scholarly journals THE STUDY OF NATURAL POLYSACCHARIDES: ORGANOLEPTIC, PHYSICAL, CHEMICAL, MICROBIOLOGICAL PROPERTIES, AND THERMODYNAMIC CHARACTERISTICS OF AQUEOUS SOLUTIONS

2016 ◽  
pp. 72-79
Author(s):  
Dar’ya Belova ◽  
Dar’ya Belova ◽  
Lyubov Dyshlyuk ◽  
Lyubov Dyshlyuk
Keyword(s):  
Aqueous Solutions ◽  
Biodegradable Polymers ◽  
Chemical Properties ◽  
Thermodynamic Characteristics ◽  
High Sensitivity ◽  
Raw Material ◽  
Scanning Calorimetry ◽  
Safety Standards ◽  
Kappa Carrageenan ◽  
Physical And Chemical

Natural polysaccharides is a promising raw material for biodegradable polymers production. To properly select sources of their origin would require conformity with safety standards in force for the similar products. This work conducts a study with a view to examine the extent to which the organoleptic, physical and chemical properties of the polysaccharides in question, as well as their safety indicators conform with the provisions of GOST 16280-2002, CAS 11114-20-8 and CAS 9004-65-3. It is determined that the samples selected, namely, agar-agar produced by Panreac (Germany) and Helicon (USA), carrageenan produced by Boc Sciences (USA) and Newgreen Pharmchem Co. (China) and hydroxypropylmethyl cellulose produced by Acros (Belgium) and Ashland Aqualon Functional Ingredients (USA), meet safety requirements for this type of raw material. Simultaneously, we employ high-sensitivity differential scanning calorimetry method to analyze thermodynamic characteristics of natural polysaccharides’ aqueous solutions. It is shown that gels based on agar-agar have high melting temperature and can withstand temperature rise; after, their microscopic structure is not affected by thermal history, and the gel system remains stable. Thermodynamically, aqueous solution of kappa-carrageenan forms more stable gel than iota-carrageenan; strength and melting point of kappa-carrageenan gels can be adjusted by changing the concentration of potassium chloride in the solution. Aqueous solutions of hydroxypropylmethylcellulose are thermodynamically stable. The experimental data obtained confirm the feasibility of natural polysaccharides application in the production of biodegradable polymers.

Chitosan-based Magnetic Composites - Efficient Adsorbents for Removal of Pb(II) and Cu(II) from Aqueous Mono and Bicomponent Solutions

2018 ◽  
Vol 69 (9) ◽  
pp. 2323-2330 ◽  
Author(s):  
Daniela C. Culita ◽  
Claudia Maria Simonescu ◽  
Rodica Elena Patescu ◽  
Nicolae Stanica
Keyword(s):  
Aqueous Solutions ◽  
Metal Ions ◽  
Chemical Properties ◽  
Order Kinetic ◽  
Mass Ratio ◽  
Magnetic Adsorbent ◽  
Magnetic Composites ◽  
Initial Ph ◽  
Order Kinetic Model ◽  
Physical And Chemical

A series of three chitosan-based magnetic composites was prepared through a simple coprecipitation method. It was investigated the influence of mass ratio between chitosan and magnetite on the physical and chemical properties of the composites in order to establish the optimum conditions for obtaining a composite with good adsorption capacity for Pb(II) and Cu(II) from mono and bicomponent aqueous solutions. It was found that the microspheres prepared using mass ratio chitosan / magnetite 1.25/1, having a saturation magnetization of 15 emu g--1, are the best to be used as adsorbent for the metal ions. The influence of different parameters such as initial pH values, contact time, initial concentration of metal ions, on the adsorption of Pb(II) and Cu(II) onto the chitosan-based magnetic adsorbent was investigated in details. The adsorption process fits the pseudo-second-order kinetic model in both mono and bicomponent systems, and the maximum adsorption capacities calculated on the basis of the Langmuir model were 79.4 mg g--1 for Pb(II) and 48.5 mg g--1 for Cu(II) in monocomponent systems, while in bicomponent systems were 88.3 and 49.5 mg g--1, respectively. The results revealed that the as prepared chitosan-based magnetic adsorbent can be an effective and promising adsorbent for Pb(II) and Cu(II) from mono and bicomponent aqueous solutions.

Identification of Amber and the Copal under Heat Pressurized Process

2012 ◽  
Vol 554-556 ◽  
pp. 2112-2115
Author(s):  
Hui Li ◽  
Xuan Wang ◽  
Yong Zhu ◽  
Qin Ren
Keyword(s):  
Chemical Properties ◽  
Peak Position ◽  
Exothermic Peak ◽  
Endothermic Peak ◽  
Scanning Calorimetry ◽  
Natural Resin ◽  
Before And After ◽  
Artificial Heat ◽  
Physical And Chemical ◽  
And Chemical Properties

Amber and copal belong to the natural resin, which are similar and transitional in the physical and chemical properties. The artificial heat-pressurized treatment is contributed to the polymerization of the natural copal, and turns into green, yellow-green and deep orange-yellow copal. It is very difficult to identify amber from the heat- pressurized treatment copal only based on the gemological parameters.The thermal behavior of amber and the copal before and after heat-pressurized treatment were analyzed by means of differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy(FTIR) and nuclear magnetic resonance(NMR). The results show that amber exists an evident endothermic peak around 123~132°C, and copal reveals an obvious endothermic peak at about 174~178°C, and the heat pressurized treatment copal occurs a clear exothermic peak around 150~152°C. The differences between endothermic or exothermic transition and peak position reveal occurring thermal oxidation or the bond breaking or the melting, which are of great significance in the identification.

Synthesis of Cu2O and ZnO Nanowires and their Heterojunction Nanowires by Thermal Evaporation: A Short Review

2014 ◽  
Vol 71 (5) ◽  
Author(s):  
Muhammad Arif Khan ◽  
Samsudi Sakrani ◽  
Syahida Suhaima ◽  
Yussof Wahab ◽  
Rosnita Muhammad
Keyword(s):  
Physical Vapor Deposition ◽  
Thermal Evaporation ◽  
Chemical Properties ◽  
High Sensitivity ◽  
Short Review ◽  
Zno Nanowires ◽  
Oxide Semiconductor ◽  
The Individual ◽  
Photovoltaic Solar Cells ◽  
Physical And Chemical

One dimensional metal oxide semiconductor nanowires of copper (I) oxide (Cu2O), zinc oxide (ZnO), and their heterojunction nanowires possess remarkable physical and chemical properties. ZnO and Cu2O areattractive because the metals are abundant on earth, inexpensive, nontoxic.Moreover, these oxides have useful optical and electrical properties suitable for a wide variety of electrical devices, because their electrical conduction can be predictably controlled by doping. We here restrict the disscussion using a Hot Tube Vacuum Thermal Evaporation. The NWs in these devices will be studied by physical vapor deposition known as vapor-liquid-solid (VLS). Therefore, we explore conventional methods, particularly the VLS of growing ZnO and Cu2O nanowires which are assisted by the catalyst.  In this short review, we report the individual and combined (Cu2O/ZnO) junction nanowires by PVD method.  The main advantages of these composite nanowires are the natural p-n characteristics, the broad light absorption, the high sensitivity to humidity changes, and the fast dynamic response. The combination of all characteristics offered by Cu2O/ZnO nanowires can enable the fabrication of diverse sensing devices, and photovoltaic solar cells.

scholarly journals Synthesis and thermal properties of some phenolic resins

2019 ◽  
Vol 7 (1) ◽  
pp. 1-15
Author(s):  
Alshawi F M ◽  
Abdul Razzq K ◽  
Hanoosh W S
Keyword(s):  
Phenol Formaldehyde ◽  
Chemical Properties ◽  
Decomposition Temperature ◽  
Industrial Applications ◽  
Stability Study ◽  
Curing Temperature ◽  
Molar Ratio ◽  
Scanning Calorimetry ◽  
Phenolic Resins ◽  
Physical And Chemical

Introduction: Phenolic resins have been in use since the early twentieth century and are considered the first class of synthetic polymers to achieve commercial success, moreover phenolic resins continue to succeed and attract special interest in a large range of industrial applications such as adhesives, paints, and composites; because of their unique physical and chemical properties. Materials and Methods: Prepolymers resol resins (RR, RH, RP, and RC) were synthesized by the reaction of phenolic compounds (resorcinol, hydroquinone, phloroglucinol, and catechol) respectively, with formaldehyde at molar ratio phenol/ formaldehyde 1/1.5, using sodium hydroxide as a catalyst. These resins were characterized by FTIR. The curing reaction of these resins was evaluated using differential scanning calorimetry (DSC), while the thermal stability study was evaluated using thermogravimetric analysis (TGA). Results and Discussion:From the results showing that these prepolymers have different curing temperatures and curing energy, while the TGA study showed that the cured resins have decomposition temperature more than 300 ºC, and char residue at 650 ºC more than 60%. Conclusions: These resol resins have different gel times (8-55) min, and viscosities (435-350) mpa.s. The curing temperature of these resin obtained from DSC curves was (120, 129, 105 and 127 °C), while the thermal behavior of the cured resins obtained from TGA curves showed that these cured resin have two decomposition temperatures and the rate of decomposition in the order of RC < RR< .

Fabrication of 1D Nanometer Tungsten Trioxide under Different Solvent System

2019 ◽  
Vol 944 ◽  
pp. 1144-1151
Author(s):  
Lin Yan Zhao ◽  
Yue Gang Shen ◽  
You Shu Fan ◽  
Li Wen Ma ◽  
Xiao Li Xi
Keyword(s):  
Tungsten Trioxide ◽  
Dye Sensitized Solar Cells ◽  
Chemical Properties ◽  
Lithium Ion ◽  
Solvent System ◽  
Raw Material ◽  
Solvent Type ◽  
Photocatalytic Activities ◽  
Size And Morphology ◽  
Physical And Chemical

As a cheap and stable transition metal oxide, tungsten trioxide (WO3) has received extensive attentions due to superior physical and chemical properties that could be used in electronic devices, lithium-ion batteries, gas sensors, dye sensitized solar cells, catalysts. In this study, the well-designed 1D architecture of nanowires and nanorods was successfully synthesized via a simple and facile solvethermal method with no template or additives. It is found that both solvent type and concentration of W raw material can affect the size and morphology of WO3significantly in a regular way. Different products showed distinct photocatalytic activities during the processing of degradation methylene blue under visible light, and the underlying reasons for the different photocatalytic activities were discussed.

Synthesis and Characteristics of Energetic Materials Based on 1,2-Dinitroguanidine

2014 ◽  
Vol 67 (7) ◽  
pp. 1037 ◽  
Author(s):  
Bingcheng Hu ◽  
Xinghui Jin ◽  
Huanqing Jia ◽  
Zuliang Liu ◽  
Chunxu Lv
Keyword(s):  
Mass Spectrometry ◽  
Energetic Materials ◽  
Chemical Properties ◽  
Detonation Properties ◽  
Physical And Chemical Properties ◽  
Scanning Calorimetry ◽  
Energetic Salts ◽  
Thermal Kinetic Parameters ◽  
Physical And Chemical ◽  
And Chemical Properties

A series of energetic salts based on 1,2-dinitroguanidine were successfully synthesised and fully characterised using 1H NMR, 13C NMR, and IR spectroscopy, mass spectrometry, elemental analysis, and differential scanning calorimetry. The results show that all the salts possess higher detonation properties (detonation pressures and velocities ranging from 24.8 to 30.3 GPa and 7665 to 8422 m s–1, respectively) than those of trinitrotolouene (TNT, 2,4,6-trinitromethylbenzene). The thermal stability and thermal kinetic parameters were also investigated to give a better understanding of the physical and chemical properties of these energetic salts.

scholarly journals Inter-molecular physiochemical characterization for etodolac-hydroxypropyl-β-cyclodextrin polymeric systems in solid and liquid state

2010 ◽  
Vol 8 (4) ◽  
pp. 953-962 ◽  
Author(s):  
Vivek Sinha ◽  
Renu Chadha ◽  
Honey Goel ◽  
Keyword(s):  
Solid State ◽  
Inclusion Complexes ◽  
Liquid State ◽  
Chemical Properties ◽  
Aqueous Solubility ◽  
Phase Solubility ◽  
Scanning Calorimetry ◽  
Polymeric Systems ◽  
Hydrophobic Molecule ◽  
Physical And Chemical

AbstractThe purpose of this study was to explore the utility of hydroxypropyl-β-cyclodextrin (HP-β-CD) systems in forming inclusion complexes with the anti-rheumatic or anti-arthritic drug, etodolac (EDC), in order to overcome the limitation of its poor aqueous solubility. This inclusion system achieved high solubility for the hydrophobic molecule. The physical and chemical properties of each inclusion compound were investigated. Complexes of EDC with HP-β-CD were obtained using the kneading and co-evaporation techniques. Solid state characterization of the products was carried out using Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), powder X-ray diffraction (XRD) and Scanning electron microscopy (SEM). Studies in the solution state were performed using UV-Vis spectrophotometry and 1H-NMR spectroscopy. Phase solubility profiles with HP-β-CD employed was found to be AL type. Stability constants (Kc) from the phase solubility diagrams were calculated indicating the formation of 1:1 inclusion complex. Stability studies in the solid state and in liquid state were performed; the possible degradation by RP-HPLC was monitored. The dissolution studies revealed that EDC dissolution rate was improved by the formation of inclusion complexes.

Sugarcane Biochar for Agricultural Use Produced in Different Conditions of Pyrolysis

2019 ◽  
pp. 1-8
Author(s):  
Juliany Barbosa de Pinho ◽  
Aloisio Bianchini ◽  
Pedro Silvério Xavier Pereira ◽  
Letycia Cunha Nunes ◽  
Rodrigo Fernandes Daros ◽  
...  
Keyword(s):  
Chemical Properties ◽  
Exchange Capacity ◽  
Raw Material ◽  
Physical And Chemical Properties ◽  
Oxidizing Atmosphere ◽  
Different Temperatures ◽  
Agricultural Use ◽  
Physical And Chemical ◽  
And Chemical Properties

From the pyrolysis process, biochar is a carbon rich and recalcitrant organic material with potential for long term carbon sequestration because of its aromatic structure. However, the physical and chemical properties of the biochar vary due to the diversity of raw material and the conditions of production. The present study aimed to evaluate the biochar from the sugarcane bagasse at different temperatures and under two conditions of pyrolysis. The biochar was produced at two final temperatures 200°C (1 hour); 250°C (1h) and 250°C (2h), with pyrolysis of an oxidizing and non-oxidizing atmosphere for both. PH, cation exchange capacity (CTC), carbon content (C), Nitrogen (N), hydrogen (H), H:C, C:N and ash ratios were evaluated. The contents of C, H, N and the atomic ratios H:C and C:N were higher in Biochar produced in a non-oxidizing atmosphere (BNO). However, the content of ash, pH and CTC were higher in Biochar produced in oxidizing atmospheres (BO). One can conclude the direct influence of the pyrolysis condition.

scholarly journals Preparation and Properties of Composite PAN/PANI Membranes

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Beata Fryczkowska ◽  
Zofia Piprek ◽  
Marta Sieradzka ◽  
Ryszard Fryczkowski ◽  
Jarosław Janicki
Keyword(s):  
Surface Morphology ◽  
Transport Properties ◽  
Chemical Properties ◽  
High Sensitivity ◽  
Sensory Properties ◽  
Inversion Method ◽  
Phase Inversion Method ◽  
Physical And Chemical ◽  
Polyacrylonitrile Solution ◽  
Interesting Solution

The methods of modifying PAN membranes have been known and used for many years. An interesting solution seems to be to give the sensory properties to this type of membranes. This paper presents the results of research on the method of obtaining PAN/PANI membranes using phase inversion method from a solution in DMF, following two methods: (1) dissolving both polymers (PAN and PANI) and then coagulating in water or in an aqueous solution of CSA and (2) forming the membranes from polyacrylonitrile solution and coagulation in water, followed by coating of CSA with a solution of TFE. The membranes obtained as a result of the experiment were tested for physical and chemical properties, transport properties, surface morphology, degree of dispersion of composite components, and sensitivity to the presence of dilute acids and bases. FTIR microspectroscopy and scanning electron microscopy were used to study the surface morphology. The sensory properties of membranes that are inherently colored were determined visually and by UV-Vis spectrophotometry. Furthermore, when choosing the method of membrane forming, we can obtain membranes with good physical and chemical and transport properties or ones characterized by high sensitivity to the pH of the solution.

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