MMT Clay Research Articles

Effect of fiber hybridization and montmorillonite clay on properties of treated kenaf/aloe vera fiber reinforced PLA hybrid nanobiocomposite

Hybrid fiber reinforced polymer nanobiocomposites were prepared from kenaf fiber, aloe vera fiber, polylactic acid (PLA), and montmorillonite (MMT) clay through the compression molding method. The effects of fiber hybridization and MMT clay on their mechanical, water absorption, thermal and biodegradability properties were studied. Before fabrication, kenaf and aloe vera fibers were treated with the 6% sodium hydroxide solution to improve the bonding nature and compatibility between fibers and PLA matrix. Results indicated that the biocomposites thermal, tensile, flexural, impact, abrasion resistance, and water resistance properties were increased by adding of MMT clay. The mechanical properties were found to be increased upon 15 wt% kenaf fiber, 15 wt% aloe vera fiber hybridization and 1 wt% MMT clay incorporated. In addition, the 1 wt% MMT clay included hybrid nanobiocomposite exhibited increased tensile strength, flexural strength, impact strength, and abrasion resistance by 5.24, 2.46, 37.10, and 23.91%, respectively compared to virgin PLA. Additionally, the tensile and flexural moduli of these nanobiocomposite are improved by 24.61 and 108.09%, respectively, than neat PLA. With the addition of 3 wt% MMT clay resulted in the biocomposite decomposition temperature from 280 to 307 °C at T10 likewise 337 to 361 °C at T75 SEM analysis disclosed that MMT clay strongly enhances the bonding and compatibility among fibers and PLA. TEM result reveals that the quality of MMT dispersion decreases with increase in MMT content. The fiber hybridization improved the biodegradability and water resistance properties of biocomposites, however, the addition of MMT clay improved water resistance but decreased biodegradability.

Effect of montmorillonite clay on the fluorescence resonance energy transfer between two cationic dyes Acridine Orange and Rhodamine B in solution

In this article the Fluorescence resonance energy transfer (FRET) between two important cationic dyes namely Acridine Orange (AO) and Rhodamine B (RhB) in aqueous solution in presence and absence of montmorillonite (MMT) is demonstrated. The energy transfer is also studied in ethanolic solution. Excited state energy migration is occurred from AO to RhB molecules and the extent of energy transfer efficiency linearly increases with increase in RhB concentration in the solution. Interestingly the incorporation of MMT clay significantly increases the energy transfer efficiencies between the dye pair in the solution but the nature of interaction depends on the clay concentrations studied in the present work. The nature of quenching of steady state fluorescence emission of AO in presence of RhB as well as MMT clay in the mixed ensemble is systematically investigated and further confirmed by Time-resolved fluorescence and temperature-dependent steady state fluorescence emission experiments. AO and RhB dye molecules formed ground state complex with MMT clay followed by static quenching. As the clay platelets successfully control the FRET efficiency and it is also well known that MMT clay can host wide diversity of molecular species therefore, the present studies may provide a new insight for the design and the development of FRET-based molecular sensors.

Influence of Montmorillonite Clay Content on Thermal, Mechanical, Water Absorption and Biodegradability Properties of Treated Kenaf Fiber/ PLA-Hybrid Biocomposites

Nowadays, the starring attentions of the polylactic acid based composites are improved due to environmental awareness and diminution of petroleum oil. The bio-plastics were restricted to limited applications due to its higher cost. The bio-plastics filled fiber and or fillers lessen the cost with enhanced properties. In this research, the PLA- biocomposite and PLA-hybrid biocomposites were prepared with twin screw extruder, two-roll mill, and compression molding method. The PLA based bio and hybrid biocomposites are fabricated with 30 wt% of treated kenaf fiber and 0, 1, 2 and 3 wt% montmorillonite clay filler. The influence of MMT clay on thermal, mechanical, water absorption and biodegradable properties of PLA-biocomposite and PLA-hybrid biocomposites has been studied. The PLA-hybrid biocomposites thermal, mechanical and water resistance properties are increased with adding of MMT clay. However, 1 wt% MMT clay included PLA-hybrid biocomposite exhibits increased tensile, flexural and impact properties, and abrasion resistance than other PLA-hybrid biocomposites. The PLA-bio and hybrid biocomposites showed higher tensile and flexural modulus than pure- PLA. The results TGA analysis depicted that inclusion of MMT clay can improve the decomposition temperature of the biocomposite. SEM analysis discloses that, MMT clay it acts as a transfer mechanism. The water absorption and biodegradability properties results illustrates that water resistance of hybrid biocomposites improved and biodegradability decreased due to adding of MMT clay.

Preliminary study of the prepared polysulfone/AN69/clay composite membranes intended for the hemodialysis application

In this work, we target the preparation and characterization of asymmetric polysulfone nanocomposite charged membranes for hemodialysis application. The phase inversion technique was applied, using N-methylpyrrolidone and water as solvent and non-solvent, respectively. With the aid of blend method, the control membrane was modified using poly(acrylonitrile-co-sodium methallyl sulfonate) copolymer (AN69) and the montmorillonite clay (MMT). The estimation of MMT effect in polysulfone solution was carried out by a thermodynamic study using the titration method. Different techniques were applied in characterization of PSf/clay and PSf/AN69/clay membrane composites as Fourier transform infrared spectroscopy technique, coloration test, thermogravimetric analysis, differential scanning calorimetry analysis, X-ray diffraction, scanning electron microscopy, and water flux measurement. The obtained results show that the combination of hemocompatible PSf/AN69 blend and MMT nanocharge induces the formation of new hemodialysis composite membranes, with enhanced hydrophilic properties, good thermal sterilization resistance, better water permeability, and good capacity of protein adsorption. Besides, the obtained composite membranes have the ability to be easily functionalized due to the high density of negative charge resulting by the presence of AN69 and MMT clay at the membrane surfaces.

Adsorption properties of flouroquinolone type antibiotic ciprofloxacin into 2:1 dioctahedral clay structure: Box-Behnken experimental design

In this study, the removal of ciprofloxacin (CPx) from aqueous solutions by usingmontmorillonite (MMT) clay was studied. The effect of adsorbent amount, contact time, solution pH and temperature were experimentally performed in batch adsorption experiments to examine the adsorption capacity, isotherm, kinetic and thermodynamic parameters of the adsorption process. Under the experimental conditions the system reached equilibrium in 60 min and adsorption capacity was obtained 113.64 mg g−1. The maximum adsorption of CPx on the MMT clay was around 98% and the maximum adsorption capacity was found as 128 mg g−1 at pH 7. Adsorption mechanism was clarified with Langmuir, Freundlich, DubininRadushkevich and Temkin isotherm models. Adsorption experiments were performed at different temperatures to explain kinetic studies with pseudo first order, pseudo second order, intraparticle diffusion and Elovich model. The pseudo second-order kinetic model and Temkin isotherm model could better define the experimental data. Thermodynamic parameters showed that the CPx adsorption was endothermic and spontaneous. Also, the effect of such parameters as solid/liquid ratio (S/L), temperature (T) and pH on the adsorption of CPx was examined using response surface methodology based on Box–Behnken surface statistical design. According to Box-Benhken design, higher values of the correlation coefficients and p-values greater than 0.05 were in good adaptation with the optimum combination of process parameters, which demonstrated the fitness of the chosen model for evaluating the experimental data. In order to explain the interaction mechanism between MMT and CPx, FTIR, XRD, zeta potential and BET surface area analysis were performed before and after adsorption.

ZINC HYDROXIDE NANOPARTICLES-MODIFIED CLAY FOR ULTRASOUND-ASSISTED REMOVAL OF METHYLENE BLUE

The objective of the present work was to introduce a novel adsorbent with high adsorption potential toward methylene blue by decorating montmorillonite clay (MMT clay) with Zn(OH)2 nanoparticles (Zn(OH)2 NPs). The adsorbent was characterized structurally by FE-SEM and FTIR techniques. Central composite design response surface methodology was applied to optimize experimental variables including adsorbent dosage, pH, initial MB concentration, NaCl concentration, and sonication time. A modified quadratic model was used to establish a relationship between the removal percent of MB and the experimental variables. F value of 74.99 and squared correlation coefficient of 0.96 confirmed the significance and reliability of the model. Under the optimum conditions of pH 8.0, sonication time 3.5 min, adsorbent dosage 73 mg, analyte concentration 7.5 mg L-1, and electrolyte concentration (2 % w/v), the removal percentage of 99.3 0.70 % were attained. Freundlich isotherm was agree well with the adsorption isotherm data. The adsorption kinetic was best described by pseudo second order kinetic model. Thermodynamic study of the MB uptake on the sorbent shows the spontaneous (.G = -13.45 -34.15 kcal mol-1 in the temperature range of 15 45 C). These results infer that Zn(OH)2 NPs MMT clay can be applied as a new, low cost adsorbent in adsorbing MB from aqueous solution.

Mechanical, thermal, electrical and crystallographic behaviour of EPDM rubber/clay nanocomposites for out-door insulation applications

ABSTRACTIn this study, the degradation of tensile properties is investigated by placing the neat ethylene propylene diene monomer (EPDM) rubber and different weight percentages (2 wt%, 4 wt% and 6 wt%) of MMT clay dispersed in the EPDM rubber samples in a humidity chamber for 0, 5, 7, 12 and 14 days. The thermal properties of neat EPDM rubber and its clay nanocomposites were studied by using different instruments, namely dynamic mechanical analyser (DMA), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The viscoelastic properties are studied over the temperature range of −80°C to 80°C at different frequencies by using DMA. An increase in storage modulus and the decrease in loss tangent values are observed with the increase in clay content from 0 wt% to 6 wt% in EPDM rubber. Increase in storage modulus and glass transition temperature (Tg) values is observed with the increase in frequency from 1 Hz to 50 Hz. Also, the thermal stability and change in mass of these materials as a function of temperature and time are studied using TGA. It is found that EPDM/4 wt% clay composites exhibit the highest residual weight at 690°C while neat EPDM exhibits the highest weight loss compared to samples dispersed with other clay weight percentages. Using X-ray diffraction (XRD), 2θ value was measured and the crystal structure is investigated. Fourier transformed infrared spectroscopy (FTIR) was used to characterise the grafting of clay in the EPDM rubber. The dielectric constant and conductivity were studied for different frequencies and temperatures.

Influence of gold nanostructures incorporated into sodium montmorillonite clay based on LbL films for detection of metal traces ions

We report the effects of different gold nanostructures incorporated into sodium montmorillonite clay mineral (Na+-MMT) through thin films based on electrostatic interactions. The nanocomposite films were fabricated by layer-by-layer (LbL) technique using gold nanosphere (AuNSs) and gold nanorods (AuNRs) as cationic colloidal solutions, interacting with Na+-MMT clay as anionic dispersion. Higher performance was evaluated from electrochemical measurements for the detection of metal ions traces (Cd2+ and Cu2+). The interactions between materials were confirmed by UV–vis and FTIR spectroscopies and the effects of the Au nanostructures shape on Na+-MMT clay structures properties are confirmed by X-ray diffraction patterns. The results demonstrate that the AuNRs increase the lamellar space of Na+-MMT clay, consequently, increasing the roughness and favoring directly electrochemical response, with higher sensitivity and lower limits detection. Recovery was found to be 98.1% for cadmium but as high as 103.1% for copper, indicating that the modified electrode provides excellent reproducibility, stability, and promising applicability in the real water sample.

Synthesis of Montmorillonite Clay/Poly(vinyl alcohol) Nanocomposites and Their Mechanical Properties

The montmorillonite/poly(vinyl alcohol) (MMT/PVA) nanocomposites films were synthesized by aqueous dispersion of MMT clay to PVA solution at 70-75 °C for 4 h. The average thicknesses of the MMT/PVA films were 85-120 μm. The amount of clay was varied between 0-5 wt%. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis revealed the coexistence of exfoliated and intercalated structure of MMT clay in PVA. The Raman analysis of 1 wt% MMT/PVA showed, increased peak intensity at 1146.5 cm-1, that is indicator of higher crystallinity compare to pure PVA. Dynamic mechanical analysis (DMA) of MMT/PVA nanocomposite films showed an increase in the storage modulus. The optimum value of storage modulus obtained was 8,752 MPa on dispersing 1.0 wt% MMT clay in the PVA yielding 20.0% increase in the storage modulus compare to the pure PVA films. Thermo-gravimetric, analysis (TGA) of the MMT/PVA nanocomposite films also showed the increase in the thermal stability with respect to pure PVA films. The 1.0 wt% MMT clay loading in PVA, improved the thermal stability of MMT/PVA to 325 °C compared to 250 °C for pure PVA.

Effect of MMT Clay on Mechanical, Thermal and Barrier Properties of Treated Aloevera Fiber/ PLA-Hybrid Biocomposites

In this research, the PLA- biocomposite and PLA- hybrid biocomposites were prepared with twin screw extruder, two-roll mill, and compression molding method. The PLA based bio-composites are fabricated with 30% of treated aloevera fiber and 0, 1, 2 and 3 wt% nanoclay filler. The influence of MMT clay on thermal, mechanical and barrier properties of PLA-biocomposite and PLA-hybrid biocomposites has been studied. The PLA-hybrid biocomposites thermal, mechanical and water resistance properties are increased with adding of MMT clay. However, 1 wt.% MMT included PLA-hybrid biocomposites exhibits increased tensile, flexural, impact and abrasion resistance properties than PLA- biocomposite, the improvements 5.72, 6.08, 10.43, and 45.71% respectively are observed. The PLA-bio and hybrid biocomposites showed higher tensile modules 25.76, 18.84, 31.53 and 32.30% respectively, and flexural modules 61.42, 60.95, 66.66 and 79.04% respectively, than pure- PLA. The results TGA analysis depicted that inclusion of MMT clay can improve the decomposition temperature of the PLA-biocomposites. The addition of 3 wt.% MMT clay can improve the PLA- biocomposite decomposition temperature from 295 to 299o C in T 10% likewise 338 to 350o C in T 75%. SEM analysis discloses that, MMT clay not only improves micro-structure and also it acts as a load transfer mechanism. The Physical barrier properties and biodegradability results show that water resistance of biocomposites improved and biodegradability decreased due to adding of MMT clay.

Sepiolite Clay Attenuates the Development of Hypercholesterolemia and Obesity in Mice Fed a High-Fat High-Cholesterol Diet.

Obesity reduces the quality of life and life expectancy, whereas nonoperative interventions have shown poor results so far. Statins effectively combat hypercholesterolemia but are not well tolerated at high doses, raising the need for coprescription with cholesterol sorbents and/or absorption inhibitors. Montmorillonite (MMT) clay was found to attenuate hypercholesterolemia and obesity by reducing cholesterol and fat absorption. However, acicular clay-like sepiolite may offer better results due to its more substantial adsorption of nonpolar molecules. We herein aimed at (1) assessing in vitro the capacity of sepiolite to adsorb edible oil and cholesterol compared with that of MMT and (2) assessing in vivo the effect of continuous feeding on a high-fat high-cholesterol diet (HFD) (53.6% w/w fat and 0.2% cholesterol) supplemented with 5% (w/w) edible sepiolite, on diet-induced obesity rate, hypercholesterolemia, and hyperlipidemia. Fourier transform infrared spectroscopy showed in vitro that sepiolite adsorption of olive oil and cholesterol was five to eight times greater than that of MMT clay. Sepiolite supplementation to HFD fed to mature mice for 12.5 weeks resulted in lower total blood cholesterol and triacylglycerol levels and attenuated body weight gain, by reducing fat gain. Sepiolite supplementation did not affect energy intake but increased fecal extraction of sterols and lipids, without notable side effects. These results demonstrate that supplementing a HFD with sepiolite attenuates gastrointestinal absorption of dietary lipids and sterols, thus mitigating obesity, hyperlipidemia, and hypercholesterolemia. Further exploration of the efficacy, mechanism of action, and safety of sepiolite as a food supplement for combating the metabolic syndrome is needed.

Development of Optimum Combination of MMT Clay Reinforced Composite

The Montmorillonite (MMT) clay toughened epoxy (85%) / unsaturated polyester (15%) polymer blend system is developed. Studies on Mechanical, Thermal and Damping properties are conducted to determine the effect of the variations of MMT clay on the polymer blend. The Mechanical property studies showed that 3% clay reinforced polymer blend system exhibited optimum results, while the Damping property studies showed that 4% clay reinforced polymer blend system exhibited optimum results and Thermal property studies revealed that 5% clay reinforced polymer blend system exhibited optimum results. The prime objective of this work is to validate the obtained experiment results and to identify the best-fit combination. The results are validated by using Design Expert Version 8 Software. Validation of the experimental results, indicate negligible variations with the software generated results. Since different variations of clay percentages are achieved for different properties, a decision table is constructed to determine the best-fit combination suitable for the selected applications.

Rheological, morphological, mechanical, and water-barrier properties of agar/gellan gum/montmorillonite clay composite films

Agar (A), gellan gum (G) and montmorillonite (M) based ternary nanocomposite films were prepared via the solution-casting method for food packaging applications. The prepared nanocomposites were investigated for the effect of MMT clay on the structure–property relationships by studying the microstructural, rheological, mechanical, thermal, ultraviolet, and water-barrier properties of AG hydrogel composites. The results indicated that the thermal stability (T5%: 119.4–174.7) and tensile strength (29.9–44 MPa) were significantly enhanced in the reinforced MMT nanoclay. The water barrier (1.9–1.7) and contact angle (56.8°–49.4°) were reduced by the incorporation of MMT clay whereas the rheological properties improved. The AGM composite solution exhibited shear thinning behavior and viscosity reduction at a high rate. Additionally, the composites exhibited significantly higher storage and loss modulus at high frequencies. The complex viscosity differed from the shear viscosity and remained higher than the shear viscosity. The nanocomposite structure, molecular interaction, and interaction in the multicomponent were investigated by FT-IR, XRD and SEM analysis. The AG and AGM nanocomposites exhibited a synergistic reinforcement effect. The results of this study might introduce a new route for enhancing the nanocomposites for sustainable materials.

Carbon dioxide adsorption studies on modified montmorillonite clay/reduced graphene oxide hybrids at low pressure

The effect of modification of Montmorillonite clay (MMT) and the development of its hybrid with reduced graphene oxide was studied for CO2 adsorption at low pressure. Novel polyphosphoric acid modified montmorillonite (PMMT) clay was synthesized by cation exchange reaction to improve the surface area and thereby improving the carbon dioxide adsorption capacity. The MMT clay, polyphosphoric acid modified clay (PMMT), and amino modified clay (AMMT) were hybridized with reduced graphene oxide (rGO) by in-situ hydrothermal reduction of graphite oxide for CO2 adsorption studies. The hybrids were characterized using X-ray diffraction (XRD) analysis, Fourier Transform Infrared (FTIR) analysis, Field Emission Scanning Electron Microscopic (FESEM) and Transmission Electron Microscopic (TEM) analyses. The Brunauer–Emmett–Teller (BET) surface area analysis confirmed a surface area of 50.7709 m²/g for PMMT/rGO hybrid, which was higher than that of MMT/rGO and AMMT/rGO hybrids. In general, all hybrids were active in CO2 adsorption at comparatively low pressure [ranging from 0 to 900 mmHg]. PMMT/rGO hybrid showed highest CO2 adsorption of 0.49 mmol/g and this was 42% more in CO2 adsorption when compared to other materials studied in this paper. The low pressure CO2 adsorption values obtained for PMMT/rGO hybrid was substantially good when compared to the literature results and this shows the importance of clay based materials for the development of efficient adsorbent for CO2.

Membranes of polyamide 6/clay/salt for water/oil separation

In this work, polyamide 6 membranes (PA6) and nanocomposites with 1.0 wt%, 3.0 wt% and 5.0 wt% of montmorillonite clay (MMT) were obtained, adding inorganic salt. The MMT clay was characterized by x-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). The membranes were characterized by XRD, FTIR, scanning electron microscopy (SEM), contact angle (CA), flow measurements (FM) and yield. The viscosities of the solutions decreased with the increasing percentage of clay. By means of the XRD, it was seen that the nanocomposites membranes suggest an exfoliated and/or partially exfoliated structure. From the results of the FTIR the bands obtained in the PA6 membranes and its nanocomposites remained practically unchanged, as there was an increase in the clay content. By SEM, it was observed that the gradual addition of clay in the membranes provided an increase in the number and size of pores. By means of the CA, it was verified that the nanocomposites membranes presented smaller angles when compared to the PA6. The water-oil separation tests of the membranes, regardless of the pressure used, indicated a significant reduction of permeate oil with promising yields above 87%, presenting potential for the treatment of wastewater contaminated by oil.

Durability of Mortars Modified with Calcined Montmorillonite Clay

This study aims to evaluate the performance of mortars containing locally available Pakistani montmorillonite (Mmt) clay mineral as partial replacement of cement in various curing environments. The local montmorillonite clay in “As is” (20°C) and “heated” (100°C, 200°C, 300°C, 400°C, 500°C, 600°C, 700°C, 800°C, 900°C & 1000°C) conditions was incorporated in mortar cubes as partial replacement of cement. Montmorillonite clay of all the temperatures was replaced by 15%, 20%, 25%, 30% and 35% of cement mass in mortar cubes. The Strength Activity Index (SAI) was calculated to determine the optimum activation temperature for the clay. Compressive strengths of the controlled mix and montmorillonite modified mortars were evaluated under the Sodium Sulfate (SS) (5% solution) and mixed (Sodium Sulfate + Sodium Chloride (SCS)) (5% +3.5% solution) curing environments to study its durability performance. Upon thermal treatment montmorillonite clay showed maximum activation at 800°C temperature. Mortar containing (800°C) calcined montmorillonite clay with 25% cement replacement exhibit competent compression results. Moreover, up on exposure to aggressive environments, montmorillonite clay mortars performed better than the control samples. The mortar cubes exposed to Sulfate environment (SS) were more damaged in compression than that exposed to mixed environment (SCS), for all replacement levels and time exposures.

Synthesis of green emissive carbon dots@montmorillonite composites and their application for fabrication of light-emitting diodes and latent fingerprints markers

Multifunctional solid-state luminescent materials are strongly desired in a wide variety of applications. In this work, green emissive carbon dots@montmorillonite (g-CDs@MMT) composites were synthesized based on green emissive carbon dots and MMT clays in a convenient method by embedding g-CDs into the MMT clays. Due to the confinement of g-CDs in the layered structure of the MMT clay matrix, g-CDs are uniformly dispersed in the resulting g-CDs@MMT solid-state composites. This efficiently prevents the aggregation-induced solid-state luminescence quenching of g-CDs, and a photoluminescence quantum yield of 11% could be achieved by the g-CDs@MMT composites under a 405 nm light. Additionally, the g-CDs@MMT composites exhibit low-toxicity, excellent thermal stability, photostability, resistance to organic solvents, and a small particle size. All of these advantages enable applications in fabricating white light-emitting diodes with different color temperatures, where the g-CDs@MMT composites are applied as the color conversion layer. Furthermore, by using the g-CDs@MMT composites as a fluorescence labeling marker, the latent fingerprint detection on a variety of object surfaces could be realized.

Rheological mucoadhesion and cytotoxicity of montmorillonite clay mineral/hybrid microparticles biocomposite

A biocomposite based on montmorillonite clay mineral (MMT) and hybrid biopolymer microparticles (MP) carrying atorvastatin (AC), these were designed for oral drug carrier was characterized by scanning and transmission electron microscopy (SEM &TEM), differential scanning calorimetry (DSC) and in vitro biocompatibility by cell viability on fibroblast cells. The rheological synergism relation (by linear oscillatory tests at different pH and frequency) with the mucoadhesive properties revealed interactions between isolated mucin and the MP/MMT biocomposite and those between the mucin and the individual components. Results of these tests showed that the MP/MMT biocomposite provides an improvement in the thermal stability and hence good biocompatibility exhibiting anti-proliferation effects at high concentrations. To our knowledge, no previous reports exist on the determination of the rheological synergism in biocomposites with MMT clay either alone. Moreover, we found a dependence of the rheological synergism on pH and frequency provided by linear viscoelastic data at low frequencies. The MP/MMT biocomposite possesses the highest rheological synergism related to the strongest interaction with mucin at pH 1.6.

Valorization of waste rice husk by preparing nanocomposite with polyvinyl chloride and montmorillonite clay

Naturally available waste biomass rice husk (RH) was modified and used to prepare nanocomposites with polyvinyl chloride (PVC) and montmorillonite clay (MMT) in a green pathway of melt blending. Three different percentages of MMT were introduced into the RH/PVC composites and their effects on various properties of composite were examined. The interaction between PVC, RH, polyethylene-grafted maleic anhydride, and MMT clay in the nanocomposite (RHPNC) was studied by Fourier transform infrared spectroscopy and thermal properties were studied using dynamic mechanical analysis and thermogravimetric analysis. Universal testing machine and limiting oxygen index flammability tester were used to study the mechanical and flame retardency properties, respectively. The delamination of MMT layers and surface morphology of clay-incorporated nanocomposites were analyzed by X-ray diffractometry, scanning electron microscopy, and transmission electron microscopy. Surface of 5 phr (parts per hundred) MMT-loaded composites appeared smoother than those of composites containing 2 or 5 phr MMT. RHPNC with 5 phr MMT showed an overall improvement in mechanical, thermal, and flame-retardant properties. Composites containing 5 phr MMT showed a decrease in water uptake capacity compared to either 2 phr or 10 phr MMT-loaded composites.

Effective Adsorption of Cr(VI) by High Strength Chitosan/Montmorillonite Composite Hydrogels Involving Spirulina Biomass/Microalgae

The “3-in-1 type” biopolymer composite (chitosan/montmorillonite clay/biosorbent) hydrogels were produced and used as adsorbents for Cr(VI) ion. Na-Montmorillonite (NaMMT) clay was modified with Spirulina (Sp) biosorbent by using lyophilization based “cryoscopic expansion” (C-XP) method. The Sp immobilized MMT (SpMMT) clay containing hydrogels were found to have an open/extended form of Sp structure on their pores’ walls, presenting all possible receptor groups for adsorption of Cr(VI) ions. SpMMT loaded hydrogels showed higher adsorption capacities than NaMMT loaded ones. The physically crosslinked hydrogel including only 1% SpMMT (1SpM-H) clay exhibited 150% higher adsorption capacity as compared to neat chitosan hydrogel even in 50 ppm Cr(VI) solution. The same composite hydrogel was found to adsorp about 780% Cr(VI) with respect to the clay’s weight while individual uses of Sp and MMT can remove only about 4.80 and 0.36% Cr(VI) with respect to their weights. The pseudo-first order model was found to be the most suitable for the kinetic data of NaMMT loaded hydrogels while that of SpMMT containing hydrogels followed the pseudo-second order kinetics. The isotherm data of all the hydrogels exhibited a better fit to the Freundlich and Sips model. The maximum adsorption capacity (3333 mg g−1) calculated by Sips model was achieved via the hydrogel having 1% SpMMT which is in good agreement with the experimental kinetic data. The highest adsorption with the lowest amount of SpMMT clay could be attributed to its looser Sp network structure whose functional groups are in long-distance, releasing more adsorption sites for the Cr(VI). The highest compression modulus and toughness were also obtained with the 1SpM-H hydrogel which is probably due to increased physical and reversible interactions between chitosan molecules and SpMMT clay layers at optimum clay loading (1%).