Vermiculite

About: Vermiculite is a research topic. Over the lifetime, 2320 publications have been published within this topic receiving 37142 citations.

Method for forming a vermiculite film

Abstract: The present invention provides a method for forming a coherent vermiculite film which can be performed on a continuous basis. An exemplary method comprises the steps of providing a non-flocculated dispersion of delaminated vermiculite platelets, providing a flexible release carrier having a surface operative for retaining thereupon a wet film of said dispersion and further operative for releasing the vermiculite film when dried, applying a wet vermiculite film to the moving carrier, and drying the vermiculite film, whereby the dried film is releasable from the carrier. The flexible release carrier preferably comprises paper having a release agent coating thereon. The invention also provides a flexible carrier-supported releasable vermiculite film, a film made from an vermiculite-aziridine composition, a composition of vermiculite and an aziridine, and a composition of vermiculite and amine resulting from an aziridine.

Clay mineralogy and its relationship with potassium forms in some paddy and non-paddy soils of northern Iran

Abstract: Forms of potassium in soils have been a key focus in soil-fertility studies. Clay minerals are the main source of plant nutrients in soil, as their specific surface characteristics determine the release pattern of some important nutrients, such as potassium. Three forms of K consist of unavailable, slowly available and readily available exist in equilibrium in the soil system. Relationships between soil potassium forms within the clay mineralogical suite were determined in twenty four soil samples in three pedons from paddy soils, two from kiwifruit and one from citrus land in the north of Iran. The results showed that, the characteristics of different forms of potassium in adjacent pedons under different land uses depended on their specific clay mineralogy. Mineralogical analyses showed that smectite, illite and vermiculite were the most abundant clay minerals in the studied soils. Mean soluble and exchangeable potassium in paddy soils were rather low compared to non-paddy soils due to potassium fertilization in non-paddy soils. Non-exchangeable potassium in the samples, which was dominated by smectite, was lower than that in samples dominated by vermiculite, hydroxy-interlayer vermiculite (HIV) and illite; this was related to the inability of smectite in potassium fixation. Therefore, taking into account both exchangeable and HNO3-extractable K gives a better indication for K potential and soil-quality management.

Effect of interlayer cations on high-temperature phases of vermiculite

Abstract: Static and dynamic heating of vermiculite samples from Santa Olalla, Huelva, Spain, saturated with different cations, i.e. Na+, Cs+, NH4+, Mg2+, Ca2+, Ba2+ and Al3+, have been studied. The characterization of the phases formed during heating has been carried out by X-ray diffraction. The phases formed depend on the cation present in the interlamellar position and the heating process. The phases identified in the vermiculite samples saturated with different cations and heated at different temperatures are the following: enstatite, forsterite, spinel, cordierite, anorthite, pollucite, nepheline, coesite, celsian and others various mixed silicates; also some dehydrated and amorphous phases have been observed. On static heating, at the maximum temperature reached in this work, the phases formed appear mixed with a glassy phase.

Vermiculite Nanomaterials: Structure, Properties and Potential Applications

Abstract: Vermiculite is a natural phyllosilicate clay mineral with a 2:1 type layer crystalline structure that holds interlayer cations to maintain electrical neutrality. Although it has a similar sandwiched structure with other clay minerals (i.e., montmorillonite, illite, mica, sapolite, laponite), some of its structure features and properties are significantly different from those of clay minerals. For instance, vermiculite can be expanded to form expanded vermiculite when heated, just like graphite can be expanded into expanded graphite after high-temperature treatment. The expanded vermiculite has some unique properties different from other clay minerals, such as excellent thermal insulating properties and thermal stability. Vermiculite can be exfoliated into nanolayers with a thickness of about 1.4 nm by a special physical and chemical approach, which can be used as “building blocks” to construct various functional materials. The interlayered spacing and the type or number of interlayered cations of vermiculite can be controlled by ion exchange, and the surface groups and hydrophilic/hydrophobic properties can be changed by chemical grafting, surface coating, or intercalation processes. These changes impart great application potential for vermiculite in many fields, such as adsorption separation, energy, polymer composites, catalysis, and biomedicine. This chapter summarizes the latest research progress in the mineralogical origin, basic structure, physical and chemical properties, exfoliation/intercalation, functional modification, and nanocomposition of vermiculite. This chapter clarifies the promising applications of vermiculite in functional materials in order to provide useful reference for understanding vermiculite and using vermiculite effectively.

In-Depth Analysis of Physicochemical Properties of Particulate Matter (PM10, PM2.5 and PM1) and Its Characterization through FTIR, XRD and SEM–EDX Techniques in the Foothills of the Hindu Kush Region of Northern Pakistan

Abstract: The current study investigates the variation and physicochemical properties of ambient particulate matter (PM) in the very important location which lies in the foothills of the Hindu Kush ranges in northern Pakistan. This work investigates the mass concentration, mineral content, elemental composition and morphology of PM in three size fractions, i.e., PM1, PM2.5 and PM10, during the year of 2019. The collected samples were characterized by microscopic and spectroscopic techniques like Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy and scanning electron microscopy (SEM) coupled with energy-dispersive X-ray (EDX) spectroscopy. During the study period, the average temperature, relative humidity, rainfall and wind speed were found to be 17.9 °C, 65.83%, 73.75 mm and 0.23 m/s, respectively. The results showed that the 24 h average mass concentration of PM10, PM2.5 and PM1 were 64 µgm−3, 43.9 µgm−3 and 22.4 µgm−3, respectively. The 24 h concentration of both PM10 and PM2.5 were 1.42 and 2.92 times greater, respectively, than the WHO limits. This study confirms the presence of minerals such as wollastonite, ammonium sulphate, wustite, illite, kaolinite, augite, crocidolite, calcite, calcium aluminosilicate, hematite, copper sulphate, dolomite, quartz, vaterite, calcium iron oxide, muscovite, gypsum and vermiculite. On the basis of FESEM-EDX analysis, 14 elements (O, C, Al, Si, Mg, Na, K, Ca, Fe, N, Mo, B, S and Cl) and six groups of PM (carbonaceous (45%), sulfate (13%), bioaerosols (8%), aluminosilicates (19%), quartz (10%) and nitrate (3%)) were identified.