Academic literature on the topic 'Procesy hydrotermalne'

Chitosan is a natural substance that has many applications in the fields of pharmacy and medicine. Because it hashigh molecular weight and does not dissolved easily in a neutral pH solution, then there is an effort todepolymerize chitosan into low molecular weight chitosan and oligomers. Nowdays, one of the methods used todegrade biomass is hydrothermal. Hydrotermal is one method of biomass degradation and polymers that is quiteeffective and environmentally friendly. Because chitosan has strong hydrogen bonds in addition to highmolecular weight, it is necessary to treat chitosan by sonication before subjected to hydrothermal process. Thisstudy will compare degrading chitosan by only hydrothermal process and also sonication–hydrothermalprocesses. The hydrothermal of chitosan was carried out using a stainless steel tube reactor of 4-mL capacity at200 °C for 4 s under pressures of 25 MPa for both of hydrothermal systems. For sonication– hydrothermalprocesses, chitosan was treated with sonication at 40 oC for 30 and 120 min before subjected to hydrothermalprocess. After hydrothermal, chitosan was characterized by viscosimetry and HPLC to determine molecularwight and also the dissolved product. Based on the product yield of the process, the sonication (40 °C,120 mins,1 %)-hydrothermal process (200 °C, 4 mins) was the best process on this study and gave lactose yield as much as90 %.

Abstract The East Motoling area is one of the prospect areas in the Minahasa region of North Sulawesi, which has indications of low sulfidation epithermal-type mineralization. The research was conducted as a preliminary study to determine the characteristics of geological conditions, alteration, and ore mineralization in the epithermal system. The research method is divided into two main parts, such as fieldwork including surface geological mapping (lithology, stratigraphy, geomorphology, structural geology, alteration and mineralization) and laboratory analysis methods including petrographic analysis. The stratigraphy of the study area consists of altered volcaniclastic breccia, altered lapilli tuff, altered tuff, limestone, welded lapilli tuff, and andesitic breccia. Volcaniclastic breccia, altered lapilli tuff, and altered tuff, member of the Volcanic Rock Formation which is Late – Middle Miocene age, are the host rock for ore mineralization and hydrotermal alteration process. There are 3 types of alterations that have developed, namely argillic (illite + quartz ± kaolinite), sericitic (sericite + illite ± chlorite), and propylitic (chlorite + epidote ± illite). The dextral slip fault with NW – SE trend present as a main control structure to formation of extention fracture/vein. The epithermal veins are relatively north-northeast – south-southwest, north-northwest – south-southeast, and northwest – southeast. The textures of the veins divided into 7 main groups, namely that is bladed-quartz, breccia, calcedony, colloform, comb, mold, and massive quartz. Ore mineralization is forms in the veins as pyrite and banded sulfide. Apart from that, the disseminated pyrite also limitedly found around the veins.

This study aimed to determine the effect of energy and time hydrothermal microwave time variations on the crystal structure and N-TiO2 nanotube photocatalytic activity. The synthesis of N-TiO2 nanotube was performed with the hydrothermal microwave method. The N-TiO2 preparationwas carried out by dissolving ethylenediamine precursor in 80 ml of 96% ethanol and 3 ml TTIP which was reacted at 70 °C for 4 hours. The obtained N-TiO2 was formed into nanotubes used the hydrotermal microwave method in low temperature (180W), medium temperature (360 W), and high temperature (720 W) with time variations of 30 minutes, 1 hour, and 2 hours. The microwave hydrothermal process in this study used 10 M NaOH to form a tubular structure and 0.5 M HCl as an ion exchange. The characterization analysis performed by X-Ray Diffraction, UV-Diffuse Reflectance Spectroscopy, and blue methylene degradation. The results of this study indicate that the variations of time and energy of the microwave hydrothermal method affect the crystal structure of the N-TiO2 nanotubes. The nanotubes structure has been formed at a variety of low energy 2 hours, medium energy 0.5 hours, 1 hour and 2 hours, and high energy 2 hours. Energy and time variations of hydrothermal microwave affect the photocatalytic activity of N-TiO2 nanotubes showed second-order kinetics. The best percentage of degradation produced in the T2 variation is the photocatalyst reaction of 71.89% and the adsorbs reaction of 64.81%.

The region of the Ribeira Valley is known for its metallic sulphide deposits (lead, zinc, copper, silver and gold), being the major lead producer of the Brazil in the 1950s. Since then, it has become the target of several geological studies from which two models of lead and zinc mineralization known as Perau and Panelas models were proposed. This study is particularly interested in the Panelas model, which is characterized by its vein morphology, association with carbonate rocks and structural control. Based on literature, this paper proposes to verify the applicability of the hierarchical analysis process (AHP) as auxiliary of the geographic information system (GIS) in the favorability mapping of hydrothermal veins-type Pb deposits which fit in the Panelas model. The study area is the western region of the Ribeira Valley, located in the southern portion of the São Paulo State, Brazil. In order to perform this work, four parameters were used: geological structure, stratigraphy, lithology and geochemistry. The result obtained highlights areas corresponding to Mina de Furnas, Bairro da Serra and Água Clara Formations as highly favorable areas to lead mineralization according this model. In addition, it shows the negative association of these geological formations with potassium concentration.

The study of variation in chemical composition of chromites associated with mafic/ultramafic sequenceshas a growing in importance because presents a close relation to gold and platinum group elementsconcentration. The researched areas : Serro, Alvorada de Minas and Morro do Pilar present chromites(massive, disseminated and accessory), which show a strong zoning due to hydrotermal/metamorphicprocess. These zones reflect changes in chemical composition of crystals, which are related to neoformationof mineral paragenesis based mainly on leaving of the elements in chromites ( for example the origin ofkammererites).In chromitites from Serro and Alvorada de Minas, as well as in accessory chromites from Morro doPilar, the zoning of the grains was observed. They have a core composed by chromites (aluminous chromites)and a broad margin with ferriferous composition (chromium magnetites to magnetites). In same cases thechromite crystals have a core with primary chemical composition preserved. In the Rio Mata Cavalovolcano-sedimentary sequence a Ir-Pt alloy was found as inclusion in chromium-magnetite. In othersmafic/ultramafic complex of Minas Gerais and Ceará States, high relations of PGE and Au has beenrecorded, and they are associated with chromitites submitted to this alteration process.