Topic
Vermiculite
About: Vermiculite is a research topic. Over the lifetime, 2320 publications have been published within this topic receiving 37142 citations.
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TL;DR: In this article, two representative cation exchange materials, vermiculite and 5A zeolite, were added at mass ratio of 5% and 10% to slag activated by sodium hydroxide.
16 citations
TL;DR: In this article, a two-phase history of alteration involving acidic weathering and alkaline metasomatism is suggested for the dioctahedral vermiculite and secondary Fe-rich phlogopite, respectively.
Abstract: Dioctahedral vermiculite occurs in an isolated metagabbro klippe (Kurancali Metagabbro) that belongs to the Central Anatolian Ophiolites from central Turkey. Both the metagabbro and the structurally underlying high-grade metamorphic rocks are intruded by granitic rocks. The Kurancali Metagabbro is characterized by its well-developed compositional layering, and the presence of vermiculitized phlogopite-rich layers. Petrographic and mineralogic studies show that the primary mineral phases in the host rock are diopside, tschermakitic hornblende, Fe-rich phlogopite, and plagioclase. Secondary minerals are hornblende, actinolitic hornblende, Fe-rich phlogopite, and vermiculite. A two-phase history of alteration involving acidic weathering and alkaline metasomatism is suggested for the dioctahedral vermiculite and secondary Fe-rich phlogopite, respectively. The alteration of phlogopite to dioctahedral vermiculite proceeded both along cleavage planes and at crystal edges. The vermiculite is colorless to pale yellow with weak pleochroism and shows optical continuity with the parent mineral. Vermiculite flakes, analyzed semi-quantitatively by scanning electron microscope-energy dispersive analysis (SEM-EDS) and electron microprobe (EMP), are characterized by partially expanded interlayers, K depletion, and Mg and/or Al enrichment. X-ray diffraction (XRD) and differential thermal analysis-thermal gravimetric (DTA-TG) analyses indicate that phlogopite is not a pure phase, although it is the dominant one. The XRD patterns show the presence of both dioctahedral vermiculite having dehydrated interlayers and hydroxy-Al interlayers, and interstratified phlogopite-vermiculite. The transformation of phlogopite to vermiculite is thought to represent an initial stage of weathering in an acidic environment.
16 citations
TL;DR: In this article, three columns were assembled by filling the columns with the same amount of vermiculite and palygorskite but in different arrangements, and the simulated groundwater containing ammonium (NH 4 + ) and humic acid (HA) was pumped to the columns in an upward direction.
16 citations
TL;DR: In this article, the ion exchange behavior of cesium on vermiculite in various grain sizes was investigated, and the effect of the vermiculate grain size was clearly identified.
Abstract: BACKGROUND
Expanded vermiculite is widely used in many fields, especially as an ameliorant in agriculture. Although it is known as a cation-exchanger, in a search for a new cesium adsorbent for environmental conservation, the ion-exchange behaviour of cesium on vermiculite in various grain sizes was investigated. The adsorption of cesium from artificial seawater was also investigated.
RESULTS
The effect of the vermiculite grain size was clearly identified. The preferred gain size for general use was found to be 500 µm. The amount of adsorption was low in these artificial seawater samples, however, almost similar ion-exchange behaviour was observed in both of the pure water and artificial seawater samples.
CONCLUSION
Adjustment of grain size according to the end use enables unlimited availability for application as an adsorbent of cesium. The results showed that vermiculite is a promising material for the recovery of cesium from contaminated seawater. © 2013 Society of Chemical Industry
15 citations
TL;DR: In this article , CoNiCrAIY metallic bond coatings were coated on Inconel 718 super alloy using a high velocity oxygen-fuel (HVOF) deposition technique.
Abstract: Thermal barrier coatings (TBCs) are protective coating systems that are mostly utilized to improve the thermal insulation and functional performance of gas turbine engines and other aircraft components that are both stable and movable. These coatings protect materials operating in harsh conditions from structural damage caused by corrosion, oxidation, the CaO-MgO-Al 2 O 3 -SiO 2 effect (CMAS), thermal shock , volcanic ash, and vermiculite deposits at high temperatures. In this study, CoNiCrAIY metallic bond coatings were coated on Inconel 718 super alloy using a high velocity oxygen-fuel (HVOF) deposition technique. Then, single YSZ, Gd 2 Zr 2 O 7 (GZ), and double YSZ/GZ based ceramic topcoats were applied to the bond coats by using the electron beam physical vapor deposition (EB-PVD) method. The produced TBC samples and the uncoated Inconel 718 superalloy substrate were subjected to vermiculite (VM) deposition at 1250 °C for 4 h, and then the coatings were characterized. To determine the phase structures, microstructural and mechanical properties of the TBCs, X-ray diffractometer (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer elemental mapping analysis (EDS), stereo microscopy analyses, porosity, and hardness measurements were used. The obtained results were comparatively evaluated with the recent related studies in the literature. • The aim of this study is to investigate the VM behavior of innovative single- and double-layer TBC systems. • The VM infiltration has occurred through the surface of the Inconel 718 superalloy substrate and all other TBC systems. • HVOF-bond coating and EB-PVD GZ coating were used for deposition of the TBCs. • On the Inconel 718 super alloy surface, YSZ, Gd 2 Zr 2 O 7 , and YSZ/Gd 2 Zr 2 O 7 coatings were deposited. • The TBC systems' initial porosity percentages decreased, but the top coating hardnesses increased. • The TGO structure formed at the interface with the effect of high temperature.
15 citations