scholarly journals ZEÓLITA NaA SINTETIZADA SOBRE FIBRA DE VIDRO COMO ESTRATÉGIA PARA OTIMIZAÇÃO DO ABRANDAMENTO DE ÁGUAS DURAS

Química Nova ◽  
2021 ◽  
Author(s):  
Edipo Oliveira ◽  
Conceição Alves ◽  
Antonia França ◽  
Ronaldo Nascimento ◽  
José Sasaki ◽  
...  
Keyword(s):  
Glass Fiber ◽  
High Performance ◽  
Fiber Surface ◽  
Hard Water ◽  
Complete Removal ◽  
Alkaline Treatment ◽  
Water Softening ◽  
Wide Range ◽  
Zeolite Naa ◽  
Softening Process

NaA ZEOLITE SYNTHESIZED OVER FIBERGLASS AS A STRATEGY FOR OPTIMIZING HARD WATER SOFTENING. Zeolite NaA has been successfully synthesized over glass fiber surface previously activated by alkaline treatment. By varying the time of the treatment and the amount of silica and alumina precursors used in the reaction mixture, a sample with higher zeolite concentration could be obtained. This material was evaluated for water softening process as an alternative substitute for the use of the zeolite in its powder form, in which several drawbacks related to recovery and reuse limit its application. Water softening experiments, carried out in a continuous flow system, with a column containing the glass fiber-zeolite NaA, showed high performance in decreasing the Ca2+ ions, with complete removal achieved for 20 mL of simulated hard water (Ca2+ 100.0 mg L– ¹) by using 200 mg of the sample in form of column (10 mm diameter × 300 mm high). The sample maintained this performance in a wide range of pH (3.0-9.0), and also presented a feasible regenerability, with no decrease in its performance during the first four cycles of use, reaching 87.3% of efficiency over the tenth cycle.

Mechanical and thermal properties of polyoxymethylene-matrix composites filled with multi-walled carbon nanotubes-coated milled glass fiber

2019 ◽  
Vol 54 (15) ◽  
pp. 1961-1976
Author(s):  
Xu Xiangmin ◽  
Hongxiang Zhang ◽  
Tong Beibei ◽  
Li Binjie ◽  
Yudong Zhang
Keyword(s):  
Carbon Nanotubes ◽  
Thermal Stability ◽  
Thermal Properties ◽  
Electron Microscope ◽  
Glass Fiber ◽  
Crystallization Temperature ◽  
High Performance ◽  
Multiwall Carbon Nanotubes ◽  
Fiber Surface ◽  
Mechanical And Thermal Properties

The advanced multifunctional filler has become one of the main challenges in developing high-performance polymer composites. In this study, the acid-treated multiwall carbon nanotubes (MWCNTs) were adhered to the surface of milled glass fiber under the combined effect of 3-aminopropyltriethyloxy silane and tetraethyl orthosilicate to fabricate a hierarchical fiber (MWCNTs-MGF). The morphologies of the hierarchical fibers were characterized using field-emission scanning electron microscope and transmission electron microscope, which showed evidence of a coating layer of MWCNTs on each fiber surface. The MWCNTs-MGF was employed as a multifunctional filler to prepare polyoxymethylene-based composites using a twin-screw extruder by melt blending. The obtained composites exhibited improved mechanical and thermal properties. The composite tensile strength and notched impact strength and Young's modulus increased by 10%, 32%, and 32%, respectively, as the MWCNTs-MGF content varies from 0 to 10 wt.%. Meanwhile, the reinforcing and toughing mechanisms of MWCNTs-MGF were also elaborated by analyzing the interfacial adhesion and fracture morphologies of the composites. Moreover, the study on thermal stability and crystallization behavior indicated that the polyoxymethylene/MWCNTs-MGF composites had higher thermal stability, crystallization temperature, and crystallinity as compared to the polymer matrix. The improvement of thermal stability originates from the unique surface structure of MWCNTs-MGF, while the increase in crystallization temperature and crystallinity is due to the strong heterogeneous nucleation ability of the hierarchical fibers.

Effects of Acid Treatment on The Recovery of Outdated Pre-preg Composite Fibers

2021 ◽  
Author(s):  
Zaara Ali ◽  
Eylem Asmatulu
Keyword(s):  
Carbon Fiber ◽  
Glass Fiber ◽  
Acid Treatment ◽  
High Performance ◽  
Treatment Time ◽  
Surface Damage ◽  
Chemical Recycling ◽  
Composite Fibers ◽  
Wide Range ◽  
Different Temperatures

Abstract Purpose Carbon fiber, Kevlar® fiber, and glass fiber are the most widely used polymer prepregs in manufacturing high-performance composites to produce vital parts for a wide range of applications. The production of carbon and Kevlar® fibers is an energy-intensive process, requiring 198–595 MJ to produce 1 kg of virgin carbon fiber. However, chemically recycling these expired prepregs takes only 38.4 MJ/kg, which could be significantly sustainable. The work described in this study involves an array of experiments involving acid treatment of outdated prepreg composite fibers to study its effects and reclaim the fibers for future applications.Method The experiments were carried out at two different temperatures: 25°C and also 60°C. Sulfuric acid, nitric acid, acetone, and distilled water were used in the process, with varying treatment times of 60, 120, 240, 360, and 420 seconds. The recovered fibers were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Result The optimum treatment time and temperature were different for all three types of fibers. Initially, the glass fiber yielded promising results at room temperature and with a minimal 120-s processing time. Carbon fiber treatment was successful at 60°C with a 420-s treatment time. However, some surface damage was observed in the Kevlar® fiber at 60°C. Conclusion The chemical recycling process is the most sustainable, energy- and cost-efficient approach compared to all other available recycling processes. Also, it is possible to recover much cleaner fibers with the weave intact with an acid treatment and solvent-based recovery.

FTIR ANALYSIS OF ION EXCHANGE RESINS WITH APPLICATION IN PERMANENT HARD WATER SOFTENING

2014 ◽  
Vol 13 (9) ◽  
pp. 2145-2152 ◽  
Author(s):  
Liliana Lazar ◽  
Laura Bulgariu ◽  
Bogdan Bandrabur ◽  
Ramona-Elena Tataru-Farmus ◽  
Mioara Drobota ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Hard Water ◽  
Ion Exchange Resins ◽  
Ftir Analysis ◽  
Water Softening ◽  
Exchange Resins

Validated Stability Indicating HPTLC Method for the Estimation of Amoxapine in Different Stress Conditions

2019 ◽  
Vol 15 (3) ◽  
pp. 273-279
Author(s):  
Shweta G. Rangari ◽  
Nishikant A. Raut ◽  
Pradip W. Dhore
Keyword(s):  
High Performance ◽  
Limit Of Detection ◽  
Degradation Products ◽  
Analysis Data ◽  
Peak Height ◽  
Good Resolution ◽  
Stability Indicating ◽  
Limit Of Quantitation ◽  
Wide Range ◽  
Hptlc Method

Background:The unstable and/or toxic degradation products may form due to degradation of drug which results into loss of therapeutic activity and lead to life threatening condition. Hence, it is important to establish the stability characteristics of drug in various conditions such as in temperature, light, oxidising agent and susceptibility across a wide range of pH values.Introduction:The aim of the proposed study was to develop simple, sensitive and economic stability indicating high performance thin layer chromatography (HPTLC) method for the quantification of Amoxapine in the presence of degradation products.Methods:Amoxapine and its degraded products were separated on precoated silica gel 60F254 TLC plates by using mobile phase comprising of methanol: toluene: ammonium acetate (6:3:1, v/v/v). The densitometric evaluation was carried out at 320 nm in reflectance/absorbance mode. The degradation products obtained as per ICH guidelines under acidic, basic and oxidative conditions have different Rf values 0.12, 0.26 and 0.6 indicating good resolution from each other and pure drug with Rf: 0.47. Amoxapine was found to be stable under neutral, thermal and photo conditions.Results:The method was validated as per ICH Q2 (R1) guidelines in terms of accuracy, precision, ruggedness, robustness and linearity. A good linear relationship between concentration and response (peak area and peak height) over the range of 80 ng/spot to 720 ng/spot was observed from regression analysis data showing correlation coefficient 0.991 and 0.994 for area and height, respectively. The limit of detection (LOD) and limit of quantitation (LOQ) for area were found to be 1.176 ng/mL and 3.565 ng/mL, whereas for height, 50.063 ng/mL and 151.707 ng/mL respectively.Conclusion:The statistical analysis confirmed the accuracy, precision and selectivity of the proposed method which can be effectively used for the analysis of amoxapine in the presence of degradation products.

Phytochemical, Analytical and Medicinal Studies of Holoptelea integrifolia Roxb. Planch - A Review

2019 ◽  
Vol 5 (4) ◽  
pp. 270-277 ◽  
Author(s):  
Vijay Kumar ◽  
Simranjeet Singh ◽  
Ragini Bhadouria ◽  
Ravindra Singh ◽  
Om Prakash
Keyword(s):  
Liquid Chromatography ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
High Performance ◽  
Biologically Active ◽  
Toxicological Studies ◽  
Wide Range ◽  
Layer Chromatography

Holoptelea integrifolia Roxb. Planch (HI) has been used to treat various ailments including obesity, osteoarthritis, arthritis, inflammation, anemia, diabetes etc. To review the major phytochemicals and medicinal properties of HI, exhaustive bibliographic research was designed by means of various scientific search engines and databases. Only 12 phytochemicals have been reported including biologically active compounds like betulin, betulinic acid, epifriedlin, octacosanol, Friedlin, Holoptelin-A and Holoptelin-B. Analytical methods including the Thin Layer Chromatography (TLC), High-Performance Thin Layer Chromatography (HPTLC), High-Performance Liquid Chromatography (HPLC) and Liquid Chromatography With Mass Spectral (LC-MS) analysis have been used to analyze the HI. From medicinal potency point of view, these phytochemicals have a wide range of pharmacological activities such as antioxidant, antibacterial, anti-inflammatory, and anti-tumor. In the current review, it has been noticed that the mechanism of action of HI with biomolecules has not been fully explored. Pharmacology and toxicological studies are very few. This seems a huge literature gap to be fulfilled through the detailed in-vivo and in-vitro studies.

Study of Transcrystallization in Polymer Composites

1989 ◽  
Vol 170 ◽  
Author(s):  
Benjamin S. Hsiao ◽  
J. H. Eric
Keyword(s):  
Thermal Conductivity ◽  
Free Energy ◽  
Carbon Fiber ◽  
Plasma Treatment ◽  
Polymer Composites ◽  
High Performance ◽  
Interfacial Strength ◽  
Fiber Surface ◽  
Semicrystalline Polymers ◽  
First Case

AbstractTranscrystallization of semicrystalline polymers, such as PEEK, PEKK and PPS, in high performance composites has been investigated. It is found that PPDT aramid fiber and pitch-based carbon fiber induce a transcrystalline interphase in all three polymers, whereas in PAN-based carbon fiber and glass fiber systems, transcrystallization occurs only under specific circumstances. Epitaxy is used to explain the surface-induced transcrystalline interphase in the first case. In the latter case, transcrystallization is probably not due to epitaxy, but may be attributed to the thermal conductivity mismatch. Plasma treatment on the fiber surface showed a negligible effect on inducing transcrystallization, implying that surface-free energy was not important. A microdebonding test was adopted to evaluate the interfacial strength between the fiber and matrix. Our preliminary results did not reveal any effect on the fiber/matrix interfacial strength of transcrystallinity.

scholarly journals RELaTED Project: New Developments on Ultra-Low Temperature District Heating Networks

Proceedings ◽  
2020 ◽  
Vol 65 (1) ◽  
pp. 25
Author(s):  
Antonio Garrido Marijuan ◽  
Roberto Garay ◽  
Mikel Lumbreras ◽  
Víctor Sánchez ◽  
Olga Macias ◽  
...  
Keyword(s):  
Low Temperature ◽  
High Performance ◽  
Waste Heat ◽  
District Heating ◽  
Hot Water ◽  
Thermal Systems ◽  
Heating Source ◽  
Wide Range ◽  
Thermal Sources ◽  
Heating Networks

District heating networks deliver around 13% of the heating energy in the EU, being considered as a key element of the progressive decarbonization of Europe. The H2020 REnewable Low TEmperature District project (RELaTED) seeks to contribute to the energy decarbonization of these infrastructures through the development and demonstration of the following concepts: reduction in network temperature down to 50 °C, integration of renewable energies and waste heat sources with a novel substation concept, and improvement on building-integrated solar thermal systems. The coupling of renewable thermal sources with ultra-low temperature district heating (DH) allows for a bidirectional energy flow, using the DH as both thermal storage in periods of production surplus and a back-up heating source during consumption peaks. The ultra-low temperature enables the integration of a wide range of energy sources such as waste heat from industry. Furthermore, RELaTED also develops concepts concerning district heating-connected reversible heat pump systems that allow to reach adequate thermal levels for domestic hot water as well as the use of the network for district cooling with high performance. These developments will be demonstrated in four locations: Estonia, Serbia, Denmark, and Spain.

scholarly journals Applicability of Cork as Novel Modifiers to Develop Electrochemical Sensor for Caffeine Determination

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 37
Author(s):  
Mayra K. S. Monteiro ◽  
Djalma R. Da Silva ◽  
Marco A. Quiroz ◽  
Vítor J. P. Vilar ◽  
Carlos A. Martínez-Huitle ◽  
...  
Keyword(s):  
Electrochemical Sensor ◽  
Linear Response ◽  
High Performance ◽  
Low Cost ◽  
Pharmaceutical Formulations ◽  
Caffeine Concentration ◽  
Real Samples ◽  
Wide Range ◽  
Potential Use

This study aims to investigate the applicability of a hybrid electrochemical sensor composed of cork and graphite (Gr) for detecting caffeine in aqueous solutions. Raw cork (RAC) and regranulated cork (RGC, obtained by thermal treatment of RAC with steam at 380 °C) were tested as modifiers. The results clearly showed that the cork-graphite sensors, GrRAC and GrRGC, exhibited a linear response over a wide range of caffeine concentration (5–1000 µM), with R2 of 0.99 and 0.98, respectively. The limits of detection (LOD), estimated at 2.9 and 6.1 µM for GrRAC and GrRGC, suggest greater sensitivity and reproducibility than the unmodified conventional graphite sensor. The low-cost cork-graphite sensors were successfully applied in the determination of caffeine in soft drinks and pharmaceutical formulations, presenting well-defined current signals when analyzing real samples. When comparing electrochemical determinations and high performance liquid chromatography measurements, no significant differences were observed (mean accuracy 3.0%), highlighting the potential use of these sensors to determine caffeine in different samples.

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