scholarly journals Effect of Corrosive Media on the Chemical and Mechanical Resistance of IPS e.max® CAD Based Li2Si2O5 Glass-Ceramics

Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 365
Author(s):  
Anna Švančárková ◽  
Dagmar Galusková ◽  
Aleksandra Ewa Nowicka ◽  
Helena Pálková ◽  
Dušan Galusek
Keyword(s):  
Wear Resistance ◽  
Acetic Acid ◽  
Prolonged Exposure ◽  
Glass Ceramics ◽  
Mechanical Resistance ◽  
Two Stage ◽  
Lithium Metasilicate ◽  
Dynamic Conditions ◽  
One Stage ◽  
Stage Process

The influence of 4% acetic acid (pH~2.4) and an alkaline solution of NaOH (pH~10) on the corrosion resistance and micromechanical properties of disilicate crystals containing glass-ceramics (LS2-GC’s) is studied. Partially crystallized lithium metasilicate crystal containing glass-ceramics (LS-GC’s) are annealed to fully LS2-GC’s using a one stage and a two-stage heating to induce nucleation. Materials with various chemical and wear resistance are prepared. The content of the crystalline phase in the material annealed in the two-stage process A is 60.0% and increases to 72.2% for the material heated in the one-stage process B. The main elements leached in the acidic medium are lithium and phosphorus, while lithium, silicon, and phosphorus leached into the alkaline environment. Material B exhibits better chemical resistance to the corrosive influence of 4% acetic acid under quasi-dynamic conditions. In the alkaline corrosion medium, silicon is leached from material A faster compared to the material B. After prolonged exposure to acidic or basic environments, both materials show evidence of surface structural changes. A decrease of the sliding wear resistance is observed after corrosion in the acidic environment under dynamic conditions. In both materials, the wear rate increases after corrosion.

scholarly journals Comparison of the Properties of Activated Carbons Produced in One-Stage and Two-Stage Processes

2018 ◽  
Vol 4 (3) ◽  
pp. 41 ◽  
Author(s):  
Davide Bergna ◽  
Toni Varila ◽  
Henrik Romar ◽  
Ulla Lassi
Keyword(s):  
Carbon Content ◽  
Activated Carbons ◽  
Total Carbon ◽  
Activation Process ◽  
Two Stage ◽  
One Stage ◽  
Surface Areas ◽  
Significant Difference ◽  
Stage Process ◽  
The One

Activated carbons (ACs) can be produced from biomass in a thermal process either in a direct carbonization-activation process or by first carbonizing the biomass and later activating the bio-chars into activated carbons. The properties of the ACs are dependent on the type of process used for production. In this study, the properties of activated carbons produced in one-stage and two-stage processes are considered. Activated carbons were produced by physical activation of two types of starting materials: bio chars produced from spruce and birch chips in a commercial carbonization plant and from the corresponding raw chips. The activated carbons produced were characterized regarding specific surfaces, pore volumes, and pore size distributions. The un-activated bio chars had varying surface areas, 190 and 140 m2 g−1 for birch and spruce, respectively, and pore volumes of 0.092 and 0.067 cm3 g−1, respectively. On the other hand, 530–617 and 647–679 m2 g−1 for activated bio chars from birch and spruce, respectively, and pore volumes 0.366–0.509 and 0.545–0.555 cm3 g−1, respectively, were obtained. According to the results obtained, two slightly different types of activated carbons are produced depending on whether a one-stage or a two-stage carbonization and activation process is used. The ACs produced in the one-stage process had higher specific surface areas (SSA), according to the BET-model (Brunauer–Emmett–Teller), compared to the ones produced in a two-stage process (761–940 m2 g−1 vs. 540–650 m2 g−1, respectively). In addition, total pore volumes were higher in ACs from the one-stage process, but development of micro-pores was greater compared to those of the two-stage process. This indicates that the process can have an influence on the ACs’ porosity. There was no significant difference in total carbon content in general between the one-stage and two-stage processes for spruce and birch samples, but some differences were seen between the starting materials. Especially in the one-stage procedure with 2 and 4 h steam activation, there was nearly a 10% difference in carbon content between the spruce and birch samples.

scholarly journals Comparison of the Properties of Activated Carbons Produced in a One-stage And a Two-Stage Process

2018 ◽  
Author(s):  
Davide Bergna ◽  
Toni Varila ◽  
Henrik Romar ◽  
Ulla Lassi
Keyword(s):  
Activated Carbons ◽  
Total Carbon ◽  
Physical Activation ◽  
Activation Process ◽  
Two Stage ◽  
Total Carbon Content ◽  
One Stage ◽  
Pore Size Distributions ◽  
Significant Difference ◽  
Stage Process

Activated carbons (ACs) can be produced from biomass in a thermal process either in a direct carbonization-activation process or first by carbonizing the biomass and later on activating the biochars into activated carbons. The properties of the ACs are dependent on the type of process used for production. In this study, the properties of activated carbons produced in a one-stage and a two-stage process are considered. Activated carbons were produced by physical activation of two types of starting materials, biochars produced from spruce and birch chips in a commercial carbonization plant and from the corresponding raw chips. The activated carbons produced were characterized regarding specific surfaces, pore volumes and pore size distributions. The unactivated biochars had some degree of surface area and some porosity. According to the results obtained, two slightly different types of activated carbons are produced depending if a one-stage or a two-stage carbonization and activation process is used. The ACs produced in the one-stage process had higher specific surface areas compared to the ones produced in a two-stage process. In addition, total pore volumes were higher in one-stage process but development of micropores is greater compared to two-stage process. There was no significant difference in total carbon content between one-stage and two-stage process.

scholarly journals Activated carbons from golden shower upon different chemical activation methods: Synthesis and characterizations

2017 ◽  
Vol 36 (1-2) ◽  
pp. 95-113 ◽  
Author(s):  
Hai Nguyen Tran ◽  
Huan-Ping Chao ◽  
Sheng-Jie You
Keyword(s):  
Thermal Stability ◽  
Activated Carbons ◽  
Chemical Activation ◽  
Two Stage ◽  
One Stage ◽  
Crystal Properties ◽  
Boehm Titration ◽  
Stage Process ◽  
The One ◽  
Subsequent Chemical

Activated carbons (ACs) were synthesized from golden shower (GS) through chemical activation. Two synthesis processes were used: one-stage and two-stage processes. In the one-stage process, GS that was impregnated with K2CO3 was directly pyrolyzed (GSAC), and the two-stage process consisted of (1) pyrolytic or hydrolytic carbonization to produce biochar or hydrochar and (2) subsequent chemical activation was defined as GSBAC and GSHAC, respectively. The activated carbon’s characteristics—thermal stability and textural, physicochemical, structural, and crystal properties—were thoroughly investigated. Results demonstrated that the characteristics of activated carbons strongly depend on the method used for their synthesis. The Brunauer–Emmett–Teller surface area followed the order GSAC (1413 m2/g) > GSHAC (1238 m2/g) > GSBAC (812 m2/g). The existence of acidic groups was determined through Fourier transform infrared spectroscopy and Boehm titration. The excellent adsorptive capacities of the activated carbons were confirmed from the iodine number (1568–2695 mg/g) and methylene number (143–233 mg/g).

Application of acidic thermal treatment for one- and two-stage anaerobic digestion of sewage sludge

2010 ◽  
Vol 62 (11) ◽  
pp. 2647-2654 ◽  
Author(s):  
M. Takashima ◽  
Y. Tanaka
Keyword(s):  
Anaerobic Digestion ◽  
Sewage Sludge ◽  
Thermal Treatment ◽  
Phosphorus Recovery ◽  
Attractive Alternative ◽  
Two Stage ◽  
Digested Sludge ◽  
One Stage ◽  
Stage Process ◽  
The One

The effectiveness of acidic thermal treatment (ATT) was examined in a 106-day continuous experiment, when applied to one- or two-stage anaerobic digestion of sewage sludge (4.3% TS). The ATT was performed at 170°C and pH 5 for 1 hour (sulfuric acid for lowering pH). The one-stage process was mesophilic at 20 days hydraulic retention time (HRT), and incorporated the ATT as pre-treatment. The two-stage process consisted of a thermophilic digester at 5 days HRT and a mesophilic digester at 15 days HRT, and incorporated the ATT as interstage-treatment. On average, VSS reduction was 48.7% for the one-stage control, 65.8% for the one-stage ATT, 52.7% for the two-stage control and 67.6% for the two-stage ATT. Therefore, VSS reduction was increased by 15–17%, when the ATT was combined in both one- and two-stage processes. In addition, the dewaterability of digested sludge was remarkably improved, and phosphate release was enhanced. On the other hand, total methane production did not differ significantly, and color generation was noted in the digested sludge solutions with the ATT. In conclusion, the anaerobic digestion with ATT can be an attractive alternative for sludge reduction, handling, and phosphorus recovery.

scholarly journals Two-Stage Polyhydroxyalkanoates (PHA) Production from Cheese Whey Using Acetobacter Pasteurianus C1 and Bacillus sp. CYR1

2021 ◽  
Vol 8 (11) ◽  
pp. 157
Author(s):  
Young-Cheol Chang ◽  
M. Venkateswar Reddy ◽  
Kazuma Imura ◽  
Rui Onodera ◽  
Natsumi Kamada ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Carbon Source ◽  
Cheese Whey ◽  
Bacillus Sp ◽  
Two Stage ◽  
Acetobacter Pasteurianus ◽  
13C Nuclear Magnetic Resonance ◽  
Ft Ir ◽  
Stage Process ◽  
Pha Production

Cheese whey (CW) can be an excellent carbon source for polyhydroxyalkanoates (PHA)-producing bacteria. Most studies have used CW, which contains high amounts of lactose, however, there are no reports using raw CW, which has a relatively low amount of lactose. Therefore, in the present study, PHA production was evaluated in a two-stage process using the CW that contains low amounts of lactose. In first stage, the carbon source existing in CW was converted into acetic acid using the bacteria, Acetobacter pasteurianus C1, which was isolated from food waste. In the second stage, acetic acid produced in the first stage was converted into PHA using the bacteria, Bacillus sp. CYR-1. Under the condition of without the pretreatment of CW, acetic acid produced from CW was diluted at different folds and used for the production of PHA. Strain CYR-1 incubated with 10-fold diluted CW containing 5.7 g/L of acetic acid showed the higher PHA production (240.6 mg/L), whereas strain CYR-1 incubated with four-fold diluted CW containing 12.3 g/L of acetic acid showed 126 mg/L of PHA. After removing the excess protein present in CW, PHA production was further enhanced by 3.26 times (411 mg/L) at a four-fold dilution containing 11.3 g/L of acetic acid. Based on Fourier transform infrared spectroscopy (FT-IR), and 1H and 13C nuclear magnetic resonance (NMR) analyses, it was confirmed that the PHA produced from the two-stage process is poly-β-hydroxybutyrate (PHB). All bands appearing in the FT-IR spectrum and the chemical shifts of NMR nearly matched with those of standard PHB. Based on these studies, we concluded that a two-stage process using Acetobacter pasteurianus C1 and Bacillus sp. CYR-1 would be applicable for the production of PHB using CW containing a low amount of lactose.

Evaluation of a two-stage hydrothermal process for enhancing acetic acid production using municipal biosolids

2012 ◽  
Vol 65 (1) ◽  
pp. 149-155 ◽  
Author(s):  
Anderson Aggrey ◽  
Peter Dare ◽  
Robert Lei ◽  
Daniel Gapes
Keyword(s):  
Acetic Acid ◽  
Acid Production ◽  
Oxidation Process ◽  
Hydrothermal Process ◽  
Wet Oxidation ◽  
Thermal Hydrolysis ◽  
Two Stage ◽  
Acetic Acid Production ◽  
Stage Process ◽  
Municipal Biosolids

A two-stage hydrothermal process aimed at improving acetic acid production using municipal biosolids was evaluated against thermal hydrolysis and conventional wet oxidation process in a 600 ml Parr batch reactor. Thermal hydrolysis was conducted at 140 °C, wet oxidation at 220 °C and the two-stage process, which acted as a series combination of thermal hydrolysis and wet oxidation, at 220 °C. Initial pressure of 1 MPa was maintained in all the three processes. The results indicated that the highest acetic acid production of up to 58 mg/g dry solids feed was achieved in the wet oxidation process followed by the two-stage process with 36 mg/g dry solids feed and 1.8 mg/g dry solids feed for thermal hydrolysis. The acetic acid yield obtained by the thermal processes increased from 0.4% in the thermal hydrolysis process to 12% during the single stage wet oxidation, with the two-stage process achieving 8%. The purity of the acetic acid improved from 1% in thermal hydrolysis to 38% in the wet oxidation process. The two-stage process achieved acetic acid purity of 25%. This work demonstrated no enhancement of acetic acid production by the two-stage concept compared with the single stage wet oxidation process. This is in contrast to similar work by other researchers, investigated on carbohydrate biomass and vegetable wastes using hydrogen peroxide as the oxidant. However, the data obtained revealed that substrate specificity, reaction severity or oxidant type is clearly important in promoting reaction mechanisms which support enhanced acetic acid production using municipal biosolids.

scholarly journals Comparison of the Properties of Activated Carbons Produced in a One-Stage and a Two-Stage Process

2018 ◽  
Author(s):  
Davide Bergna ◽  
Toni Varila ◽  
Henrik Romar ◽  
Ulla Lassi
Keyword(s):  
Activated Carbons ◽  
Total Carbon ◽  
Physical Activation ◽  
Activation Process ◽  
Two Stage ◽  
Total Carbon Content ◽  
One Stage ◽  
Pore Size Distributions ◽  
Significant Difference ◽  
Stage Process

Activated carbons can be produced from biomass in a thermal process either in a direct carbonization-activation process or by first carbonizing the biomass and later on activating the biochars into activated carbons. The properties of the ACs are dependent on the type of process used for production. In this study, the properties of activated carbons produced in a one-stage and a two-stage process are considered. Activated carbons were produced by physical activation of two types of starting materials, bio chars produced from spruce and birch chips in a commercial carbonization plant and from the corresponding raw chips. The activated carbons produced were characterized regarding specific surfaces, pore volumes and pore size distributions. The un-activated bio chars had some degree of surface area 190 and 140 m2g-1 for spruce and birch and pore volumes of 0.067 and 0.092 cm3g-1. According to the results obtained, two slightly different types of activated carbons are produced depending if a one-stage or a two-stage carbonization and activation process is used. The ACs produced in the one-stage process had higher specific surface areas compared to the ones produced in a two-stage process (761-940 m2g-1 vs. 540-650 m2g-1) . In addition, total pore volumes were higher in one-stage process but development of micropores is greater compared to two-stage process. There was no significant difference in total carbon content between one-stage and two-stage process.

Extracting value-added products before pulping: Hemicellulosic ethanol from Eucalyptus globulus wood

Holzforschung ◽  
2012 ◽  
Vol 66 (5) ◽  
pp. 591-599 ◽  
Author(s):  
Julio Rodríguez-López ◽  
Aloia Romaní ◽  
María J. González-Muñoz ◽  
Gil Garrote ◽  
Juan C. Parajó
Keyword(s):  
Acetic Acid ◽  
Eucalyptus Globulus ◽  
Value Added ◽  
Pichia Stipitis ◽  
Two Stage ◽  
Stage Process ◽  
Hot Compressed Water ◽  
Fermentation Media ◽  
Value Added Products ◽  
Membrane Concentration

Abstract Xylose solutions have been produced from Eucalyptus globulus wood by autohydrolysis (with hot, compressed water) and post-hydrolysis (in presence of sulfuric acid). This two-stage process led to solids enriched in cellulose and lignin (suitable as a substrate for pulping) and liquors containing xylose as the major component. The liquid phase from post-hydrolysis also contained other sugars (glucose, arabinose) and acetic acid. Neutralized liquors (as obtained, or after membrane concentration), were employed (directly or after detoxification by ion exchange) as fermentation media for the production of hemicelluosic bioethanol with the yeast Pichia stipitis CECT 1922T. Under the best conditions assayed (fermentation of neutralized, concentrated and detoxified two-stage hydrolysis liquors), bioconversion took place at nearly stoichiometric yield, with a volumetric productivity of 0.37 g l-1·h-1.

Molecular genetic background of haemophilia A patients with discrepancy between one-stage and two-stage factor VIII assays

2010 ◽  
Vol 30 (S 01) ◽  
pp. S153-S155
Author(s):  
D. Delev ◽  
S. Pahl ◽  
J. Driesen ◽  
H. Brondke ◽  
J. Oldenburg ◽  
...  
Keyword(s):  
Factor Viii ◽  
Genetic Background ◽  
Molecular Genetic ◽  
Haemophilia A ◽  
Two Stage ◽  
One Stage
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