Bentonite functionalized with propyl sulfonic acid groups used as catalyst in esterification reactions

AbstractThe main objective of this work is the functionalization of bentonite from the Amazon (region) by the grafting of propyl sulfonic acid groups to catalyze the esterification reaction of acetic acid and 1-propanol. Functionalization was accomplished by anchoring, oxidation and acid activation of (3-mercaptopropyl)trimethoxysilane, (MTPS). The procedure gave acid properties to the raw bentonite. This material, acting as a catalyst, increased the reaction speed and improved the yield by about 12% compared to the uncatalyzed reaction. The functionalized bentonite was characterized by XRD, TG/DTA, FTIR, N2 adsorption/desorption at 77K and XRF, and the surface acidity was determined by titration

Atividade pozolânica dos resíduos cauliníticos das indústrias de mineração de caulim da Amazônia

As regiões do Rio Capim e do Rio Jari são os principais distritos caulinitícos da Região Amazônica, detentores das maiores reservas brasileiras de caulim de alta alvura para aplicações como cobertura de papel. No processamento do caulim são gerados vários tipos de resíduos processados e não processados. O objetivo deste trabalho foi investigar a reatividade das pozolanas produzidas a partir da calcinação e moagem destes resíduos, avaliando a influência da mineralogia de cada tipo de caulinita (com maior ou menor quantidade de defeitos na estrutura cristalina) sobre a temperatura de queima e, consequentemente, nas características do produto final, de modo a obter o material de maior reatividade com um menor dispêndio de energia. Os resultados mostraram que as pozolanas produzidas a partir dos resíduos apresentaram alta reatividade, sendo inclusive superiores as das obtidas com as pozolanas disponíveis comercialmente. As pozolanas produzidas das caulinitas com maior grau de defeitos na estrutura cristalina demandaram temperaturas mais reduzidas que a com menor grau de defeitos. O emprego de caulinitas com maior quantidade de defeitos na estrutura cristalina reduz os custos de produção das pozolanas, sem que haja perda de qualidade ou de reatividade do produto

Factors of paleosol formation in a late cretaceous eolian sand sheet paleoenvironment, Marilia Formation, Southeastern Brazil

FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOThe Marilia Formation, which crops out in southeastern Brazil, is interpreted as a Late Cretaceous eolian sand sheet area The sedimentary succession, ca 110 m thick, is characterized by alternating strata of eolian deposits and paleosols The paleosols constitute more than 66% of the thickness, and are an important element in the interpretation of the paleoenvironmental controlling factors which affected the soil formation in this eolian sand sheet. In this paper six paleosol profiles are described and assigned to two pedotypes Raja and Apore. The ltaja pedotype is constituted of a sequence of five superimposed polygenetic profiles which show different phases of clay illuviation and carbonate precipitation, and it has been classified as Andisol. The Apore pedotype overlies the Itaja pedotype. This pedotype shows an increase in leaching. CIA-K ratios, reddening, and illuvial clay features in respect to Itaja, and has been classified as Alfisol The analysis of the factors which controlled the soil formation revealed that both pedotypes formed on a stable landscape probably covered by a community of low stature plants, in which the soils had sufficient time to develop very mature profiles. The changes in soil-forming processes were driven principally by variations in available soil moisture from precipitation Using depth-to-carbonate functions from Bk and CIA-K proxy from Bt horizons of the Itaja pedotype, mean annual precipitation (MAP) estimates range from 240 to 1078 mm/yr. respectively. These contrasting climatic conditions resulted in the superimposition of and or semi-and with more humid climates and determined the considerable change in the pedogenic features, with many horizons showing the interlacing of calcite and clay features In the Apore pedotype CIA-K proxy from Bt horizons estimates that averaged MAP was around 900 mm/yr. and the prevalent humid conditions can be attested by soil properties and abundance and depth of root traces Our results show that the diversity in pedotypes is mainly attributed to differences in paleoclimatic conditions during Maastrichtian time, and that eolian sedimentation was restricted to periods of harsh and conditions, as in semi-and climates, with MAP estimates around 240 mm/yr, the formation of soils with well developed calcic horizons was possible2921-2349365FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPESP [07/00140-6, 07/02079-2]sem informaçãosem informaçã

Green synthesis of LaCrO3 powder mediated by the extract of the Amazon rainforest native plant Himatanthus drasticus (Mart.) Plumel and their photocatalytic activity

Lanthanum chromite (LaCrO3) powder was successfully synthesized by plant-extract-assisted sol–gel method using milk of Janaguba (Himatanthus drasticus (Mart.) Plumel) as an eco-effective chelating agent. X-ray diffraction (XRD), Rietveld refinement, Fourier-transform infrared spectroscopy (FT-IR), and Scanning electron microscopy (SEM) analysis revealed an orthorhombic crystalline structure, with average crystallite and particle sizes of ~40 and ~640 nm, respectively, confirming the obtaining of LaCrO3 powder. UV–vis absorption spectrum reveals a band with a well-defined maximum in the range of 230–350 nm, with an optical band-gap energy value of 3.33 eV. The photocatalytic degradation efficiency of MB in the presence of LaCrO3 as photocatalyst after 120 min of illumination (in low light intensity of 2.87 Wcm−2) was 6.3%. Therefore, our study provides preliminary evidence that the LaCrO3 powder is a potential photocatalyst for MB dye degradation, a pigment widely used by the textile industry that generates large amounts of effluents to be treated. Finally, the present synthesis proposal presents a cheap and eco-friendly alternative for the production of LaCrO3 powder