scholarly journals Compressive Strength and Microstructural Characteristics of Natural Zeolite-based Geopolymer

2017 ◽  
Author(s):  
Sevgi Özen ◽  
Burhan Alam
Keyword(s):  
Compressive Strength ◽  
Natural Zeolite ◽  
Low Cost ◽  
Main Reaction ◽  
Main Reaction Product ◽  
Reaction Products ◽  
Zeolitic Tuff ◽  
Microstructural Characteristics ◽  
Alkaline Activator ◽  
Geopolymer Cement

A detailed study of geopolymeric reaction products and mechanical properties of geopolymer pastes prepared with natural zeolite has been investigated by means of compressive strength, XRD and SEM/EDX analysis. Sodium silicate and sodium hydroxide solutions are used as an alkaline activator. The results of the investigation show that the activator ratio plays an important role on the mechanical development of geopolymer pastes. The geopolymeric gel and CSH phase with a low Ca/Si ratio are found as the main reaction product. The increased intensity of CSH phase has a significant effect on the improvement of the compressive strength. Decreased intensity of clinoptilolite and totally consumed clay mineral upon geopolymerization proves the involvement of the aluminosilicate phases in the geopolymeric reaction. The existence of sodium and increment of Si/Al ratio with respect to original zeolitic tuff were detected. The results also show that the investigated natural zeolite, which is emerged as an environmentally friendly, low-cost material, is suitable for the production of geopolymer cement.

scholarly journals Chemical Denitrification with Mg0 Particles in Column Systems

2020 ◽  
Vol 12 (7) ◽  
pp. 2984 ◽  
Author(s):  
Alessio Siciliano ◽  
Giulia Maria Curcio ◽  
Carlo Limonti
Keyword(s):  
Kinetic Constant ◽  
Operating Parameter ◽  
Process Efficiency ◽  
Main Reaction ◽  
Main Reaction Product ◽  
Reaction Products ◽  
Metallic Elements ◽  
Reactive Material ◽  
Maximum Reaction Rate ◽  
Maximum Reaction

The removal of nitrate from aqueous environments through zero-valent metallic elements is an attractive technique that has gained increasing interest in recent years. In comparison to other metallic elements, zero-valent magnesium (ZVM) has numerous beneficial aspects. Nevertheless, the use of Mg0 particles for nitrate reduction in column systems has not been investigated yet. To overcome the lack of research, in the present study, a wide experimental activity was carried out to develop a chemical denitrification process through ZVM in batch column equipment. Several tests were executed to evaluate the effects of recirculation hydraulic velocity, pH, Mg0 amount, N-NO3− initial concentration and temperature on the process performance. The results show that the process efficiency is positively influenced by the recirculation velocity increase. In particular, the optimal condition was detected with a value of 1 m/min. The process pH was identified as the main operating parameter. At pH 3, abatements higher than 86.6% were reached for every initial nitrate concentration tested. In these conditions, nitrogen gas was detected as the main reaction product. The pH increase up to values of 5 and 7 caused a drastic denitrification decline with observed efficiencies below 26%. At pH 3, the ratio (RMN) between Mg0 and initial nitrate amount also plays a key role in the treatment performance. A characteristic value of about RMN = 0.333 gMg0/mgN-NO3− was found with which it is possible to reach the maximum reaction rate. Unexpectedly, the process was negatively affected by the increase in temperature from 20 to 40 °C. At 20 °C, the material showed satisfactory denitrification efficiencies in subsequent reuse cycles. With the optimal RMN ratio, removals up to 90% were detected by reusing the reactive material three times. By means of a kinetic analysis, a mathematical law able to describe the nitrate abatement curves was defined. Moreover, the relation between the observed kinetic constant and the operating parameters was recognized. Finally, the reaction pathways were proposed and the corrosion reaction products formed during the treatment were identified.

COMPRESSIVE STRENGTH OF GEOPOLYMER MORTAR USING GROUND FERRONICKEL SLAG AND FLY ASH

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Jhutan Chandra Kuri ◽  
Md Nabi Newaz Khan ◽  
Prabir Kumar Sarker
Keyword(s):  
Stainless Steel ◽  
Compressive Strength ◽  
Fly Ash ◽  
Nickel Alloy ◽  
Strength Increase ◽  
Reaction Products ◽  
Huge Amount ◽  
Alkaline Activator ◽  
Ferronickel Slag

A huge amount of ferronickel slag is produced as a by-product of manufacturing ferronickel, which is used in stainless steel and nickel alloy. This paper presents the effect of using different percentages of ground ferronickel slag (GFNS) with fly ash (FA) on the workability and compressive strength of geopolymer mortar. A mixture of NaOH and Na2SiO3 solutions was used as the alkaline activator. It was found that the flow of fresh mortar decreased with the increase of GFNS content. This is attributed to the higher fineness and angular shape of GFNS particles as compared to spherical fly ash particles. The mortar cube specimens were heat-cured at 60 °C for 24 hours. The compressive strength of geopolymer mortar using 100% FA was 54 MPa and it increased by 17%, 21% and 36% for using 25%, 50% and 75% GFNS as fly ash replacement, respectively. The strength increase is attributed to the increase of Si/Al ratio by GFNS that favoured the production of alkali aluminosilicate reaction products.

scholarly journals Characterization of Tribofilm from Sulfurized Mohwa Oil

2011 ◽  
Vol 2011 ◽  
pp. 1-12
Author(s):  
Arun Kumar Singh
Keyword(s):  
Surface Characterization ◽  
Iron Sulfide ◽  
Analysis Data ◽  
Main Reaction ◽  
Main Reaction Product ◽  
Iron Sulfides ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
Load Carrying

The reaction products of sulfurized Mohwa oil with iron powder in hydrocarbon medium at 150°C for 8 h were studied to investigate the type of lubricant films formed during their application as antiwear and extreme pressure additives. The main reaction product was isolated on the basis of its solubility in mixed solvent. Surface characterization was carried out using ultraviolet-visible spectroscopy (UV), fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), X-ray diffraction spectroscopy (XRD), scanning electron microscope (SEM), and high frequency reciprocal rig (HFRR). An examination of their elemental analysis and instrumental analysis data reveals that there is reduction in the length of the alkyl chains and carbonyl ester groups with formation of inorganic iron sulfides. Polymerized product with a number of ketonic and aldehydic groups containing iron and sulfur in the polymeric films in the form of unsaturated cyclic rings was also formed. The films are organo-inorganic in nature, unlike the purely inorganic iron sulfide type. The load-carrying characteristic of this product is strongly influenced by the type of the film formed on the iron surfaces.

scholarly journals Hydration of Calcium Sulfoaluminate-Based Binder Incorporating Red Mud and Silica Fume

2019 ◽  
Vol 9 (11) ◽  
pp. 2270 ◽  
Author(s):  
Yubin Jun ◽  
Jae Hong Kim ◽  
Taewan Kim
Keyword(s):  
Compressive Strength ◽  
Silica Fume ◽  
Red Mud ◽  
Drying Shrinkage ◽  
Pozzolanic Activity ◽  
Main Reaction ◽  
Main Reaction Product ◽  
Replacement Level ◽  
Calcium Sulfoaluminate ◽  
Expansive Agent

This study investigated the properties of hardened pastes made with calcium sulfoaluminate expansive agent (CSA), red mud, and silica fume. Five different ratios of 10:90, 20:80, 30:70, 40:60, and 50:50 were applied as the weight ratios of CSA and red mud. Red mud was replaced with 0, 5, and 10% silica fume by weight. Compressive strength, drying shrinkage, XRD, MIP, and SEM/EDS of the hardened pastes were performed. The results indicated that as the amount of CSA increased (i.e., as the amount of red mud decreased) up to 30%, sample strengths showed a tendency to increase. The main reaction product of the pastes was expansive ettringite, which was formed from the consumption of ye’elimite, anhydrite, gypsum, and Ca(OH)2. It was expected that C-S-H would be formed by the reaction of C2S in red mud; however, C-S-H phase was not present, and the pozzolanic activity due to the use of silica fume did not occur. The increase of CSA replacement level was effective for controlling the drying shrinkage of the samples. However, 50% replacement level of CSA induced excessive expansion, leading to the reduction in strength. It was found that the excessive expansion in the sample was reduced by the addition of silica fume.

Effect of Activator Concentration on the Properties of Metakaolin-Based Geopolymer

2019 ◽  
Vol 11 (11) ◽  
pp. 1566-1573
Author(s):  
Chao Cui ◽  
Zhen Liu ◽  
Jianren Zhang ◽  
Chunsheng Cai ◽  
Hui Peng ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Energy Dispersive Spectrometer ◽  
Curing Temperature ◽  
Activator Concentration ◽  
Reaction Products ◽  
Sem Images ◽  
Homogeneous Matrix ◽  
Ft Ir ◽  
Alkaline Activator

In the present study, an alkaline solution, prepared by sodium silicate (Na2SiO3) and sodium hydroxide (NaOH), was used as an activator for the preparation of a metakaolin-based geopolymer with high compressive strength. The effects of the factors, including the modulus (SiO2/Na2O ratio) of the alkaline activator, activator concentration, curing temperature, and curing time on the mechanical properties of the geopolymer were examined using orthogonal tests. Test results showed that the concentration of the alkaline activator is the primary factor affecting the mechanical properties of the geopolymer, followed by the modulus of the alkaline activator. The compressive strength of the geopolymer increases with an increase in activator concentration and decrease in the modulus of the alkaline activator. Subsequently, the reaction degree of the geopolymer and the reaction products corresponding to various concentrations of the activator were investigated using microcalorimetric analysis, Fourier Transform Infrared (FT-IR) analysis, and Scanning electron microscopy-Energy Dispersive Spectrometer (SEM-EDS) analysis, and the mechanism of the activator concentration affecting the geopolymer properties was also studied. It was found that the hydrolysis reaction and the polymerization degree were improved with an increase in the activator concentration. When the activator concentration increased from 50% to 80%, the compressive strength of the geopolymer increased from 21.54 MPa to 99.89 MPa. In addition, the SEM images also showed that the reaction products with a higher activator concentration, had a denser and more homogeneous matrix than that of products with a lower activator concentration.

Microstructure Study on Optimization of High Strength Fly Ash Based Geopolymer

2012 ◽  
Vol 476-478 ◽  
pp. 2173-2180 ◽  
Author(s):  
Mohd Mustafa Al Bakri Abdullah ◽  
Kamarudin Hussin ◽  
Mohammed Binhussain ◽  
Ismail Khairul Nizar ◽  
Rafiza Abd Razak ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Hydroxide ◽  
High Strength ◽  
Curing Temperature ◽  
Mix Design ◽  
Dense Matrix ◽  
Microstructural Characteristics ◽  
Naoh Solution ◽  
Alkaline Activator

The compressive strength and microstructural characteristics of fly ash based geopolymer with alkaline activator solution were investigated. The sodium hydroxide and sodium silicate were mixed together to form an alkaline activator. Three parameters including NaOH molarity, mix design (fly ash/alkaline activator ratio and Na2SiO3/NaOH ratio), and curing temperature were examined. The maximum strength of 71 MPa was obtained when the NaOH solution of 12M, fly ash/alkaline activator of 2.0, Na2SiO3/NaOH of 2.5 and curing temperature of 60°C were used at 7th days of testing. The results of SEM indicated that for geopolymer with highest strength, the structure was dense matrix and contains less unreacted fly ash with alkaline activator

scholarly journals CO2 Reforming of CH4 on Co-Containing Supported Catalysts

2016 ◽  
Vol 2 (1) ◽  
pp. 41 ◽  
Author(s):  
Sh.S. Itkulova ◽  
K.Z. Zhunusova ◽  
I.S. Chanycheva ◽  
G.D. Zakumbaeva
Keyword(s):  
Carbon Dioxide ◽  
Bimetallic Catalysts ◽  
Supported Catalysts ◽  
Coke Formation ◽  
Carbon Oxide ◽  
Main Reaction ◽  
Main Reaction Product ◽  
Reaction Products ◽  
Co2 Reforming ◽  
Co2 Reforming Of Ch4

<p>Mono- and bimetallic cobalt-containing catalysts supported on alumina have been investigated in the reaction of interaction between carbon dioxide and methane at variation of experiment temperature and pressure. It was shown, that the bimetallic catalysts have a high activity in this reaction in compare with monometallic ones. The main reaction products are carbon oxide, hydrogen, water and oxygenates. The yield of latter reaches 30% at certain conditions (P &gt; 0.5 MPa, T &lt; 853K). The maximum conversion of both methane (100%) and carbon dioxide (94%) is reached at lower pressure (0.1MPa) and 1023 K. In these conditions the synthesis-gas is a main reaction product. One of the advantages of the bimetallic catalysts is their resistance to coke formation.</p>

Determination of deoxynivalenol sulphonates in cereal samples: method development, validation and application

2014 ◽  
Vol 7 (3) ◽  
pp. 233-245 ◽  
Author(s):  
H.E. Schwartz-Zimmermann ◽  
M. Paulick ◽  
S. Dänicke ◽  
D. Schatzmayr ◽  
F. Berthiller
Keyword(s):  
Thermal Treatment ◽  
Moisture Content ◽  
Method Development ◽  
Matrix Effects ◽  
Main Reaction ◽  
Prolonged Storage ◽  
Main Reaction Product ◽  
Reagent Concentration ◽  
Reaction Products

The first short and simple RP-UHPLC-MS/MS based method for co-determination of the Fusarium mycotoxin deoxynivalenol (DON) and its reaction products upon treatment with sulphur reagents, the DON sulphonates (DONS) 1, 2 and 3, in cereals was developed and validated. Recoveries of extraction from maize, wheat and barley were between 88 and 107%. Matrix effects ranging between 93 and 234% in concentrated extracts and between 99 and 134% in diluted extracts were compensated by quantitation against matrix matched standards. Measurement of concentrated and diluted extracts enabled determination of DONS-1, -2, -3 and DON in cereals in a concentration range from 0.015 to 120 mg/kg. The method was then applied to investigate the influence of reagent concentration, type of sulphur reagent, moisture content, presence of propionic acid, storage time and thermal treatment in the presence of sodium metabisulphite (SBS) and monomethylamine (MMA) on DON reduction and DONS formation. DON reduction greater than 80% was obtained in several experiments and required storage at moisture contents between 25 and 30% (at reagent concentration of 0.5%) for less than one week, storage with 0.5% SBS at 14% moisture for 6 weeks or thermal treatment in the presence of SBS and MMA. The efficiency of sodium sulphite for DON reduction was systematically compared with that of SBS and found to be lower at 14% moisture content, but similar at 30% moisture. Under most storage conditions, DONS-3 was the main reaction product, followed by DONS-2. Prolonged storage for more than 6-8 weeks shifted the pattern of formed DON sulphonates towards DONS-2. Likewise, thermal treatment in the presence of SBS and MMA caused exclusive formation of DONS-1 and -2. Due to partial degradation of DONS-3 to DON under physiological conditions, predominant conversion of DON into DONS-1 and DONS-2 is desirable.

BioArena System for Knowing and Understanding the Biological World: A Review with New Experimental Results

2013 ◽  
Vol 96 (6) ◽  
pp. 1189-1199 ◽  
Author(s):  
Ernő Tyihák ◽  
Ágnes M Móricz ◽  
Péter G Ott ◽  
Zsuzsa Király-Véghely ◽  
György Kátay ◽  
...  
Keyword(s):  
Antimicrobial Effect ◽  
Main Reaction ◽  
Main Reaction Product ◽  
Reaction Products ◽  
Chemical Structures ◽  
Antibiotic Effect ◽  
New Findings ◽  
Biological World

Abstract A simple observation is the basis of the development of BioArena system: according to the first observations during the biological incubation after inoculation there is formaldehyde (HCHO) emission from the chromatographic spots; in this emission process, the level of HCHO molecules decreases time dependently. In fact, the antibiotic effect of an antibiotic-like compound decreases in parallel with the HCHO emission. The investigations demonstrated clearly a unique function and role of endogenous HCHO and its one main reaction product, ozone (O3), in the antiproliferative (e.g., antimicrobial) effect of different molecules with diverse chemical structures. The results in BioArena can be extended for in vivo conditions (e.g., greenhouse experiments), as well. For the pretreatment with different doses of inducers (immunostimulation-inducing molecules) there are always four bioequivalent immunostimulating response ranges (quadruple bioequivalent immune response system) in plants. The inducers (e.g., N-methylated basic amino acids, salicylic acid, cinnamic acid, and trace elements) do not participate directly in the induction of the immunostimulating effect. These new findings support a statement that HCHO and its reaction products (mainly O3), as bioreactive small molecules, are responsible for the immunostimulating activity (in vivo conditions), as well.

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