Pink Clay Research Articles

Solid-state properties of pink clay from Jequitinhonha Valley in Brazil for pre-formulation study

Solid-state properties of pink clay from Jequitinhonha Valley in Brazil for pre-formulation study

Clay chips and beads capture in situ barley root microbiota and facilitate in vitro long-term preservation of microbial strains.

Capturing the diverse microbiota from healthy and/or stress resilient plants for further preservation and transfer to unproductive and pathogen overloaded soils, might be a tool to restore disturbed plant–microbe interactions. Here, we introduce Aswan Pink Clay as a low-cost technology for capturing and storing the living root microbiota. Clay chips were incorporated into the growth milieu of barley plants and developed under gnotobiotic conditions, to capture and host the rhizospheric microbiota. Afterward, it was tested by both a culture-independent (16S rRNA gene metabarcoding) and -dependent approach. Both methods revealed no significant differences between roots and adjacent clay chips in regard total abundance and structure of the present microbiota. Clay shaped as beads adequately supported the long-term preservation of viable pure isolates of typical rhizospheric microbes, i.e. Bacillus circulans, Klebsiella oxytoca, Sinorhizobium meliloti, and Saccharomyces sp., up to 11 months stored at −20°C, 4°C, and ambient temperature. The used clay chips and beads have the capacity to capture the root microbiota and to long-term preserve pure isolates. Hence, the developed approach is qualified to build on it a comprehensive strategy to transfer and store complex and living environmental microbiota of rhizosphere toward biotechnological application in sustainable plant production and environmental rehabilitation.

HRTEM evidences of Tajo Basin mineralogical complexity: Crystal chemistry and genetic relationship

In this study, a new genetic interpretation of the Mg-bentonite deposits from the Tajo Basin is given through a high-resolution transmission electron microscopy study. These bentonites, belonging to the Green Clays and Pink Clays lithostratigraphic units, are afforded by the sum of processes occurring during the weathering of parent rocks and the evolution of the materials by the transformation of phyllosilicates in the sedimentary environment. The primary phyllosilicates progressively change their microstructure and crystal chemistry, resulting in very complex clay minerals assemblages. The Green Clays are relatively enriched in Al, Fe, and K, whereas Pink Clays are enriched in Mg and Si, corresponding to almost pure trioctahedral smectites. Although the point analysis of the particles showed a continuous compositional variation that evidences their genetical relationship, they were statistically classified in groups that represented the evolution from the primary phyllosilicates (dioctahedral and trioctahedral micas and chlorites) to the final products comprise very low-charge saponite and scarce sepiolite. The intermediate steps in this transformation included the following: 1) particles of structural formulas with an excess of octahedral cations that were interpreted as hydroxy-interlayer minerals and 2) random mixed-layers of illite/smectite progressively poorer in illitic component as the more evolved particles. Green Clays correspond to the state of transformation to smectites where partially transformed detrital components were still predominant, corresponding to more proximal facies, whereas Pink Clays represented most evolved stages in the mineral transformation. The alternation of Green and Pink Clay levels was related to climatic changes with alternation of wetter and drier periods.

On the Tracks of Aswan Pink Clay. New Studies on the Local Clay Deposits in the Region of Aswan/Upper Egypt

Using Ptolemaic to late antiquity pottery assemblages from Aswan (ancient Syene) as a case study, we demonstrate the imperative nature of petrographic analyses combined with geological field surveys when investigating ancient potting centres. The combination of archaeological (i.e. abundance of ceramics, vessel shapes etc.), macroscopic and natural-scientific methods allows the reconstruction of the possible extraction areas of clays utilised in Aswan, Upper Egypt. Knowledge of specific clays and their compositional characteristics helps to establish archaeometric reference groups, necessary for differentiating kaolinitic clay sediments of the Aswan area from similar geological environments further down the Nile valley.

Removal of amaranth dye over surfactant modified dull pink clay from aqueous medium

ABSTRACT The focus of this study was to modify the low cost, environment friendly and abundantly available dull pink clay (DPC) with cetyltrimethylammonium bromide (CTAB, a cationic surfactant) in order to increase its adsorption capacity. Surfactant-modified clays are known to enhance the adsorption capacity of hydrophobic organic contaminants from aqueous solution owing to their increased organic content. Herein, we described the modification of DPC with CTAB to produce modified adsorbent (CTAB-DPC) and its application for adsorptive removal of amaranth (AM) dye from water. The surface morphology of CTAB-DPC was revealed using scanning electron microscopy (SEM). The Brunauer–Emmett–Teller (BET) surface area, pore volume and pore diameter of CTAB-DPC was found to be 271.85 m2/g, 0.464 cm3/g and 10.068 nm, respectively. The adsorption of AM on CTAB-DPC strongly followed the Langmuir and Dubinin-Radushkevich isothermal models; whereas the kinetics studies revealed that the adsorption process was better explained by pseudo second order. At all temperatures the values of ΔG° are negative (−14.06 to −14.98 KJ/mol and −20.654 to −21.997 KJ/mol for DPC and CTAB-DPC, respectively), which shows that adsorption of AM onto DPC and CTAB-DPC is feasible and spontaneous at all temperatures. The CTAB-DPC displayed remarkable efficiency towards the removal of widely used AM from aqueous system. The results revealed that the maximum removal efficiency (~97%, 73 mg/g) was achieved at 0.5 g/L of CTAB-DPC dose, 50 ppm AM concentration, pH 2 and temperature 55°C, which suggests that CTAB-DPC could be an effective adsorbent that could easily be scaled-up into adsorption applications.

Comparison of clay soils of different colors existing under the same conditions in a location

Background: The choice of a suitable soil for an intended application depends, basically on one's thorough knowledge of soil properties. Soil color and thermal properties have been found to vary from place to place. However, there is no scientific information on the properties of a soil type formed with different colors in a location and exposed to the same influence for a reasonable interval of time. Consequently, this leaves room for a great deal of speculation and assumption. Aims and Objectives: This work was aimed at examining and comparing some vital properties of two soil samples of the same soil type formed in a place of a particular relief but are observed to be completely distinct in their colors. In addition, a model for prediction of temperature variation with the thickness of each sample was considered. Materials and Methods: Pink clay and yellow clay got from a location were used to prepare six test samples each. The samples were allowed to dry completely under ambient conditions before they were subjected to laboratory- based tests. Results: The results of each test differed for two clay samples. Apart from values of solar radiation absorptivity and flaking concentration, the mean values of sorptivity, bulk density, specific heat capacity, thermal conductivity and thermal diffusivity were found to be greater for pink clay soil compared to yellow clay soil. Conclusion: Clay soils of different colors can differ in their other properties even if they exist under same conditions in a particular location. During the time of minimum temperature or the hottest time of the day, pink clay would record a lower temperature than yellow clay.

STUDY OF PURIFICATION PROCESS OF VEGETABLE OIL BY PINK CLAY

The phase composition of natural pink clay was studied and influence of sorption properties on purification of mustard oil was investigated. The clay was activated by treatment with oxalic acid and sodium carbonate before using. The acid-base activation of natural material was shown to promote the creation of the new centers on its surface. The new materials demonstrated a positive effect on the oil purification process from fatty acids, peroxide compounds and no effect on the concentrations of carotenoids.

Indian China Clays: Vagaries in Process and Flow Sheet Development

Process and flow sheet development for the beneficiation of China clay remains always unique to each deposit since the mineral characteristics changes from deposit to deposit. The difference in characteristics has got a great bearing on the geological formation, setting and the transformation of the resource over millions of years. Each clay deposit differs in its type and extent of impurities, particle size distribution, pH and other characteristics. Hence it is imperative that flow sheet for beneficiation for any clay can be made only after detailed laboratory processing studies. The present paper discusses about the above mentioned aspect by carrying out process development studies on five typical clays from different states of India, viz., Mamuara clay from Kutch (Gujarat), Thonnakkal Pink clay from Trivandrum (Kerala), Thonnakkal Grey clay from Trivandrum (Kerala), Koraput clay from Orissa and Guda clay from Bikaner, Rajasthan so as to bring out the vagaries in process and develop flow sheet. Studies shows that, besides the normal operations, high gradient magnetic separation and calcination are essential for Mamuara clay so as to get a premium grade calcined clay, reductive bleaching is unavoidable for Thonnakkal Pink clay, shear-floc flotation is required for Thonnakkal Grey clay to remove graphite and a non-conventional (pH controlled) water washing is required for Koraput clay even before blunging since it is highly acidic (pH 1.7). Finally, Guda clay responds only to magnetic separation and can not be upgraded to any premium grade. Incidentally, reductive bleaching, flotation and selective flocculation are not effective for Guda clay. Thus the investigations reveal that each deposit needs different unit operations and hence different beneficiation flow sheets.

Natural radioactivity and trace element composition of natural clays used as cosmetic products in the Greek market

AbstractSeven commercial cosmetic clays having different colour (white, green, pink and red) available in pharmacies and herbalists’ shops in the Greek market have been examined for their trace element concentrations (Ag, As, Ba, Be, Cd, Ce, Co, Cr, Cs, Cu, Ga, Hf, Hg, La, Mo, Ni, Pb, Rb, Sb, Sc, Se, Sr, Tl, V, Y, Zn and Zr). According to EC Regulation 1223/2009 the presence of As, Be, Cd, Cr, Hg, Ni, P, Pb, Sb, Se, Te, Tl, Zr and their compounds is prohibited in cosmetics. The most abundant trace elements in the white clays were P (330 μg/g), Pb (220 μg/g) and Zr (11 μg/g) and for the green clays were P (1250 μg/g), As (43 μg/g), Cr (31 μg/g), Pb (30 μg/g) and Ni (23 μg/g). Red and pink clays had lower concentrations of these elements than their white and green counterparts. The green clays are three times enriched in As and the kaolinite-rich white clays are nine times enriched in Pb compared to the Average Shale. The main mineral phase in the white clays is either kaolinite or calcite, in green clays smectite, in pink clay kaolinite and talc and in red clays it is vermiculite. The specific activities of 238U, 226Ra, 228Ra, 228Th and 40K were determined by γ-ray spectroscopy. The kaolinite-rich white clays are more enriched in 238U-series radionuclides (238U and 226Ra) than the smectitic green clays. In contrast, the green clays were more enriched in 232Th-series radionuclides (228Ra and 228Th) and 40K than the white clays.

Pink marine sediments reveal rapid ice melt and Arctic meltwater discharge during Dansgaard–Oeschger warmings

The climate of the last glaciation was interrupted by numerous abrupt temperature fluctuations, referred to as Greenland interstadials and stadials. During warm interstadials the meridional overturning circulation was active transferring heat to the north, whereas during cold stadials the Nordic Seas were ice-covered and the overturning circulation was disrupted. Meltwater discharge, from ice sheets surrounding the Nordic Seas, is implicated as a cause of this ocean instability, yet very little is known regarding this proposed discharge during warmings. Here we show that, during warmings, pink clay from Devonian Red Beds is transported in suspension by meltwater from the surrounding ice sheet and replaces the greenish silt that is normally deposited on the north-western slope of Svalbard during interstadials. The magnitude of the outpourings is comparable to the size of the outbursts during the deglaciation. Decreasing concentrations of ice-rafted debris during the interstadials signify that the ice sheet retreats as the meltwater production increases.

Antibacterial Effect of some Mineral Clays In Vitro

Background:- The use of geological mineral clay to heal bacterial infections has been evident, since the earliest recorded history, and specific clay minerals may prove valuable in the treatment of bacterial diseases, including infections for which there are no effective antibiotics, such as multi-drug resistant infections. Objectives:- The aim of this study is to identify new inhibitory agents in an era when bacterial antibiotic resistance continues to challenge human health and the availability of new antimicrobial compounds is limited. Materials and methods:- Two bacterial isolates were taken from patient with different infections (UTI, skin infection). The two isolates were used to study the antibacterial effect of four types of mineral clays (gray clay, yellow clay, white clay, and pink clay). Result:- Three types of clays (white clay, gray clay, and yellow clay,) have an antibacterial effect against Staphylococcus aureus that was isolated from skin infection. And have no effect against Pseudomonas aeruginosa that was isolated from patient with UTI. On the other hand, pink mineral clay explained an antibacterial effect against Pseudomonas aeruginosa, and has low effect against Staphylococcus aureus. Conclusions:- Our results indicated that mineral clay could provide an alternative treatment against numerous human bacterial infections.

Tracing and dating recent chemical transfers in weathering profiles by trace-element geochemistry and 238U234U230Th disequilibria: the example of the Kaya lateritic toposequence (Burkina-Faso)

Abstract The paper presents a synthesis of the approach recently developed to constrain the nature and the age of recent element mobility in weathering profiles. The approach relies on a comparison of variations of trace elements and U-series disequilibria in weathering profiles. It is exemplified in the case of old lateritic profiles from the Kaya toposequence, Burkina Faso. Trace elements and 238 U 234 U 230 Th disequilibria have been analysed in whole rock samples from two pits located in very contrasted topographical positions. Trace element data show that the whole toposequence is marked by an intense chemical remobilization, including uranium, from the cap to the lower part of the profiles. 238 U 234 U 230 Th disequilibrium data outline that all the levels of the profiles are affected by recent UTh fractionations, and that each level of the toposequence is marked by U gains and losses. The chronological approach developed in this paper leads to an age of about 400 kyr for the dismantling of the iron cap, and ages ranging from 0 to 400 kyr for U accumulation in the pink clay horizon of the profiles. The depth repartition of U accumulation in the profile implies that the remobilisation processes in this toposequence varied through time, on time constants similar to those of climatic variations. To cite this article: F. Chabaux et al., C. R. Geoscience 335 (2003).

Characterization of Mg-clays from the Neogene of the Madrid Basin and their potential as backfilling and sealing material in high level radioactive waste disposal

Three types of sedimentary materials are studied, referred to as green, brown and pink clays. They are exploited in a number of 0.25-3 m thick layers and contain magnesium smectites. The smectite content in the green and brown clays averages over 80%, with illite and sepiolite and small quantities of quartz and feldspar. The pink clay composition corresponds to disordered interstratified kerolite-stevensite, with a varying stevensite content (20dash45%). The structural formula of the smectite in the <0.5 μm fraction of the the green clays corresponds to a saponite type (unit cell tetrahedral charge −0.65; octahedral charge: −0.24) and significant Fe 2+ presence. In the brown clays the saponite increases the charge in the octahedral layer to −0,44 and tends towards stevensite terms. Adsorption, external specific surface and swelling pressure are very similar in the saponitic clays, with, respectively, average values of: 73–75 meq/100 g ( CEC), : 160–170 m 2/g ( S BET) and 4.6-5.28 MPa ( Ps) (precompacted at dry density 1.4 g.cm −3). When there is more than 15–20% sepiolite in the green clays, however, the CEC drops, the external specific surface increases and with unvarying density the swelling pressure doubles. This increase in swelling pressure is related to an additional increase in osmotic pressure produced in the external surfaces. This reaches 15–16 MPa in the pink clays with a specific surface of 250–260 m 2/g. Maximum values of 19.4 MPa are reached in discrete levels of green clays containing 70% sepiolite and with a specific surface of 287 m 2/g. The genesis of these materials is related to weathering processes in the fluviolacustrine environment in the different zones (lake centre and edge, swamp soils and vadose zone), associated with the evolution of reducing conditions and an alkalinity increase in the water table. The kinetics of these processes would appear to be extremely slow, as long periods without sedimentation are required in order to form significant quantities of magnesium clays and especially saponite. Saponitic clays display qualities that were suitable for their possible use as backfilling and sealing material, although the green clays appear to provide better conditions regarding the rehydration properties associated with the exchange complex and their lower carbonate content.

Co-ordination compounds on the surface of laponite: tri-2-pyridylamine complexes

Freshly prepared [Co(tripyam)2](ClO4)2(tripyam = tri-2-pyridylamine) contains some low-spin isomer (2E ground state)‘frozen’ into the solid; this reverts to the 4T form over 3 months. Ion exchange of orange [Co(tripyam)2]2+ from aqueous solution onto laponite gives a pink clay, the exchanged cation being [Co(tripyam)2(H2O2)]2+ with bidentate pyridylamine ligands. Isomeric [Cu(tripyam)2](ClO4)2(tridentate ligands) and [Cu(tripyam)2(ClO4)2](bidentate ligands) are absorbed onto laponite as [Cu(tripyam)2(H2O)2]2+ with bidentate ligands; however, the copper clay is thermochromic undergoing a reversible change from green to blue at 100 °C. The temperature of the colour change may be increased by employing copper(II) complexes of substituted tri-2-pyridylamines. The thermochromism is a function of the variable denticity of the ligands.Orange [Co(tripyam)2]2+(terdentate ligands) may be exchanged using a novel microwave method which accelerates the ion-exchange reaction, but not the aquation reaction; however, over 1 year the sorbed complex aquates to [Co(tripyam)2(H2O)2]2+. Although low-spin [Fe(tripyam)2]2+(terdentate ligands) is stable on laponite, in general the clay surface has greater affinity for the bis(bidentate) complex species.Cyclic voltammetric studies of acetonitrile solutions show an order of ease of oxidation of cobalt(II) Complexes: [Co(bipy)3]2+ > [Co(6-dmdpa)2]2+ > [Co(tripyam)2]2+ where bipy = 2, 2′-bipyridyl and 6-dmdpa =(6-methyl-2-pyridyl)-di-(2-pyridyl)amine. Clay(laponite)-modified platinum electrodes dipped into acetonitrile solutions of [Co(bipy)3]3+ or [Co(tripyam)2]2+ give very similar E1/2 values to those obtained for the free complexes in acetonitrile solution. However, electrodes prepared from laponite pre-exchanged with pink [Co(tripyam)2(H2O)2]2+or [Co(bipy)3]3+ were rigorously electro-inactive.

§ 4. Objects of Terracotta from Palaikastro and Praisos

[Though some of these objects have already been published, they are better represented in the photographs in Plates 17–20.The descriptions are based on notes left by Mr. Hutchinson when he left England for Crete in 1940, and it has not been possible to submit them to him for revision.]A Bull's-head of Terracotta (Plate 20 A; CM 2070) was found at Praisos, but the circumstances of the find are not recorded. It may be the fragment which Bosanquet thought (BSA Suppl. I (1923) 153 n.) to be the end of the ridge-pole of the larnax from Tholos B. The larnakes in Candia afford nothing like it, but Dr. Schachermayer reports a similar head on a LM.III larnax in the Museum at Hierapetra. This head is of pink clay, covered with a pink slip; across the horns (one of which is broken) it measures ·13m. and from the top of the head to the tip of the muzzle ·10m. One ear is missing. Strongly marked characteristics are the bold modelling of the eyes and brow, the incised lines above the nostrils, the slit for the mouth, the narrow neck and nose, and the forward stretching of the head.

Societies and Academies

LONDON. Mineralogical Society, June 19.—Dr. A. Hutchin-son, president, in the chair.—L. J. Spencer, with chemical analyses by E. D. Mountain: New copper-lead minerals from the Mendip Hills (Somerset). Mendipite (2PbO PbCl2), which occurs as crystalline nodules in manganese-ore, is recorded from new localities. Chloroxiphite (2PbO.Pb(OH)2.CuCl2) as green monoclinic blades resembling epidote, and diaboleite (2Pb(OH)2. CuCl2) as bright-blue tetragonal plates resembling boleite, both occur embedded in the mendipite. Hydrocerussite (2PbCO3.Pb(OH)2) is abundant, sometimes as large crystals (i.e. crystallised “white lead”). Crednerite (CuO Mn2O3) forms fan-like aggregates of thin plates. Pyromorphite was, some centuries ago, evidently an important ore of lead in the Mendips. Wulfenite and mimetite have been found at Higher Pitts near Priddy. The various minerals show progressive stages of alteration with some well-marked pseudomorphs: mendipite→hydrocerussite→cerussite; chloroxiphite→hydrocerussite + malachite I→cerussite + crednerite→malachite II.—W. F. P. McLintock: On a petalite-bearing rock from Devonshire. The well-known aplite from Meldon in Devonshire develops in certain parts of the intrusion a soda-lithia phase rich in the rare lithium-aluminium silicate, petalite. This mineral, not previously known from Britain, occurs as one of the final products of consolidation of the aplite either in coarse-grained veins of pegmatite associated with quartz, orthoclase, albite, a lithia-bearing mica, tourmaline, and apatite, or as irregularly shaped masses throughout the rock itself. The petalite gives rise by decomposition to the pink clay, montmorillonite, so well known from this locality. Certain other veins, free from petalite, are also present, the most interesting constituents of the rarer types being prehnite, axinite, and a pleochroic cordierite. The apatite in the aplite is a pneumatolytic mineral occurring not only in the rock as ophitic patches enclosing quartz and felspar, but also impregnating certain-xenoliths of peculiar type.—A. Brammall and H. F. Harwood: The accessory minerals of the Dartmoor granite. Tourmaline, which is one of the minerals identified, originated at two stages in the cooling history of the intrusion: (1) pre-solidincation-primary and secondary; (2) post-solidification-secondary. The more severe and widespread pneumatorysis and the lodes are referred to a post-solidification stage.— Seitaro Tsuboi: (1) Optical dispersion of three intermediate plagioclases. The principal refractive indices, α β, γ, of (a) oligoclase from Hawke mine, Bakersville, North Carolina, (b) andesine from Maeyama, Shinano, Japan, and (c) labradorite from County Down, Ireland, for light of 9 different wavelengths, and lie optical orientations of the first and the third of these felspars, for light of 5 different wave-lengths (700, 644, 589.3, 535, 508.5μμ) were determined. (2) A dispersion method of determining plagioclases in cleavage-flakes. The method is based on the principle of H. E. Merwin's improved immersion method. By means of a diagram a quick and exact determination of plagioclases is possible. It is applicable to small crystals such as are common in rocks.—C. S. Garnett: The “toadstone-clays” of Derbyshire. The olivine-dolerites (“toadstones”) of Derbyshire undergo two types of alteration: (1) by ordinary weathering to limonite or ochreous deposits; (2) in the absence of oxidising agents under a limestone covering, they may pass through dolerite-greenstone and “green-earth” to a greenish-white or almost white clay (“toadstone-clay”) with the composition 2Al2O3. 6SiO2. 3H2O.—G. T. Prior: (1) The meteoric stone which was seen to fall at Ashdon, near Saffron Walden, Essex, on March 9, 1923. The stone, which weighed about 1300 grams, is a white chondrite showing on one face well-marked radiating lines of flow of the fused crust. (2) The Sinai meteorite. The meteoric stone of 1455 grams which was seen to fall near Kantara in the north of the Sinai Peninsula in July 1916 is an intermediate hypersthene-chondrite, having a percentage of nickel-iferous iron of about 8.6 in which the nickel amounts to about 15 per cent.—G. Greenwood: Communications from the Crystallographic Laboratory of the University of Manchester. No. 1. The detection of rotatory polarisation in an orthorhombic crystal exhibiting crossed axial dispersion. A plate perpendicular to the acute bisectrix of a crystal of tri-phenyl-bismuthine dichloride when in the extinction position transmits a brilliant green monochromatic light due to circular polarisation.—A. F. Hallimond: The chemical classification of the mica group. I. The acid micas.