Unmodified Montmorillonite Clay Research Articles

Comparative studies of response surface modeling and Plackett-Burman optimization of particles removal from paint industrial wastewater using modified Aguleri montmorillonite clay

In this study, response surface methodology (RSM) based on a statistically designed experiment (CCD) and Placket-Burman design was used as tools for simulation and optimization of particles removal from paint effluent using coagulation method. The studied input variables were dosage, time and temperature. The un-modified montmorillonite clay (UC) and modified montmorillonite clay (MMC) were characterized for elemental/structural elucidation using XRF, FTIR and SEM techniques and the results indicate that UC is rich in silicion (Si) followed by aluminum (AL) and ferrous (Fe). The acid modification confers on MMC net positive charges, making these useful as coagulants. The RSM optimization revealed that 91.9% particles removal can be achieved at 3 g/L, 38 min and 37 °C, while PBD shows that optimal particles removal of 86.4% is possible at 1 g of MMC, 30min and 45oC. Experimental validated of RSM result (89.8% particles removal) correlated with the model predicted value. The results obtained indicate that MMC can be very effective in removal of particles from paint wastewater. In addition, RSM is a better optimization tool than PBD.

Thermogravimetric Analysis of Modified Montmorillonite Clay for Mycotoxin Decontamination in Cereal Grains.

Thermogravimetric analysis (TGA) was carried out to study the stability of nanoformulations used for the decontamination of mycotoxins. The TGA patterns of the nanoformulations from montmorillonite clay and Cymbopogon citratus (lemongrass) extracts were assessed with temperature ranging from ambient (20°C) to 1000°C. The various nanoformulations studied included unmodified montmorillonite clay (Mont), montmorillonite washed with sodium chloride (Mont-Na), montmorillonite mixed with lemongrass essential oil (Mont-LGEO), and montmorillonite mixed with an equal quantity of lemongrass powder (Mont-LGP). There was no significant difference in the median of the various nanoformulations within 4 weeks at p < 0.05 using the Kruskal–Wallis nonparametric test. For the TGA, the first degradation for montmorillonite clay and the nanoformulations occurred at a temperature between 80 and 101°C and was attributed to the loss of lattice water outside the coordination sphere with a range of 3.5–6.5% weight loss. The second degradation occurred within the temperature of 338 to 344°C, and the third, at a temperature between 640 and 668°C for Mont and the formulations of Mont-Na, Mont-LGEO, and Mont-LGP. There were strong similarities in the degradation patterns of Mont and Mont-Na with the minimum difference being the relatively higher weight loss of the sodium-exchanged cation for Mont-Na at the third degradation step. Hence, the order of stability from the most resistant to the least resistant to degradation is as follows: Mont-LGEO ≥ Mont-Na ≥ Mont ≥ Mont-LGP.

Studies on FT-IR Spectroscopy of modified Montmorillonite clays applied for the removal of T-2 toxin in maize

Montmorillonite clay has a wide range of industrial applications which include the removal of mycotoxins in foods and feed because of its low toxicity both in vitro and in vivo. T-2 toxin is produced mostly by fungal species of Fusarium. Other T-2 producing fungal species are Myrothecium and Stachybotrys. T-2 toxin poses several health hazards such as dystrophy in the brain, heart, kidney and liver as well as ulceration and necrosis of the digestive tract in man and animals. To reduce T-2 toxin in maize, montmorillonite clay modified with lemongrass essential oil (MMT-LGEO) and montmorillonite clay washed with NaCl (Na-MMT) were applied to maize at a concentration of 8% and 12% and kept under storage for one month at 30°C. Untreated maize samples and unmodified montmorillonite clay (MMT) served as controls. The FTIR spectra were recorded for the two treatments and unmodified montmorillonite clay (MMT) used for the removal of T-2 toxin in maize. The FTIR spectra of the two treatments and unmodified clay (MMT) showed the major functional groups as Si-O and -OH. All the treatments reduced the level of T-2 toxin in maize. However, sodium montmorillonite (Na-MMT) and montmorillonite clay modified with lemongrass essential oil (MMT-LGEO) were more efficient than unmodified montmorillonite clay (MMT) in the removal of T-2 toxin in maize.

Decontamination of T-2 Toxin in Maize by Modified Montmorillonite Clay.

Montmorillonite clay has a wide range of applications, one of which includes the binding of mycotoxins in foods and feeds through adsorption. T-2 toxin, produced by some Fusarium, Myrothecium, and Stachybotrys species, causes dystrophy in the brain, heart, and kidney. Various formulations that include lemongrass essential oil-modified montmorillonite clay (LGEO-MMT), lemongrass powder (LGP), montmorillonite clay washed with 1 mM NaCl (Na-MMT), montmorillonite clay (MMT), and lemongrass powder mixed with montmorillonite clay (LGP-MMT) were applied to maize at concentrations of 8% and 12% and stored for a period of one month at 30 °C. Unmodified montmorillonite clay and LGP served as the negative controls alongside untreated maize. Fourier Transform Infrared (FTIR) spectra of the various treatments showed the major functional groups as Si-O and -OH. All treatment formulations were effective in the decontamination of T-2 toxin in maize. Accordingly, it was revealed that the inclusion of Na-MMT in maize at a concentration of 8% was most effective in decontaminating T-2 toxin by 66% in maize followed by LGP-MMT at 12% inclusion level recording a 56% decontamination of T-2 toxin in maize (p = 0.05). Montmorillonite clay can be effectively modified with plant extracts for the decontamination of T-2 toxin.

Modification of montmorillonite clay with Cymbopogon citratus for the decontamination of zearalenone in millet

Montmorillonite clay due to its abundance and environmental friendliness, has several industrial applications among which is the adsorption of mycotoxins in foods and feeds as binding agents. Fungal species from the genus Fusarium produce zearalenone (ZEA); an oestrogenic compound, which has been implicated in hormonal and reproductive issues for both animal and man. In this study, various nanoformulations from montmorillonite clay and Cymbopogon citratus (lemongrass) extracts were developed for the decontamination of ZEA in millet. The various formulations developed included montmorillonite clay and essential oil of Cymbopogon citratus (Mont-LGEO), montmorillonite clay mixed with C. citratus (lemongrass) powder (Mont-LGP) and montmorillonite clay washed with 1 mM NaCl (Mont-Na). Unmodified montmorillonite clay (Mont) and C. citratus (lemongrass powder) (LGP) served as the negative controls for the treatment. Each of the formulations was exposed to millet grains at concentrations of 8 and 12% and stored for 4 weeks. All the formulations were effective in the decontamination of ZEA in millet after 4 weeks with LGP exposed at 12% recording the highest reduction of 98.3% while the second most effective formulation, Mont-LGP exposed at 12% showed a 66% reduction of ZEA in millet (p = 0.05).

Monitoring lipid oxidation in a processed meat product packaged with nanocomposite poly(lactic acid) film

One of the most detrimental processes in fatty foodstuffs is lipid oxidation, which occurs during production and storage, and influences food composition and safety. Polylactic acid (PLA), a commercially available biopolymer, is biodegradable thermoplastic aliphatic polyester derived from renewable resources. Polymer layered silicate (PLS) nanocomposites have shown potential for enhancing physical, chemical, and mechanical properties of both conventional materials and biopolymers. In the present work nanocomposite films were prepared by incorporating unmodified montmorillonite clay (Cloisite® Na+) in the PLA. Moreover, the lipid oxidation status of a processed meat product packaged with a film incorporating this nanocomposite was evaluated. In line with this, hexanal, Thiobarbituric Acid Reactive Substances (TBARS) and p-anisidine value were monitored after packaging salami during different storage times (15, 30, 60 and 90 days). The results of this study showed that the presence of montmorillonite (MMT) in the polymer film can reduce the lipid oxidation of processed meat products, extending their shelf life and, thus, suggesting that the new film is a potential good alternative to conventional bioplastics.

In situ characterization of organo-modified and unmodified montmorillonite aqueous suspensions by UV–visible spectroscopy

UV–visible (UV–Vis) spectroscopy (Tyndall spectra) was applied and tested for its ability to measure organo-modified and unmodified montmorillonite (MMT) clays in aqueous suspensions. A full factorial design of experiments was used to study the influence of pH, NaCl and clay concentrations on the average particle size of the clay agglomerates. The methodology was evaluated by observing results that were consistent with previous research about the unmodified clay’s behavior in aqueous suspensions. The results from this evaluation corresponded to accepted theories about the unmodified clay’s behavior, indicating that the methodology is precise enough to distinguish the effects of the studied factors on these clay suspensions. The effect of clay concentration was related to the amount of ions per clay particle for the unmodified clay, but was not significant for the organo-modified MMT. The average particle size of the organo-modified MMT in suspension was significantly larger than that of the unmodified clay. Size of the organo-modified MMT agglomerates in suspension decreased in the presence of NaCl and at both high and low pH; this behavior was opposite to that of the unmodified clay. These results demonstrate that the UV–Vis methodology is well-suited for characterizing clay particle size in aqueous suspensions. The technique also is simple, rapid, and low-cost.

Effect of the Solvent on the Size of Clay Nanoparticles in Solution as Determined Using an Ultraviolet–Visible (UV-Vis) Spectroscopy Methodology

Ultraviolet-visible (UV-Vis) spectroscopy methodology was developed and utilized for the in situ nanoscale measurement of the size of mineral clay agglomerates in various liquid suspensions. The clays studied were organomodified and unmodified montmorillonite clays (I.44p, Cloisite 93a, and PGN). The methodology was compared and validated against dynamic light scattering (DLS) analysis. The method was able to measure clay agglomerates in solvents in situations where DLS analysis was unsuccessful due to the shapes, polydispersity, and high aspect ratios of the clay particles and the complexity of the aggregates, or dispersion medium. The measured clay agglomerates in suspension were found to be in the nanometer range in the more compatible solvents, and their sizes correlated with the Hansen solubility parameter space distance between the clay modifiers and the solvents. Mass detection limits for size determination were in the range from 1 to 9 mg/L. The methodology thus provides simple, rapid, and inexpensive characterization of clays or particles in the nano- or microsize range in low concentrations in various liquid media, including complex mixtures or highly viscous fluids that are difficult to analyze with DLS. In addition, by combining UV-VIS spectroscopy with DLS it was possible to discern flocculation behavior in liquids, which otherwise could result in false size measurements by DLS alone.

The Effect of Montmorillonite Clay on the Crystallinity of Poly(vinyl alcohol) Nanocomposites Obtained by Solution Intercalation and In Situ Polymerization.

In this study, PVAL/sodic clay nanocomposite materials were obtained using different clay ratios. The nanocomposites were prepared by solution and in situ polymerization. They were characterized through proton relaxometry and X-ray diffraction, the latter technique used to determine the crystallinity of the PVAL matrix in the nanocomposites through the addition of unmodified montmorillonite clay. The relaxation data for the nanocomposite films obtained by solution intercalation showed a decrease in the proton spin-lattice relaxation values with increased clay proportion, forming a nanostructured material with high exfoliation degree, as a result of two phenomena: the higher molecular mobility of the polymer chains around the clay layers and the presence of paramagnetic metals in the clay layers, which accelerates the hydrogen relaxation process, causing a decrease in the relaxation value. The samples obtained through in situ polymerization were mixed nanocomposites (partly exfoliated and partly intercalated). The NMR relaxation data for the systems analyzed showed the solution intercalation process was more efficient than in situ polymerization in relation to the generation of nanostructured polymers with higher degree of exfoliated clay.

Treatment of an automobile effluent from heavy metals contamination by an eco-friendly montmorillonite

Unmodified montmorillonite clay was utilized as a low cost adsorbent for the removal of heavy metals from a contaminated automobile effluent. Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy were used to characterize the adsorbent. Batch sorption experiments were performed at an optimum effluent pH of 6.5, adsorbent dose of 0.1g, particle size of 100μm and equilibrium contact time of 180min. Thermodynamic analysis was also conducted. Equilibrium data were analyzed by the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich models. A heterogeneous surface of the adsorbent was indicated by the Freundlich model. The Langmuir maximum adsorption capacity of the montmorillonite for metals was found in the following order: Zn (5.7mg/g)>Cu (1.58mg/g)>Mn (0.59mg/g)>Cd (0.33mg/g)>Pb (0.10mg/g)≡Ni (0.10mg/g). This was directly related to the concentration of the metal ions in solution. The pseudo-first order, pseudo-second order, intraparticle diffusion and liquid film diffusion models were applied for kinetic analysis. The mechanism of sorption was found to be dominated by the film diffusion mechanism. The results of this study revealed the potential of the montmorillonite for treatment of heavy metal contaminated effluents.

Prediction and Verification of Compatibility of MMT Nanofiller in PA6 Matrix

This contribution deals about study of mechanical properties and compatibility between PA6 polymer as matrix and modified and unmodified montmorillonite clay nanofiller Cloisite. For this purposes in the first part of study the Hamaker constants, Adhesion work and B parameter for systems PA6/Cloisite 30B, PA6/Cloisite 93A and Pa6/Cloisite Na+ were calculated and compared. The second part of article consists of mechanical tests (tensile test, impact test) of moulded samples and Scanning Electron Microscope (SEM) study of these samples.

Reinforcement and curing characteristics of organoclay filled natural rubber nanocomposites

Natural rubber (NR) - organoclay nanocomposites (NROCN) and NR-clay (un-modified montmorillonite clay) composites (NRCC) were prepared using different loading of OC/unmodified clay by melt compounding process using a laboratory scale internal mixer in view of investigating the organoclay (OC) effect on curing characteristics and reinforcing behaviour in NR compound formulations. X-ray diffraction analysis of NROCN’s revealed predominantly exfoliated OC structures within the NR nanocomposite materials, especially with a lower loading of OC where as NRCC’s showed MMT clay aggregates with larger clay stacks leading to conventional NR composite materials. Vulcanization characteristics of the clay filled NR compounds, especially processing safety, curing time and delta torque, have been interpreted with respect to the organic modifier in the OC and OC clay loading. NROCN vulcanizates have shown a significant enhancement in solid-state mechanical properties compared to those of NR gum and NRCC vulcanizates. Mechanical property data have been explained in terms of compatibility, degree of exfoliation and clay loading.

Synthesis and dynamic mechanical analysis of nanocomposite UV crosslinkable 100% solid acrylic pressure sensitive adhesives

A synthesis and characterization of nanocomposite solventless acrylic UV crosslinkable pressure sensitive adhesives is presented. Different prepolymers were synthesized using bulk polymerization procedure. The reaction mixture consisted of acrylic monomers (2-ethylhexyl acrylate, acrylic acid and t-butyl acrylate), azobisisobutyronitrile initiator, chain transfer agent n-dodecylmercaptan and unsaturated UV photoinitiator 4-acryloyloxybezophenone. Different formulations with different amounts of modified and unmodified montmorillonite (MMT) clays were tested and the prepolymer was characterized by viscosity measurements. UV crosslinking process was monitored using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Gel phase amount in crosslinked samples was determined by Soxhlet extraction. Clay dispersion in polymer matrix was investigated by X-ray diffraction analysis (XRD). Three basic adhesive properties, the tack, peel and shear strength were measured and the viscoelastic properties of crosslinked adhesive films were characterized using dynamic mechanical analysis (DMA). Results of the study showed high increase in prepolymer viscosity, when hydrophobic types of MMT clays were added in the reaction mixture. The addition of clay had a negative effect on UV crosslinking process. XRD analysis confirmed complete exfoliation and/or intercalation of modified clays in polymer matrix, depending on modifier amount and type. Results of adhesive properties testing showed a major influence of clay addition on adhesive properties, especially on shear strength. DMA analysis showed an increase in storage modulus (G′) and a decrease of tanδ values for adhesives synthesized with clay what also concurs with higher shear strength and implies an improved cohesion of adhesive.

Weathering performance of spruce coated with water based acrylic paint modified with TiO2 and clay nanoparticles

This work examines the effect of wood specimens coated with water based acrylic coatings modified with TiO2 and clay nanoparticles against weathering strain. The long-term durability of the specimens towards climate strain was studied within a relatively short time frame by accelerated climate ageing. The surface changes that occurred as a result of photodegradation of the specimens subjected to accelerated climate exposures were studied using colour measurements and Fourier transform infrared (FTIR) spectroscopy. The results revealed a significant decrease in the intensity of lignin bands attributed to degradation of the lignin component of the wood. However, the intensity of the lignin photodegradation was lower for coated specimens, with slightly lower degradation for the specimens coated with paints modified with TiO2 and unmodified montmorillonite clay nanoparticles.

Preparation of cetyltrimethylammonium intercalated Indonesian montmorillonite for adsorption of toluene

Organo-clays of cetyltrimethylammonium(CTMA)-intercalated montmorillonite from a naturally occurring Indonesian montmorillonite were prepared. Previous research showed that the insertion of surfactants into interlayer spaces in montmorillonite improved the adsorption of hydrophobic chemicals. The current research focused on the effects of preparation variables, the concentration of CTMA surfactant, the cation exchange capacity (CEC) of the montmorillonite clay and their ratio (CTMA/CEC) on the physicochemical characteristics of the organo-clays and adsorption of toluene. X-ray diffraction (XRD), surface area analysis, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) were used to compare the physicochemical characteristics of the modified and unmodified montmorillonite clays. The adsorption of toluene was studied in kinetics and isotherm. It was found that the CTMA/CEC ratio strongly affected the physicochemical properties and adsorption capacities of the montmorillonite surfaces. Adsorption kinetics was evaluated by pseudo-first order, pseudo-second order and Elovich models. Adsorption isotherm was assessed with the Langmuir, Freundlich and Temkin isotherms. The data were best fit by the pseudo-second order model and the Langmuir model.

Micromechanical Modeling of the Effective Viscoelastic Response of Polyamide-6-Based Nanocomposites Reinforced with Modified and Unmodified Montmorillonite Clay

A micromechanics-based approach using a self-consistent scheme based on the double-inclusion model is adopted to develop a pertinent model for describing the viscoelastic response of polymer/clay nanocomposites. The relationship between the intercalated nanostructure and the effective nanocomposite stiffness is constructed using an equivalent stiffness method in which the clay stacks are replaced by homogeneous nanoparticles with predetermined equivalent anisotropic stiffness. The capabilities of the proposed micromechanics-based model are checked by comparing with the experimental viscoelastic (glassy to rubbery) response of two polyamide-6-based nanocomposite systems reinforced with a modified montmorillonite clay (Cloisite 30B) and an unmodified sodium montmorillonite clay (Cloisite Na+), favoring, respectively, exfoliation and intercalation states.

Studies of reinforcement behavior of unique elastomer‐based nanocomposite gels

AbstractUnique nanocomposite (NC) gels were prepared by blending water swollen unmodified montmorillonite clay suspension with natural rubber (NR) and styrene‐butadiene rubber (SBR) latices followed by prevulcanization. These were extensively characterized by dynamic light scattering, solvent swelling, tensile, and dynamic mechanical measurements. Reinforcement behavior of NC gels was investigated by adding NC gels into virgin NR and SBR matrices at various loadings. The distribution and morphology of NC gels in the elastomer matrices was studied by X‐ray dot mapping and high‐resolution transmission electron microscopy. Experimental results indicated tremendous improvement of tensile strength (TS) and modulus of the NC gel‐filled matrices along with noticeable changes in dynamic mechanical and rheological properties. Compared with virgin NR, the TS of 16 phr NC gel‐filled NR system increased by 117%. Similar level of enhancement of TS was also registered for the NC gel‐filled SBR systems. NC gel‐filled systems showed higher shear viscosities and lower die‐swell values compared with their virgin counterparts. Contemporary particulate composite and nanofiller reinforcement models were used to understand the reinforcing behavior of these NC gels. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers

Exfoliation of Nanolayer Assemblies for Improved Natural Rubber Properties: Methods and Theory

Natural rubber (NR)-based nanocomposites were prepared by conventional processing techniques using various natural and modified nanoclays. For modified montmorillonite (Cloisite® 15A), the 300% modulus, tensile, and tear strength exhibited substantial increments of over the gum due to better dispersion. The unmodified montmorillonite clay (Cloisite® Na+) failed to improve the above properties significantly. The limitations of Cloisite® Na+-based NR nanocomposites prepared by the conventional method were alleviated using latex blending technique. Pre-exfoliated aqueous suspension of Cloisite® Na+ was blended with NR latex under special conditions and cured by pre-vulcanization as well as conventional curing. These showed predominantly exfoliated morphology along with substantially improved physical and mechanical properties. A simple theory based on effective surface area factor was proposed to account for the structure—property correlations.

Preparation and characterization of elastomer-based nanocomposite gels using an unique latex blending technique

Nanocomposite (NC) gels based on natural rubber (NR) and styrene butadiene rubber (SBR) were prepared by using a unique latex blending technique. These NC gels were prepared by first blending the water swollen unmodified montmorillonite clay (Na+-MMT) suspension into the respective latices followed by prevulcanization to generate crosslinked nanogels. Use of water assisted fully delaminated Na+-MMT suspension resulted in predominantly exfoliated morphology in the NC gels, as revealed by X-ray diffraction study and transmission electron microscopy. Addition of Na+-MMT significantly improved various physical, mechanical and thermal properties of these NC gels. For example, 6 phr of Na+-MMT loaded NR based NC gels registered 54% and 200% increase in tensile strength and Young's modulus, respectively, compared to the unfilled NR gels. SBR based NC gels also showed similar level of improvement in mechanical properties. Mechanical properties of NC gels prepared using this route were also compared with the NC gels prepared by co-coagulation and conventional curing technique and found to be superior. In the case of dynamic mechanical properties, NC gels showed higher glass transition temperatures along with a concomitant increase in storage moduli, compared to the unfilled gels. These Na+-MMT reinforced NC gels also exhibited markedly improved thermal stability. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Effect of different nanoparticles on thermal, mechanical and dynamic mechanical properties of hydrogenated nitrile butadiene rubber nanocomposites

AbstractOrganically modified and unmodified montmorillonite clays (Cloisite NA, Cloisite 30B and Cloisite 15A), sepiolite (Pangel B20) and nanosilica (Aerosil 300) were incorporated into hydrogenated nitrile rubber (HNBR) matrix by solution process in order to study the effect of these nanofillers on thermal, mechanical and dynamic mechanical properties of HNBR. It was found that on addition of only 4 phr of nanofiller to neat HNBR, the temperature at which maximum degradation took place (Tmax) increased by 4 to 16°C, while the modulus at 100% elongation and the tensile strength were enhanced by almost 40–60% and 100–300% respectively, depending upon nature of the nanofiller. It was further observed that Tmax was the highest in the case of nanosilica‐based nanocomposite with 4 phr of filler loading. The increment of storage modulus was highest for sepiolite‐HNBR and Cloisite 30B‐HNBR nanocomposites at 25°C, while the modulus at 100% elongation was found maximum for sepiolite‐HNBR nanocomposite at the same loading. A similar trend was observed in the case of another grade of HNBR having similar ACN content, but different diene level. The results were explained by x‐ray diffraction, transmission electron microscopy, and atomic force microscopy studies. The above results were further explained with the help of thermodynamics. Effect of different filler loadings (2, 4, 6, 8, and 16 phr) on the properties of HNBR nanocomposites was further investigated. Both thermal as well as mechanical properties were found to be highest at 8 phr of filler loading. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010