Ceramic macro-needles incorporation as reinforcement in commercial refractory castable was studie... more Ceramic macro-needles incorporation as reinforcement in commercial refractory castable was studied. Ceramic macro-needles (Ø2x20 mm) were made from kaolinite clay and gibbsite to obtain mullite as the main crystalline phase. Specimens with the ceramic reinforcement were evaluated by compression after being treated at two temperatures (815 and 1400 °C). The results were compared with those obtained using the same commercial concrete but reinforced with steel fibers and without reinforcement. Compression values presented by specimens with ceramic macro-needles were 74% and 50% higher than specimens with steel fibers after exposition to 815 and 1400 °C, respectively. Based on these results, it was established that ceramic macro-needles are a feasible solution to improve the mechanical resistance of castables exposed to high temperatures.
Monoclinic ZrO, has been milled for various times down to a crystallite size of 145 A. Using the ... more Monoclinic ZrO, has been milled for various times down to a crystallite size of 145 A. Using the time-differential perturbed-angular-correlation technique, it was possible to associate the resulting growing amount of disordered material with two different, very distributed and milling- ...
En este trabajo se estudio la modificacion de un soporte de silice-carbon con precursores de Al, ... more En este trabajo se estudio la modificacion de un soporte de silice-carbon con precursores de Al, P y P-Al para mejorar la selectividad de catalizadores de Ni hacia la formacion de 1-propanol, por hidrogenolisis de glicerol en fase acuosa. Los resultados mostraron que la modificacion con P y P-Al producen un incremento en la acidez superficial y la formacion de una fase Ni2P.
The present work is about the development of a Novel Composite that has several properties in onl... more The present work is about the development of a Novel Composite that has several properties in only one material. This material is composed by a silica network with a sharpened pore size distribution- diameter near 1000 Å- intercrossed with another carbon network that has carbonaceous microdomains of high activity. The first network facilitates the entrance of big molecules to the interior of the material grains so they quickly reach the active sites of the carbonous network, minimizing the diffusional resistance observed when high performance activated carbons are used in adsorption processes or catalytic applications. These two intercrossed structures are self-supporting and independent among them, so one from the other can be isolated without losing the original shape and volume of the starting composite, then, their possible uses may be multiplied. The Novel Composite is stable with respect to other support or adsorbent materials due to its high obtention temperature (1550 oC). T...
International Journal of Environment and Health, 2020
The diphenylamine antiscale (n-phenylbencenamine) is an agrochemical widely used in the post-harv... more The diphenylamine antiscale (n-phenylbencenamine) is an agrochemical widely used in the post-harvest treatment of stone fruits in the Upper Rio Negro Valley, Argentina and the discharge exceeds the allowable limits in the water courses. Removal was evaluated using a composite whose matrix allows bentonite to maintain its adsorbent capacity without thereby reducing the porosity of the bed. This was formed in self-supporting, porous and adsorbent monoliths, emulating the operation in fixed bed columns with the advantage over a conventional fixed bed filled column of reducing the packing variables being the pressure drop, bed height, porosity, and others. If we compare with batch operation what is proposed requires less amount of adsorbent material and reduces the generation of liquid waste. Also, removal was evaluated and compared using a bentonite composite with carbon added. The composites had a maximum adsorption capacity of 80% and desorption of 15% in 1 h.
The effect of monoaluminum phosphate (Al(H2PO4)3) addition in the thermochemical process of a kao... more The effect of monoaluminum phosphate (Al(H2PO4)3) addition in the thermochemical process of a kaolinitic clay was studied and compared with the pure clay. Monoaluminum phosphate incorporation is of technological interest for the widely use of this material as an effective binder. From this point of view is important to clarify the processing strategy of kaolinitic clay-MAP based ceramics. This work comprised the characteristics of the obtained ceramics using differential thermal analysis, thermogravimetric analysis (TG), dilatometric analysis, X-ray powder diffraction with Rietveld refinement, mechanical resistance and textural properties. The addition of MAP did not affect the temperature of the kaolinite dehydroxilation (600–500 °C) but reduced this transformation as it was observed in TG curve. The amount of mullite decreased and cristobalite formation was stimulated with MAP presence in the samples fired at 1400 °C. Mullite cell parameters were not modified. The present study gives information for further clay-based materials designed with MAP. It can be concluded that the incorporation of low percentages of MAP in the potential formulation of technological ceramics would not imply important changes in the macroscopic properties of these type of ceramic materials.
The present work is about the development of a Novel Composite that has several properties in onl... more The present work is about the development of a Novel Composite that has several properties in only one material. This material is composed by a silica network with a sharpened pore size distribution diameter near 1000 Å intercrossed with another carbon network that has carbonaceous microdomains of high activity. The first network facilitates the entrance of big molecules to the interior of the material grains so they quickly reach the active sites of the carbonous network, minimizing the diffusional resistance observed when high performance activated carbons are used in adsorption processes or catalytic applications. These two intercrossed structures are self-supporting and independent among them, so one from the other can be isolated without losing the original shape and volume of the starting composite, then, their possible uses may be multiplied. The Novel Composite is stable with respect to other support or adsorbent materials due to its high obtention temperature (1550 oC). The...
Las centrales termoeléctricas generan una gran cantidad de residuos sólidos como producto de la c... more Las centrales termoeléctricas generan una gran cantidad de residuos sólidos como producto de la combustión del carbón, conocidos como cenizas. Existen dos tipos de cenizas: volantes - de tamaño muy fino -, que son arrastradas por la corriente de humos de los sistemas de eliminación de partículas y, - las sedimentadas - más gruesas, que se funden y se aglomeran acumulándose en el fondo del horno o en los tubos de las calderas. Intentando resolver factores técnico-económicos y ecológicos al mismo tiempo, en este trabajo presentamos los resultados obtenidos de la incorporación de un 20% en peso de cenizas sedimentadas (Cs) como adición activa al cemento Portland. Se estudia la potencial puzolanidad de la adición y se muestran resultados de seguimiento de la hidratación a temprana edad, variación de color y resistencia mecánica del material compuesto obtenido por molienda conjunta del clinker portland y el material residual.
Porous ceramic materials exhibit high permeability, specific surface, and thermal shock resistanc... more Porous ceramic materials exhibit high permeability, specific surface, and thermal shock resistance, and therefore they may be used successfully in the production of filters, membranes, and as a substrate for catalytic reactions, etc. One method for preparing high material porosity is addition of a pore-forming substance. Porosity (open and closed), pore size distribution, their size and shape, depend on the nature, amount, and morphology of pore-forming substance. In this article the effect is elucidated of three different types of carbon additives on porosity of ceramic prepared from clay and chemical binder precursor. Carbon materials are studied in an x-ray diffractometer. Ceramic material properties are studied using a mercury porosimeter, the Archimedes method, scanning electron and optical microscopes, and microcomputer tomography.
TEOS, phenol-formaldehyde resin and ethyl alcohol were mixed and gelled at room temperature. Afte... more TEOS, phenol-formaldehyde resin and ethyl alcohol were mixed and gelled at room temperature. Afterward, the gel was dried and submitted to thermal treatment at high temperature (1550°C) in a strongly reducing atmosphere and transformed into a composite of general formula SiO2-C. This composite consists on an amorphous porous silica network intercrossed with another carbon network that has carbonaceous microdomains of high activity; this new material has a sharpened pore size distribution near 1000diameter mainly assigned to the silica network. Both mentioned networks are self supported and independent among them, so one from the other can be isolated without losing the original shape and volume of the starting composite; then this new material has the property of generating two other different porous solids. The new composite was characterized by: LOI, XRD, IR, BET surface area, pore size distribution and SEM. Its adsorption rate was tested with méthylène blue solutions by using different techniques, and the results were compared with those obtained for a commercial high performance activated carbon. Experiments with different gelling and drying temperatures were performed in order to control the range in which the composite shows the sharpened pore size distribution. The catalytic activity was tested and compared on FISCHER-TROPSCH process (hydrogénation of CO) on doped iron composite and on doped iron isolated carbon network. Other potential uses of the new composite are presented.
In this paper cordierite-mullite refractory concretes were prepared using the magnesia-phosphate ... more In this paper cordierite-mullite refractory concretes were prepared using the magnesia-phosphate chemical bond. Such concretes were constituted by cordieritic aggregates, a matrix of alumina, silica fumed and magnesium oxide, and different bonds (phosphoric acid, monoaluminum phosphate or monoammonium phosphate solutions). The setting occurred at room temperature in few minutes and then, cordierite-mullite was generated for heating at 1350 ºC. These
In this work three cold-setting refractory concretes using the chemical magnesia-phosphate bond w... more In this work three cold-setting refractory concretes using the chemical magnesia-phosphate bond were prepared. A mixture of calcined alumina, microsilica, magnesium oxide and phosphoric acid was designed to form cordierite during the heating. This cementitious paste acts like a matrix in which the aggregates are embedded. Three different aggregates were used: cordierite-mullite (C), mullite chamotte (M) and tabular alumina (T) with the objective to analyze its behaviour and the matrix-aggregate interaction. These concretes set at room temperature, being observed by XRD, in addition to the typical reflections of each aggregate, the presence of MgHPO 4 ·3H 2 O (newberyite) in low proportion and predominantly amorphous phase. At 110 °C were not detected crystalline hydrated phosphates. At 1100 °C was formed aluminium orthophosphate, AlPO 4 cristobalite type. At 1350 °C the matrix was transformed into cordierite-mullite, being also detected small amounts of Mg 3 (PO 4 ) 2 . Although the phases developed in the matrix during heating were similar for three concretes, performance at elevated temperatures was different. The possible causes of unsatisfactory behaviour of concretes made with aggregates of mullite chamotte and tabular alumina were analyzed. The main properties of concrete made with cordierite-mullite aggregates were presented.
Ceramic macro-needles incorporation as reinforcement in commercial refractory castable was studie... more Ceramic macro-needles incorporation as reinforcement in commercial refractory castable was studied. Ceramic macro-needles (Ø2x20 mm) were made from kaolinite clay and gibbsite to obtain mullite as the main crystalline phase. Specimens with the ceramic reinforcement were evaluated by compression after being treated at two temperatures (815 and 1400 °C). The results were compared with those obtained using the same commercial concrete but reinforced with steel fibers and without reinforcement. Compression values presented by specimens with ceramic macro-needles were 74% and 50% higher than specimens with steel fibers after exposition to 815 and 1400 °C, respectively. Based on these results, it was established that ceramic macro-needles are a feasible solution to improve the mechanical resistance of castables exposed to high temperatures.
Monoclinic ZrO, has been milled for various times down to a crystallite size of 145 A. Using the ... more Monoclinic ZrO, has been milled for various times down to a crystallite size of 145 A. Using the time-differential perturbed-angular-correlation technique, it was possible to associate the resulting growing amount of disordered material with two different, very distributed and milling- ...
En este trabajo se estudio la modificacion de un soporte de silice-carbon con precursores de Al, ... more En este trabajo se estudio la modificacion de un soporte de silice-carbon con precursores de Al, P y P-Al para mejorar la selectividad de catalizadores de Ni hacia la formacion de 1-propanol, por hidrogenolisis de glicerol en fase acuosa. Los resultados mostraron que la modificacion con P y P-Al producen un incremento en la acidez superficial y la formacion de una fase Ni2P.
The present work is about the development of a Novel Composite that has several properties in onl... more The present work is about the development of a Novel Composite that has several properties in only one material. This material is composed by a silica network with a sharpened pore size distribution- diameter near 1000 Å- intercrossed with another carbon network that has carbonaceous microdomains of high activity. The first network facilitates the entrance of big molecules to the interior of the material grains so they quickly reach the active sites of the carbonous network, minimizing the diffusional resistance observed when high performance activated carbons are used in adsorption processes or catalytic applications. These two intercrossed structures are self-supporting and independent among them, so one from the other can be isolated without losing the original shape and volume of the starting composite, then, their possible uses may be multiplied. The Novel Composite is stable with respect to other support or adsorbent materials due to its high obtention temperature (1550 oC). T...
International Journal of Environment and Health, 2020
The diphenylamine antiscale (n-phenylbencenamine) is an agrochemical widely used in the post-harv... more The diphenylamine antiscale (n-phenylbencenamine) is an agrochemical widely used in the post-harvest treatment of stone fruits in the Upper Rio Negro Valley, Argentina and the discharge exceeds the allowable limits in the water courses. Removal was evaluated using a composite whose matrix allows bentonite to maintain its adsorbent capacity without thereby reducing the porosity of the bed. This was formed in self-supporting, porous and adsorbent monoliths, emulating the operation in fixed bed columns with the advantage over a conventional fixed bed filled column of reducing the packing variables being the pressure drop, bed height, porosity, and others. If we compare with batch operation what is proposed requires less amount of adsorbent material and reduces the generation of liquid waste. Also, removal was evaluated and compared using a bentonite composite with carbon added. The composites had a maximum adsorption capacity of 80% and desorption of 15% in 1 h.
The effect of monoaluminum phosphate (Al(H2PO4)3) addition in the thermochemical process of a kao... more The effect of monoaluminum phosphate (Al(H2PO4)3) addition in the thermochemical process of a kaolinitic clay was studied and compared with the pure clay. Monoaluminum phosphate incorporation is of technological interest for the widely use of this material as an effective binder. From this point of view is important to clarify the processing strategy of kaolinitic clay-MAP based ceramics. This work comprised the characteristics of the obtained ceramics using differential thermal analysis, thermogravimetric analysis (TG), dilatometric analysis, X-ray powder diffraction with Rietveld refinement, mechanical resistance and textural properties. The addition of MAP did not affect the temperature of the kaolinite dehydroxilation (600–500 °C) but reduced this transformation as it was observed in TG curve. The amount of mullite decreased and cristobalite formation was stimulated with MAP presence in the samples fired at 1400 °C. Mullite cell parameters were not modified. The present study gives information for further clay-based materials designed with MAP. It can be concluded that the incorporation of low percentages of MAP in the potential formulation of technological ceramics would not imply important changes in the macroscopic properties of these type of ceramic materials.
The present work is about the development of a Novel Composite that has several properties in onl... more The present work is about the development of a Novel Composite that has several properties in only one material. This material is composed by a silica network with a sharpened pore size distribution diameter near 1000 Å intercrossed with another carbon network that has carbonaceous microdomains of high activity. The first network facilitates the entrance of big molecules to the interior of the material grains so they quickly reach the active sites of the carbonous network, minimizing the diffusional resistance observed when high performance activated carbons are used in adsorption processes or catalytic applications. These two intercrossed structures are self-supporting and independent among them, so one from the other can be isolated without losing the original shape and volume of the starting composite, then, their possible uses may be multiplied. The Novel Composite is stable with respect to other support or adsorbent materials due to its high obtention temperature (1550 oC). The...
Las centrales termoeléctricas generan una gran cantidad de residuos sólidos como producto de la c... more Las centrales termoeléctricas generan una gran cantidad de residuos sólidos como producto de la combustión del carbón, conocidos como cenizas. Existen dos tipos de cenizas: volantes - de tamaño muy fino -, que son arrastradas por la corriente de humos de los sistemas de eliminación de partículas y, - las sedimentadas - más gruesas, que se funden y se aglomeran acumulándose en el fondo del horno o en los tubos de las calderas. Intentando resolver factores técnico-económicos y ecológicos al mismo tiempo, en este trabajo presentamos los resultados obtenidos de la incorporación de un 20% en peso de cenizas sedimentadas (Cs) como adición activa al cemento Portland. Se estudia la potencial puzolanidad de la adición y se muestran resultados de seguimiento de la hidratación a temprana edad, variación de color y resistencia mecánica del material compuesto obtenido por molienda conjunta del clinker portland y el material residual.
Porous ceramic materials exhibit high permeability, specific surface, and thermal shock resistanc... more Porous ceramic materials exhibit high permeability, specific surface, and thermal shock resistance, and therefore they may be used successfully in the production of filters, membranes, and as a substrate for catalytic reactions, etc. One method for preparing high material porosity is addition of a pore-forming substance. Porosity (open and closed), pore size distribution, their size and shape, depend on the nature, amount, and morphology of pore-forming substance. In this article the effect is elucidated of three different types of carbon additives on porosity of ceramic prepared from clay and chemical binder precursor. Carbon materials are studied in an x-ray diffractometer. Ceramic material properties are studied using a mercury porosimeter, the Archimedes method, scanning electron and optical microscopes, and microcomputer tomography.
TEOS, phenol-formaldehyde resin and ethyl alcohol were mixed and gelled at room temperature. Afte... more TEOS, phenol-formaldehyde resin and ethyl alcohol were mixed and gelled at room temperature. Afterward, the gel was dried and submitted to thermal treatment at high temperature (1550°C) in a strongly reducing atmosphere and transformed into a composite of general formula SiO2-C. This composite consists on an amorphous porous silica network intercrossed with another carbon network that has carbonaceous microdomains of high activity; this new material has a sharpened pore size distribution near 1000diameter mainly assigned to the silica network. Both mentioned networks are self supported and independent among them, so one from the other can be isolated without losing the original shape and volume of the starting composite; then this new material has the property of generating two other different porous solids. The new composite was characterized by: LOI, XRD, IR, BET surface area, pore size distribution and SEM. Its adsorption rate was tested with méthylène blue solutions by using different techniques, and the results were compared with those obtained for a commercial high performance activated carbon. Experiments with different gelling and drying temperatures were performed in order to control the range in which the composite shows the sharpened pore size distribution. The catalytic activity was tested and compared on FISCHER-TROPSCH process (hydrogénation of CO) on doped iron composite and on doped iron isolated carbon network. Other potential uses of the new composite are presented.
In this paper cordierite-mullite refractory concretes were prepared using the magnesia-phosphate ... more In this paper cordierite-mullite refractory concretes were prepared using the magnesia-phosphate chemical bond. Such concretes were constituted by cordieritic aggregates, a matrix of alumina, silica fumed and magnesium oxide, and different bonds (phosphoric acid, monoaluminum phosphate or monoammonium phosphate solutions). The setting occurred at room temperature in few minutes and then, cordierite-mullite was generated for heating at 1350 ºC. These
In this work three cold-setting refractory concretes using the chemical magnesia-phosphate bond w... more In this work three cold-setting refractory concretes using the chemical magnesia-phosphate bond were prepared. A mixture of calcined alumina, microsilica, magnesium oxide and phosphoric acid was designed to form cordierite during the heating. This cementitious paste acts like a matrix in which the aggregates are embedded. Three different aggregates were used: cordierite-mullite (C), mullite chamotte (M) and tabular alumina (T) with the objective to analyze its behaviour and the matrix-aggregate interaction. These concretes set at room temperature, being observed by XRD, in addition to the typical reflections of each aggregate, the presence of MgHPO 4 ·3H 2 O (newberyite) in low proportion and predominantly amorphous phase. At 110 °C were not detected crystalline hydrated phosphates. At 1100 °C was formed aluminium orthophosphate, AlPO 4 cristobalite type. At 1350 °C the matrix was transformed into cordierite-mullite, being also detected small amounts of Mg 3 (PO 4 ) 2 . Although the phases developed in the matrix during heating were similar for three concretes, performance at elevated temperatures was different. The possible causes of unsatisfactory behaviour of concretes made with aggregates of mullite chamotte and tabular alumina were analyzed. The main properties of concrete made with cordierite-mullite aggregates were presented.
Uploads
Papers by A. Scian