Bentonite Clay Particles Research Articles

Sorption of non‐ferrous metal ions from aqueous solutions by polymer compositions based on polyacrylic acid and bentonite clay

AbstractComposite hydrogels (CH) were obtained by copolymerization of acrylic acid with N,N‐methylene‐bis‐acrylamide in the suspension of bentonite clay (BC) by the method “in situ.” At this CH of cross‐linking structure was formed in which, in the space between parts of polymer hydrogels (PH) on the base of polyacrylic acid (PAAc), were introduced particles of mineral. The morphology and structure of CH have been investigated by scanning electron microscopy, which has shown that particles of BC are distributed throughout the whole volume of the composite. The sorption of Cu2+, Ni2+, and Cr3+ ions from aqueous solutions of their salts by sorbents using the spectrophotometric method was studied. It has been determined that the introduction of BC particles into the composition of PH leads to a noticeable increase in their sorption capacity. Determination of the elemental analysis of the composition of sorbents after sorption by X‐ray fluorescence analysis showed that the sorption of non‐ferrous metal ions increases in the row Cr3+ < Ni2+ < Cu2+.

Study of the Reinforcing Effect and Antibacterial Activity of Edible Films Based on a Mixture of Chitosan/Cassava Starch Filled with Bentonite Particles with Intercalated Ginger Essential Oil.

Edible films based on biopolymers are used to protect food from adverse environmental factors. However, their ample use may be hindered by some challenges to their mechanical and antimicrobial properties. Despite this, in most cases, increasing their mechanical properties and antibacterial activity remains a relevant challenge. To solve this problem, a possible option is to fill the biopolymer matrix of films with a functional filler that combines high reinforcing and antibacterial properties. In this work, biocomposite films based on a mixture of chitosan and cassava starch were filled with a hybrid filler in the form of bentonite clay particles loaded with ginger essential oil (GEO) in their structure with varied concentrations. For this purpose, GEO components were intercalated into bentonite clay interlayer space using a mechanical capture approach without using surface-active and toxic agents. The structure and loading efficiency of the essential oil in the obtained hybrid filler were analyzed by lyophilization and laser analysis of dispersions, ATR-FTIR spectroscopy, thermogravimetry, and X-ray diffraction analysis. The filled biocomposite films were analyzed using ATR-FTIR spectroscopy, optical and scanning electron spectroscopy, energy dispersive spectroscopy, mechanical analysis under tension, and the disk diffusion method for antibacterial activity. The results demonstrated that the tensile strength, Young's modulus, elongation at the break, and the antibacterial effect of the films increased by 40%, 19%, 44%, and 23%, respectively, compared to unfilled film when the filler concentration was 0.5-1 wt.%.

ФЛОКУЛЯЦИЯ БЕНТОНИТОВОЙ ГЛИНЫ НАНОЧАСТИЦАМИ МАГНЕТИТА И ПОВЕРХНОСТНО-АКТИВНЫМИ ВЕЩЕСТВАМИ РАЗЛИЧНОЙ ПРИРОДЫ

The effect of cationic, anionic and nonionic surfactants and magnetic nanocomposites including magnetite and analyzed surfactants on the size of floccule aggregates in a bentonite clay suspension has been studied. Magnetic nanocomposites (MN) were synthesized using the Rene Massart technique and studied by dynamic light scattering. At a concentration of 10 g/dm3, the magnetite particles had an average size of d = 50.8 nm and were negatively charged ζ = -40.6 mV, which indicates a high aggregative stability of Fe3O4 particles. The effect of the various nature surfactants concentration and magnetic nanocomposites based on them on the sedimentation stability of a bentonite clay suspension with varying pH under the influence of an external magnetic field was analyzed at the quantitative level in the mode of constrained sedimentation. The concentration region in which surfactant additives of various nature cause acceleration of sedimentation of bentonite clay has been determined. The appearance of differences in the values of flocculating activity with varying pH of the medium is due to a change in the structure of the double electric layer around bentonite clay particles. In the highly alkaline pH region (pH = 12), the value of flocculating activity with the participation of the MN-C sample at C = 75 × 10-2% is 4.25 times higher than that of the MN-A sample, which is due to the neutralization coagulation of particles due to a decrease in their surface charge and electrokinetic potential due to adsorbing CTAB cations in the MN-C. It should be noted that molecular binding is possible not only at the moment of interaction of bentonite clay particles with the formed adsorbed layer, but also during the gradual formation of the surface layer during the interaction of aggregates of macromolecules with the surface of bentonite clay particles. An increase in the compaction constant for systems involving magnetic nanocomposites was noted compared with a suspension of bentonite clay without additives. The research results presented in this paper can be applied to control the properties of multicomponent dispersed systems involving magnetic nanocomposites.

Magnetized Bentonite Clay Particles: An Eco-friendly and Economical Adsorbent for efficient Remediation of Crystal Violet Dye-Polluted Water

Magnetized Bentonite Clay Particles: An Eco-friendly and Economical Adsorbent for efficient Remediation of Crystal Violet Dye-Polluted Water

Effect of bentonite clay particles on the behavior of foam stabilized by SDS–PVA complexes

In recent years, there has been increased interest in studies on the stabilization of liquid foams with solid particles. In such three-phase foams it is possible to completely stop the process of syneresis, reduce coalescence and diffusion of gas. The presence of particles can significantly increase the time of the foam lifetime. Such Pickering foams are also of interest as an environmentally friendly and cost-effective alternative to surfactants and high molecular weight foaming agents. This work is focused on investigating the foam stability containing SDS–PVA composite foaming agents with bentonite clay particles. Foam stability was characterized via the time of foam drainage. The stability of foams of SDS–PVA mixtures in absence and presence of bentonite particles was determined. The stability of foams is higher in presence of the bentonite particles.

Synthesis of Asphalt Nanoparticles and Their Effects on Drilling Fluid Properties and Shale Dispersion

Summary Asphalt nanoparticles (ANs) were developed by synthesizing asphalt powders with chloroacetic acid (ClCH2COOH). The objective of this synthesis was to develop engineered ANs with a cationic point capable of adsorbing on the net negatively charged clay platelets, thereby improving drilling fluid functionality and pore-plugging performance, reducing shale dispersion, and ultimately enhancing shale stability. Tests carried out to study the performance of the synthesized ANs include particle size analysis, Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy, drilling fluid rheology, and filtration rate and shale dispersion tests. FT-IR spectrum results confirming the occurrence of a chemical reaction between asphalt and ClCH2COOH showed a shift in NH vibration from 3,439.95 cm−1 (before synthesis) to 3,435.05 cm−1 (after synthesis). Based on particle size analysis, an average particle size diameter of 92.9 nm was observed, suggesting the tendency of ANs to invade and seal nanopore spaces. The shape of ANs ranged from spherical to irregular, because intercalated structures were observed from the scanning electron microscopic analysis on the interaction between ANs and sodium bentonite (Na-Bent). An increase in attracting force between the Na-Bent particles caused by the adsorption of ANs cationic point on bentonite clay particles led to an increase in drilling fluid rheological properties as the ANs %w/v increased. The drilling fluid filtration rate was, however, not significantly affected by the %w/v increase in ANs because results indicated slight decrease in fluid loss when compared with the base mud (BM). According to the shale dispersion test, the shale cuttings percentage recovery of the 2%w/v ANs sample was 76.5%, owing to the decrease in fluid-rock interaction caused by ionic adsorption and encapsulation of shale surfaces by the ANs. Experimental results from this investigation indicate that the likely mechanisms of the effect of ANs on shale formations would be sealing off nanopore spaces in formations because of its ultratiny particle size; adsorption of the net negatively charged shale cuttings by the ANs cationic point, thereby reducing drilling cuttings dispersion; and improving hole-cleaning performance due to its effect on the drilling fluid rheological properties.

Synthesis of novel poly (vinyl alcohol)/tamarind gum/bentonite-based composite films for drug delivery applications

In this study, a series of novel composite films comprised of poly (vinyl alcohol) (PVA), tamarind gum (TG), and bentonite clay particles were prepared using the solvent casting method. The prepared composite films appeared colorless and transparent. Ultraviolet-visible (UV–vis) spectroscopy revealed that the prepared films showed higher absorption in the UV region as compared to the visible region. Bright-field microscopy analysis showed that the matrix of the films contained globular architectures. The analysis of the surface topological features of the prepared films suggested the agglomeration of clay particles in the PVA/TG matrix when the bentonite content was higher. Bentonite-containing films had higher %swelling as compared to the control (PVA/TG) film. FTIR spectroscopy indicated that the incorporation of the bentonite clay enhanced the hydrogen bonding among the components of the films. X-ray diffraction analysis of the films suggested the intercalation of polymer chains within the bentonite clay layers when the bentonite content was lower. However, the filler particles assumed agglomerated forms as the loading concentration of bentonite was increased, which was in agreement with SEM analysis. On the other hand, mechanical studies suggested that above a critical amount (i.e., 20 mg), bentonite weakened the network structure of the films. The resistive component of the films showed a gradual increment with a corresponding rise in the bentonite content. The in vitro release study confirmed that the films loaded with ciprofloxacin HCl supported the sustained diffusion of the drug molecules and hence, can be utilized for controlled drug delivery applications. Moreover, the drug-loaded films showed an effective antimicrobial effect against Gram-positive and Gram-negative microbes as compared to the control films. In gist, the above analyses suggested that the prepared PVA/TG/bentonite films have promising potential to be utilized as drug delivery systems.

Insights to the transport of heavy metals from an industrial effluent through functionalized bentonite incorporated mixed matrix membrane: Process modeling and analysis of the interplay of various parameters

Ethylene diamine tetraacetic acid (EDTA) was immobilized on bentonite clay particles by single step synthesis process and the prepared functionalized bentonite (FB) particles were incorporated in polysulfone membrane. The FB particles made the membrane surface negative (zeta potential of M-2 membrane having 2 wt% FB was –22 mV at pH 7) facilitating adsorption of heavy metals. They imparted hydrophilic properties to the mixed matrix membrane (MMM) indicated by the reduction of contact angle which in turn reduced membrane fouling. M-2 membrane exhibited the highest permeability 7.4 × 10-11 m/Pa.s and metal ion removal in the range of 92–98 % for Ni (II), Cu (II), Zn (II) and Pb (II). Among the heavy metals studied, lead showed the maximum retention. FT-IR study precisely indicated the presence of chemical interaction among FB particles and polymer matrix thus, restricting the leaching of additives from the membranes. The mechanism of heavy metal removal by MMM was identified as adsorption promoted by ion-exchange. The MMM exhibited about 98% lead rejection and breakthrough time of 9 h for a battery effluent. A first principle-based modified convection-adsorption model was utilized to predict both the permeate flux and concentration profiles for a long term filtration experiment. The same model was used to generate a performance curve for scaling up of a real industrial wastewater to identify the suitable operating conditions and the membrane area. An in-depth analysis of the parameter space was carried out to establish the inter-relation between various parameters, like, membrane resistance and membrane-solute interaction variables (adsorption capacity, adsorption kinetic constant and adsorption resistance parameter). This analysis would be helpful in making a MMM with desirable properties for an optimal performance.

Soft nanocomposites based on nanoclay particles and mixed wormlike micelles of surfactants

Stable viscoelastic suspensions of bentonite clay particles in semi-dilute solutions of wormlike micelles of mixed zwitterionic (oleyl amidopropyl dimethyl carboxybetaine) and anionic (sodium dodecyl sulfate) surfactants were elaborated. They represent a novel type of soft nanocomposite with tunable viscoelastic matrix. Structural studies revealed that the clay is dispersed in a dense network of entangled wormlike micelles in the form of 100-nm tactoids. Rheological investigations demonstrated that clay particles can induce an increase of viscosity by up to one order of magnitude. The effect of the clay becomes more pronounced with increasing content of anionic surfactant in the mixture with zwitterionic surfactant, when the micelles become branched. This behavior was explained by the stabilization of micelle-nanoclay junction points due to the screening of the repulsion between positively charged fragments of zwitterionic head groups by added anionic surfactant. As a result of stabilization, the lifetime of surfactant-nanoclay junctions becomes much larger than the breaking time of micelles. The elaborated systems are of interest for many industrial applications.

Hetero-nanostructured iron oxide and bentonite clay composite assembly for the determination of an antiviral drug acyclovir

Fabrication of chemically modified electrodes for a variety of applications has gained much interest in sensor applications. In search of new materials, carbon paste electrodes (CPEs) loaded with one or more nanoparticles have shown good results for the trace detection of molecules. In this research, a blend of bentonite clay particles and γ-Fe2O3 nanoparticles were employed as a modifier in CPE for the quantification of acyclovir (ACV), an antiviral agent. The sensor demonstrated a quantitative assessment of acyclovir with the limit of detection (LOD) value of 1.5 nM. The sensor had good reproducibility, the stability of signal response, and high selectivity for the electrochemical analysis of ACV in pharmaceutical formulations and spiked human urine samples. The results also revealed a sensitive performance of the sensor in pharmacokinetic studies, quality control, and clinical research.

Effects of turbulent aggregation on clay floc breakup and implications for the oceanic environment.

Understanding how turbulence impacts marine floc formation and breakup is key to predicting particulate carbon transport in the ocean. While floc formation and sinking rate has been studied in the laboratory and in-situ, the breakup response to turbulence has attracted less attention. To address this problem, the breakup response of bentonite clay particles flocculated in salt water was studied experimentally. Flocs were grown in a large aggregation tank under unmixed and mixed aggregation conditions and then subjected to turbulent pipe flow. Particle size was quantified using microscope imaging and in-situ measurements obtained from standard optical oceanographic instruments; a Sequoia Scientific LISST-100X and two WET Labs ac-9 spectrophotometers. The LISST instrument was found to capture the breakup response of flocs to turbulent energy, though the resulting particle size spectra appear to have underestimated the largest floc lengthscales in the flow while overestimating the abundance of primary particles. Floc breakup and the resulting shift towards smaller particles caused an increase in spectral slope of attenuation as measured by the ac-9 instruments. The Kolmogorov lengthscale was not found to have a limiting effect on floc size in these experiments. While the flocs were found to decrease in overall strength over the course of the two-month experimental time period, repeatable breakup responses to turbulence exposure were observed. Hydrodynamic conditions during floc formation were found to have a large influence on floc strength and breakup response. A non-constant strength exponent was observed for flocs formed with more energetic mixing. Increased turbulence from mixing during aggregation was found to increase floc fractal dimension and apparent density, resulting in a shift in the breakup relationships to higher turbulence dissipation rates. The results suggest that marine particle aggregation and vertical carbon transport concepts should include the turbulence energy responsible for aggregate formation and the resulting impact on floc strength, density, and the disruption potential.

REMOVAL OF LEAD FROM POLLUTED WATER BY ADSORPTION ON BENTONITE CLAY PARTICLES

REMOVAL OF LEAD FROM POLLUTED WATER BY ADSORPTION ON BENTONITE CLAY PARTICLES

Ionic strength dependence of aggregate size and morphology on polymer-clay flocculation

Polymer-driven flocculation of suspended particles is a critical process for many applications, including composite materials synthesis, paper manufacturing, and water treatment. However, the role of solution physicochemical properties on the polymer-particle assembly dynamics is nontrivial, particularly for non-spherical, polydisperse particulates such as natural clays. In this work, we study the effects of ionic strength and aggregate size and structure on the polymer behavior and flocculation performance with anisotropic bentonite clay particles. Using jar tests, laser diffraction, confocal microscopy, and X-ray diffraction, we demonstrate that for smectite clay particles, the final floc structure is largely informed by ionic-strength driven changes to the initial clay aggregate size and surface structure. With increasing bentonite aggregate size, a transition from a networked to a patched polymer − aggregate floc structure is observed, independent of ionic strength during flocculation. Solutions were studied over four orders of magnitude of NaCl ionic strength. Initial, pre-flocculated bentonite aggregate sizes ranging from 0.015μm to 15μm were used, produced by tuning the initial solution ionic strength. Bentonite aggregate size and structure were measured with laser and X-ray diffraction, internal floc structure was visualized using confocal microscopy, and macro floc structure (fractal dimension) was measured with optical imaging. These results shed new light on the fundamental complexity of ionic strength dependence and the importance of the aggregate size and structure of the initial dispersion, in determining optimal reagent dosing and structure control for flocculation of anisotropic clays.

Influence of clays on the slurry rheology and flotation of a pyritic gold ore

The presence of clay minerals in ores has been known to adversely affect the flotation performance. This work investigated the influence of kaolin and bentonite clays on the flotation of gold-bearing pyrite in the gold ore. The changes in rheological properties of the flotation pulp under normal operating conditions were also studied with the additions of kaolin and bentonite clays at various solid concentrations. The zeta potential measurements also were carried out to understand the mechanism of adsorption of potential determining ions. It was found that bentonite clay reduced the pyrite recovery, and modified the pulp rheology more than kaolin. The addition of Ca2+ ions to the pulp containing bentonite improved the pyrite flotation recovery by its ability to modify the rheological characteristics. It is consistent with the published literature that Ca2+ ions suppressed the swelling properties of bentonite, and altered the surface charge properties of bentonite clay particles. Additionally, the rheological characteristics such as the flow index and the consistency index affected the flotation performance as the former indicates the extent of movement of bubbles and particles within flotation pulp. This suggests the possibility of using the rheological measures to monitor the changes in the flotation performance in routine plant operations.

Formation of composites between polyvinylimidazole and bentonites and their use for removal of remazol black B from water

ABSTRACTPoly(vinyl imidazole) (PVI)–clay (sodium bentonite and calcium bentonite) composites were designed and characterized for the removal of remazol black B (RB) that is an anionic dye water pollutant. The adsorption properties of PVI on bentonite clay particles were investigated and then PVI–clay composites were prepared at the optimum conditions for RB adsorption. X-ray diffraction (XRD) method was used for researching the intercalation behaviors of polymer–clay composites. Besides, Fourier-transform infrared spectroscopy and scanning electron microscopy analyses were carried out in order to identify the interaction mechanisms between PVI and bentonite in the composites.

A Novel Method of Investigating Wet Bentonite Clay Particles in TEM

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

Laboratory measurements of the light scattering properties of bentonite clay particles embedded in a cylindrical polymer matrix

The volume scattering function and degree of linear polarization of randomly oriented bentonite clay particles were investigated as a function of scattering angle at 543.5 nm, 594.5 nm and 632.8 nm incident laser wavelengths by using a detector array-incorporated laboratory light scattering setup. Readings were taken in steps of 1° from an angle of 10° to 170° and each detector was separated from the next one by an angle of 10°. A transparent cylindrical polymer matrix made of cycloaliphatic amine-cured thermosetting epoxy resin was used to hold the scattering samples in front of the laser beam. For background correction the measurements were taken in differential mode.

Desorption of metacide on thermoacid activated bentonite clay

The interaction of water soluble flocculant metacide with thermoacid activated bentonite clay particles by method of secondary flocculation was investigated. It was established the adsorption of metacide thermoacid activated bentonite clay has irreversible character. Metacide adsorption depends on pH and metacide concentration.

MEASUREMENT OF ANGULAR SCATTERING FUNCTION AND DEGREE OF LINEAR POLARIZATION OF BENTONITE CLAY PARTICLES EMBEDDED IN CYLINDRICAL EPOXY MATRIX

Scattering properties of bentonite clay particles were investigated at 543.5 nm incident laser wavelength by using a designed and fabricated light scattering setup. The scattering samples were held in front of a laser beam by using a transparent cylindrical thermosetting epoxy matrix.

Drag and relaxation in a bentonite clay suspension

We measure the drag force on a sphere moving slowly through a 6% by weight suspension of bentonite clay particles in water. The steady state drag force depends only weakly of the speed of the sphere, indicating that yield stress effects dominate the drag in the range of pulling speeds studied. The drag force increases as a function of time as the suspension gels. The yield stress of the suspension as a function of suspension age is determined from the zero-velocity intercept of our force-pulling speed data. Both the initial transient build-up of the force and its relaxation when the motion stops are described by two exponential time constants, each of which shows an inverse power law dependence on pulling speed. We also determine the yield stress from the force remaining after the relaxation; it is significantly smaller than that determined from the steady-state force data due to the disruption of the structure of the suspension by the motion of the sphere.