Montmorillonite Organoclay Research Articles

Removal and detoxification of iprodione in water using didodecyldimethylammonium bromide-montmorillonite organoclay and manganese dioxide.

Combination of organoclay sorption with manganese(IV) oxide (MnO2) catalyzed catechol oxidation was studied for the removal of a dicarboximide fungicide, iprodione, from water. Iprodion in water was sorbed on didodecyldimethylammonium bromide (DDAB)-modified montmorillonite (MT) organoclay and converted into the degraded product, 3,5-dichloroaniline (DCA). The degree of sorption increased by the modification with DDAB, because of the formation of a hydrophobic region for the incorporation of iprodione and negligibly interfered by coexisting MnO2. The half-life for the degradation of irodione in water at 25°C was 7 days, whreas it reduced to 15min in the organoclay. The activation energy, 65.4 ± 4.8kJmol-1, for the first-order reaction in the aqueous solution (pH 7.0) decreased to 43.9 ± 1.8kJmol-1 in the organoclay, indicating the catalytic activity of the organoclay that accelerates the hydrolysis reaction of iprodione. In the coexistence of appropriate amounts of MnO2 and catechol, the degraded product, DCA, reacted with oxidized products of catechol to form a water-insoluble precipitate and was successfully eliminated from water. The results obtained in the present study strongly suggest the applicability of the combined method of organoclay sorption method and MnO2-catalyzed oxidation for the diffusion control of toxic agrochemicals.

Development and characterization of alginate@montmorillonite hybrid microcapsules for encapsulation and controlled release of quercetin: Effect of clay type

In the present study, different organic and hybrid systems for quercetin (Qr) encapsulation were developed, namely Ca-Alginate (Qr-Alg), Ca-Alginate@Na-montmorillonite (Qr-Alg@Na-Mnt), and Ca-Alginate@CPC-montmorillonite (Qr-Alg@CPC-Mnt).Attenuated total reflecting-Fourier-transform infrared (ATR-FTIR) analysis was used to characterize and prove quercetin encapsulation in the developed microcapsules. The encapsulation efficiency (EE) and loading capacity (LC) of quercetin in elaborated biomaterials were determined. Besides, the release kinetics of quercetin molecules from organic and hybrid microcapsules were carefully investigated in two different aqueous mediums; pure distilled water and distilled water containing Tween 20 (1%, w/v).The obtained results show that all developed microcapsules have a good encapsulation efficiency and loading capacity within the range 97.65 ± 0.57–99.47 ± 0.38% for the EE and 19.26 ± 0.46–23.29 ± 0.82 mg/g for the LC. The release rates of Qr from organic microcapsules Qr-Alg, hybrid microcapsules Qr-Alg@Na-Mnt, and Qr-Alg@CPC-Mnt in distilled water containing Tween 20 (1%, w/v) are 52, 49, and 113 times bigger, respectively, than release rate in distilled water.In addition, the kinetics release from hybrid microcapsules was slower in comparison to organic microcapsules. Also, in the case of hybrid microcapsules, the rate of kinetic release of quercetin from Qr-Alg@Na-Mnt was greater than the one from Qr-Alg@CPC-Mnt. This is due to the strong interactions of quercetin molecules with nanoparticle functional groups of cetylpyridinium chloride modified montmorillonite organoclay (CPC-Mnt) compared to sodium montmorillonite (Na-Mnt). The kinetics of Quercetin release from all developed organic and hybrid microcapsules follows the Korsmeyer–Peppas model and is controlled by non-Fickian diffusion.

Fabrication and Characterization of Cellulose Acetate/Organo-Montmorillonite Composite Membrane for Ion Adsorption

This study presents the results of modifications done to cellulose acetate (CA) membranes intended for filtration purposes using organo-montmorillonite (O-MMT) clay. The researchers incorporated O-MMT with CA to synthesize composite CA/O-MMT membranes via hand casting. The produced membranes were then characterized to determine the effect of O-MMT of varying % wt. concentrations to its surface morphology and wettability. Morphology of the membranes were observed under a Scanning Electron Microscope (SEM), while its wettability was accounted for by subjecting the samples to contact angle and porometer analysis. SEM images revealed that the presence of O-MMT generally affects the membrane’s surface roughness while the pore size test results show that increasing the concentration of O-MMT leads to a larger average pore size. Conductivity test data suggest that though becoming less hydrophilic, the modified membranes still hold efficient in removing the salt ions from the solution and that the amount of O-MMT concentration present in the CA/O-MMT membranes is the main determining factor behind its efficacy for ion adsorption.

Localization of different types of organoclay montmorillonite in the compatibilized polyamide 6/carboxylated acrylonitrile butadiene rubber nanocomposites: Morphology and rheological properties

AbstractIn this study, nanocomposites based on polyamide 6/carboxylated acrylonitrile butadiene rubber (PA6/XNBR) reinforced by the clay montmorillonite (OMMT) (Cloisite 20A and Cloisite 30B) were prepared by melt mixing. Glycidyl methacrylate‐grafted XNBR (XNBR‐g‐GMA) compatibilizer was used for immiscible blends of PA6/XNBR. The results illustrated that OMMT wanted to be selectively present in the more hydrophilic PA6 phase. Also, by adding the XNBR‐g‐GMA compatibilizer and increasing OMMT content, tensile strength, rheological and dynamic mechanical properties of the nanocomposites improved. According to transmission electron microscopy (TEM) images, a few layers of OMMT (Cloisite 20A) in the XNBR‐g‐GMA compatibilizer phase was observed. The results of X‐ray diffractometry and TEM analyses demonstrated that the formation of intercalated or exfoliated structures for both types of OMMT nanocomposites. In end of all analysis was found PA6/XNBR reinforced by the Cloisite 30B could be substantially improved by adding XNBR‐g‐GMA as a compatibilizer when compared to those reinforced by Cloisite 20A.

Synthesis and Characterization of Polycaprolactone(PCL)/Organo-Montmorillonite(O-MMT) Blendvia Solvent Casting

Polycaprolactone (PCL) is a hydrophobic, semi-crystalline polymer that has been broadly applied in long term implants, drug release applications, and in the tissue engineering field due to its availability, relatively inexpensive price and suitability for modification. Organo-montmorillonite (O-MMT) clay has been extensively used for various polymer-nanocomposite studies and widely used as adsorbent due to its high specific surface area. Most polymer clay nanocomposites are involved in biomedical applications such as in drug delivery systems and wound healing. In this study, O-MMT was incorporated to PCL via solvent casting, which resulted into film membranes that were characterized to identify its surface morphology, chemical structure, wettability, mechanical property, pore size, and antibacterial properties upon its varying concentrations. The SEM and FTIR results indicated the presence of both PCL and O-MMT within the membrane. The mechanical properties of the film membranes showed an improvement upon reaching an optimal point. An increase in pore size was determined relative to its hydrophilicity. The film membrane showed an antibacterial activity only at the higher concentrations of the O-MMT using the S. aureus strain. As such, the results showed that there is an improvement in the mechanical, wettability, water absorption and antibacterial properties of the PCL with the incorporation of the O-MMT, making it a viable candidate dressing material for wound healing.

Photo-stabilization of biopolymers-based nanocomposites with UV-modified layered silicates

Eco-friendly in-situ stabilised biopolymer nanocomposites based on polyamide 11 (PA11) and polylactic acid (PLA) were prepared by melt mixing in the presence of a modified organo-montmorillonite clay containing a chemically-bound hindered amine UV-stabilising function, [(UV)OM-MMt]. Characterisation of the newly synthesised organo-modifier containing the reactive hindered amine (HAS) UV-stabilising function [(UV)OM] has confirmed a successful synthesis. The (UV)OM was then introduced into NaMMt through ion exchange reaction to prepare the UV stabiliser-bound organo-modified-MMt, [(UV)OM-MMt]. The in-situ stabilised PA11- and PLA- nanocomposites (PA11-(UV)OM-MMt and PLA-(UV)OM-MMt) were characterised and their photoxidative stabilities (under accelerated weathering conditions) were compared with their nanocomposite analogues containing either the organo-modified MMt (OM-MMt) alone (i.e. without UV-stabiliser) or the OM-MMT containing conventionally added commercial hindered amine HAS-UV-stabiliser (Cyasorb® UV-3853). It was found that both of the newly prepared in-situ stabilised PA11- and PLA- nanocomposites gave good clay dispersion and have demonstrated a much higher, especially in PLA-nanocomposites, photo-oxidative stability compared to the corresponding nanocomposites but in the absence, or the presence, of the conventionally added HAS-UV-stabiliser.

Rapid sorption of fenitrothion on didodecyldimethylammonium bromide-montmorillonite organoclay followed by the degradation into less toxic 3-methyl-4-nitrophenolate

Abstract Didodecyldimethylammonium bromide (DDAB)-modified montmorillonite (MT) organoclay was used for the sorption and degradation of an organophosphate pesticide, fenitrothion, in water. The degree of sorption increased by the modification of MT with DDAB, because of the formation of hydrophobic DDAB assemblies for the sorption of hydrophobic fenitrothion. Fenitrothion ([M + 1] = 278) sorbed on the organoclay rapidly converted to the degraded product anion ([M] = 262) followed by the further degradation into 3-methyl-4-nitrophenol ([M-1] = 152). The activation energy for the first-order reaction of the primary degradation of fenitrothion (79.9 kJ mol-1) in the organoclay was lower than the value (94.1 kJ mol-1) in water. Organoclay-mediated catalytic activity expressed over a wide pH region (pH 5-9), being advantageous for the application to different wastewaters and environmental waters. Continuous sorption and degradation of fenitrothion in contaminated water was examined by using a laboratory-scale organoclay-packed column. Fenitrothion-free effluent containing its degraded product, 3-methyl-4-nitrophenol, having lower toxicity to aquatic organisms outflowed from the bottom of the column. These results strongly suggests the usefulness of DDAB-MT organoclay as a barrier material for diffusion control of organophosphate pesticides.

Synthesis and Characterization of Organo- Montmorillonite Clay and its Metal complexes for Polypropylene Clay Nano composites Applications

1-acetylpyridinium Chloride-salicyolhydrazone (H2ACSH) was prepared from Salicylaldehyde and 1-acetylpyridinium chloride hydrazide for using in modification of sodium montmorillonite clay in order to prepare organo - montmorillonite clay (OMC) and its Zinc (OMC-Zn) and Zirconium (OMC-Zr) complexes in two different weight percentage (3 and 7 wt %). Polypropylene /clay nanocomposites were prepared by melt intercalation technique using the prepared organo - montmorillonite clay and its metal complexes The obtained nanocomposites were characterized by infrared absorption spectroscopy (FTIR) and atomic force microscopy (AFM) to determine the morphology of obtained materials. The thermal behavior was evaluated from thermo gravimetric analysis (TGA). The combustion behavior of these intercalated ratios was studied using cone calorimeter measurement to assess the PP/clay nanocomposites behavior during combustion. The obtained results indicate decreased flammability properties of PP/clay nanocomposites due to better char enhancement. The new clay provides opportunities for melt blending of polymers with clay to obtain composites materials with important properties.

Enhancing the physico-mechanical properties of irradiated rubber/waste plastic blend via incorporation of different fillers for industrial applications

Abstract The effect of gamma radiation on the physico-mechanical properties of ethylene propylene diene monomer rubber/styrene butadiene rubber/waste high density polyethylene blend EPDM/SBR/wHDPE (50/50/30) blend reinforced with different types of fillers 10 phr (part per 100 part of rubber, by weight) of HAF-carbon black, Hisil, and prepared modified organo-montmorillonite (OMMT) clay was investigated. The results obtained showed that the organo-montmorillonite (OMMT) clay is the most effective filler for enhancing the physico-mechanical properties of EPDM/SBR/wHDPE vulcanized composites. Scanning electron microscopy and thermogravimetric analysis characteristics were also, studied.

Formulation of Petrolatum/Clay Nanocomposite Coating and Characterization of its Corrosion Resistance Properties

Montmorillonite organoclay, in different amounts (between 1 to 5 wt %), was incorporated into the petrolatum using mechanical stirring and sonication process. Anti-corrosive properties of the compounded nanocomposites were investigated using salt spray and electrochemical impedance spectroscopy (EIS) methods. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy analysis (EDX) showed that the interlayer spacing of clays was increased after addition of petrolatum resin along with applying shear force and ultrasounication. Electrochemical analyses showed improvement in the barrier and anti-corrosive characteristics of formulated nanocomposite coatings. The best performance of formulated coatings was achieved with coating containing 1 wt % clay concentration.

2,4-Dichlorophenoxyacetic acid adsorption on montmorillonite organoclay for controlled release applications

2,4-Dichlorophenoxyacetic acid (2,4-D) is one of the most used herbicides for weed control. However, the use of large concentrations of 2,4-D is dangerous and have great carcinogenic potential. Thus, this work evaluated the 2,4-D sorption behavior by an organically modified montmorillonite nanoclay using kinetic and thermodynamic approaches. Adsorption isotherms and kinetic studies, conducted under controlled temperature and pH conditions, indicated a high capacity of the nanoclay to remove 2,4-D from aqueous medium, being that the adsorption mechanism probably involved physisorption and chemisorption. Besides, thermodynamic parameters obtained showed that the adsorption was enthalpically driven for the physisorption step, with $$\Delta H^{ \circ }$$ = − 9.849 kJ mol−1. The analyses showed that 2,4-D adsorption caused a partial exfoliation of the montmorillonite structure, probably due to the high herbicide concentration utilized. Release studies of 2,4-D from the nanoclay showed that the desorption process occurred in two steps, a burst release of the 2,4-D molecules followed by a slow release. The results demonstrated by this study indicates the feasibility of the proposed system for controlled release or even water treatment applications.

Investigating the effect of organoclay montmorillonite and rubber ratio composition on the enhancement compatibility and properties of carboxylated acrylonitrile-butadiene rubber/ethylene-propylene-diene monomer hybrid elastomer nanocomposites

In this work, a reinforcing organoclay montmorillonite (OMMT) (i.e., 0, 2.5, 5, 7.5 and 10 phr) and novel alloys were prepared, which significantly improved the thermal, mechanical and rheological properties of immiscible XNBR/EPDM alloys. Results revealed that optimum cure time (t90) and scorch time (t5), decrease with increasing OMMT (Cloisite 15A) content; while the cure time was prolonged with increasing EPDM content. The results of X-ray diffraction show an increase in the distance between the layers of the silicate plates in the continuous XNBR/EPDM rubber phase in all of the compositions compared with the nanoclay powder. This indicates the penetration of rubber chains among the silicate layers. This phenomenon was also confirmed by direct observation of the intercalated and exfoliated microstructure of the nanocomposite by a transmission electron microscopy (TEM).

Pressure Sensibility of Conductive Rubber Based on NBR- and Polypyrrole-Designed Materials

Conductive rubbers combine features such as elasticity and electrical conductivities. Here, we developed an elastic conductive material based on nitrile rubber (NBR) and polypyrrole (PPy) by melt processing. PPy was also synthesized in three different media as silver (PPy-Ag), organomontmorillonite (PPy-OMt) and silver-organomontmorillonite (PPy-Ag-OMt) before mixture with NBR. Chemical structure, morphology, and stress-strain properties were evaluated. Pressure sensibility was evaluated in the range of 0-67 MPa during ten cycles. During the compression and expansion processes, the electrical conductivity changes from high to low values and the difference of loading and unloading cycles demonstrate the repeatability and low hysteresis. The organomontmorillonite clay improves the homogeneity of particles into the matrix and based on SEM images the dispersity follows the sequence PPy-OMt, PPy-Ag-OMt and PPy-Ag-OMt. This behavior affects the electrical conductivity, mechanical and electromechanical properties. The higher elastic modulus for composites compares to neat NBR is assigned to the reinforcing effect of the fillers. NBR/PPy-Ag-OMt (5wt.%) is the best material in the absolute value of Scomp (46.3 %/MPa) and the Scomp/hysteresis ratio (8.5%). In spite of different formulations displayed the best performance on the evaluated criteria (highest absolute conductivity, the highest percentage change in conductivity, lowest hysteresis and lack of sample disruption), we can suggest that a lower amount of conducting particles benefits the reticulation process (as observed by the gel fractions values). Additionally, the possibility to use mechanical processing to obtain large scales pressure sensor materials are without doubts the most important outcomes for this research area.

Effects of two types of nanoparticles on the cure, rheological, and mechanical properties of rubber nanocomposites based on the NBR/PVC blends

ABSTRACTThe effects of graphene nanoplatelet (GNP) and organoclay montmorillonite (OMMT) on the curing, relaxation, and the mechanical properties of acrylonitrile‐butadiene rubber/polyvinyl chloride (NBR/PVC) nanocomposites were investigated. Scorch and cure times of nanocomposites reinforced with GNP increased, while these parameters for nanocomposites reinforced with OMMT decreased. Maximum torque and cure rate increased after adding the nanoparticles. In the relaxation curves, with increasing nanoparticle and acrylonitrile (ACN) content, both the slopes of short‐ and long‐term regions, raised. Cured compounds have the significantly higher initial and final modulus, the greater elastic slope, and lower viscous slope than the uncured ones. The results of the relaxation test showed that the relaxation percentage in the uncured samples was much higher than the cured ones. Also, with the addition of both GNP and OMMT, this parameter had an upward trend. DGS/DGL parameter increased with the addition of nano‐reinforcements in the uncured state while decreasing in the cured state. For example, the blend containing N3 reinforced via GNP showed an 11% increase in the uncured state, whereas 14% reduction in the cured state. Tensile strength, elastic modulus, and hardness were improved by incorporating nanoparticles, while the effect of GNP was more intense. The similar trend observed in samples with NBR type of higher ACN content. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47550.

Preparation and Flammability Properties of Polyethylene/Organoclay Nanocomposites

Polyethylene (PE) nanocomposites were prepared by melt intercalation, in order to evaluate the flame retardant effect of this material. For the development of nanocomposites were used the montmorillonite clay (MMT), organoclay (OMMT) and flame retardant product (FRP) with the percentage of 1, 3, 6 and 9 wt%. Grafted polyethylene with maleic anhydride (PE-g-MA) was used as a compatibilizer of the systems. PE and its systems were evaluated: XRD, TEM, TG and flammability (UL94HB, oxygen index (LOI) and cone calorimetry). The X-ray diffraction showed a partial intercalation and exfoliation as well as formation of microcomposite. The phase morphology of the systems was observed by TEM that it showed that the system with 1% OMMT clay presented a predominance of exfoliation. Already the system with 3% OMMT showed partial exfoliation and this exfoliation reduced as the clay content increased. By TG it was seen that MMT, OMMT and FRP acted improving the thermal behavior of the nanocomposites compared to PE matrix. The results obtained for the oxygen index showed that both PE and its systems presented flame retardancy behavior. By means of the horizontal flammability tests, it was found that the presence of 1% MMT clay reduced 25% the flammability of PE. By cone calorimetry it was found that the system that contains 9% of OMMT clay decreased by about 33% the flammability of PE.

The use of montmorillonite organoclay in preparation of UV-cured DGBA epoxy anticorrosive coatings

ABSTRACTIn this study, montmorillonite organoclay (OMMT) at various concentrations were tested as nanofillers in preparation of UV-cured DGEBA epoxy anticorrosive coatings and applied on carbon steel substrates. The effect of incorporating different compositions of OMMT in UV-cured Araldite 506 coatings on the aqueous corrosion resistance of carbon steel in 5 wt-% aqueous NaCl electrolyte was evaluated. Analysis showed that the OMMT was homogenously dispersed in the polymer matrix. The result of X-ray diffraction showed that a certain degree of intercalation occurred for the OMMT in the polymer matrix. The OMMT addition affects the UV cured of the Araldite 506, as evidenced by Fourier transform infrared spectroscopy. The anticorrosive properties were evaluated by electrochemical impedance spectroscopy at various exposure periods. Coatings with 3 wt-% OMMT possessed the best corrosion performance among the coating specimens. In fact, the NC3 coating provided corrosion protection properties even after a long exposure to NaCl solution.

Flame retarding polyamide 11 with exfoliated vermiculite nanoflakes

Polyamide 11‐based bionanocomposites were prepared by melt compounding with 10 wt% clays of different chemistry and morphology. This included vermiculite nanoflakes obtained by consecutive thermal and ultrasonic exfoliation in both neat and organo‐modified form. The mechanical reinforcement‐ and flame‐retardant performance of the vermiculite clays were compared to organo‐modified montmorillonite (Cloisite 30B) and needle‐shaped sepiolite (Pangel S9). Electron microscope investigations revealed different structures and dispersion levels of the clay nanoparticles in the polymer matrix. Tensile tests showed that the addition of clays led to considerable improvements in Young's modulus without compromising the elongation at break. Compared to the neat polymer, all clays reduced the peak heat release rate and the smoke production rate in cone calorimeter testing. Surprisingly, the needle‐shaped sepiolite clay and the two vermiculites outperformed the montmorillonite organoclay in the fire testing even though it featured the highest degree of exfoliation in the polymer matrix. POLYM. ENG. SCI., 58:1746–1755, 2018. © 2017 Society of Plastics Engineers

Novel strategic approach for the thermo- and photo- oxidative stabilization of polyolefin/clay nanocomposites

Polyolefin/clay nanocomposites were prepared by melt mixing and their oxidative stability was studied under long-term thermo- and photo-oxidative test conditions in the absence and presence of a modified organo montmorillonite clay (OM-MMt) containing a chemically-bound hindered phenol antioxidant function, (AO)OM-Mt. It was found that nanocomposites based on both polyethylene (PE) and polyethylene-grafted-maleic anhydride (PEgMA) containing the (AO)OM-Mt gave a higher oxidative stability, along with better clay dispersion, compared to analogous PE or PEgMA-based nanocomposites containing an added (free) conventional antioxidant with a similar hindered phenol function (using the commercial hindered phenol Irganox® 1076). These findings can be explained in terms of the ability of the organo-modifier containing the in-built antioxidant function to act locally at the interface between the clay silicate layers and the polymer macromolecules thus contributing to the improved stability of the polymer observed both during long-term thermal- and photo-oxidative treatments.

Complete Defluorination of Perfluorinated Compounds by Hydrated Electrons Generated from 3-Indole-acetic-acid in Organomodified Montmorillonite.

Here we describe a unique process that achieves complete defluorination and decomposition of perfluorinated compounds (PFCs) which comprise one of the most recalcitrant and widely distributed classes of toxic pollutant chemicals found in natural environments. Photogenerated hydrated electrons derived from 3-indole-acetic-acid within an organomodified clay induce the reductive defluorination of co-sorbed PFCs. The process proceeds to completion within a few hours under mild reaction conditions. The organomontmorillonite clay promotes the formation of highly reactive hydrated electrons by stabilizing indole radical cations formed upon photolysis, and prevents their deactivation by reaction with protons or oxygen. In the constrained interlayer regions of the clay, hydrated electrons and co-sorbed PFCs are brought in close proximity thereby increasing the probability of reaction. This novel green chemistry provides the basis for in situ and ex situ technologies to treat one of the most troublesome, recalcitrant and ubiquitous classes of environmental contaminants, i.e., PFCs, utilizing innocuous reagents, naturally occurring materials and mild reaction conditions.

Effects of nanoclay and nanocomposites on bitumen rheological properties

Nanoclays have been successfully introduced into the asphalt, either separated or in the form of polymer/bitumen blends, improving mechanical and rheological properties. In this paper, the organoclay montmorillonite (OMMT) was prepared to be used as an additive for bitumen and for a polymer modified bitumen. A nanoclay Cloisite® 20Å (CLO), was also investigated for comparison purposes. A bitumen was modified with 4% nanoclays (OMMT and CLO), with 4% SBS, and with 4% SBS/nanoclay. All modified bitumens (MB) exhibited higher G∗ and lower δ, indicating an improvement in the stiffness and in the elasticity. SBS/Nanoclay MB presented similar rheological behavior compared to SBS MB which may result in cost savings. The addition of SBS and SBS/OMMT resulted in increase in PG grade and decrease in non-recoverable creep compliance (Jnr) indicating a better rut resistant compared to pure bitumen.