María Isabel Carretero

The influence of shaping and firing technology on ceramic properties of calcareous and non-calcareous illitic–chloritic clays

Abstract Two very different illitic–chloritic clays (calcareous and non-calcareous), both currently used in the Italian brickmaking industry, were used. Technological testing consisted in a simulation of the industrial processing performed at a laboratory scale. The pieces were obtained by three shaping techniques, pressing, extrusion and moulding, and fired at 1000 and 1100 °C, in fast and slow heating cycles. In each case their technological properties were studied. The microstructure and technological parameters of the ceramic pieces vary greatly, depending on the clay composition and the processing techniques. Pressing always produces pieces made from non-calcareous clay with the lowest drying and firing shrinkage, open porosity and water absorption. As it regards the calcareous clay, the lowest values of drying and firing shrinkage and water absorption are obtained by extrusion and moulding, respectively. The mechanical resistance, pore size distribution and critical pore diameter do not reflect clearly the influence of shaping techniques. Independently from the shaping technique adopted, all non-calcareous bodies show higher Maages indexes than the calcareous ones. In any case, the Maages durability factor is higher in extruded samples.

Late Holocene evolution of the southwestern Doñana National Park (Guadalquivir Estuary, SW Spain): a multivariate approach

Four phases are distinguished in the Late Holocene evolution of the southwestern Donana National Park (SW Spain), based on a multidisciplinary analysis of the sediments present in drill cores. In the oldest phase (>2400–2500 cal. yr BP), a coastal lagoon (the Roman Lacus Ligustinus) was recognized in the central part of this area, partly closed by the Donana spit and limited by fluvial levees. The following phase (∼2400–2200 cal. yr BP) is characterized by high-energy events, which caused the breakthrough of the Donana spit and the creation of new littoral strands in the inner areas. In the third phase (∼2200–2050 cal. yr BP), this new outlet was closed, coinciding with the progradation of the Donana spit. The last phase (∼2050 cal. yr BP–Recent) comprises three periods: (a) an unstable period (∼2050–1950 cal. yr BP), with the deposit of cheniers over the previous levees; (b) an infilling period, with a diminution of the marine influence; and (c) the appearance of temporary ponds between the emerged levees and cheniers.

The effect of maturation upon the mineralogical and physicochemical properties of illitic-smectitic clays for pelotherapy

Abstract Illitic-smectitic clays were matured with a ferruginous, bicarbonate-rich and sulphate-rich water for different periods of time (7, 15, 30, 60 and 90 days), and subjected to discontinuous stirring, to test their use in pelotherapy. A progressive degradation of the clay minerals was observed during the maturation process, with a reduction in the illite and smectite crystallinity, in the percentage of smectites and in the phyllosilicate content. The percentage of <2 μm particles also decreased. These modifications caused changes in the clays’ physicochemical properties, which are evident in an increase in their plasticity index and in slower cooling of the peloid, both of which improved the clays’ effect in pelotherapy.

Chapter 11.5 Clays and Human Health

Publisher Summary This chapter describes the beneficial and harmful effects of clay mineral. Clay minerals can be beneficial to human health by serving as active principles or excipients in pharmaceutical preparations, in spas, and in beauty therapy medicine. In some cases, however, these minerals may be harmful to human health. In pharmaceutical formulations, spas and beauty therapy, clay minerals are used for therapeutic purposes and their beneficial effect on human health. In pharmaceutical formulations, these minerals are used as active principles (gastrointestinal protectors, antacids antidiarrhoeaics, dermatological protectors, cosmetics) and excipients (inert bases, delivery systems, lubricants, emulsifiers). In spas and beauty therapy, clay minerals are used in geotherapy, pelotherapy, and paramuds to treat dermatological diseases, alleviate the pain of chronic rheumatic inflammations, moisturize the skin, and combat compact lipodystrophies and cellulite. However, clay minerals can also have an adverse effect on human health when they are inhaled over a very long period. In the lung, clay minerals can cause diverse pathologies such as cancer, mesothelioma, or pneumoconiosis, but the toxicity of these minerals is generally related to the presence of quartz or asbestos from mining operations. The pathogenicity of fibrous clay minerals (sepiolite and palygorskite) is related to the geological conditions of formation.

Behaviour of sepiolite, vermiculite and montmorillonite as supports in anaerobic digesters

Abstract The effect of some clay minerals as support for methane production by an anaerobic process was studied. The clay minerals used were: natural sepiolite, treated sepiolite (both from Vallecas, Spain), vermiculite from Santa Olalla (Spain) and montmorillonite from Gador (Spain). Expanded polyurethane and PVC were also used in order to compare these materials, frequently used as supports in anaerobic digesters, and clay minerals. Treated sepiolite in suspension is the material that produces more methanobacteria. This is the only mineral able to fix the bacteria when it is in suspension. The best results for sedimentation are also obtained with this material. Magnesium released from the supports may play an important role in anaerobic digestion.

Chapter 5.5 – Clays, Drugs, and Human Health

Abstract In this chapter, the beneficial and harmful effect of clays and clay minerals is described. Clays and clay minerals can be beneficial to human health by serving in pharmaceutical (as active ingredients and excipients) and cosmetic products (creams, powders and emulsions), in spas and beauty therapy (in pelotherapy to treat dermatological diseases, alleviate the pain of chronic rheumatic inflammations, moisturize the skin, and combat compact lipodystrophies and cellulite), or in other medical applications as diagnosis techniques. On the other hand, the toxicity of clay minerals is reviewed. Clay minerals can have an adverse effect on human health when they are inhaled over a very long period. Inside the lung, clay minerals can cause diverse pathologies such as cancer, mesothelioma, or pneumoconiosis, but the toxicity of these minerals is generally related to both the presence of quartz or asbestos from mining works, or with the geological conditions of formation.

INFLUENCE OF CLAY MINERALS, USED AS SUPPORTS IN ANAEROBIC DIGESTERS, IN THE PRECIPITATION OF STRUVITE

This work studies the influence of clay minerals used as supports in anaerobic digesters on the precipitation of ammonium magnesium phosphate. The magnesium exchange cation present in the sample originally or from experimental saturation plays an important role in the precipitation of struvite crystal growth depending on the greater or lesser facility of its liberation to the medium. Vermiculite, and probably stevensite, influence the formation of struvite, transferring the magnesium cation only from their exchange positions, while sepiolite does so by contributing from its structure. In vermiculite, struvite crystal formation is on the edges or fractures of the laminas. The presence of other cations in the supports, such as exchange Ca2+—either structural or as a component of accessory minerals, as in the case of stevensite—causes precipitation of calcium ammonium phosphate. In minerals with a high iron content, such as nontronite, iron phosphates are produced. The type of digester influences the size of the struvite crystals, these being larger in the semi-continuous digesters.

A methodology for locating the original quarries used for constructing historical buildings: application to Málaga Cathedral, Spain

Abstract It is often necessary to locate the original quarry which supplied the stone for a particular historical building. This stones could be used for future restoration work and for testing in the laboratory (artificial aging tests, physical properties determination, control of the efficacy of conservation treatments, etc.). Generally, reviewing historical documentation gives information about the geographical setting of quarries and location of the stones in the monument, but this information needs to be proved by field and laboratory studies. The comparative study of stone from quarries and monuments should basically include the following: (1) mineralogical and petrographical studies; (2) the chemical analysis of major, minor and trace elements; (3)stable isotopes determinations; (4) physical properties of quarry materials and unweathered building stone (water absorption, ultrasound transmission velocity, porosity and porous system, density, bulk density, compressive strength, etc.). This methodology was applied to Malaga Cathedral stones represented in the main facade, towers, and the western zone of the terrace, which, according to historical literature, came from Almayate (Miocene–Pliocene limestones) and Cerro Coronado (Permotriassic sandstone) in Malaga. The conclusion of the comparative study carried out on quarries and building stones was consistent with the information available from the historical documentation.

The geological record of the oldest historical tsunamis in southwestern Spain

A regressive sequence was determined in the late Holocene evolution of the southwestern Donana National Park (SW Spain), based on a multidisciplinary study of sediments obtained in a drill core. In an initial phase (> cal. 2400 years BP), a shallow coastal lagoon with a partial marine connection occupied this area, with a progressive transition from subtidal to supratidal conditions. The following phase (cal. 2400-2350 years BP) is characterized by a tsunami, with the deposition of an upper chenier. This sedimentological layer is characterized by a ridge morphology, an erosive base, high bioclastic contents and the introduction of marine species toward the inner areas of this old lagoon. This tsunami may be assimilated to one of the historical tsunamis that occurred between 218 and 209 BC. A comparison with other deposits derived from these high-energy events permits to draw the differential effects produced along the western Iberian coasts. SHORT NOTES

Effect of some clay minerals on the growing of sulphate-reducing bacteria in anaerobic reactors

Abstract Natural and treated sepiolite, vermiculite and montmorillonite were studied as supports in cultures of methanobacteria and sulphate-reducing bacteria. Treated sepiolite produces large quantities of methanobacteria and inhibits the growth of sulphate-reducing bacteria. Polyurethane produces methanobacteria in large quantities and many sulphate-reducing bacteria. The hydrogen sulphide reduces the quality of the gas.