Search results for "sheet silicates"
showing 2 items of 2 documents
Origin of clay minerals in soils on pyroclastic deposits in the island of Lipari (Italy)
2005
The island of Lipari (Italy) is characterized by calc-alkaline to potassic volcanism and a Mediterranean-type climate. The mineralogical and chemical features of two different soil profiles with ages of 92,000 and 10,000–40,000 y, respectively, have been investigated. There were no Andisols, but Vitric and Vertic Cambisols have developed at both sites. Although the morphology of the soils was similar, remarkable differences in the clay mineralogy between the two sites were observed. The site with the Vitric Cambisol was associated with the weathering sequence: glass → halloysite → kaolinite or interstratified kaolinite-2:1 clay minerals. Both sites had smectite in the clay fraction and, to …
New approach for synthesis of poly(ethylglyoxylate) using Maghnite-H + , an Algerian proton exchanged montmorillonite clay, as an eco-catalyst
2017
International audience; In this works, we have explored a new method for a green synthesis of poly(ethylglyoxylate) (PEtG). This method consists on using a montmorillonite clay called Maghnite-H+ as an eco-catalyst to replace triethylamine which is toxic. Cationic polymerization experiments are performed in bulk conditions at three temperatures (-40 degrees C, 25 degrees C, 80 degrees C) and in THF solutions at room temperature (25 degrees C). At 25 degrees C, an optimum ratio of 5 wt% of catalyst leads to molar masses up to 22000 g/mol in THF solutions. Polymerizations in bulk conditions lead to slightly lower masses than experiments conducted in THF solutions. However, bulk polymerization…