Standard Kaolin Research Articles

The efficiency of the electro-osmosis method on the consolidation and strength properties of the gray clay of Tabriz

BackgroundConsolidation of clays could be a very time-consuming procedure. However, preloading can increase the speed of consolidation; applying an electric field can accelerate this procedure significantly. The efficiency of the electroosmosis approach has been studied for different types of clays previously. At the same time, there is no information about the performance of the EO method for Tabriz gray clay.MethodsThis paper investigates the effects of the EO technology on Tabriz gray clay using a modified oedometer consolidation apparatus. The achieved results of the EO consolidation of the Gray clay of Tabriz are compared with the standard Kaolin clay (KC-which produced industrially). Three different electrodes (Iron, Copper, and Aluminum) are employed to study about effects of the electrode type, and two different voltages (12 V and 24 V) are applied to assess the impact of the input electric field on the settlement of samples.ResultsIt is shown that the copper electrode leads to maximum volumetric strains while the iron electrode results in minimum volumetric strains. In addition, it is shown that the larger input voltage leads to larger settlements. The results indicate that the EO approach is more efficient for the Gray clay of Tabriz in comparison to the KC, where gray clay shows larger settlements while subjected to an electric field. Unconfined compression tests are also applied to some samples, and the EO method’s influence on the samples’ strength is discussed.ConclusionsThe achieved results demonstrated that the EO method can be efficiently used to improve the consolidation and strength properties of the gray clay of Tabriz.

Destabilization of Multi-walled carbon nanotubes suspension using novel functionalized biomaterial synthesized via microwave irradiations

Flocculants are one of the most essential tools in the hand of an environmental engineer or mineral processing technologist. However, most of the flocculants available in the market are polyacrylamide based. This always poses the threat of acrylamide release during the degradation process and also the chances of occluded acrylamide during synthesis. Acrylamide is a powerful neurotoxin and a teratogen. Our work endeavors to develop next-generation safer flocculants that are acrylamide free and hence are safer alternatives. Guar gum, an industrial crop native to the Indian subcontinent was grafted with monomer Diallyl Dimethyl Ammonium chloride (DADMAC) by microwave-assisted technique. This novel grafted product was characterized via standard physico-chemical techniques. The flocculation efficacy of the grafted biomaterial was studied through standard jar test and settling test procedures in standard kaolin and coal fine suspensions. Once superior flocculation properties of the grafted product were ascertained, it was studied as a flocculant for the destabilization of Multi-walled carbon nanotubes (MWCNTs) from its suspension. This study endeavors the synthesis of a value-added product of guar gum with established efficacy towards nanoparticle destabilization properties.

Cinética de dissolução de um metacaulim amazônico em ácido nítrico

Abstract The kinetic study of Amazon metakaolin dissolution was performed with the application of the shrinking core model for spherical and ‘flat plate’ particles with constant size. The Amazon kaolin was calcinated at 700 ºC in order to produce metakaolin. This metakaolin was leached with 5% excess nitric acid at 70, 80 and 95±3 ºC for 3 h. Samples were collected every 15 min and subjected to aluminum analysis. The acid leaching was a chemically controlled process. The spherical morphology showed better fit than the flat plate particles when taking into account the regression coefficients. 91.58 kJ/mol of activation energy was found as well as an aluminum leaching reaction of the first order. The results found in this work using 5% excess acid and Amazon kaolin were consistent with previous research results using excess acid above 50% and standard kaolin.

Variations in the molecular weight response of anionic polyacrylamides under different flocculation conditions

The influence of applied mixing (intensity and duration), solids concentration, and liquor chemistry on the molecular weight (MW) response of seven anionic (30%) polyacrylamides was investigated in the flocculation of standard kaolin slurry at pH 8. Continuous flocculation was achieved in a Couette mixing device (CSIRO Shear Vessel) with a vertical flow-through arrangement allowing operator-independent settling rate measurements to be made under tightly controlled mixing conditions. It was found that the relative performance of the flocculants was strongly dependent on the hydrodynamic conditions prevailing during flocculation. The lower MWs gave a more dosage-effective response under mild mixing, producing denser, faster-settling aggregates than equivalent sizes produced with the higher MWs. Conversely, the larger sizes created by the higher MWs gave access to faster settling rates under intense mixing, except in the instance where polymer size and concentration led to chain entanglements. Sodium cations (<0.01 M) in the slurry favoured some degree of particle coagulation, whereas calcium cations had an adverse effect on settling rates even at low concentrations (<0.002 M), with the effects of a reduced bridging capacity most apparent in the lower MWs. The results advance the fundamental understanding of how chain length can substantially alter inter-particle bridging behaviour under different conditions, and thus provide a more robust basis for enhanced dewatering of clay suspensions through flocculant MW selection.

The effect of dalteparin on thromboelastography in pregnancy: an in vitro study

BackgroundDalteparin is often used for prophylaxis or treatment of venous thromboembolism during pregnancy, yet there is no laboratory test to accurately reflect its clinical activity. Thromboelastography is a point-of-care monitor of whole blood coagulation. The aim of this study was to determine if serial doses of dalteparin added in vitro to whole blood samples from term, pregnant women are detectable as changes in thromboelastography parameters. MethodsThirty healthy parturients presenting for elective caesarean section were recruited. Dalteparin was added to whole blood samples to yield final concentrations of 0 (control), 0.05, 0.25, 0.5, 0.75 and 1.0U/mL anti-Xa activity. Thromboelastography tracings were obtained for all six samples using the standard kaolin protocol. ResultsSignificant differences were noted in median thromboelastography r time, k time, alpha angle and maximal amplitude between non-anticoagulated (⩽0.05U/mL) and samples ⩾0.5U/mL (P<0.05). The r time and k time presented with the highest sensitivities of 97.5 and 84.0, respectively. ConclusionThis pilot study provides proof-of-concept that thromboelastography can discriminate differences in blood anticoagulated with varying doses of dalteparin in a dose-dependent manner. This suggests that thromboelastography may be a feasible monitor of anticoagulation in the presence of dalteparin in maternal whole blood and may potentially translate to a point-of-care test that can be used to determine real-time coagulation status in patients.

A comparative study of tissue factor and kaolin on blood coagulation assays using rotational thromboelastometry and thromboelastography.

Rotational thromboelastometry (ROTEM) and thromboelastography (TEG) have been increasingly used to diagnose acute coagulopathy and guide blood transfusion. The tests are routinely performed using different triggering activators such as tissue factor and kaolin, which activate different pathways yielding different results. To optimize the global blood coagulation assays using ROTEM and TEG, we conducted a comparative study on the activation methods employing tissue factor and kaolin at different concentrations as well as standard reagents as recommended by the manufacturer of each device. Key parameter values were obtained at various assay conditions to evaluate and compare coagulation and fibrinolysis profiles of citrated whole blood collected from healthy volunteers. It was found that tissue factor reduced ROTEM clotting time and TEG R, and increased ROTEM clot formation time and TEG K in a concentration-dependent manner. In addition, tissue factor affected ROTEM alpha angle, and maximum clot firmness, especially in the absence of kaolin activation, whereas both ROTEM and TEG clot lysis (LI30, CL30, and LY30) remained unaffected. Moreover, kaolin reduced ROTEM clotting time and TEG R and K, but to a lesser extent than tissue factor, in-tem and ex-tem. Correlations in all corresponding parameters between ROTEM and TEG were observed, when the same activators were used in the assays compared with lesser correlations between standard kaolin TEG and ROTEM (INTEM/EXTEM). The two types of viscoelastic point-of-care devices provide different results, depending on the triggering reagent used to perform the assay. Optimal assay condition was obtained to reduce assay time and improve assay accuracy.

Role of thromboelastography and rapid thromboelastography to assess the pharmacodynamic effects of vitamin K antagonists.

Thromboelastography (TEG) measures the effects of antithrombotic agents by assessing global functional clotting status by evaluating the viscoelastic properties of in vitro clot formation. Recently, rapid TEG (r-TEG), which uses tissue factor in addition to standard kaolin to accelerate activation of the clotting cascade, has been proposed to obtain more immediate results. The correlation between results of TEG or r-TEG with international normalized ratio (INR) in patients on vitamin K antagonist (VKA) therapy has not been explored and represents the aim of this study. Patients on chronic therapy with VKAs (n = 100) were included in an observational prospective pharmacodynamic study. The correlation between TEG parameters, in particular markers of thrombus generation [Reaction time (R), maximum rate of thrombus generation (MRTG), and time to maximum rate of thrombus generation (TMRTG)], and INR values as well as the concordance between these parameters and therapeutic INR ranges were evaluated. In addition, in a subgroup of subjects (n = 17), the correlation of r-TEG parameters with TEG parameters and INR values was also assessed. No correlation was found between INR and TEG parameters of thrombus generation, in particular between INR and R (r = 0.189, p = 0.06), MRTG (r = -0.027, p = 0.79), and TMRTG (r = 0.188, p = 0.06). Further, no concordance was found between these parameters and recommended INR ranges. Significant Spearman correlations were found between INR and activated clotting time (rS = 0.546, p < 0.001), r-R (rS = 0.572, p = 0.017), and r-TMRTG (rS = 0.510, p = 0.037), but not r-MRTG (rS = 0.131, p = 0.617). Results were obtained in 24 ± 6 versus 12 ± 4 min with TEG and r-TEG, respectively (p < 0.001). In patients on chronic VKA therapy, TEG is not a useful tool to evaluate VKA anticoagulant effect, compared with standard INR measurements. However, r-TEG parameters of thrombus generation correlate with INR levels, suggesting a possible role of this assay for measuring more expeditiously anticoagulant treatment effects.

Salmon Thrombin-Fibrinogen Dressing Allows Greater Survival and Preserves Distal Blood Flow Compared to Standard Kaolin Gauze in Coagulopathic Swine with a Standardized Lethal Femoral Artery Injury

We have previously shown that lyophilized salmon thrombin and fibrinogen (STF) embedded in a dissolvable dextran dressing is as efficacious as Combat Gauze (CG) with regard to controlling hemorrhage and survival in non-coagulopathic swine with femoral artery lacerations. A major limitation of currently available advanced field dressings is the inability to control hemorrhage in coagulopathic casualties because of the exhaustion of host coagulation proteins. We tested the hypothesis that the STF dressing would be better able to control hemorrhage and prolong survival in coagulopathic swine compared to CG. Survival rate was 50% in CG-treated animals versus 90% in STF-treated animals. Survival time was significantly greater in STF-treated animals. Clots formed over the arterial injury in 100% of STF-treated animals compared to 0% in CG-treated animals (p < 0.001). STF-treated animals consumed less host coagulation factors, including platelets (p = 0.03). Survival after limb manipulation that simulated casualty evacuation was significantly higher with the STF dressing (p < 0.005). Angiographic observation of distal blood flow was seen twice as often with the STF dressing as with CG. The STF dressing allows a high survival rate, significantly greater survival time, and a significantly more stable dressing than CG in coagulopathic swine. The clot formed by the STF dressing also enables restoration of distal blood flow to the limb potentially resulting in higher limb salvage.

Isolation and characterization of heavy metal removing bacterial bioflocculants

Thirteen metal-tolerant bacteria capable of producing metal-removing bioflocculants were isolated from an industrial effluent sample. Pseudomonas sp. was found to be the pre-dominant species among the isolates (8 out of 13), followed by Herbaspirillium spp. (4) and one Paenibacillus sp. The flocculating activity of bioflocculants produced by these microorganisms was assayed using the kaolin clay. The heavy-metal-removal efficiency was determined using atomic absorption spectrometer before and after mixing the bioflocculant with the heavy metal solutions. Bioflocculants exhibit different flocculating abilities of removing kaolin clay in the presence of different heavy metals. Bioflocculants produced by Pseudomonas sp. CH9 possessed the highest flocculating activity (1.8) compared to the remaining bioflocculants. The flocculating activities of CH11 and CH13increased to 0.95 and 0.87 in the presence of Pb2+ and to 0.89 and 0.98 in the presence of Hg2+ respectively from 0.015 in the presence of Ca2+ in the standard kaolin clay assay. Up to 90% of Pb2+ was removed by Pseudomonas sp. CH8 bioflocculants. Seventy-eight percent of Hg2+ and 66% of Cd2+ was removed by Pseudomonas sp. CH6 andHerbaspirillium sp. CH13 bioflocculants respectively. Most of the bioflocculants demonstrated a higher percentage of heavy-metal removal at low concentrations. This study demonstrates that microbial bioflocculants have potential to be used as an alternative bioremedial tool for industrial effluents and wastewater treatments which are co-contaminated with heavy metals. Key words: Bioflocculant; heavy metals, Pseudomonas sp., Herbaspirillium sp.,Paenibacillus sp., Industrial effluent.

The preparation and ageing of acrylamide/acrylate copolymer flocculant solutions

The flocculation activity achieved with aqueous solutions of polyacrylamide and acrylamide/acrylate copolymers is shown to be highly dependent upon the solution age. Continuous flocculation with a standard kaolin slurry in a Couette mixing device, giving settling rate and in-line chord length distributions, allows the comparison of different flocculant properties and make-up conditions. The multiple-stage ageing process proposed by Owen et al. [Owen, A.T., Fawell, P.D., Swift, J.D. and Farrow, J.B. (2002), The impact of polyacrylamide flocculant solution age on flocculation performance. Int. J. Miner. Process., 67, 123–144.] for nonionic flocculant stock solutions is found to also apply for the wider range of products, although the relative effects of each stage varies, depending on the flocculant form and molecular weight. For powder-based products, the initial wetting, swelling and dispersion of the solid polymer is influenced by the powder size, such that activity may be extremely poor even after several hours. Emulsion-based flocculants effectively eliminate this stage, but both forms of the high molecular weight flocculants require at least an additional 24 h to achieve maximum activity. This is attributed to the slow disentanglement of highly agglomerated polymer. The practical implications for flocculant make-up and use in mineral processing are discussed.

&lt;b&gt;Ceramic properties of Pugu kaolin clays. Part I: Porosity and modulus of rupture&lt;/b&gt;

The utilisation of Pugu kaolin clay as a raw material in porcelain has been tested by laboratory scale experiments. Physical characteristics of the clay have shown it to be of satisfactory quality and comparable to commercial clays found elsewhere. The chemical analysis has indicated the presence of high levels of iron oxide (~ 1.43%) which could adversely affect the translucency of whitewares. The “as mined” material could be suitable for ceramics that do not require high brightness specifications, such as stoneware and sanitary ware. The level of this oxide can, however, be reduced by appropriate means to give a relatively cleaner product that could be excellent for other types of whiteware products. Porcelain materials prepared using Pugu kaolin clay have shown to have similar properties as those prepared using other standard kaolin clays. The bulk density and flexural strength of the fired masses increase with firing temperature to a maximum at the soak temperature of 1200 o C. Beyond this soak temperature the flexural strength decreases. The decrease in strength is attributable to bloating which takes place as gasses are expelled from the matrix. Strictly firing procedures should be enforced in order to obtain a porcelain material of required strength. KEY WORDS: Kaolin clay, Ceramic properties, Porcelain materials, Bulk density, Sintering, Modulus of rupture, Bloating Bull. Chem. Soc. Ethiop. 2003 , 17(2), 147-154.

The Problem of an External Quality Control and a Standard Kaolin Suspension in the Analysis of Turbidity of the water

The Problem of an External Quality Control and a Standard Kaolin Suspension in the Analysis of Turbidity of the water

Drinking water production by coagulation-microfiltration and adsorption-ultrafiltration

Microfiltration (MF) and ultrafiltration (UF) pilot plants were operated to produce drinking water from surface water from 1992 to 1996. Microfiltration was combined with pre-coagulation by polyaluminium chloride and was operated in a dead-end mode using hollow fiber polypropylene and monolith type ceramic membranes. Ultrafiltration pilot was operated in both cross-flow and dead-end modes using hollow fiber cellulose acetate membrane and was combined occasionally with powdered activated carbon (PAC) and granular activated carbon (GAC) adsorption. Turbidity in the raw water varied in the range between 1 and 100 mg/L (as standard Kaolin) and was removed almost completely in all MF and UF pilot plants to less than 0.1 mg/L. MF and UF removed metals such as iron, manganese and aluminium well. The background organics in the river water measured as KMnO4 demand varied in the range between 3 and 16 mg/L. KMnO4 demand decreased to less than 2 mg/L and to less than 3 mg/L on the average by the coagulation-MF process and the sole UF process, respectively. Combination of PAC or GAC adsorption with UF resulted in an increased removal of the background organics and the trihalomethanes formation potential as well as the micropollutants such as pesticides. Filtration flux was controlled in the range between 1.5 and 2.5 m/day with the trans-membrane pressure less than 100 kPa in most cases for MF and UF. The average water recovery varied from 99 to 85%.

Drinking water production by coagulation-microfiltration and adsorption-ultrafiltration

Microfiltration (MF) and ultrafiltration (UF) pilot plants were operated to produce drinking water from surface water from 1992 to 1996. Microfiltration was combined with pre-coagulation by polyaluminium chloride and was operated in a dead-end mode using hollow fiber polypropylene and monolith type ceramic membranes. Ultrafiltration pilot was operated in both cross-flow and dead-end modes using hollow fiber cellulose acetate membrane and was combined occasionally with powdered activated carbon (PAC) and granular activated carbon (GAC) adsorption. Turbidity in the raw water varied in the range between 1 and 100 mg/L (as standard Kaolin) and was removed almost completely in all MF and UF pilot plants to less than 0.1 mg/L. MF and UF removed metals such as iron, manganese and aluminium well. The background organics in the river water measured as KMnO4 demand varied in the range between 3 and 16 mg/L. KMnO4 demand decreased to less than 2 mg/L and to less than 3 mg/L on the average by the coagulation-MF process and the sole UF process, respectively. Combination of PAC or GAC adsorption with UF resulted in an increased removal of the background organics and the trihalomethanes formation potential as well as the micropollutants such as pesticides. Filtration flux was controlled in the range between 1.5 and 2.5 m/day with the trans-membrane pressure less than 100 kPa in most cases for MF and UF. The average water recovery varied from 99 to 85%.

A method for determination of inorganic dust content of grain in the presence of grain dust

Summary. A method was developed for the determination of insecticidal ‘inert dusts’, particularly the diatomaceous earth product Dryacide, on grain. The method was also evaluated for another physical insecticide, magnesite, and 2 standard clays, bentonite and kaolin. The method consists of isolation of dusts (both inert dust and grain dust) from grain, followed by density centrifugation and ashing of the bottom pellet. The ash content of the bottom pellet is linearly related to the percentage inorganic dust in grain dust (w/w). The method can serve 2 functions. First, it can quantify total inorganic ash. Second, it can quantify the total amount of a specific inorganic additive, for example, Dryacide, thus enabling studies on the fate of inorganic additives during grain processing.

The flocculation of kaolin suspensions with anionic polyacrylamides of varying molar mass and anionic character

Standard kaolin suspensions were flocculated using anionic polyacrylamides of varying molar mass and charge density. Flocculant performance was assessed by determining the extent of polymer adsorption, the subsidence rates of the flocculated suspensions, the residual turbidities of the supernatant, the mobilities of the particles and floc size. The sol concentration was kept constant at 20 g kaolin dm −3 in 10 −3mol dm −3NaCl solution; the pH was varied from 3 to 10. Subsidence rates increased with dosage and molar mass, and followed the trend in polymer adsorption. The subsidence rates are less than cationic polyacrylamides of the same molar mass and charge density, and maximum values are reached at much lower dosages. The polymer charge, which is of the same sign as the clay particles, does not counteract the molecular lengths in determining the capability of flocculation by polymer bridging, although the flocs formed had an open structure in contrast to those formed by cationic polyacrylamides. Above pH 7 the polymer could not counteract the increasing self-repulsion of the clay particles with resulting inadequate flocculation.

The effect of colloid concentration and pH on kaolin suspensions flocculated with cationic polyacrylamides of high molar mass

Standard kaolin suspensions were flocculated by two cationic polyacrylamides of the same charge density but differing in molar mass by a factor of ten. Floc size measurements were determined as a function of kaolin concentration, pH and polymer dosage using the Malvern 3600-D particle sizer and subsidence rates were measured. The sol concentration was varied between 2 to 50 g kaolin dm −3 in 10 −3 mol dm −3 NaCl solution; pH was varied from 3 to 11 and polymer dosage from 0.1 to 0.9 mg (g clay) −1. Floc size increased with increasing polymer molar mass, but the distribution of floc size was not significantly affected by variations in the kaolin concentration above a sol concentration of 2 g dm −3. The floc size increased with increasing polymer dosage, the effect being most marked at pH values below 7. The wide spread of small-sized flocs at a kaolin concentration of 2 g dm −3 indicates that even these polymers of relatively high molar mass are not effective flocculants as the distance between the sol particles increases. The lack of correlation between floc size and sol concentration implies that floc size is determined by the polymer molar mass and dosage rather than by the proximity of sol particles.

Floc size studies on kaolin suspensions flocculated with cationic polyacrylamides

Standard kaolin suspensions were flocculated with four cationic polyacrylamides of varying molar mass but the same cationic charge density. Floc size measurements at pH 5.0 were carried out using the Malvern 3600-D particle sizer. For all the polymers floc size increased with increasing applied dosage. The trend is for floc size to increase with increasing polymer molar mass, but, whereas the polymer of lowest molar mass produces flocs significantly smaller than the other three polymers, the latter produce flocs not so different in size, particularly at low dosages. The results are discussed in the light of published earlier studies on adsorption and subsidence rates of the same four polymers on kaolin. A ‘pincushion’ model for adsorption is postulated to explain why the considerably greater adsorption of the polymer of lowest molar mass in terms of g polymer (g clay) −1 produces a more open type of floc structure.

The flocculation of kaolin suspensions using polyethylenimine and cationic polyacrylamides of the same molar mass but different charge density

Standard kaolin suspensions were flocculated using cationic polyacrylamides of similar high molar mass (2.6–2.7×10 6 g mol −1) but different charge densities (78–221 C g −1). Flocculant performance was assessed by measuring the extent of polymer adsorption, the subsidence rates of the flocculated suspensions, the residual turbidities of the resulting supernatants, and the electrophoretic mobilities of the treated particles at pH 5.0. It was found that varying the cationic charge density of the polymers did not significantly affect flocculant performance and bridging was the predominant mechanism of suspension destabilisation. Similar experiments carried out using polyethylenimine, a polymer of much lower molar mass (2×10 3g mol −1) and of relatively high cationic charge density (1.6×1O 3C g −1 at pH 5.0) revealed a different mechanism of particle destabilisation to be in operation; particle aglomeration occurred by charge neutralisation.

On Turbidity and Transmittance Grade Tests for Water Analysis. III : Standardization of the Standard Kaolin Suspension and Alteration of the Transmittance Grade Meter.

In the examination of water, the standard of turbidity is the kaolin suspension of 1 g/L in Japan officially. In this method, the coefficient of variation is about 28% in intensity of turbidity of standard suspension prepared from various kaolin articles of commerce, and is about 8%, prepared from purified kaolin obtained through the sedimentation method (reference to report I). In the method that kaolin suspension is standardized by transmissible light path length in the standard turbidimeter based on"the standard methods for the examination of water and waste water of APHA" the coefficient of variation is about 3.9% in intensity of turbidity of standard suspension standardized. This standard turbidimeter is more convenient for routine works than the candle turbidimeter of"the standard methods of APHA" In stead of the standard turbidimeter, the transmittance grademeter with double cross mark is available as simple method, but in this case the coefficient of variation is about 8%. In the examination of transmittance grade of water by this transmittance grademeter with double cross mark, precision is higher than by the Japan water works association method with No. 5 type character mark.