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Showing records 1 to 25 of 201. [First] Page: 1 2 3 4 5 Last
Flow Behavior and Hot Processing Map of GH4698 for Isothermal Compression Process
Rongchuang Chen, Haifeng Xiao, Min Wang, Jianjun Li
September 30, 2019 (v1)
Subject: Materials
Keywords: arrhenius equation, flow behavior, nickel-based alloy, processing maps
An in-depth understanding of the flow behaviors of materials deformed at high temperatures is of paramount significance. However, insufficient research on the nickel-based GH4698 alloy has resulted in inaccurate material flow prediction or even cracking in the practical billet opening of GH4698 large forgings. In this study, hot compressions were performed at 950−1150 °C and 0.001−3 s−1. Single-peaked strain-stress curves were obtained under various conditions, owing to dislocation motions in dynamic recrystallizations. The Arrhenius model was formulated to accurately describe the flow stress evolutions and the mean prediction error of the flow stress was 5.90%. Processing maps were constructed at various hot working conditions. It was found that the hot working ability of GH4698 markedly decreased under lower temperatures (950−1080 °C) and higher strain rates (0.1−3 s−1). Optimal thermal processing parameters were suggested. In sum, this study systematically investigated the flow beha... [more]
Experimental Study on Precipitation Behavior of Spinels in Stainless Steel-Making Slag under Heating Treatment
Jianli Li, Qiqiang Mou, Qiang Zeng, Yue Yu
September 30, 2019 (v1)
Subject: Materials
Keywords: Cr2O3, crystal size, heating time, spinel, stainless steel slag
The stability of chromium in stainless steel slag has a positive correlation with spinel particle size and a negative correlation with the calcium content of the spinel. The effect of heating time on the precipitation of spinel crystals in the CaO-SiO2-MgO-Al2O3-Cr2O3-FeO system was investigated in the laboratory. Scanning electron microscopy with energy-dispersive and X-ray diffraction were adopted to observe the microstructure, test the chemical composition, and determine the mineral phases of synthetic slags, and FactSage7.1 was applied to calculate the crystallization process of the molten slag. The results showed that the particle size of the spinel crystals increased from 9.42 to 10.73 μm, the calcium content in the spinel crystals decreased from 1.38 at% to 0.78 at%, and the content of chromium in the spinel crystal increased from 16.55 at% to 22.78 at% with an increase in the heating time from 0 min to 120 min at 1450 °C. Furthermore, the species of spinel minerals remained con... [more]
Thermal Analysis of Nigerian Oil Palm Biomass with Sachet-Water Plastic Wastes for Sustainable Production of Biofuel
Bello Salman, Mei Yin Ong, Saifuddin Nomanbhay, Arshad Adam Salema, Revathy Sankaran, Pau Loke Show
September 23, 2019 (v1)
Subject: Materials
Keywords: activation energy, co-pyrolysis, oil palm empty fruit bunch, physio-thermal analysis, sachet-water plastic waste, TGA-DSC analysis
Nigeria, being the world’s largest importer of diesel-powered gen-sets, is expected to invest in bio-fuels in the future. Hence, it is important to examine the thermal properties and synergy of wastes for potential downstream resource utilization. In this study, thermal conversion as a route to reduce the exploding volume of wastes from sachet-water plastic (SWP) and oil palm empty fruit bunch (OPEFB) biomass was studied. Thermogravimetric (TGA) and subsequent differential scanning calorimeter (DSC) was used for the analysis. The effect of heating rate at 20 °C min−1 causes the increase of activation energy of the decomposition in the first-stage across all the blends (0.96 and 16.29 kJ mol−1). A similar phenomenon was seen when the heating rate was increased from 10 to 20 °C min−1 in the second-stage of decomposition. Overall, based on this study on the synergistic effects during the process, it can be deduced that co-pyrolysis can be an effective waste for energy platform.
An Overview of Recent Advances in State-of-the-Art Techniques in the Demulsification of Crude Oil Emulsions
M. A. Saad, Mohammed Kamil, N. H. Abdurahman, Rosli Mohd Yunus, Omar I. Awad
September 23, 2019 (v1)
Subject: Materials
Keywords: crude oil, demulsification, emulsion, mechanism, stability
The processing of crude oil often requires the extraction of a large amount of water. Frequently, crude oil is mixed with water to form water-in-crude oil emulsions as the result of factors such as high shear at the production wellhead and surface-active substances that are naturally present in crude oil. These emulsions are undesirable and require demulsification to remove the dispersed water and associated inorganic salts in order to meet production and transportation specifications. Additionally, the demulsification of these crude oil emulsions mitigates corrosion and catalyst poisoning and invariably maximizes the overall profitability of crude oil production. Recently, there has been growing research interest in developing workable solutions to the difficulties associated with transporting and refining crude oil emulsions and the restrictions on produced water discharge. Therefore, this paper reviews the recent research efforts on state-of-the-art demulsification techniques. First... [more]
Spectroscopic Examination and Chemometric Analysis of Essential Oils Obtained from Peppermint Herb (Mentha piperita L.) and Caraway Fruit (Carum carvi L.) Subjected to Pulsed Electric Fields
Urszula Sadowska, Arkadiusz Matwijczuk, Agnieszka Niemczynowicz, Tomasz Dróżdż, Andrzej Żabiński
September 23, 2019 (v1)
Subject: Materials
Keywords: caraway fruit, chemometric analysis and spectroscopic studies, essential oils, peppermint herb, pulsed electric field, spectroscopic studies
In the food industry, the pulsed electric field (PEF) technique is used to support the process of extraction of various substances. The aim of this study was to analyze the effect of a number of PEF pulses applied to peppermint and caraway on both the content of essential oils (EO) and their spectroscopic properties. The examined herb species were placed in a special vessel in the working chamber of the device between two electrodes providing high voltage electric pulses. The pulses were delivered 0, 150, 250, and 350 times per a studied sample of each herb. Essential oils were then obtained by way of hydrodistillation. The infrared spectra for all samples were measured using an FTIR spectrometer in the spectral range of 3700−730 cm−1. The applied electric field of a predetermined number of pulses had no significant effect on the amount of distilled essential oil from caraway fruit, while in the case of peppermint, it caused a slight decrease in relation to the raw material not subject... [more]
Topological Characterization of Nanosheet Covered by C3 and C6
Sumiya Nasir, Fozia Bashir Farooq, Nazeran Idrees, Muhammad Jawwad Saif, Fatima Saeed
September 23, 2019 (v1)
Subject: Materials
Keywords: M-polynomial, nanosheet, Randic index, topological index, Zagreb index
A topological index of a graph is a single numeric quantity which relates the chemical structure with its underlying physical and chemical properties. Topological indices of a nanosheet can help us to understand the properties of the material better. This study deals with computation of degree-dependent topological indices like the Randic index, first Zagreb index, second Zagreb index, geometric arithmetic index, atom bond connectivity index, sum connectivity index and hyper Zagreb index of nanosheet covered by C3 and C6. Furthermore, M-polynomial of the nanosheet is also computed, which provides an alternate way to express the topological indices.
Effect of Dissolved Organic Matter on Agglomeration and Removal of CuO Nanoparticles by Coagulation
Rizwan Khan, Muhammad Ali Inam, Muhammad Akram, Ahmed Uddin, Sarfaraz Khan, Ick Tae Yeom
September 23, 2019 (v1)
Subject: Materials
Keywords: agglomeration, coagulation, copper oxide nanoparticles, dissolved organic matter, polyaluminum chloride
Engineered nanomaterials (ENMs), such as copper oxide nanoparticles (CuO NPs), are emerging as pollutants extensively used in many commercial and industrial applications, thus raising environmental concerns due to their release into water bodies. It is, therefore, essential to remove these pollutants from water bodies in order to minimize the potential threat to the aquatic environment and human health. The objective of this study was to investigate the removal of CuO NPs from waters by the coagulation process. This study also explored the efficiency of coagulation to remove hydrophobic/hydrophilic dissolved organic matter (DOM) and turbidity with varying polyaluminum chloride (PACl) doses. According to the results, a high concentration of DOM affects both the CuO NPs zeta potential and hydrodynamic diameter, thereby decreasing the agglomeration behavior. At effective coagulation zone (ECR), high removal of CuO NPs (>95%) was observed for all studied waters (hydrophobic and hydrophilic... [more]
Preparation and Performance Analysis of Graphite Additive/Paraffin Composite Phase Change Materials
Wei Li, Yan Dong, Xu Zhang, Xueling Liu
September 23, 2019 (v1)
Subject: Materials
Keywords: composite phase change material, graphite additives, nanomaterials, thermal conductivity, thermal management
In the thermal energy storage system, the thermal properties of phase change materials (PCM) have a great influence on the system performance. In this paper, paraffin-based composite phase change material with different graphite additive (expanded graphite, EG; graphene, GR; and graphene oxide, GO) and different concentrations (0.5 to 2.0%) are manufactured by a two-step method combining mechanical agitation and ultrasonic vibration. The characteristics of charge/discharge processes are studied, and the thermophysical properties are measured by T-history method. The experimental results show that the thermal conductivity and heat charge rate of the composite PCM are effectively improved by adding the graphite additive to the PCM, and the addition of additives can improve the melting point of the material. When the same graphite additive is added, the higher the concentration, the higher the thermal conductivity of the composite PCM, and the latent heat decreases with the increase of co... [more]
The Effect of Very Cohesive Ultra-Fine Particles in Mixtures on Compression, Consolidation, and Fluidization
Abbas Kamranian Marnani, Andreas Bück, Sergiy Antonyuk, Berend van Wachem, Dominique Thévenin, Jürgen Tomas
September 23, 2019 (v1)
Subject: Materials
Keywords: binary mixtures, compression, consolidation, fine and ultra-fine particles, fluidization, history effect
This paper focuses on the effect of ultra-fine ( d < 10 µm) powders in mixtures with fine ( d < 100 µm) bulk material on compression processes and also evaluates the re-fluidization behavior of the compressed bed (history effect). Achieving this goal, different mixtures of fine and ultra-fine Ground-Carbonate-Calcium were compressed at three pressure levels. The results show that by increasing the applied pressure, the compressibility decreases due to change in compaction regime. Subsequently, for the higher pressure, the slope of packing density versus applied stress curves is noticeably different. However, this slope does not depend on the size distribution of mixtures, but on the type of material. Comparing fluidization and re-fluidization curves (bed pressure drop vs. gas velocity) shows an increase in the maximum bed pressure drop ( Δ P p e a k ) for re-fluidization. By increasing the portion of ultra-fine particles in the binary mixture, Δ P p e a... [more]
Some Eccentricity-Based Topological Indices and Polynomials of Poly(EThyleneAmidoAmine) (PETAA) Dendrimers
Jialin Zheng, Zahid Iqbal, Asfand Fahad, Asim Zafar, Adnan Aslam, Muhammad Imran Qureshi, Rida Irfan
September 23, 2019 (v1)
Subject: Materials
Keywords: Eccentric connectivity index, molecular topological indices, PolyEThyleneAmidoAmine (PETAA) dendrimer
Topological indices have been computed for various molecular structures over many years. These are numerical invariants associated with molecular structures and are helpful in featuring many properties. Among these molecular descriptors, the eccentricity connectivity index has a dynamic role due to its ability of estimating pharmaceutical properties. In this article, eccentric connectivity, total eccentricity connectivity, augmented eccentric connectivity, first Zagreb eccentricity, modified eccentric connectivity, second Zagreb eccentricity, and the edge version of eccentric connectivity indices, are computed for the molecular graph of a PolyEThyleneAmidoAmine (PETAA) dendrimer. Moreover, the explicit representations of the polynomials associated with some of these indices are also computed.
Modelling Hydration Swelling and Weakening of Montmorillonite Particles in Mudstone
Changlun Sun, Guichen Li, Yuantian Sun, Jintao He, Haoyu Rong
September 13, 2019 (v1)
Subject: Materials
Keywords: hydration, montmorillonite, mudstone, particle, swelling and weakening
It is of paramount importance to understand the hydration swelling and weakening properties of clay minerals, such as montmorillonite, to determine their mechanical responses during deep underground argillaceous engineering. In this study, the mineral components and microscopic structure of mudstone were characterised using X-ray powder diffraction and field-emission scanning electron microscopy. Experimental schemes were devised to determine the properties of mudstone under the influence of underground water and stress; these involved compacting montmorillonite particles with various water contents and conducting uniaxial compression tests. Experimental results demonstrated that compaction stress changes the microscopic structure of the montmorillonite matrix and affects its properties, and stress independency was found at particular water and stress conditions. Two equations were then obtained to describe the swelling and weakening properties of the montmorillonite matrix based on th... [more]
Irregularity Molecular Descriptors of Hourglass, Jagged-Rectangle, and Triangular Benzenoid Systems
Zafar Hussain, Shazia Rafique, Mobeen Munir, Muhammad Athar, Maqbool Chaudhary, Haseeb Ahmad, Shin Min Kang
September 13, 2019 (v1)
Subject: Materials
Keywords: benzenoid systems, complexity of structure, hourglass benzenoid system, irregularity measures
Determining the degree of irregularity of a certain molecular structure or a network has been a key source of interest for molecular topologists, but it is also important as it provides an insight into the key features used to guess properties of the structures. In this article, we are interested in formulating closed forms of irregularity measures of some popular benzenoid systems, such as hourglass H (m, n), jagged-rectangular J (m, n), and triangular benzenoid T (m, n) systems. We also compared our results graphically and concluded which benzenoid system among the above listed is more irregular than the others.
Removal of Lead and Cadmium Ions from Aqueous Solution by Adsorption on a Low-Cost Phragmites Biomass
Abdulaziz N. Amro, Mohammad K. Abhary, Muhammad Mansoor Shaikh, Samah Ali
September 5, 2019 (v1)
Subject: Materials
Keywords: cadmium, Freundlich isotherm, kinetic study, Langmuir isotherm, lead, treated phragmites biomass
In recent years, the interest in waste water treatment increased to preserve the environment. The objective of this study is the removal of lead and cadmium ions from aqueous solution by treated Phragmites biomass (TPB). TPB was characterized by using Fourier transform infrared spectroscopy (FTIR) and energy dispersive X-ray analysis (EDS) which indicates the presence of functional groups that may be responsible of metal adsorption such as hydroxyl, carbonyl, sulfonate and carboxylate. Characterization by scanning electron microscopy (SEM) and surface area analysis using the Brunauer−Emmett−Teller method (BET) illustrated that TPB is nonporous with a small surface area. The influences of various experimental factors were investigated; the proposed method recommended the extraction of Pb+2 and Cd+2 metal ions by TPB at pH 5.0. A contact time of 60 and 45 min was required for the adsorption 50 mL (50 ppm) Pb+2 and Cd+2 respectively to reach equilibrium when 0.10 g TPB was used. The optim... [more]
Effect of the Marangoni Convection in the Unsteady Thin Film Spray of CNT Nanofluids
Ali Rehman, Taza Gul, Zabidin Salleh, Safyan Mukhtar, Fawad Hussain, Kottakkaran Sooppy Nisar, Poom Kumam
August 15, 2019 (v1)
Subject: Materials
Keywords: extending cylinder, Marangoni convection, OHAM and ND-solve methods, SWCNT/MWCNT nanofluid
The gradient of surface temperature is known as Marangoni convection and plays an important role in silicon melt, spray, atomic reactors, and thin fluid films. Marangoni convection has been considered in the liquid film spray of carbon nanotube (CNT) nanofluid over the unsteady extending surface of a cylinder. The two kinds of CNTs, single-wall carbon nanotubes (SWCNTs) and multiple-wall carbon nanotubes (MWCNTs), formulated as water-based nanofluids have been used for thermal spray analysis. The thickness of the nanofluid film was kept variable for a stable spray rate and pressure distribution. The transformed equations of the flow problem have been solved using the optimal homotopy analysis method (OHAM). The obtained results have been validated through the sum of the total residual errors numerically and graphically for both types of nanofluids. The impact of the physical parameters versus velocity, pressure, and temperature pitches under the influence of the Marangoni convection ha... [more]
Increasing Iron and Reducing Phosphorus Grades of Magnetic-Roasted High-Phosphorus Oolitic Iron Ore by Low-Intensity Magnetic Separation−Reverse Flotation
Junhui Xiao, Lingli Zhou
August 15, 2019 (v1)
Subject: Materials
Keywords: iron increase, low-intensity magnetic separation, phosphorous reduction, phosphorus mineral flotation reagent, reverse flotation, suspended magnetic roast
High-phosphorus oolitic iron ore, treated by suspended flash magnetic roasting, contained 42.73% iron (mainly present as magnetite) and 0.93% phosphorus (present as collophane). Low-intensity magnetic separation (LIMS) was combined with reverse flotation to increase the iron and reduce the phosphorus contents of the roasted product. The results showed that an optimized iron ore concentrate with an iron grade of 67.54%, phosphorus content of 0.11%, and iron recovery of 78.99% were obtained under LIMS conditions that employed a grind of 95% −0.038 mm and a magnetic field of 0.10 T. Optimized rougher reverse-flotation conditions used a pulp pH of 9 and dosages of toluenesulfonamide, starch, and pine alcohol oil of 800 g/t, 1000 g/t, and 40 g/t, respectively; optimized scavenging conditions used a pulp pH of 9 and dosages of toluenesulfonamide, starch, and pine alcohol oil of 400 g/t, 500 g/t, and 20 g/t, respectively. Study of the mechanism of phosphorus reduction showed that the toluenes... [more]
Influence of Particle Charge and Size Distribution on Triboelectric Separation—New Evidence Revealed by In Situ Particle Size Measurements
Johann Landauer, Petra Foerst
August 15, 2019 (v1)
Subject: Materials
Keywords: binary mixture, charge estimation, in situ particle size measurement, particle charge, particle size distribution, triboelectric separation
Triboelectric charging is a potentially suitable tool for separating fine dry powders, but the charging process is not yet completely understood. Although physical descriptions of triboelectric charging have been proposed, these proposals generally assume the standard conditions of particles and surfaces without considering dispersity. To better understand the influence of particle charge on particle size distribution, we determined the in situ particle size in a protein−starch mixture injected into a separation chamber. The particle size distribution of the mixture was determined near the electrodes at different distances from the separation chamber inlet. The particle size decreased along both electrodes, indicating a higher protein than starch content near the electrodes. Moreover, the height distribution of the powder deposition and protein content along the electrodes were determined in further experiments, and the minimum charge of a particle that ensures its separation in a give... [more]
The Use of Polymers in the Flotation Treatment of Wastewater
Brian Bolto, Zongli Xie
August 14, 2019 (v1)
Subject: Materials
Keywords: flotation, hydrophobic polymers, oil recovery, polyelectrolyte, polymer, Wastewater
The use of flotation for the treatment of wastewaters in general, but especially for the removal of oil, grease, general organic matter, and suspended solids, is well established as a low energy process. Polyelectrolytes (PEs) can enhance performance without adding to the solids load that occurs with inorganic additives such as alum. The bridging of pollutants and the attachment of the resulting aggregates to the air-water interface can be effectively carried out with most wastewaters. Hydrophobic modification of the PEs can be useful for difficult species. It should be applied to the flotation of polyfluoroalkyl substances, for example, as they are not amenable to economical conventional treatment. Similarly, the removal of microplastic particles from sewage effluents by flotation could be enhanced.
Development and Permeability Testing of Self-Emulsifying Atorvastatin Calcium Pellets and Tablets of Compressed Pellets
Mine Diril, Yesim Karasulu, Miltiadis Toskas, Ioannis Nikolakakis
August 8, 2019 (v1)
Subject: Materials
Keywords: atorvastatin calcium, cytotoxicity, drug release, permeability, self-emulsifying pellets, self-emulsifying tablets
Self-emulsifying pellets (SEPs) of Atorvastatin Calcium (AtrCa) were developed and processed into tablets (SETs). Self-emulsifying drug delivery system (SEDDS) composed of oleic acid, Tween 20, Span 80 and N-Methyl-2-pyrolidone gave great solubility improvement and was used as oil in water emulsion for the preparation of SEPs. Due to the high 60% w/w SEDDS content required to achieve a therapeutic dose in the final tablet form, sonication was necessary to improve fluidity and stability. Colloidal silicon dioxide (CSD) and microcrystalline cellulose (MCC) were the solids in the pellet formulation employed at a ratio 7:3, which enabled production of pellets with high SEDDS content and acceptable friability as well. Emulsions were characterized physico-chemically, SEPs for physical properties and reconstitution, and tablets of compressed pellets for mechanical strength, disintegration into pellets and drug release. SEPs compressed with 30% MCC at 60 MPa gave tablets of adequate strength t... [more]
Effect of Heating Oxidation on the Surface/Interface Properties and Floatability of Anthracite Coal
Guoqiang Rong, Mengdi Xu, Dongyue Wang, Xiahui Gui, Yaowen Xing
August 8, 2019 (v1)
Subject: Materials
Keywords: bubble-particle wrap angle, floatability, heating oxidation, induction time, surface/interface properties
Oxidation processes of coal surfaces are both fundamental and interesting from academic and engineering points of view. In this work, we comprehensively analyzed the mechanism of heating oxidation at 200 °C on the surface/interface characters and the floatability of anthracite coal. The variations of surface/interface characters were studied using SEM (scanning electron microscopy), FTIR (Fourier transform infrared spectroscopy), and XPS (X-ray photoelectron spectroscopy). The floatability was further identified using Induction Time and Bubble-Particle Wrap Angle. It was found that, after heating oxidation at 200 °C, both surface ravines and oxygen-containing groups were increased. The degradation of hydroxyl on anthracite could be neglected during the heating, while the oxidation of hydrocarbon chains dominated the balance of hydrophobicity and hydrophilicity on coal surface. The induction time significantly increased from 200 ms to 1200 ms and 2000 ms after 10 h and 20 h of heating o... [more]
Biopolymer Solution Evaluation Methodology: Thermal and Mechanical Assessment for Enhanced Oil Recovery with High Salinity Brines
Mohammad A. Al-Saleh, Abdirahman A. Yussuf, Mohammad A. Jumaa, Abbas Hammoud, Tahani Al-Shammari
August 7, 2019 (v1)
Subject: Materials
Keywords: biopolymer, mechanical degradation, polymer flooding, rheology, thermal stability
The methodology to study an eco-friendly and non-toxic, Schizophyllan, biopolymer for enhanced oil recovery (EOR) polymer flooding is described. The methodology is divided into two parts; the first part estimates the molar concentration of the biopolymer, which is needed to prepare the biopolymer solution with optimal viscosity. This is required to improve the sweep efficiency for the selected reservoir in Kuwait. The second part of this generalized methodology evaluates the biopolymer solution capability to resist degradation and maintain its essential properties with the selected reservoir conditions. The evaluation process includes thermal and mechanical assessment. Furthermore, to study the biopolymer solution behavior in both selected reservoir and extreme conditions, the biopolymer solution samples were prepared using 180 g/L and 309 g/L brine. It was found that the prepared biopolymer solution demonstrated great capability in maintaining its properties; and therefore, can be int... [more]
Electrolyte Effects on Poly (Acrylic Acid)-Based Aircraft De-icing Fluids
Yuchen Wang, Nicholas E. Hudson, Richard A. Pethrick, Carl J. Schaschke
August 7, 2019 (v1)
Subject: Materials
Keywords: calcium and potassium ions, poly (acrylic acid), polyelectrolytes, rheology, salt effects, water/glycol mixtures
Poly (acrylic acid) [PAA]-based aircraft de-icing fluids are widely used commercially but are known to be subject to the formation of insoluble gel particles within wing structures. In this study, the rheological effects of the sodium chloride, potassium formate, and calcium acetate with commercially used PAA-based fluids are reported across the temperature range of −15 to 15 °C. Calcium ions have the potential to create gel particles, reflected in the shifts in the viscosity−temperature profile, while PAA aggregation is influenced by the concentrations and compositions of sodium and potassium salts in the water used for dilution. From the data presented, it is possible to create de-icing fluid formulations with the necessary rheological characteristics from stock solutions by dilution using available water sources, providing that the ion concentration is known.
Photocatalytic Treatment of Paracetamol Using TiO2 Nanotubes: Effect of pH
S. Alejandro Lozano-Morales, Graciela Morales, Miguel Ángel López Zavala, Augusto Arce-Sarria, Fiderman Machuca-Martínez
August 5, 2019 (v1)
Subject: Materials
Keywords: emerging contaminants, paracetamol, pH, photocatalysis, TiO2 nanotubes
Pharmaceuticals are considered among the group of emerging contaminants. Paracetamol is a moderate painkiller, which has been detected in ground and surface water. Photodegradation of paracetamol at a wavelength of radiation of 254 nm with TiO2 nanotubes was studied by UV-spectroscopy, HPLC and measurement of the potential zeta in dependence of the solution pH. The efficiency of the photodegradation of paracetamol (20 mg L−1) was 99% after 100 min exposure. Application of the Langmuir-Hinshelwood equation allowed the evaluation of the rate constant. Non-organic by-products were detected under the conditions of the chromatographic analysis. The photoreaction was faster at pH 6.5, a value at which adsorption was favored, leading to higher efficiency.
Comparative Study of the Performances of Al(OH)3 and BaSO4 in Ultrafine Powder Coatings
Weihong Li, Diego Cárdenas Franco, Marshall Shuai Yang, Xinping Zhu, Haiping Zhang, Yuanyuan Shao, Hui Zhang, Jingxu Zhu
July 31, 2019 (v1)
Subject: Materials
Keywords: Al(OH)3, BaSO4, filler, ultrafine powder coatings
Ultrafine powder coatings are one of the development directions in the powder coating industry, as they can achieve thin coatings with good leveling and high surface smoothness comparable to liquid coatings. Compared to regular coatings, they experience a higher sensitivity to any incompatibilities, e.g., filler from coating components. The properties of fillers play a great role in the performance of coating films. Aluminum trihydrate (Al(OH)3) is a well-known filler in solvent-based coatings and other polymer industries. To study and evaluate the performances of Al(OH)3 in ultrafine powder coatings, a popular filler, barium sulfate (BaSO4) is used for comparison. Both fillers are added in ultrafine powder coatings based on two of the most commonly used resin systems (polyester-epoxy and polyester). The differences of physical and chemical properties between both fillers have significant influences on several properties of powder paints and coating films. The polar groups (hydrogen bo... [more]
Hydroxymethylation-Modified Lignin and Its Effectiveness as a Filler in Rubber Composites
Nor Anizah Mohamad Aini, Nadras Othman, M. Hazwan Hussin, Kannika Sahakaro, Nabil Hayeemasae
July 31, 2019 (v1)
Subject: Materials
Keywords: bio-filler, hydroxymethylation, lignin, rubber composite
Kraft lignin was modified by using hydroxymethylation to enhance the compatibility between rubber based on a blend of natural rubber/polybutadiene rubber (NR/BR) and lignin. To confirm this modification, the resultant hydroxymethylated kraft lignin (HMKL) was characterized using Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. It was then incorporated into rubber composites and compared with unmodified rubber. All rubber composites were investigated in terms of rheology, mechanical properties, aging, thermal properties, and morphology. The results show that the HMKL influenced the mechanical properties (tensile properties, hardness, and compression set) of NR/BR composites compared to unmodified lignin. Further evidence also revealed better dispersion and good interaction between the HMKL and the rubber matrix. Based on its performance in NR/BR composites, hydroxymethylated lignin can be used as a filler in the rubber industry.
Process Optimization by a Response Surface Methodology for Adsorption of Congo Red Dye onto Exfoliated Graphite-Decorated MnFe2O4 Nanocomposite: The Pivotal Role of Surface Chemistry
Van Thinh Pham, Hong-Tham T. Nguyen, Duyen Thi Cam Nguyen, Hanh T. N. Le, Thuong Thi Nguyen, Nhan Thi Hong Le, Kwon Teak Lim, Trinh Duy Nguyen, Thuan Van Tran, Long Giang Bach
July 31, 2019 (v1)
Subject: Materials
Keywords: Boehm titration, Congo red decontamination, exfoliated graphite, MnFe2O4 nanoparticles, response surface methodology, surface functional groups
Natural graphite, a locally available, eco-friendly, and low-cost carbonaceous source, can be easily transformed into exfoliated graphite (EG) with many surface functional groups via a chemical oxidation route. Combination between EG and magnetic MnFe2O4 is a promising strategy to create a hybrid kind of nanocomposite (EG@MnFe2O4) for the efficient adsorptive removal of Congo red (CR) dye from water. Here, we reported the facile synthesis and characterization of chemical bonds of EG@MnFe2O4 using several techniques such as Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). In particular, the quantity method by Boehm titration was employed to identify the content of functional groups: Carboxylic acid (0.044 mmol/g), phenol (0.032 mmol/g), lactone (0.020 mmol/g), and total base (0.0156 mmol/g) on the surface of EG@MnFe2O4. Through the response surface methodology-optimized models, we found a clear difference in the adsorption capacity between EG-... [more]
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