1. Surface area, crystal morphology and characterization of transition alumina powders from a new gibbsite precursor

A new procedure was used to prepare a microcrystalline powder constituted by thin euhedral hexagonal gibbsite plates, 0.2 to 0.6 µm in diameter and 32 nm thick. The powder, fired between 200 and 1000 °C, produced chi and kappa transition aluminas. Alpha-alumina is formed from 1000 °C and recrystallized up to 1500 °C. At 1000 °C, kappa- and alpha-alumina

Materials Research. Publicado em: 2007-06

2. Synthesis and Characterization of Boehmites Obtained from Gibbsite in Presence of Different Environments

In this study, results related to boehmite synthesis by hydrothermal processes starting from a Bayer commercial gibbsite are reported. The processes have been conducted from aqueous suspensions with initial acidic or alkaline pH, without or with acetate ion, at 160oC for 72h to 168h. The final materials were characterized by X-ray diffraction (XRD), thermal

Mat. Res.. Publicado em: 15/04/2016

3. EFFECTS OF CLAY FRACTION MINERALOGY ON PHYSICAL ATTRIBUTES OF A YELLOW ULTISOL TREATED WITH CHISELING

ABSTRACT The objective of this study was to evaluate the influence of minerals in the clay fraction on physical attributes of Yellow Ultisol cultivated with sugarcane and prepared with two different treatments: chiseling across the entire area and chiseling only in planting rows. The samples were collected from four layers of soil at eight months after plant

Eng. Agríc.. Publicado em: 2020-08

4. Relationship between macrofauna, mineralogy and exchangeable calcium and magnesium in Cerrado Oxisols under pasture.

Abstract ? The objective of this work was to assess the relationship between macrofauna, mineralogy and exchangeable calcium and magnesium in Cerrado Oxisols under pasture. Twelve collection points were chosen in the Distrito Federal and in Formosa municipality, Goiás state, Brazil, representing four soil groups with varied levels of calcium + magnesium and

Pesquisa Agropecuária Brasileira. Publicado em: 2011

5. Adsorção e dessorção aniônicas individuais por gibbsita pedogenética

Anion adsorption/desorption dynamics was studied as individual processes on surface of particles of a gibbsitic clay. The data suggest a remarkable gibbsite role as nitrate leaching retardant in soil. The opposite behavior of gibbsite towards adsorption/desorption of silicate and phosphate suggests the need of an adequate compromise solution regarding interv

Química Nova. Publicado em: 2009

6. Methods of soil organic carbon determination in Brazilian savannah soils

Several methods exist for determining soil organic carbon, and each one has its own advantages and limitations. Consequently, a comparison of the experimental results obtained when these methods are employed is hampered, causing problems in the comparison of carbon stocks in soils. This study aimed at evaluating the analytical procedures used in the determin

Sci. agric. (Piracicaba, Braz.). Publicado em: 2014-08

7. Kaolinite removal from bauxite by flotation

Abstract This paper presents a potential condition to separate kaolinite through flotation when it is present in bauxite ore. This research anticipates a Brazilian industry requirement, considering the tendency towards the need for aluminosilicates removal from bauxite ores, as has already occurred in China. Kaolinite is the most abundant aluminosilicate, an

REM, Int. Eng. J.. Publicado em: 2016-09

8. Mineralogical and chemical attributes of soils from the Brazilian Atlantic Forest domain

ABSTRACT: The Atlantic Forest is one of the most important and yet the most devastated Brazilian biome, occupying in the past the majority of the East Atlantic Coast. Therefore, a detailed knowledge of the soils near the coastal line influenced by this biome is essential for land use and management of these environments. The aim of this study was to acquire

Sci. agric. (Piracicaba, Braz.). Publicado em: 2019-02

9. Gênese, classificação e mapeamento de solos desenvolvidos de rochas pelíticas em áreas cultivadas com eucalipto em Minas Gerais / Genesis, classification and mapping of soils developed from pellitic rocks in areas cultivated with eucalyptus in Minas Gerais

Because the demand for arable areas has turned very intense in the last years, soils then considered as not appropriate to agricultural use are now being revalued and studied in order to use them for forest plantings, to example of Cambisols developed from pellitic rocks of Bambui Group. In reason of the expressiveness of these soils, usually associated Lato

Publicado em: 2008

10. Do Aggregate Size Classes of the Subsurface Soil Horizon Have Different Chemical/Mineralogical Properties?

ABSTRACT Variations in chemical and mineralogical properties of a soil can occur at short vertical and horizontal distances. The objective of the present study was to evaluate the chemical and mineralogical soil properties of different aggregate classes from young (Ustrochrept) and highly weathered (Acrustox) soils from the state of Paraná, Brazil. Undistur

Rev. Bras. Ciênc. Solo. Publicado em: 14/02/2019

11. Standard transition aluminas. Electron microscopy studies

The aim of this paper is to present the results of characterization of the particle shapes of six standard transition aluminas samples using transmission and scanning electron microscopies; selected area electron diffraction, in parallel with X-ray powder diffraction were used for confirmation of the different transition aluminas types. The transition alumin

Materials Research. Publicado em: 2000-10

12. Estudo geoquímico da disposição de lodo de estação de tratamento de água em área degradada

This survey determined the physical and chemical properties of the gravel place where urban sludge from Rio Descoberto's Water Treatment Plant is disposed. Physical, chemical and biological analysis of the soil samples (n=54), sludge samples (n=2), chemical coagulant (n=20) and samples from superficial waters (n=9) and water table (n=60) were performed. As r

Química Nova. Publicado em: 2009