Search results for "Kaolin"

Nanocomposites based on esterified colophony and halloysite clay nanotubes as consolidants for waterlogged archaeological woods

2017

We have designed an innovative protocol for the consolidation of waterlogged archaeological woods by using acetone mixtures of halloysite clay nanotubes and a chemically modified colophony (Rosin). Firstly, we have investigated the thermal properties of HNTs/Rosin nanocomposites, which have been prepared by means of the casting method from acetone. The HNTs content have been systematically changed in order to study the influence of the inorganic filler on the thermal stability and glass transition process of Rosin. We have observed that the thermal properties of the hybrids are affected by the specific HNTs/Rosin interactions. Then, acetone dispersions of HNTs/Rosin composites at variable f…

Continental weathering and climatic changes inferred from clay mineralogy and paired carbon isotopes across the early to middle Toarcian in the Paris…

2014

Abstract Lower Toarcian strata (Lower Jurassic) have been extensively studied with a view to understanding the oceanographic, climatic and biological processes that drove the Earth's system into an Oceanic Anoxic Event (OAE). For this time period, the evolution of the European marine seaways is now relatively well constrained owing to multiple geochemical studies, but investigations regarding climatic trends in the continental realm remain sparse. In the present study, we test the clay mineralogy as a continental climate-sensitive proxy in the well-documented Sancerre core (southern Paris Basin). We compare variations in the kaolinite content with p CO 2 fluctuations (derived from paired ca…

The role of pedogenic overprinting in the obliteration of parent material in some polygenetic landscapes of Sicily (Italy)

2016

Abstract Many soils older than the Holocene have experienced several changes, and possess properties that may be due to the complex effect of several stages of soil development; these soils are called polygenetic. It is still rather unclear, however, if, as time elapses, pedogenic processes tend to diverge generating different soils, or converge towards increasingly similar soils. We studied five pedons (37°60′N, 13°90′E) exposed to present weathering simultaneously since the Holocene but located on Upper Miocene or Holocene parent material. Their XRD and FTIR clay mineralogy reveal an overall homogeneity; smectites, calcite and gypsum reach the thermodynamic equilibrium, a slight undersatu…

A new FESEM procedure for assessment of XRD microstructural data of kaolinites

2007

Abstract A sample preparation method for FESEM microstructural analysis of sheet silicates using oriented aggregates on metallic strips parallel to the electronic beam is described. The method allows the easy measurement of thickness of kaolinite crystallites. The results have been compared to the apparent crystallite size measured by XRD The performed measurements for a set of selected kaolinites are in the range 15–60 nm and show a good correlation with XRD crystallite thickness (in the range 11–48 nm) obtained by the Voigt function method.

Effects of Kaolin on Ophelimus maskelli (Hymenoptera: Eulophidae) in Laboratory and Nursery Experiments

2011

Although recent research has demonstrated that clays provide satisfactory control of some agricultural insect pests, the effect of clays on gall wasps that damage forest trees has not been previously reported. The aim of the current study is to evaluate the effectiveness of the clay kaolin in the laboratory and in the field in reducing the damage caused by the eulophid Ophelimus maskelli (Ashmead) on seedlings of eucalyptus (Eucalyptus L'Hér.) species. In the laboratory, kaolin + wetting agent significantly reduced the percentage of infested leaves and the number of galls per leaf. In the nursery, gall number per leaf was not correlated with leaf area with kaolin + wetting agent but was rel…

A structural comparison of halloysite nanotubes of different origin by Small-Angle Neutron Scattering (SANS) and Electric Birefringence

2018

The structure of halloysite nanotubes (Hal) from different mines was investigated by Small-Angle Neutron Scattering (SANS) and Electric Birefringence (EBR) experiments. The analysis of the SANS curves allowed us to correlate the sizes and polydispersity and the specific surfaces (obtained by a Porod analysis of the SANS data) of the nanotubes with their specific geological setting. Contrast matching measurements were performed on patch Hal (from Western Australia) in order to determine their experimental scattering length density for a more precise analysis. Further characterization of the mesoscopic structure of Hal was carried out by Electric Birefringence (EBR), which allowed to study th…

ADSORPTION OF WATER MOLECULES ONTO 1:1 DIOCTAHEDRAL CLAY MINERALS: A BADER'S TOPOLOGICAL ANALYSIS OF THE AB-INITIO ELECTRON DENSITIES

2011

Control of Bactrocera oleae and Ceratitis capitata in Organic Orchards: Use of Clays and Copper Products.

2010

Tests on the effect of clays (kaolin and bentonite) and copper products (hydroxide and oxychloride) in the control of olive fruit fly, Bactrocera oleae (Rossi), and Mediterranean fruit fly, Ceratitis capitata (Wiedemann), were carried out from 2003 to 2006 in olive groves and in organic citrus orchards (satsuma, clementine, ‘Navelina’ orange). Results demonstrate an efficacy of kaolin products in reducing attacks of B. oleae on olives and those of C. capitata on citrus fruits; in olive groves the clays gave similar or better results than copper hydroxide. Bentonite AG/8W showed a significant reduction in punctures by C. capitata. Bentonite products and BPLK kaolin are washed off by rainfall…

Neptunium(V) sorption on kaolinite

2011

Abstract The sorption behavior of neptunium(V) onto the clay mineral kaolinite was studied in batch experiments under different experimental conditions: [Np(V)]=7 × 10−12–8 × 10−6 M, solid-to-liquid ratio 2–20 g L−1, I=0.1 and 0.01 M NaClO4, pH=6–10, ambient air and Ar atmosphere. The short-lived isotope 239Np (T 1/2=2.36 d) was used instead of 237Np (T 1/2=2.14 × 106 a) to study the sorption behavior of Np(V) at environmentally-relevant concentrations, i.e., 7 × 1012 M Np. In addition, 239Np(V) served as tracer to measure sorption isotherms over six orders of magnitude in Np concentration (4.8 × 10−12–1.0 × 10−4 M). The results show that Np(V) sorption on kaolinite is strongly influenced b…

Studies of the ternary systems humic substances – kaolinite – Pu(III) and Pu(IV)

2008

AbstractThe behaviour of plutonium with respect to its migration in the aquifer has been studied under conditions close to nature. Most relevant under these conditions are Pu(III) and Pu(IV) in contact with humic substances (HS) and minerals. As a model for the host rock, kaolinite (KGa-1b) was chosen. The complexation of Pu(III) and Pu(IV) with Aldrich humic acid (AHA) in aqueous solution at ionic strength 0.1 M was investigated by the ultrafiltration method. The sorption of Pu(III) and Am(III) onto kaolinite (K) as a function of pH and metal-ion concentration was studied under aerobic and anaerobic conditions. The pH edge was found at pH∼5.5 independent of the metal-ion concentration and …