thermal properties of the samples were studied by thermogravimetric analysis, TGA, Differential Thermogravimetry, DTG and Differential Scanning Calorimetry, DSC.