scholarly journals Efficient chemical stabilization of tannery wastewater pollutants in a single step process: Geopolymerization

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Giacomo Boldrini ◽  
Caterina Sgarlata ◽  
Isabella Lancellotti ◽  
Luisa Barbieri ◽  
Marco Giorgetti ◽  
...  
Keyword(s):  
Room Temperature ◽  
Single Step ◽  
Alkali Activation ◽  
Activation Process ◽  
Complex Task ◽  
Leaching Test ◽  
The Matrix ◽  
Wastewater Pollutants ◽  
Average Compressive Strength

AbstractThe treatment of tannery wastewaters is a complex task due to the complexity of the waste: a mixture of several pollutants, both anionic and cationic as well as organic macromolecules which are very hard to treat for disposal all together. Geopolymers are a class of inorganic binders obtained by alkali activation of aluminosilicate powders at room temperature. Such activation process leads to a cement like matrix that drastically decreases mobility of several components via entrapment. This process taking place in the matrix can be hypothesized to be the in-situ formation of zeolite structures. In this work we use a metakaolin based geopolymer to tackle the problem directly in an actual industrial environment. To obtain a geopolymer, the metakaolin was mixed with 10 wt% of wastewater added with sodium hydroxide and sodium silicate as activating solutions. This process allowed a rapid consolidation at room temperature, the average compressive strength was between 14 and 43 MPa. Leaching tests performed at different aging times confirm a high immobilization efficiency close to 100%. In particular, only the 0.008 and 2.31% of Chromium and Chlorides respectively are released in the leaching test after 7 months of aging.

scholarly journals Evaluation of Physical Properties of a Metakaolin-Based Alkali-Activated Binder Containing Waste Foam Glass

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5458
Author(s):  
Petra Mácová ◽  
Konstantinos Sotiriadis ◽  
Zuzana Slížková ◽  
Petr Šašek ◽  
Michal Řehoř ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Physical Properties ◽  
Foam Glass ◽  
Glass Production ◽  
Alkali Activation ◽  
Activation Process ◽  
X Ray ◽  
Thermal Insulating ◽  
The Matrix ◽  
Alkali Activated

Foam glass production process redounds to large quantities of waste that, if not recycled, are stockpiled in the environment. In this work, increasing amounts of waste foam glass were used to produce metakaolin-based alkali-activated composites. Phase composition and morphology were investigated by means of X-ray powder diffraction, Fourier-transform infrared spectroscopy and scanning electron microscopy. Subsequently, the physical properties of the materials (density, porosity, thermal conductivity and mechanical strength) were determined. The analysis showed that waste foam glass functioned as an aggregate, introducing irregular voids in the matrix. The obtained composites were largely porous (>45%), with a thermal conductivity coefficient similar to that of timber (<0.2 W/m∙K). Optimum compressive strength was achieved for 10% incorporation of the waste by weight in the binder. The resulting mechanical properties suggest the suitability of the produced materials for use in thermal insulating applications where high load-bearing capacities are not required. Mechanical or chemical treatment of the waste is recommended for further exploitation of its potential in participating in the alkali activation process.

STUDY ON PREPARING Al2O3 PARTICLES REINFORCED ZL109 COMPOSITE BY IN SITU REACTION OF Fe2O3/Al SYSTEM

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1413-1418
Author(s):  
JING ZHANG ◽  
HUASHUN YU ◽  
QI ZHAO ◽  
HAITAO WANG ◽  
GUANGHUI MIN
Keyword(s):  
Tensile Strength ◽  
Room Temperature ◽  
Matrix Alloy ◽  
Second Step ◽  
In Situ Reaction ◽  
Micron Size ◽  
The Matrix ◽  
Higher Temperature ◽  
Mechanism Of The Reaction

Al 2 O 3 particles reinforced ZL109 composite was prepared by in situ reaction between Fe 2 O 3 and Al . The phases were identified by XRD and the microstructures were observed by SEM and TEM. The Al 2 O 3 particles in sub-micron size distribute uniformly in the matrix and Fe displaced from the in situ reaction forms net-like alloy phases with Cu , Ni , Al , Mn ect. The hardness and the tensile strength at room temperature of the composites have a small increase compared with the matrix. However, the tensile strength at 350°C can reach 92.18 MPa, which is 18.87 MPa higher than that of the matrix. The mechanism of the reaction in the Fe 2 O 3/ Al system was studied by DSC. The reaction between Fe 2 O 3 and Al involves two steps. The first step in which Fe 2 O 3 reacts with Al to form FeO and Al 2 O 3 takes place at the matrix alloy melting temperature. The second step in which FeO reacts with Al to form Fe and Al 2 O 3 takes place at a higher temperature.

Strength and Toughness of Composite Materials Based on Nickel Aluminide Matrices

1988 ◽  
Vol 133 ◽  
Author(s):  
J. D. Rigney ◽  
P. S. Khadkikar ◽  
J. J. Lewandowski ◽  
K. Vedula
Keyword(s):  
Fracture Toughness ◽  
Composite Materials ◽  
Hot Pressing ◽  
Nickel Aluminide ◽  
Room Temperature ◽  
Matrix Composition ◽  
Matrix Composites ◽  
The Matrix ◽  
Bend Tests

ABSTRACTSeveral nickel aluminide matrix composites were prepared using vacuum hot pressing techniques. The matrix compositions, based on Ni3Al, Ni3Al+B and NiAl, were reinforced with 10 volume % TiB2 particles. Both smooth and notched bend tests were conducted at room temperature on the monolithic as well as the reinforced materials in order to determine the effects of TiB2 reinforcement on both the smooth bend and notched bend properties. TiB2 additions were shown to improve the smooth bend strengths regardless of the matrix composition while notched bend tests, conducted to provide estimates of fracture toughness, revealed somewhat lower values for the composites in comparison to the monolithic materials. Fractographic analyses and in-situ fracture observations of the composites revealed that preferential fracture in regions of clustered TiB2 particles may significantly affect the measured toughnesses.

Inertization of Mine Tailing via Cold Consolidation in Geopolymer Matrix

2018 ◽  
Vol 761 ◽  
pp. 31-34 ◽  
Author(s):  
Isabella Lancellotti ◽  
Jenni Kiventerä ◽  
Michelina Catauro ◽  
Francesco dal Poggetto ◽  
Mirja Illikainen
Keyword(s):  
Mine Tailings ◽  
Room Temperature ◽  
Gold Mining ◽  
Leaching Test ◽  
Mining Site ◽  
Granulated Blast Furnace Slag ◽  
Geopolymer Matrix ◽  
The Matrix ◽  
Naoh Solution ◽  
Furnace Slag

The consolidation via geopolymerisation is a room temperature alkaline chemical reaction of condensation between SiO2 and AlO2 monomers. Such a matrix can retain a large number of cations to compensate for the Al+3 in place of Si+4 in the tetrahedra. Arsenic-rich mine tailings from a gold mining site were activated with NaOH solution and commercial Na-Silicate (Na2O/SiO2 = 3) to produce a no-hazardous final material. Granulated blast furnace slag and metakaolin were used as co-binders to optimize the formulations. Leaching test was used to evaluate the inertization capability of the matrix after curing times of 7 and 28 days. The leaching results show that increasing curing time there is a significant decrease of As leaching due to the better consolidation of the material. Leaching of Cu, V, Ba and Zn significantly decrease, while Ni and Cr remain almost constant and Sb slightly increases.

Microstructure of Al-Cu, Al-Zn, Al-Ag-Zn, and Al-Zn-Mg Alloys

2019 ◽  
Author(s):  
Željko Skoko ◽  
Stanko Popović
Keyword(s):  
Solid Solution ◽  
Phase Transitions ◽  
Room Temperature ◽  
Thermal Hysteresis ◽  
Solution Temperature ◽  
The Matrix ◽  
History Of ◽  
Precipitate Shape ◽  
Precipitation Phenomena

The precipitation phenomena and their connection with the microstructure of several Al alloys (Al-Cu, Al-Zn, Al-Ag-Zn, Al-Zn-Mg) are described with respect to the concentration and applied thermal treatment. The alloys were rapidly quenched or slowly cooled from a temperature higher than the solid solution temperature to room temperature. Both quenched-aged and slowly cooled alloys were heated from room temperature to the solid solution state and cooled back to room temperature, and their microstructure and precipitation phenomena were followed in situ by X-ray powder diffraction, e.g., anisotropy of thermal expansion, phase transitions, thermal hysteresis in phase transitions, change of precipitate shape, partial or complete dissolution of precipitates in the matrix, and formation of solid solution. It has been shown that the microstructure strongly depends on the previous thermal history of the alloys.

Poly (N-ethyl aniline)/Ag Nanocomposite as Humidity Sensor

2017 ◽  
Vol 16 (03) ◽  
pp. 1650037 ◽  
Author(s):  
Nishigandh S. Pande ◽  
Dipika Jaspal ◽  
Jalindar Ambekar
Keyword(s):  
Room Temperature ◽  
Oxidative Polymerization ◽  
Single Step ◽  
Infrared Analysis ◽  
X Ray Diffraction ◽  
Humid Atmosphere ◽  
Vis Spectroscopy ◽  
Uv Visible ◽  
Polymerization Method

Poly (N-ethyl aniline)/Ag organic–inorganic composite has been synthesized by a single step in situ chemical oxidative polymerization method. The synthesis of Poly (N-ethyl aniline)/Ag nanocomposite has been confirmed by X-ray diffraction (XRD), Ultraviolet-Vis Spectroscopy (UV-visible), Fourier transform infrared analysis (FTIR) and FE-SEM investigations. XRD spectral study exhibited major diffraction in the range 20–80[Formula: see text] (2[Formula: see text]) and indicated the semicrystalline nature of poly (N-ethyl aniline)/Ag nanocomposite. Characteristic peaks in UV-visible and FTIR spectra of poly (N-ethyl aniline) switched to higher wave numbers in poly (N-ethyl aniline)/Ag nanocomposite. Peaks at 1789[Formula: see text]cm[Formula: see text], 1595[Formula: see text]cm[Formula: see text], 667[Formula: see text]cm[Formula: see text] and 501[Formula: see text]cm[Formula: see text] in FTIR spectrum confirmed the formation of poly (N-ethyl aniline)/Ag nanocomposite. FE-SEM photographs reported agglomerated granular particulate nature of poly (N-ethyl aniline)/Ag nanocomposite. Synthesized poly (N-ethyl aniline)/Ag nanocomposite exhibited a high response to humidity, good reproducibility and stability at room temperature. An appreciable response was shown in the presence of 40% humid atmosphere for up to successive four cycles. Composite sensitivity has been found to increase with the increasing concentration of humidity, at room temperature.

Microstructure and Mechanical Properties of Al2O3-TiC/Al in Situ Composites

2006 ◽  
Vol 326-328 ◽  
pp. 1857-1860
Author(s):  
Hong Mei Chen ◽  
Hua Shun Yu ◽  
Jing Zhang ◽  
Lin Zhang ◽  
Guang Hui Min
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Room Temperature ◽  
Volume Fraction ◽  
Matrix Alloy ◽  
Co2 Gas ◽  
In Situ Composites ◽  
In Situ Reaction ◽  
The Matrix

The Al2O3-TiC/Al composites were prepared by injecting CO2 gas into Ti contained Al-Si alloy melts. The microstructure of the composites was examined by XRD, SEM and TEM. It was indicated that both Al2O3 and TiC particles can be formed by the in situ reaction of CO2 with Ti and Al in the melten alloys. The Al2O3 and TiC particles in size of 0.3~1.5μm distributed uniformly in the matrix. The volume fraction of the particles is mainly depend upon the time of CO2 injection.The tensile strength at room temperature of the composites can reach 346.08MPa and the hardness is 149.6MPa HBS, repectively, which are higher than those of the matrix alloy.

Dislocation structures around SiO2 Particles in aged Cu-Cr-SiO2

1978 ◽  
Vol 36 (1) ◽  
pp. 594-595
Author(s):  
N.J. Long ◽  
M.H. Loretto ◽  
C.H. Lloyd
Keyword(s):  
Flow Stress ◽  
Single Crystals ◽  
Room Temperature ◽  
Thin Foil ◽  
Age Hardening ◽  
Dispersion Strengthening ◽  
Accurate Picture ◽  
The Matrix ◽  
Very High ◽  
Good Agreement

IntroductionThere have been several t.e.m. studies (1,2,3,4) of the dislocation arrangements in the matrix and around the particles in dispersion strengthened single crystals deformed in single slip. Good agreement has been obtained in general between the observed structures and the various theories for the flow stress and work hardening of this class of alloy. There has been though some difficulty in obtaining an accurate picture of these arrangements in the case when the obstacles are large (of the order of several 1000's Å). This is due to both the physical loss of dislocations from the thin foil in its preparation and to rearrangement of the structure on unloading and standing at room temperature under the influence of the very high localised stresses in the vicinity of the particles (2,3).This contribution presents part of a study of the Cu-Cr-SiO2 system where age hardening from the Cu-Cr and dispersion strengthening from Cu-Sio2 is combined.

Otoconia perfect/imperfect crystals

1994 ◽  
Vol 52 ◽  
pp. 42-43
Author(s):  
César D. Fermin ◽  
Dale Martin
Keyword(s):  
Image Processing ◽  
Room Temperature ◽  
Phosphotungstic Acid ◽  
Gallus Domesticus ◽  
Crystal Matrix ◽  
Organic Templates ◽  
Image Processing Algorithms ◽  
Processing Algorithms ◽  
Diffraction Patterns

Otoconia of higher vertebrates are interesting biological crystals that display the diffraction patterns of perfect crystals (e.g., calcite for birds and mammal) when intact, but fail to produce a regular crystallographic pattern when fixed. Image processing of the fixed crystal matrix, which resembles the organic templates of teeth and bone, failed to clarify a paradox of biomineralization described by Mann. Recently, we suggested that inner ear otoconia crystals contain growth plates that run in different directions, and that the arrangement of the plates may contribute to the turning angles seen at the hexagonal faces of the crystals.Using image processing algorithms described earlier, and Fourier Transform function (2FFT) of BioScan Optimas®, we evaluated the patterns in the packing of the otoconia fibrils of newly hatched chicks (Gallus domesticus) inner ears. Animals were fixed in situ by perfusion of 1% phosphotungstic acid (PTA) at room temperature through the left ventricle, after intraperitoneal Nembutal (35mg/Kg) deep anesthesia. Negatives were made with a Hitachi H-7100 TEM at 50K-400K magnifications. The negatives were then placed on a light box, where images were filtered and transferred to a 35 mm camera as described.

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