scholarly journals Influence of pulp characteristics on the properties of alkali cellulose

Cellulose ◽  
2020 ◽  
Vol 27 (12) ◽  
pp. 7227-7241 ◽  
Author(s):  
Catharina Fechter ◽  
Steffen Fischer ◽  
Felix Reimann ◽  
Harald Brelid ◽  
Thomas Heinze
Keyword(s):  
Maximum Yield ◽  
Industrial Applications ◽  
Aqueous Alkali ◽  
Major Influence ◽  
Alkali Concentration ◽  
High Concentration ◽  
Alkali Extraction ◽  
Alkali Cellulose ◽  
Cellulose Material ◽  
Extraction Behavior

Abstract Alkali extraction of cellulose material is a common treatment for several industrial processes—especially the viscose process, which produces fibers for textile applications. This study investigated different generic dissolving wood pulps by means of alkali extraction (10–18 wt% aq. NaOH at 20–50 °C). The regenerated residue of the pulps was characterized for its chemical composition, molecular structure, and cellulose conformation. The investigated pulps had in common that glucan was most intensely extracted at low temperature and low concentration of aqueous alkali, xylan was most intensely extracted at high temperature and high concentration of aqueous alkali, and mannan was most intensely extracted at a concentration of aqueous alkali > 14 wtwt% at all temperatures applied. The degree of transformation via alkali cellulose to cellulose II as determined with Raman spectroscopy was found to be maximized for all pulps at high alkali concentration and temperature had no major influence. Maximum yield for all investigated pulps was found when extraction was done with 18 wt% aq. NaOH. The importance of temperature differed for the investigated pulps. The reason for the differences in extraction behavior or different absolute levels of resulting properties was found to be related to differences in the homogeneity and purity of the pulps. A conclusion of interest for industrial applications was that extracting the pulps with 18 wt% aq. NaOH led to an optimal alkalization result for yield, purity, and conversion. The steeping temperature chosen was found to be important to balance the yield and the purity of xylan-containing pulps. Graphic abstract

scholarly journals Leaching Titaniferous Magnetite Concentrate by Alkaline Aqueous Solution

2021 ◽  
Author(s):  
Ke Guo ◽  
Shaoyan Wang ◽  
Renfeng Song ◽  
Zhiqiang Zhang
Keyword(s):  
Aqueous Solution ◽  
Alkali Concentration ◽  
Water Usage ◽  
X Ray Diffraction ◽  
High Concentration ◽  
X Ray ◽  
Iron Concentrate ◽  
Titaniferous Magnetite ◽  
Magnetite Concentrate ◽  
Kinetics Of

AbstractLeaching titaniferous magnetite concentrate with alkali solution of high concentration under high temperature and high pressure was utilized to improve the grade of iron in iron concentrate and the grade of TiO2 in titanium tailings. The titaniferous magnetite concentrate in use contained 12.67% TiO2 and 54.01% Fe. The thermodynamics of the possible reactions and the kinetics of leaching process were analyzed. It was found that decomposing FeTiO3 with NaOH aqueous solution could be carried out spontaneously and the reaction rate was mainly controlled by internal diffusion. The effects of water usage, alkali concentration, reaction time, and temperature on the leaching procedure were inspected, and the products were characterized by X-ray diffraction, scanning electron microscope, and energy dispersive spectroscopy, respectively. After NaOH leaching and magnetic separation, the concentrate, with Fe purity of 65.98% and Fe recovery of 82.46%, and the tailings, with TiO2 purity of 32.09% and TiO2 recovery of 80.79%, were obtained, respectively.

A Novel Approach of Fabricating Monodispersed Spherical MoSiBTiC Particles for Additive Manufacturing

2021 ◽  
Author(s):  
Zhenxing Zhou ◽  
Suxia Guo ◽  
Weiwei Zhou ◽  
Naoyoki Nomura
Keyword(s):  
Additive Manufacturing ◽  
Melting Process ◽  
Industrial Applications ◽  
Elemental Distribution ◽  
Drying Process ◽  
High Concentration ◽  
Novel Approach ◽  
Composition Ratios ◽  
Mesh Structures ◽  
Ejection Method

Abstract It is very challenging to fabricate spherical refractory material powders for additive manufacturing (AM) because of their high melting points and complex compositions. In this study, a novel technique, freeze-dry pulsated orifice ejection method (FD-POEM), was developed to fabricate spherical MoSiBTiC particles without a melting process. Elemental nanopowders were dispersed in water to prepare a high-concentration slurry, which was subsequently extruded from an orifice by diaphragm vibration and frozen instantly in liquid nitrogen. After a freeze-drying process, spherical composite particles with arbitrary composition ratios were obtained. The FD-POEM particles had a narrow size range and uniform elemental distribution. Mesh structures were formed within the FD-POEM particles, which was attributed to the sublimation of ice crystals. Furthermore, owing to their spherical morphology, the FD-POEM particles had a low avalanche angle of 42.6°, exhibiting good flowability. Consequently, the combination of FD-POEM and additive manufacturing has great potential for developing complex refractory components used in industrial applications.

scholarly journals Effect of Dissolved Organic Matter on Agglomeration and Removal of CuO Nanoparticles by Coagulation

Processes ◽  
2019 ◽  
Vol 7 (7) ◽  
pp. 455 ◽  
Author(s):  
Rizwan Khan ◽  
Muhammad Ali Inam ◽  
Muhammad Akram ◽  
Ahmed Uddin ◽  
Sarfaraz Khan ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Industrial Applications ◽  
Water Bodies ◽  
Hydrodynamic Diameter ◽  
Excess Charge ◽  
High Concentration ◽  
Potential Threat ◽  
Cuo Nps ◽  
Coagulation Process

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 waters), above ECR excess charge induced by coagulant restabilized particles in solution. Furthermore, waters containing hydrophobic DOM and those with high UV254nm values needed more coagulant dose than hydrophilic waters to obtain similar CuO NP removals. The primary mechanism involved in CuO NPs removal might be charge neutralization. These findings suggest that PACl is an effective coagulant in the removal of CuO NPs; however, water characteristics are an influencing factor on the removal performance of ENMs during the coagulation process.

SIZE OF INOCULUM, STIMULATION, AND INHIBITION OF GROWTH IN ASPERGILLUS ORYZAE

1965 ◽  
Vol 11 (1) ◽  
pp. 67-75 ◽  
Author(s):  
J. Meyrath ◽  
A. F. McIntosh
Keyword(s):  
Aspergillus Oryzae ◽  
Early Stage ◽  
Maximum Yield ◽  
Inoculum Size ◽  
High Concentration ◽  
Stages Of Growth ◽  
Inhibition Of Growth ◽  
Deep Culture ◽  
Favorable Influence ◽  
Late Stages

Culture filtrates from surface and deep cultures of Aspergillus oryzae were tested for the presence of stimulatory and inhibitory substances, by examining the effect of the nitrates, when added with the inoculum, on growth rate and maximum yield of stationary cultures of the same organism. Filtrates were prepared from various stages of both large- and small-inoculum cultures by each method of growth.Both stimulatory and inhibitory substances were found. Inhibitory substances predominated in the filtrates from early stages of a small-inoculum culture, more especially when these were derived from a deep culture, which showed a pronounced effect of inoculum size. At other stages of growth of small-inoculum cultures and all stages of growth of large-inoculum cultures tested, stimulatory substances were found.It is emphasized that the stage of production of such substances is of crucial importance. Inhibitory substances acting at an early stage of growth of small-inoculum cultures have an adverse effect on growth of late stages. If, however, stimulatory substances are present in sufficiently high concentration at a sufficiently early age, as in large-inoculum cultures, they exert a favorable influence on later stages of growth. These phenomena explain the effects of inoculum size.

scholarly journals Comparative molecular studies of halophilic bacteria from saline water and soil in the Saudi environment

2020 ◽  
Vol 36 (3) ◽  
Author(s):  
Mohamed Ahmed ◽  
Md. Mohibul Alam Khan ◽  
Saleh M. S. Al-Garni ◽  
Roop Singh Bora ◽  
Saleh A. Kabli
Keyword(s):  
Red Sea ◽  
Saline Water ◽  
Halophilic Bacteria ◽  
16S Rrna Gene Sequencing ◽  
Industrial Applications ◽  
Rrna Gene ◽  
Bacterial Isolates ◽  
High Concentration ◽  
Biochemical Tests ◽  
Water And Soil Samples

Halophilic bacteria are a microorganism that grows optimally in the presence of the very high concentration of sodium chloride. Halophiles are vital sources of various enzymes including hydrolases, which are very stable and catalytically highly efficient at high salt concentration and other extreme conditions such as high temperature, pH and presence of organic solvents.  Several hydrolases such as amylases, proteases, and lipases have been obtained from halophilic bacteria and are commonly used for various industrial applications. We initiated a screening project to isolate and characterize the halophilic bacteria from the Red Sea, which is one of the saltiest bodies of water in the world. Water and soil samples, collected from the Red Sea coast, Jeddah, Saudi Arabia, were screened for isolation of halophilic bacteria. Ten bacterial isolates were obtained, which were characterized by biochemical tests and 16S rRNA gene sequencing. Hydrolase producing bacteria among the isolates were screened by plate assay on starch and gelatin agar plates for amylase and protease, respectively.  Two bacterial isolates i.e Bacillus haynesii and Enterobacter cloacae subsp. were found to possess significant amylase and protease activity. Further characterization of both the strains is in progress.

Total Unsteadiness Downstream of an Axial Flow Fan With Variable Pitch Blades

2001 ◽  
Vol 124 (1) ◽  
pp. 280-283 ◽  
Author(s):  
Sandra Velarde-Sua´rez ◽  
Rafael Ballesteros-Tajadura ◽  
Carlos Santolaria-Morros ◽  
Eduardo Blanco-Marigorta
Keyword(s):  
Axial Flow ◽  
Industrial Applications ◽  
Operating Conditions ◽  
Major Influence ◽  
Axial Flow Fan ◽  
Variable Pitch ◽  
Fan Performance ◽  
Performance Curves ◽  
Unsteady Operation ◽  
Variable Operating Conditions

Variable pitch axial flow fans are widely used in industrial applications to satisfy variable operating conditions. The change of the blade pitch leads to a different rotor geometry and has a major influence on the unsteady operation of the machine. In this work, an experimental research on an axial flow fan with variable pitch blades has been carried out. First of all, the fan performance curves has been obtained. Then the flow field has been measured at ten radial locations both at the inlet and exit rotor plane using hot wire anemometry. Velocity components and total unsteadiness were determined and analyzed in order to characterize the influence of pitch blade and operating conditions on the flow structure.

Effect of Particle Size Distribution and Selective Alcohol Additives for Preparation of High Concentration Coal-Water Slurry

2020 ◽  
Vol 12 (2) ◽  
pp. 102-111 ◽  
Author(s):  
Debadutta Das ◽  
Anupama Routray ◽  
Swetashree Pattanaik ◽  
Pankaj K. Parhi ◽  
Bijnyan R. Das ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Static Stability ◽  
Industrial Applications ◽  
High Concentration ◽  
Oh Groups ◽  
Water Slurry ◽  
Coal Water Slurry ◽  
Water Alcohol

Background: The alternative of oil is highly essential in the present context due to the acute shortage of oil as well as increasing demand for it from different public and private sectors. Since 1980, attention has been focused on coal-water slurry as an alternative fuel for the power generation industry and a suitable substitute for oil in several industrial applications. One of the exciting areas in Coal Water Slurry (CWS) is coal–water-alcohol slurry in which different alcohol compound can act as a dispersant for the stabilisation of coal–water slurry. Objective: The objective of this paper is to prepare a high concentration coal–water-alcohol slurry using glycerol, glycol and ethanol as an additive, and different particle size distribution of coal. This will increase the surface activity of the coal thereby, decreasing the viscosity of the slurry. Method: Two bimodal samples are prepared in which coarse particles are (212 μm - 300 μm), (150 μm – 212 μm) and fine particle below 75 μm. Three types of alcohol additive namely glycerol, glycol and ethanol are used as a dispersant. Malvern Particle size analyzer is used to measure the particle size distribution of the coal samples. Rheological study of CWAS was conducted using HAAKE RHEO STRESS 1. Result: From the experiment, it has been concluded that the optimum addition of glycerol in water is taken as 90:10 of water and glycerol ratio because after that, there is no further decrease in the value of viscosity. An optimum value of glycol and ethanol mixed in water was determined and found as in the ratio of 86:14 and 82:18, respectively. Conclusion: From different parameter studies like coal concentration, pH, temperature, apparent viscosity and stability, it has been concluded that coal-water-glycerol slurry is better than other coal water- alcohol slurry. This is because of the presence of more OH- groups in glycerol. The static stability of this coal-water-alcohol slurry exists for the maximum period of 31 days.

scholarly journals Covellite (CuS) Production from a Real Acid Mine Drainage Treated with Biogenic H2S

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 206 ◽  
Author(s):  
Patricia Magalhães Pereira Silva ◽  
Adriano Reis Lucheta ◽  
José Augusto Pires Bitencourt ◽  
Andre Luiz Vilaça do Carmo ◽  
Ivan Patricio Ñancucheo Cuevas ◽  
...  
Keyword(s):  
Acid Mine Drainage ◽  
Mine Drainage ◽  
Raw Materials ◽  
Industrial Applications ◽  
Molar Ratio ◽  
High Concentration ◽  
Dissolved Metals ◽  
X Ray ◽  
Synthesis Conditions ◽  
Acid Mine

Acid Mine Drainage (AMD) is an environmental problem associated with mining activities, which resulted from the exposure of sulfur bearing materials to oxygen and water. AMD is a pollution source due to its extreme acidity, high concentration of sulfate, and soluble metals. Biological AMD treatment is one alternative to couple environmental amelioration for valuable dissolved metals recovery, as a new source of raw materials. Covellite (CuS) particles were synthetized from an AMD sample collected in a Brazilian copper mine, after 48 and 96 h of exposure to hydrogen sulfide (H2S) produced in a bioreactor containing acidophilic sulfate reducing bacteria (SRB). The time of exposure affected the morphology, nucleation, and size of CuS crystals. CuS crystals synthetized after 96 h of H2S exposure showed better ordination as indicated by sharp and intense diffractograms obtained by X-ray diffraction (XRD), and the predominance of placoid sheets with hexagonal habit structure as observed by scanning electrons microscopy (SEM). Energy dispersive X-ray fluorescence (EDXRF) spectrometry indicated a Cu:S molar ratio in agreement with CuS. Granulometric analysis demonstrated that 90% of CuS particles were less than 22 µm size. AMD biological treatment is a potential economical CuS recovery option for metallurgical process chain incorporation, or new industrial applications, since the alteration of synthesis conditions can produce different crystal forms with specific characteristics.

Solution Rheology of Saline and Polysaccharide Systems

2006 ◽  
Author(s):  
Ekmagage Don N. Almeida ◽  
Leela Rakesh ◽  
Stanley Hirschi ◽  
Anja Mueller
Keyword(s):  
Rheological Properties ◽  
Industrial Applications ◽  
Operating Conditions ◽  
Water Soluble ◽  
Effluent Treatment ◽  
High Concentration ◽  
Concentrated Suspension ◽  
Cross Model ◽  
Low Concentrations ◽  
Pharmaceutical Industries

The problem of the characterization of the solution properties of water soluble polymers is long-standing. These polymers tend to form aggregated supramolecular gels that are resistant to molecular dispersion. These materials are being widely used in a variety of industrial applications. Their principle functions are as rheological modifiers, where they thicken or gel solutions in products such as hair-care, detergents, air fresheners and foods; as flocculants for particle separation as applied to water clarification, sewage, and effluent treatment, and as stabilizers to control the properties of concentrated suspension and emulsions, for example in paints, pesticides, dyes, and pharmaceutical industries. Therefore it is important to understand their rheological properties under various operating conditions such as stress, strain, temperature etc, which will induce gelation. The rheological properties of starch gels of high concentration (up to 86% starch) have been investigated before [1]. In this paper we have investigated experimentally the shear viscosity and viscoelasticity properties of saline and polysaccharide suspensions at various low concentrations and pH at different temperatures using controlled stress and strain rheometers (Vilastic-3 and AR 2000). The data were then fitted with the power law and Cross model for low and higher concentrations respectively. The present results show that the viscosity/elasticity does not significantly change for low concentrations at different pH values. The maximum viscosity/elasticity was obtained around pH 5-7.4 at higher concentrations.

scholarly journals A novel approach of fabricating monodispersed spherical MoSiBTiC particles for additive manufacturing

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zhenxing Zhou ◽  
Suxia Guo ◽  
Weiwei Zhou ◽  
Naoyuki Nomura
Keyword(s):  
Additive Manufacturing ◽  
Melting Process ◽  
Industrial Applications ◽  
Elemental Distribution ◽  
Drying Process ◽  
High Concentration ◽  
Novel Approach ◽  
Composition Ratios ◽  
Mesh Structures ◽  
Ejection Method

AbstractIt is very challenging to fabricate spherical refractory material powders for additive manufacturing (AM) because of their high melting points and complex compositions. In this study, a novel technique, freeze-dry pulsated orifice ejection method (FD-POEM), was developed to fabricate spherical MoSiBTiC particles without a melting process. Elemental nanopowders were dispersed in water to prepare a high-concentration slurry, which was subsequently extruded from an orifice by diaphragm vibration and frozen instantly in liquid nitrogen. After a freeze-drying process, spherical composite particles with arbitrary composition ratios were obtained. The FD-POEM particles had a narrow size range and uniform elemental distribution. Mesh structures were formed within the FD-POEM particles, which was attributed to the sublimation of ice crystals. Furthermore, owing to their spherical morphology, the FD-POEM particles had a low avalanche angle of 42.6°, exhibiting good flowability. Consequently, the combination of FD-POEM and additive manufacturing has great potential for developing complex refractory components used in industrial applications.

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