Removal of silicon from green liquor with carbon dioxide in the chemical recovery process of wheat straw soda pulping

TAPPI Journal ◽  
2013 ◽  
Vol 12 (3) ◽  
pp. 35-40 ◽  
Author(s):  
XINXING XIA ◽  
MINGZHU DU ◽  
XIUJUAN GENG
Keyword(s):  
Carbon Dioxide ◽  
Particle Size ◽  
Wheat Straw ◽  
Reaction Temperature ◽  
Recovery Process ◽  
Chemical Recovery ◽  
Step Process ◽  
Green Liquor ◽  
One Step ◽  
The One

Green liquor in the chemical recovery process of wheat straw pulping was treated with carbon dioxide to precipitate silicon by a one-step process and a seeding process to address problems caused by high silicon content. The total silicon removal, the particle size, and the sedimentation performance of silica were investigated. The results showed that the pH of green liquor decreased with increasing amounts of carbon dioxide, becoming stable after the pH decreased to 8.2. Reaction temperature had no significant effect on the removal of silicon. About 99% of silicon removal was achieved at a pH of 9.2 at room temperature. In the one-step process, the particle size increased and the silica sedimentation performance improved with decreasing pH. The particle size decreased and the sedimentation performance improved with increasing reaction temperature. At a pH of 9.5 and reaction temperature of 80°C, the particle size was 10.43 μm. In the seeding process, 40% green liquor was treated with carbon dioxide at 80°C until the pH was about 10.5, then the 40% treated green liquor was mixed with the remaining 60% of green liquor. The mixture was then treated with carbon dioxide at a reaction temperature of 80°C until the pH reached 9.5. In that situation, the particle size reached 14.11 μm. Compared with the one-step process, the particle size of silica generated by the seeding process was bigger and the sedimentation performance was improved.

Effect of silicon on properties of causticized calcium carbonate produced in wheat straw soda pulping

TAPPI Journal ◽  
2014 ◽  
Vol 13 (7) ◽  
pp. 41-46 ◽  
Author(s):  
XINXING XIA ◽  
XING WANG ◽  
MINGZHU DU ◽  
ZHAOQING LU
Keyword(s):  
Particle Size ◽  
Calcium Carbonate ◽  
Wheat Straw ◽  
Silicon Content ◽  
Average Particle Size ◽  
Recovery Process ◽  
Crystal Form ◽  
Silica Content ◽  
Chemical Recovery ◽  
Average Particle

Green liquor in the chemical recovery process of wheat straw pulping was treated with carbon dioxide to precipitate silicon. We report on the properties of causticized calcium carbonate (CCC) with different silicon contents, as well as its impact on paper quality when used as filler. The research results showed that silicon content had no significant effect on the crystal form of CCC, and all crystals were formed as calcite. Calcium silicate itself did not polymerize to form crystal in the course of causticization. Instead, silicon existed as a solid solution in CCC. The morphology of CCC changed gradually from amorphous to square with the decrease of silicon content. The brightness of CCC increased slightly and the average particle size tended to grow after removal of silicon. When 97% of silicon was removed and the average particle size reached 6.84 μm, the specific surface area and sedimentation volume decreased gradually as the desilication rate increased. When CCC was used as filler and silicon in CCC decreased, opacity remained nearly the same and brightness increased slightly; however, the Cobb value decreased significantly and the sizing efficiency obviously improved. When the silica content decreased to 3.2% the Cobb value was 27.7 g/m2, which reached the standard for fine paper sizing. The tear strength increased gradually, while the tensile strength decreased with the reduction of silicon.

e+ e- ANNIHILATION INTO $\overline{N}N$ PAIRS

2003 ◽  
Vol 18 (02n06) ◽  
pp. 370-373 ◽  
Author(s):  
Y. YAN ◽  
C. KOBDAJ ◽  
W. UCHAI ◽  
AMAND FAESSLER ◽  
T. GUTSCHE ◽  
...  
Keyword(s):  
Experimental Data ◽  
Vector Meson ◽  
Quark Model ◽  
Step Process ◽  
Meson Decays ◽  
Quantum Numbers ◽  
One Step ◽  
The One

The reactions of electron-position annihilation into nucleon-antinucleon pairs have been studied in a nonperturbative quark model. The work suggests that the two-step process, in which the primary [Formula: see text] pair forms first a meson and then the meson decays into baryon pair, is dominant over the one-step process in which the primary [Formula: see text] pair is directly dressed by two additional [Formula: see text] pairs to form a baryon pair. The experimental data indicates that there exists a vector meson with quantum numbers IG(JPC) = 0-(1--) and a mass around 2 GeV.

Preparation of nanocellulose by hydrolysis with ionic liquids and two-step hydrolysis with ionic liquids and enzymes

2021 ◽  
Vol 116 ◽  
pp. 5-14
Author(s):  
Marta Babicka ◽  
Magdalena Woźniak ◽  
Kinga Szentner ◽  
Sławomir Borysiak ◽  
Krzysztof Dwiecki ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Degree Of Crystallinity ◽  
Cellulolytic Enzyme ◽  
X Ray Diffraction ◽  
Production Methods ◽  
Step Process ◽  
X Ray ◽  
One Step ◽  
Xrd Patterns ◽  
The One

The aim of this study was to compare parameters of nanocellulose obtained by two different procedures: hydrolysis with ionic liquids (1-allyl-3-methylimidazolium chloride and 1-ethyl-3-methylimidazolium acetate) and hydrolysis with ionic liquids in combination with hydrolysis using a cellulolytic enzyme from Trichoderma reesei. Avicel cellulose was treated with two ionic liquids: 1-allyl-3-methylimidazolium chloride (AmimCl) and 1-ethyl 3-methylimidazolium acetate (EmimOAc). In the two-step hydrolysis cellulose after treatment with ionic liquids was additionally hydrolyzed with a solution of enzymes. In order to characterize the obtained material, the following analyses were used: infrared spectroscopy, X-ray diffraction and dynamic light scattering. The results indicated that cellulose obtained by two-step nanocellulose production methods (first hydrolysis with ionic liquids and then with enzymes) showed similar parameters (particle size, XRD patterns and degree of crystallinity) as the material after the one-step process, i.e. hydrolysis with ionic liquids.

scholarly journals One-Step Synthesis of Spherical γ-Fe2O3 Nanopowders and the Evaluation of Their Photocatalytic Activity for Orange I Degradation

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Chunhua Liang ◽  
Hui Liu ◽  
Jianmin Zhou ◽  
Xiaochun Peng ◽  
Haizhou Zhang
Keyword(s):  
Particle Size ◽  
Reaction Time ◽  
Synthesis Method ◽  
Total Pore Volume ◽  
Xrd Analysis ◽  
Bet Surface Area ◽  
Particle Sizes ◽  
Aqueous Synthesis ◽  
One Step ◽  
The One

Maghemite (γ-Fe2O3) nanopowders were synthesized under aeration (oxidizing) conditions by aqueous synthesis in this study. The microstructures of the prepared powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and BET-BJH. The XRD analysis and the chemical experiments showed that well-crystallized γ-Fe2O3 nanoparticles were successfully obtained with a mean particle size of approximately 17 nm. The prepared γ-Fe2O3 was spherical with a BET surface area of 14.357 m2/g and a total pore volume of 0.050 cm3/g. Varying the reaction conditions, such as pH, temperature, and reaction time, we obtained crystallized γ-Fe2O3 powders with different crystallization extent and different particle sizes. When the pH of the reaction suspension was increased, the reaction time was prolonged, and the reaction temperature was increased, the γ-Fe2O3 powders underwent superior crystallization and had larger particle sizes. All the obtained γ-Fe2O3 powders had significant photocatalytic activities under both UV and visible light irradiation for Orange I degradation, and the powders with better crystallization and larger particle size had relatively lower activities for Orange I photocatalytic degradation. The one-step aqueous synthesis method presented in this paper may provide an advantageous pathway to synthesize large quantities of this important iron oxide.

Heteroepitaxy on (001) Silicon: Growth Mechanisms and Defect Formation.

1988 ◽  
Vol 116 ◽  
Author(s):  
P. Pirouz ◽  
F. Ernst ◽  
T. T. Cheng
Keyword(s):  
Defect Formation ◽  
Lattice Mismatch ◽  
Minor Role ◽  
Alternative Mechanism ◽  
Growth Mechanisms ◽  
Planar Defects ◽  
Step Process ◽  
One Step ◽  
The One ◽  
A Minor

AbstractIn the growth of thin films of compound semiconductors on (001) silicon substrates by vapor deposition techniques, it is usual to employ a two-step process. In this method, an initial (buffer) layer is first grown at a relatively low temperature; once a continuous film has formed on the substrate, its temperature is raised for the subsequent bulk growth. Carrying out the growth in a one-step process by heating the substrate to the final temperature before allowing the gases into the CVD reactor usually results in a polycrystalline aggregate. In this paper, classical nucleation and growth mechanisms are used to explain-the reasons for the different morphology of the one-step and two-step growth films.The heteroepitaxial films on (001) silicon often contain a high density of stacking faults and twins. The occurrence of these planar defects is usually attributed to stresses that arise from lattice mismatch and/or thermal mismatch (differences in coefficients of thermal expansion) between the substrate and the epilayer. It is argued that, in fact, mismatch stresses play a minor role in the generation of planar defects. Instead, an alternative mechanism for their formation is proposed which is based on the facetted shape of nuclei and errors in stacking of {111} planes which occur during deposition on the facets.Conventional and high resolution transmission electron microscopy have been used to investigate three systems grown by CVD or MOCVD: SiC/Si, GaAs/Si and GaP/Si. These systems have different lattice and thermal mismatches, and the results support the proposed model for the formation of defects.

Aminimides. II. A one-step synthesis of aminimides from carboxylic acid esters

1967 ◽  
Vol 45 (21) ◽  
pp. 2619-2623 ◽  
Author(s):  
William J. McKillip ◽  
Robert C. Slagel
Keyword(s):  
Carboxylic Acid ◽  
Reaction Temperature ◽  
Sodium Methoxide ◽  
General Applicability ◽  
Acyl Substituent ◽  
One Step ◽  
The One ◽  
Substituent Influence ◽  
Acid Esters

The general applicability of preparing aminimides from esters and insitu generated 1,1,1-trimethylaminimine is reported. Acyclic, alicyclic, aromatic, and heteroaromatic trimethylaminimides have been synthesized by the one-step reaction. The synthetic scheme consists of reacting an ester with a 1,1,1-trimethylhydrazinium salt in the presence of an anhydrous base such as sodium methoxide. The choice of solvent, reaction temperature, and base and the electronegativity of the acyl substituent influence the ease of aminimide formation.

scholarly journals Operator Approach to the Master Equation for the One-Step Process

2016 ◽  
Vol 108 ◽  
pp. 02027 ◽  
Author(s):  
M. Hnatič ◽  
E. G. Eferina ◽  
A. V. Korolkova ◽  
D. S. Kulyabov ◽  
L. A. Sevastyanov
Keyword(s):  
Master Equation ◽  
Operator Approach ◽  
Step Process ◽  
One Step ◽  
The One

scholarly journals Reducing copper leaching from treated wood by sol-gel derived TiO2 and SiO2 depositions

Holzforschung ◽  
2013 ◽  
Vol 67 (4) ◽  
pp. 429-435 ◽  
Author(s):  
Muhammad Shabir Mahr ◽  
Thomas Hübert ◽  
Ina Stephan ◽  
Michael Bücker ◽  
Holger Militz
Keyword(s):  
Cell Wall ◽  
Diffusion Barrier ◽  
Sol Gel ◽  
Effective Diffusion ◽  
Treated Wood ◽  
Emission Rates ◽  
Step Process ◽  
Copper Leaching ◽  
One Step ◽  
The One

Abstract The antileaching efficacy of sol-gel-derived TiO2- and SiO2-based precursors has been evaluated through laboratory leaching trials with pine sapwood in two different ways. In a one-step process, wood was vacuum impregnated by the precursor solutions containing CuCl2. The copper (Cu) emission rates of the sol-gel-based impregnated woods were up to 70% lower than that of wood treated with pure CuCl2 solution at the same level of concentration. More improvement (80%) could be achieved in a two-step process, in which sol-gel precursors were introduced into an already CuCl2-treated wood. The refinement was attributed to several effects. In the one-step approach, Cu was embedded in the TiO2/SiO2 gels formed in the wood texture. During a two-step impregnation, gel layers that were formed in the wooden interior acted as an effective diffusion barrier. The sol-gel impregnations made wood more hydrophobic; therefore, the low amount of water that penetrated the cell wall was less efficient to leach out Cu.

Effect of Microwave with Ultrasonic on the Morphology and Particle Size of (Y,Eu)2 O3 Precursor

2011 ◽  
Vol 347-353 ◽  
pp. 3981-3984
Author(s):  
Qing Yun Zeng ◽  
Qing Qing Chang ◽  
Xin Yu Ye
Keyword(s):  
Particle Size ◽  
Reaction Time ◽  
Reaction Temperature ◽  
Ageing Time ◽  
Preparation Conditions ◽  
Ultrasonic Assisted ◽  
The One ◽  
Co Precipitation ◽  
Average Size ◽  
The Ideal

The (Y,Eu)2O3 precursor prepared by microwave with ultrasonic-assisted co-precipitation is superior to the one prepared by co-precipitation of conventional approach as well as co-precipitation assisted by microwave. The effect of preparation conditions on the morphology and particle size of (Y,Eu)2O3 precursor was completely investigated in this study. The ideal conditions were optimized as 0.25M Ln3+ ions concentration, 80°C reaction temperature, 90 minutes reaction time and 0 minute ageing time. Consequently, the (Y,Eu)2O3 precursor in the needle-like shape with average size of 0.25μm in diameter was obtained. The possible mechanism was also presented.

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