J.C. Rendón-Angeles

Topotaxial replacement of chlorapatite by hydroxyapatite during hydrothermal ion exchange

Abstract Exchange of Cl⁻ by OH⁻ in synthesized chlorapatite single crystals was investigated under hydrothermal conditions. Hydrothermal treatments were performed at various temperatures from 200 to 500 °C, for intervals between 3 and 96 h in KOH or NaOH solutions. Ion exchange of Cl⁻ in the chlorapatite crystals was completed at low temperature (500 °C) for a short time (12 h) in 6.25 M KOH solution, and resulted in the formation of hydroxyapatite. The rate of ion exchange was accelerated by increasing the reaction temperature and/or concentration of the alkaline solutions. That the converted crystals were single crystals of hydroxyapatite was confirmed by X-ray precession photographs. The hydroxyapatite single crystals that formed from the chlorapatite single crystals by the topotaxial ion exchange under alkaline hydrothermal conditions had a characteristic texture, exhibiting channels on the surfaces and tunnels inside, both along the c axis of the crystals. A dissolution and precipitation process is proposed for the ion-exchange reaction conducted under hydrothermal conditions.

The conversion of mineral celestite to strontianite under alkaline hydrothermal conditions

The exchange of SO42− ions with CO32− ions in natural strontium sulfate (celestite) single crystals was investigated under alkaline hydrothermal conditions. The hydrothermal treatments were conducted using a stainless steel Teflon-lined vessel. Experiments were performed at different temperatures from 150 to 250 °C for various reaction times between 1 and 96 h with a molar ratio of CO32−/SO42− = 1, 5 and 10. Structural characterization of partially and completely converted strontianite (SrCO3) crystals was conducted by XRD, FTIR and SEM. X-ray diffraction results showed that under hydrothermal conditions the exchange of CO32− ions in celestite was completed at 250 °C in a Na2CO3 solution with a molar ratio CO32−/SO42− = 10 for 96 h, and celestite changed to strontianite. The morphology of the converted strontianite crystals depicted that the conversion proceeds without severe changes of the original shape and dimension of the crystals. A peculiar texture, however, consisting of elongated channels and tiny holes distributed randomly normal to the (001) cleavage plane, was formed in order to compensate the dimensional change of the lattice parameters associated with the conversion of celestite to strontianite. Details regarding the conversion mechanism are discussed in the present work.

Stability and single crystal growth of dielectric materials containing lead under hydrothermal conditions

Abstract Stability of lead magnesium niobate (PMN; Pb(Mg 1/3 Nb 2/3 )O 3 ), lead scandium niobate (PSN; Pb(Sc 0·5 Nb 0·5 )O 3 ), a solid solution in the PSN–lead titanate system (PSNT), and lead zirconate titanate (PZT; Pb(Zr 0·53 Ti 0·47 )O 3 ) were all examined in a platinum capsule under hydrothermal conditions. The perovskite PMN was formed from the low crystalline pyrochlore PMN at 600°C by the hydrothermal treatment in pure water. However, the perovskite was decomposed to the pyrochlore by further hydrothermal treatment in pure water for a longer time or at higher temperature. In KF solutions, single crystals of PMN, PSN and PSNT with a pyrochlore structure were grown at the top of the capsule by hydrothermal treatments at 600°C with a temperature gradient of 40°C. In the case of PZT, single crystals of the tetragonal PZT were grown, but the content of Zr in the grown crystals decreased in comparison with that of the starting material.

Preparation of porous materials from hydrothermally hot pressed glass compacts

The importance of the recycling of waste materials has been recognized for sustainable development of our human life. Recently, the authors [1] proposed the recycling of used glasses for building materials using the hydrothermal hot-pressing technique (hereafter referred as HHP), which is useful for preparation of solid compacts from various inorganic powders at low temperatures below 300 ◦C [2–4]. In this paper, we focused on the preparation of porous glass compacts to develop another alternative route for the recycling of used glasses. Porous materials are very attractive because of their controlled porosity and insulating properties for numerous applications such as thermal insulators, substrates for catalyst, filter systems and building materials. A wide variety of porous materials have been produced in an industrial scale using several raw materials such ceramics, glasses, cements and organic materials [5]. The porous ceramics are traditionally produced by a combination of solid state sintering and decomposition of the organic compound or calcium carbonate during the firing process, which results in the formation of a great number of pores in the ceramic bodies. Another routes to prepare porous materials are a phase transformation and a chemical reaction [6, 7]. For the preparation of porous glasses, the phase separation and sol-gel process are commonly employed [8]. The porous glasses have a very wide range of applications such as separation membranes, catalyst precursors, packing materials for chromatography, molecular sieves, and thermal insulators [8, 9]. In general, all the methods employed to produce porous glass materials involve very high cost of fabrication, because of the high sintering temperatures and a special route for the porosity control. In the present work, we prepared porous glass compacts with closed pores for insulating materials by simply heating the glass compacts densified by HHP. A powder of the used glass of blue color was employed to prepare glass compacts by HHP. The chemical analysis [1] of the glass powder showed that it consisted of SiO2 (69.58 wt%), Na2O (14.61 wt%), CaO (10.9 wt%) and other oxides. The glass powder (10 g) with particle size between 46–53 μm was well ground in a mortar with water (5–20 wt%). The mixture was placed in the cylindrical chamber of an autoclave for HHP, with inner diameter of 20 mm, uniaxially compressed at 20 MPa, and then heated to 200 ◦C at a rate of 5 ◦C/min. The temperature and pressure were kept constant for 2 h. The glass compacts prepared by HHP were heated in air for 1 h at a temperature in the range 50–750 ◦C. All the heat treatments were conducted at a constant heating rate of 5 ◦C/min. The weight of the compacts was measured before and after the heat treatment to determine the weight loss. The bulk density of the heated specimens was also determined using the cubic samples (10 × 10 × 10 mm3) shaped from the heated specimens. The weight loss of the compacts prepared with different contents of water is shown in Fig. 1. Large weight loss was observed by heating the compacts for 1 h at temperatures up to 750 ◦C. By hydrothermal hot pressing of the glass powder, a new amorphous phase was formed surrounding the original glass particles [1]. Energy dispersive X-ray analysis conducted on both the residual original glass particles and new phase showed that both of them consisted of the same elements, though infrared spectra of the compacts demonstrated that a significant amount of water was incorporated in the compacts during the hydrothermal hot-pressing treatment [10]. The new phase may be formed by the hydrothermal reaction of the glass powder with water. The weight loss observed during heating the compacts must be caused by the release of water included in the compacts prepared by HHP. Even after the heat treatment at 850 ◦C, no crystalline phases were detected by X-ray diffraction analyses.

Hydrothermal Sintering under Mild Temperature Conditions: Preparation of Calcium-deficient Hydroxyapatite Compacts

Calcium-deficient hydroxyapatite (CDHA) prepared by the coprecipitation method was solidified by the hydrothermal hot-pressing technique, and compacts of CDHA with high bulk density beyond 80% were obtained at 200 ℃. Each reaction parameter, viz. reaction temperature, pressure, and time, was systematically changed from the standard conditions to investigate its effects on density, Vickers hardness, and Ca/P ratio of the compacts obtained. The reaction temperature and pressure had a large effect on densification, but not the reaction time because the densification proceeds in a short time. The densification by hydrothermal hot-pressing involved dissolution and precipitation of the starting CDHA powder, so that the Ca/P ratio changed from 1.52 of the starting powders to 1.61 of the compact obtained by hydrothermal hot-pressing at 200 ℃ and 35 MPa for 24 h with the addition of 10 wt.-% water Graphical Abstract Hydrothermal Sintering under Mild Temperature Conditions: Preparation of Calcium-deficient Hydroxyapatite Compacts

The effect of hydrothermal hot-pressing parameters on the fabrication of porous ceramics using waste glass

The effect of varying hydrothermal hot-pressing (HHP) parameters on the expansion of waste glass powder was investigated by conventional heat treatment. Glass ceramic porous materials were prepared by hydrothermal hot pressing under standard conditions at 200°C, for 2 h at a constant uniaxial pressure of 20 MPa, while varying experimental variables such as glass particle size, water content, reaction interval, temperature and heating rate. SEM investigation showed the presence of a new glass phase, which incorporated water in its structure. The degree of reactivity attainable between glass particles and water seems to control the expansion process during heating of HHP glass compacts. It was found that the expansion process is independent of experimental parameters such as reaction time, temperature and heating rate, but does depend on the particle size and water content. During the heat treatment, the glass foaming process was preceded by decomposition of the new glass phase in the HHP compacts. A minimum apparent density of 0.40 g cm -3 was obtained on specimens prepared with low water content (5 wt%) and medium particle size (39-45 μm). X-ray diffraction patterns of the expanded glasses revealed the formation of SiO 2 (a-cristobalite and quartz) and CaSiO 3 (wollastonite).

Novel route for recycling of steelmaking slag by means of the hydrothermal hot-pressing method

In the last decade, much efforts have been directed toward the recycling of the steelmaking slags, due to their high production volume. A large amount of the slags produced at the steelmaking plants has been mainly used for building materials such as raw material for cement, roadbed material, and for fertilizer [1]. There are, however, some difficulties in recycling the slags, because they usually consist of various compounds with a large variation of the compositions depending on the processes of the steelmaking. The hydrothermal hot pressing (hereafter abbreviated as HHP) technique is an attractive method to transform these slags into useful building materials. Hitherto, the HHP technique has been used to obtain densified materials, including low sinterable materials such as carbonates, hydrates and hydroxides [2–4], under hydrothermal conditions at low temperatures below 300 ◦C with uniaxial compression of the raw powders. Glass powders were also densified by the addition of a small amount of pure water [5, 6]. The characteristics of this technique are the low temperature processing using a simple apparatus and the possibility of the densification of various compounds. The HHP technique has been applied to densify waste glass [7], sludge ash [8], radioactive wastes [9], concrete wastes [10, 11], and so on. The present work showed the feasibility of densifying the basic oxygen furnace (BOF) slag produced at NKK by means of the HHP method. The wet chemical analysis shows that the slag consists of CaO 41.8 wt%, Fe2O3 30.17 wt%, SiO2 10.28 wt%, Al2O3 3.94 wt%, Mn2O3 4.11 wt%, P2O5 3.11 wt% and other minor constituents. The large content of Ca is one of the characteristics of this slag. The slag was previously milled for 12 h and sieved to get a powder with a particle size between 46–53 μm for the HHP treatments. The slag powder (5 g) was well kneaded with different contents of water (0–15 wt%), and the mixture was then placed into the cylindrical chamber of the autoclave for HHP treatments, with inner diameter of 20 mm [12]. The slag powder was uniaxially loaded at various pressures (25– 45 MPa) and simultaneously heated at constant rate of 10 ◦C/min up to a desired temperature (150 and 250 ◦C). The densification of the slag powder was conducted by holding at the desired temperature for a fixed time in the range of 15–120 min. After the HHP treatments, the autoclave was cooled down to room temperature and the solid compact was taken out from the autoclave. The tensile strength of the compact was measured by means of the Brazilian test [13], and the bulk density was estimated by the volume and weight of the compacted specimens. The effects of reaction time, loading pressure, and water content on tensile strength and bulk density of the compacts were evaluated at 250 ◦C. The results are shown in Fig. 1. The influence of the reaction time with constant water content of 10 wt% and uniaxial load of 25 MPa is shown in Fig. 1a. The tensile strength considerably increased with the increase in reaction time up to 30 min, and its increase was reduced with the further increase in reaction time. The bulk density linearly increased with the increase in reaction time. It should be noted that the scales in Fig. 1a are smaller than those in Fig.1b and c. As a result, the reaction time had smaller effects on the properties of the compacts than the loading pressure and water content, which suggested that the densification of the slag powder proceeded in a short time. On the other hand, the increase in loading pressure and water content significantly improved the properties of the compacts (Fig. 1b and c). The high loading pressure accelerated the densification of the slag powder and increased the density and mechanical strength of the compacts as well. A considerable increase of both tensile strength and bulk density was observed with increasing the water content up to 10 wt%. The densification of the slag powder seems to be independent of high water content over 10 wt%, because the bulk density

Stability and single crystal growth of lead scandium niobate and its solid-solution with lead titanate under hydrothermal conditions

The stability of the lead scandium niobate (PSN) and itssolid solution with lead titanate (PSNT), both with the perovskitestructure, was investigated in a platinum capsule under hydrothermalconditions. The perovskite solid solution of PSNT decomposes in waterat 640°C, which results in the transformation to thetetragonal structure after the treatment. In KOH solutions, the PSNTpowder was partially dissolved, it results in the precipitation ofPb2ScNbO6 powders with the perovskite structure, and thegrowth of both lead oxide (massicot) and K4Ti3O8needle crystals at the top of the capsule. In contrast, singlecrystals of both PSNT or PSN were grown in KF solutions at the top ofthe capsule by hydrothermal treatments at 600°C with atemperature gradient of 40°C. In both cases a deficiency ofthe scandium content achieves the stabilization of the pyrochlorestructure of the grown crystals.

Spark plasma sintering of hydrothermally derived ultrafine Ca doped lanthanum chromite powders

Trabajo presentado en AIChE Annual Meeting, celebrado en Salt Lake City (Estados Unidos) del 8 al 13 de noviembre de 2015.The authors acknowledge the financial support of CINVESTAV and CONACYT (project number 39557-Y), both from Mexico. Berenice Fernandez-Arguijo thanks Eng. Felipe de Jesus Marquez-Torres of CINVESTAV-Saltillo for his assistance in the preparation of samples for SEM observations, as well as Eng. Carlos Palacios of Quimica del Rey, MET – MEX Penoles, who supplied the dolomite used in this work.Trabajo presentado en el XXIV Congreso Iberoamericano de Catalisis, celebrado en Medellin (Colombia) del 14 al 19 de septiembre de 2014.El presente trabajo reporta el estudio de la oxidacion catalitica de tolueno (1400 ppm) en catalizadores de Pd y Pt soportados en alumina promovida con 1 y 10% en peso de Ce. Los catalizadores se caracterizaron por: adsorcion fisica de N2 (BET), XRD, FTIR de piridina adsorbida, FTIR de la adsorcion de CO, XPS y TPO. Los resultados mostraron disminucion en el numero de sitios acidos con el contenido de cerio en el catalizador. Se observo una mayor dispersion en los catalizadores de Pd que en los de Pt. En los catalizadores de Pt solo se detectaron especies de Pt0 mientras que en Pd se detectaron especies de Pd0 y Pd2+. En ambas series de catalizadores la combustion total se alcanzo a contenidos de 1% peso en Ce, catalizadores Pd/ACe1 y Pt/ACe1, a 300oC. En el caso del Pd la combustion de tolueno dependen de las propiedades redox optimas (Ce3+/ Ce4+, Pd0/ Pd2+) por lo que resulta importante el tiempo de activacion del catalizador. La combustion catalitica de tolueno en Pt se vio favorecida en una superficie reductora por un proceso de demetilacion. El deposito de carbono en el catalizador disminuyo con el contenido de cerio en el catalizador debido a las propiedades redox del oxido de cerioPartial financial support from the Ministry of Science and Technology (Spain) (GrantMAT2002-04529-C03) and from CONACYT (Mexico) (fellowship to A.K. Cuentas-Gallegos) are gratefully acknowledged.Trabajo presentado en el XXIV Congreso Iberoamericano de Catalisis, celebrado en Medellin (Colombia) del 14 al 19 de septiembre de 2014.Tesis doctoral presentada por Kilian Laclavetine. Programa de doctorado de Fisica Nuclear, en el Departamento de Fisica Atomica, Molecular y Nuclear de la Universidad de Sevilla.Se propone la localizacion de fugas en redes de distribucion de agua medianteclasificadores basados en el metodo de los vecinos mas cercanos (k-NN) con metrica de distanciacosenoidal. El uso de distancias cosenoidales mejora la respuesta del clasificador, con relacional que usa metrica Euclidiana. Comparado con las tecnicas de localizacion de fugas basadasen la maxima correlacion de los residuos, se consigue una mayor robustez en condicionesaltamente ruidosas, y una menor dependencia del modelo hidraulico de la red, lo que facilita suimplementacion, pues no requiere del calculo de la matriz de sensibilidad. La tecnica propuestase programo en MATLABR©y se probo con datos sinteticos obtenidos de simulaciones conEPANET. La evaluacion del desempeno reportada se basa en el indice de perdidas (la fraccionde fugas localizadas erroneamente) y en una medida del error de localizacion obtenida de ladistancia topologicaTrabajo presentado en el XI Congreso de la Asociacion Iberica de Endocrinologia Comparada, celebrado en Vigo del 13 al 15 de julio de 2017.Resumen del trabajo presentado al 41st International Symposium on Archaeometry (ISA), celebrado en Kalamata (Grecia) del 15 al 21 de mayo de 2016.This study was financed by CONACYT-CB grant 240447 and logistically supported by MARN-El Salvador.Lanthanum chromite nano-particles, with a composition of La0.9Ca0.1CrO3 and La0.8Ca0.2CrO3, were produced by 1 h of hydrothermal reaction at 400 and 425??C respectively. The sintering of the powders was conducted using a spark plasma apparatus over the temperature range 1300-1550oC for 1 min with a constant loading pressure of 45 MPa. Additional sintering experiments using conventional firing were carried out for comparison. Fully densified (98 % r.d.) lanthanum chromite pellets with fine equiaxial grains 2.3 ?Em in size were obtained using the SPS (spark plasma sintering) method. n contrast, a maximum relative density of 97 % was produced using La0.8Ca0.2CrO3 sintered conventionally at 1400oC for 300 min, and the average grain size of the resulting sintered sample was 6 ?Em.Trabajo presentado al 10th Summer Workshop on Interval Methods, and 3rd International Symposium on Set Membership - Applications, Reliability and Theory, celebrado en Manchester (UK) del 14 al 16 de junio de 2017.The Application of Ixodicidas has been considered for a long time the alternative for control of the cattle tick Boophilus microplus, however, its use is currently limited in reducing tick infestations, due to the appearance of resistant field tick populations. Ixodicide resistance is a growing problem that needs to be attended, because, it is currently affecting the competitiveness of the Mexican Cattle industry in general and in particular the income of cattle producers. The solution to this problem needs to increase the budget dedicated to basic research in order to elucidate the molecular mechanisms of ixodicide resistance leading to the discovery of new molecular targets for ixodicide resistance detection and recombinant vaccine development. The recent use of new genomic tools, as well as reverse genetics approaches, will provide an extraordinary contribution to the improvement of tick control strategies and ixodicide resistance mitigation programs. The aim of the present review is to make a compilation of different topics related with acaricide resistance in the cattle tick Boophilus microplus, starting with some biological and molecular considerations on its new classification, to the analysis of ixodicide resistance, its impact on the Mexican cattle industry and the perspective of the genomic research in order to solve the problems associated to tick control, new diagnostic tools and development of tick vaccines.The present paper shows an interesting Optical Microscopy (OM) and Scanning Electron microscopy coupled with energy dispersive X-ray analysis (SEM/EDX) application to study degradation crust formation processes in Fort San Pedro, a historical building located at the colonial City of San Francisco de Campeche, Mexico; and the Cathedral of Seville, at Seville, Spain. The results show that while in Seville the crusts are consequence of sulfur dioxide reaction whit calcareous stone, leading to gypsum crystal formation (CaSO4 . 2H2O), in San Francisco de Campeche, deterioration crust are consequence of natural recrystallization processes of CaCO3 induced by excessive environmental humidity.Trabajo realizado en el Departamento de Biologia Molecular, CABIMER, y en el Departamento de Genetica, Facultad de Biologia, Universidad de Sevilla, para optar al grado de Doctor en Genetica Molecular y Biomedicina, por el Licenciado Andres Cruz Garcia.Proteases from the tentacles of the sea cucumber Isostichopusfuscus were partially purified and used to produce antioxidant peptides from body wall proteins of this marine species. Three proteins (105, 68, and 39 kDa) were identified by SDS-PAGE in the proteolytic extract of the tentacles. Protein hydrolyzates were generated with gelatin and crude protein substrates from body wall, and peptidic fractions lower and higher than 3 kDa were obtained to evaluate their oxygen radical scavenging capacity (ORAC). The 3 kDa-fraction obtained from the crude protein hydrolyzate showed the highest ORAC value (0.92 +/- 0.04 micromol Trolox equivalent/mg protein). This fraction was selected to purify peptides potentially responsible for the activity that might be used as ingredients for development of functional foods.The periphery of the archaeological city of Teotihuacan is going through a gradual process of destruction due to the unorganized urban growth of its neighboring communities; this has caused clashes between the National Institute of Archaeology and History (INAH) and said communities. This is a multifactorial problem that requires coordinated actions on behalf of the three levels of government involved. However, this article discusses the problem from a generational perspective, based on the fact that at this moment groups of schoolchildren and youth from these communities are creating their own opinions of the problem, learning from the placement of the people in conflict. In this context, we present the origin, development and current state of a scholastic archaeological news report called Archaeologists in a Jam, created with puppets and reported by the schoolchildren themselves, intended to stimulate critical thinking about the value, use and future of the conversation of this heritage.espanolCatalizadores de Pd, PdFe y PdCo fueron preparados por el metodo de impregnacion, usando borohidruro de sodio (NaBH4) como agente reductor y un material de carbono comercial, (Vulcan XC-72R) como soporte. Los electrocatalizadores sintetizados fueron probados para la reaccion de oxidacion de acido formico (FAOR, por sus siglas en ingles) en medio acido (H2SO4 0,5 M). La morfologia, la composicion y el tamano de particula de los electrocatalizadores se caracterizaron mediante tecnicas fisico-quimicas como difraccion de rayos X (XRD), microscopia electronica de barrido con espectroscopia por energia dispersiva (SEM-EDS) y microscopia electronica de transmision (TEM). La actividad catalitica se evaluo mediante tecnicas de voltamperometria ciclica (CV) y cronoamperometria (CA) EnglishPd, PdCo and PdFe catalysts were prepared by the impregnation method, using sodium borohydride (NaBH4) as the reducing agent and a commercial carbon material (Vulcan XC-72R) as support. The synthesized electrocatalysts were tested for the formic acid oxidation reaction (FAOR) in acid medium (H2SO4 0.5 M). The morphology, composition and particle size of the electrocatalysts were characterized by physicochemical techniques as X-ray diffraction (XRD), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and transmission electron microscopy (TEM). The catalytic activity was evaluated by cyclic voltammetry (CV) and chronoamperometry techniques (CA)Al Consejo Nacional de Ciencia y Tecnologia (CONACyT, Mexico), por el apoyo economico (beca 354779) recibida durante parte de esta investigacion.Poster presentado a la 6th International Conference on Food Digestion (ICFD), celebrada en Granada (Espana) del 2 al 4 de abril de 2019.The authors acknowledge the financial support of the Mexican National Council of Science and Technology (CONACYT), through project number 31356-U, as well as through a scholarship granted to M.G.G. to carry out her Ph.D. studies at Cinvestav-Saltillo.The Major Intrinsic Protein (MIP) is a large family of integral membrane proteins with six putative transmembrane domains conserved throughout evolution. Members of this family have been identified in many organisms, ranging from bacteria to mammals. Functional data has been reported for some members of the different subfamilies (Chrispeels and Agre, 1994; Agre et al., 1995). There are MIPs that are thought to constitute relatively simple but selective channels for a variety of ions or small uncharged molecules. In the case of the bacterial glycerol facilitator GlpF, it has been shown that it facilitates glycerol, other polyhidric alcohols, urea and glycine uptake into E. coli (Maurel et al., 1994). For the bovine prototype MIP26, there is data showing that it serves as voltage-dependent anion channel (Ehring et al., 1990). Other MIP members have been shown to facilitate transport of water in plants and animals which are known as aquaporins (Chrispeels and Agre, 1994; Chrispeels and Maurel 1994). Different subfamilies have been identified by sequence comparisons which allows to distinguish animal and plant genes and that may help to recognize different functions of MIPs (Yamada et al., 1995). Interested in the function of proteins involved in water or solutes transport, we isolated a member of the MIP gene-family from common bean (Phaseolus vulgaris) using as probe a pea cDNA encoding a putative turgor responsive MIP (Guerrero et al., 1990). The sequence analysis of the putative PvMip-1 indicated that it can be classified within the subfamily of plant MIP genes encoding aquaporins. Northern-blot analysis showed that the PvMip-1 transcript is present in roots, leaves and stems. In spite of the high homology with the pea turgor responsive PsMip-7a cDNA, drought and ABA treatments doTrabajo presentado en el XXIV Congreso Iberoamericano de Catalisis, celebrado en Medellin (Colombia) del 14 al 19 de septiembre de 2014.Resumen del trabajo presentado al 25th international Congress on X-ray optic and microanalysis (ICXOM), celebrado en EE.UU. del 5 al 9 de agosto de 2019.

Conversion of Used Glass Bottles to Porous Materials by Using Hydrothermal Technique

Conversion of used glass bottles to porous materials was investigated for recycling of used glasses. The ordinary method to prepare porous materials from glass needs vesicants such as calcium carbonate and silicon carbide that decompose at high temperatures to produce gas, and the gas is trapped in softened glass to form pores. In this study, used glass bottles were converted to porous plates by using hydrothermal technique. First, a glass powder is hydrothermally treated at low temperatures, so that water diffuses into the glass structure. Water is released as vapor to form pores in the softened glass, when the hydrothermally treated glass powder is heated at high temperatures. Thus, this process gives porous materials with a fine structure including closed pores at lower temperature than the ordinary method. The effects of hydrothermal treatment and calcination conditions on bulk density of the resulted porous materials were investigated with a small scale to determine the conditions to get light porous materials. Finally, porous plates (45x45x3 cm3 in size) with density of 0.45g/cm3 were produced by hydrothermal treatment of the glass powder at 180°C in a large autoclave with inside volume of 2.5 m3, followed by calcination at 800°C in a continuous heater with 18 m in length.