Intercalation Of Chitosan Research Articles

Synthesis and characterization of chitosan-bentonite biocomposite: Parametric optimization and adsorption potential

The study investigates the fabrication of chitosan-bentonite biocomposites through an ultrasonic-assisted technique. The influence of the chitosan: bentonite molar ratio, ultrasonication temperature, and ultrasonication time on the yield of biocomposites was assessed and juxtaposed using the response surface methodology, employing both Box Behnken design (BBD), and central composite design (CCD) methodologies. The pristine compounds and synthesized biocomposites were characterized using various spectral techniques viz. Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The optimal conditions for the synthesis of biocomposites were: uni-molar ratio of chitosan: bentonite, ultrasonication temperature of 60 °C, and ultrasonication time of 30 min. BBD demonstrated a slightly better fit (R² > 0.981) as compared to CCD (R² > 0.936). Additionally, the error values for BBD and CCD were determined to be 0.307 and 0.459, respectively, highlighting the higher accuracy of the BBD model compared to the CCD model. The structural analysis through FT-IR and XRD revealed the intercalation of chitosan into the bentonite interlayer. TGA indicated elevated thermal stability and increased resistance of the biocomposites toward degradation. Furthermore, the consistent bonding mechanism observed between chitosan and bentonite remained unchanged regardless of the molecular weight variations. The results revealed that synthesized biocomposites have the potential to be exploited as adsorbents for the removal of pesticides, dyes, drugs, and heavy metals from aqueous solution, demonstrating their application in wastewater remediation technology.

Bentonite-Chitosan composites or beads for lead (Pb) adsorption: Design, preparation, and characterisation

This study investigated the efficiency of mixing bentonite with chitosan via different preparation methods, subsequently the different forms were investigated for their ability to remove Pb(II) ions from solution. The different forms of bentonite-chitosan (Bt-Ch), composites and beads, were prepared via solution blending and precipitation methods, respectively and in the weight ratios of 90%/10%, 70%/30% and 50%/50%. The beads were further subdivided, identified as “beads-A" and “beads-B", and were formed by adding either bentonite suspension or bentonite powder, respectively, to solubilised chitosan solution. The composites and beads were characterised by X-ray fluorescence (XRF), thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and pH at zero point charge. XRF analysis showed a cation exchange mechanism occurred when chitosan was initially mixed with the bentonite. TGA results confirmed that beads contained more chitosan compared to their corresponding weight ratio equivalent composites. XRD results showed that chitosan was intercalated within the interlayer space of the bentonite for Bt-Ch composites and Bt-Ch beads-A and that the interlayer spacings increased with increasing chitosan loading. Though similar amounts of chitosan were present in both Bt-Ch beads-A and beads-B, there were fewer reflection shifts for beads B suggesting less intercalation of chitosan when the bentonite was added as a powder. FTIR spectra from the Bt-Ch composites and beads confirmed the presence of both chitosan and bentonite, and the NH bands of chitosan shifted to lower frequencies demonstrating their involvement in the bonding mechanism of chitosan with bentonite. The experimental adsorption data correlated well with both non-linear Langmuir and Freundlich isotherm models, and in which both chemisorption and physisorption processes played crucial roles. The Langmuir-maximum adsorption capacities of Pb(II) ions for all the analysed Bt-Ch composites and beads was found to range from 42.48 ± 4.22 to 94.60 ± 5.63 mg/g. The amount of chitosan present in the adsorbent and its distribution within or outside the interlayer space of the bentonite was shown to have pronounced effects on the Pb(II) uptake by the different Bt-Ch composites/beads, and although the chitosan greatly enhanced the adsorption of Pb(II) a cation exchange mechanism with the clay was still a dominant process. The adsorption of Pb(II) was also significantly affected by the presence of other multi-competing ions. Moreover, the developed Bt-Ch composites/beads exhibited good potential for re-use after five cycles of regeneration, thus, indicating their potential as cost-effective adsorbents for removal of Pb(II) ions from both drinking and wastewater.

Development of Hybrid Materials Based on Chitosan, Poly(Ethylene Glycol) and Laponite® RD: Effect of Clay Concentration.

In the context of increasing interest in biomaterials with applicability in cosmetics and medicine, this research aims to obtain and characterize some hybrid materials based on chitosan (CS) (antibacterial, biocompatible, and biodegradable), poly(ethylene glycol) (PEG) (non-toxic and prevents the adsorption of protein and cell) and Laponite® RD (Lap) (bioactive). The rheological properties of the starting dispersions were investigated and discussed related to the interactions developed between components. All samples exhibited gel-like properties, and the storage modulus of CS/PEG dispersion increased from 6.6 Pa to 657.7 Pa by adding 2.5% Lap. Structural and morphological characterization of the films, prepared by solution casting method, was performed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and polarized light microscopy (POM). These analyses proved the incorporation of Lap into CS/PEG films and revealed the morphological changes of the films by the addition of clay. Thereby, at the highest Lap concentration (43.8%), the "house of cards" structure formed by Lap platelets, which incorporate chitosan chains, as evidenced by SEM and POM. Two stages of degradation between 200 °C and 410 °C were evidenced for the films with Lap concentration higher than 38.5%, explained by the existence of a clay-rich phase (given by the clay network) and chitosan-rich one (due to the intercalation of chitosan in the clay network). CS/PEG film with 43.8% Lap showed the highest swelling degree of 240.7%. The analysis of the obtained results led to the conclusion that the addition of clay to the CS/PEG films increases their stability in water and gives them greater thermal stability.

Chitosan based smart polymer composites: Fabrication and pH-Responsive behavior for bio-medical applications

This research aimed to synthesize Chitosan/PVA-blank and a series of Cs/PVA/Sepolite based pH-sensitive membranes using a solution casting process. The synthesized Cs/PVA-blank and Cs/PVA/Sep based membranes were investigated via SEM, FTIR, XRD, and TGA techniques. The SEM results of Cs/PVA/Sep based membrane reveal that the hydrolytic stability and strength were improved in acidic and basic media owing to the incorporation of sepiolite content into chitosan. The characteristic band at 3741 cm−1 in the FTIR spectra of the Cs/PVA/Sep membrane confirmed the successful synthesis. The obtained XRD results showed higher d-spacing for Cs/PVA/Sep membranes as compared to the Cs/PVA-blank membranes owing to the intercalation of chitosan in the interlayer spacing of the sepiolite. The obtained TGA results show higher thermally stability for Cs/PVA/Sep membrane as compared to the Cs/PVA-blank sample due to the interaction of sepiolite content with the chitosan matrix. The obtained hydrolytic and swelling studies revealed that the Cs/PVA/Sep membrane displayed enhanced stability in basic and neutral media while showing minimum swelling in an acidic medium. The water uptake ability was checked for Cs/PVA/-blank and Cs/PVA/Sep-60% membrane and the results exhibited that the Cs/PVA/-blank membrane had maximum water uptake value as compared to the Cs/PVA/Sep-60% membrane. While those with a considerable amount of filler had the lowest water uptake values. As Sepolite content increased, the water uptake % values decreases because of weakness in H-bonding (of hydrophilic groups) and due to intercalation in Sepolite layers during polymer formation.

Novel chitosan-based nanocomposites as ecofriendly pesticide carriers: Synthesis, root rot inhibition and growth management of tomato plants

Novel bio-based nanocomposites were developed as carriers for loading and sustained-release of vanillin (Van.) and cinnamaldehyde (Cinn.) antioxidants. The composites were obtained by intercalation of chitosan (CS) into sodium montmorillonite (CS/Mt), incorporation of chitosan with polyaniline (CS/PANI) and chitosan/polyaniline/exfoliated montmorillonite (CS/PANI/Mt). The structure and morphology of composites were characterized by FTIR, XRD, SEM and TEM. The release data of Van. and Cinn. from CS and CS/Mt obeyed well zero-order equation. However, Higuchi and Korsmeyer-Peppas models fitted well the release data from CS/PANI and CS/Mt composites. Their antifungal activity was examined towards Fusarium oxysporum and Pythium debaryanum. In vitro assay, CS, Cinn., Van., CS/PANI and CS/PANI/Cinn., have a strong inhibitory effect on the linear growth of the target pathogens, even at lower concentrations. Greenhouse assay indicated that seedling treatment by the loaded CS/PANI/Cinn and CS/Mt/Cinn. reduced both disease index and disease incidence parameters of both pathogens and possessed seedlings growth promoting potential of tomato compared to untreated-infected controls.

Malachite green dye and its removal from aqueous solution by clay-chitosane modified

The main purpose of this work is to study the adsorption of malachite green, a cationic dye, in aqueous solution using chitosan-modified natural clay. This material was synthesized via the intercalation of chitosan into sodic bentonite, and then characterized using techniques such as Fourier transform infrared (FT-IR) spectroscopy, X-ray Diffraction (XRD) analysis, and X-ray fluorescence analysis. The effects of some process parameters such as contact time, initial dye concentration and pH of solution on the sorption of malachite green were also thoroughly investigated. In addition, it was found that the pseudo-second-order kinetic model provided the best fit to the experimental data for the adsorption of malachite green by the modified clay. Moreover, the experimental results indicated that the adsorption equilibrium data fitted quite well with the Langmuir isotherm, and the adsorption capacity was found equal to 96%.

What happens when chitosan meets bentonite under microwave-assisted conditions? Clay-based hybrid nanocomposites for dye adsorption

In this study, bionanocomposites were prepared with bentonite and chitosan in proportions of 50, 100, 200, and 300 % of the cation exchange capacity (CEC) of the bentonite using microwave heating at 50 °C for 15 and 30 min. The X-ray diffraction patterns indicated basal spacings in the range of 1.48–2.10 and 1.57–1.98 nm for nanocomposites obtained at 15 and 30 min of heating, respectively, suggesting the intercalation of chitosan in the interlayer space of montmorillonite. Fourier transform infrared spectra confirmed the incorporation of chitosan in bentonite. The results of the elemental analysis suggested a higher chitosan content for the nanocomposites prepared with 200 and 300 % of the CEC after 30 min of irradiation. Chitosan–bentonite nanocomposites obtained after 30 min of heating successfully adsorbed the Reactive Violet 5R dye from aqueous solutions. The influence of several factors such as the pH, adsorbent dosage, contact time, and initial dye concentration was investigated. The optimal adsorption conditions were a pH of 1.0 and a contact time of 20 min. The adsorption capacity reached 98.00, 207.71, 250.00, and 282.01 mg g−1 for nanocomposites prepared with 50, 100, 200, and 300 % of the CEC, respectively. In was demonstrated that the prepared bentonite–chitosan nanocomposites were good dye adsorbents.

Fabrication and chemo-physical characterization of CuO/chitosan nanocomposite-mediated tricomponent PVA films

Copper oxide/chitosan nanocomposite (CCNC) specimens were fabricated via a simple solvent evaporation route. The presence and intercalation of chitosan and CuO within the nanocomposites were explored using advanced analytical techniques of X-ray diffraction, Fourier transform infrared spectroscopy, energy-dispersive X-ray analyses and the scanning electron microscopy. The prepared nanocomposite was then incorporated into poly(vinyl alcohol) (PVA) matrix to fabricate a tricomponent composite. The resultant tricomponent composite was characterized for various chemo–physical and mechanical properties using differential scanning calorimetry (DSC) and the mechanical testing. The DSC results indicated that the glass transition temperature of PVA decreased on incorporating the CCNC into the PVA matrix; this also enhanced the tensile strength and flexibility of the resulting films. The prepared tricomponent films may find potential applications in sensing and catalysis.

Organic Montmorillonite Intercalated Nano-composites Prevent Post-Surgical Associated Infections

In this study, organic montmorillonite (OMMT) is a modified form of montmorillonite (MMT) in which chitosan (CS) intercalated MMT by ion exchange of sodium ions from Na/MMT with –NH3 + of CS. The structural analysis confirmed intercalation of CS into MMT layers, indicating that CS molecular chains incorporated into the MMT layers. The interlayer distance of the MMT layered was 1.128nm and in the OMMT layers enlarged to 2.365 nm. Antibacterial activity analysis showed that unmodified MMT could not inhibit the growth of bacteria. Nevertheless, after addition of the CS molecules, an increase in the interlayer distance of MMT was observed. No difference was observed between the viability of the human dental pulp stem cells (hDPSCs) contacted to different concentrations (ranging from 0.5 to 2mg/ml) of MMT and OMMT in all time intervals, when compared with the control samples. Furthermore, neither MMT nor OMMT showed apoptosis and cytotoxicity effect on the cells. The strong antibacterial activity of the synthesized OMMT nanocomposite was also confirmed against E. coli, S. aureus, K. pneumonia and P. aeruginosa, suggesting its high potential for the prevention of post-surgical infections.

Adsorption of Cu2+ and Ni2+ by oxalic acid-crosslinked chitosan-modified montmorillonite

ABSTRACT This study undertook the testing of Cu2+ and Ni2+ adsorption using synthesized oxalic acid-crosslinked chitosan (CTS)-modified montmorillonite (MMT), as well as a kinetic analysis and equilibrium analysis. We believe that our study makes a significant contribution to the literature because we showed that the interlayer distance of untreated MMT was increased from 1.23 to 2.05–2.21 nm, and thus verified the intercalation of CTS into the MMT interlayer. The maximum adsorption of Cu2+, as calculated using the Langmuir equation, was significantly higher for oxalic acid-crosslinked CTS-modified MMT, relative to untreated MMT or the non-crosslinked CTS-modified-MMT. The oxalic acid-crosslinked CTS-modified MMT could also take up more Cu2+ than Ni2+ from a solution containing a mixture of Cu2+-Ni2+. The selective adsorption of oxalic acid-crosslinked CTS-modified-MMT (i.e. Ni2+ < Cu2+) is governed by the selective adsorption of CTS and the oxalic acid. This reveals the effect of the complex formation with CTS and oxalic acid.

Mechanically improved porous hydrogels with polysaccharides via polyelectrolyte complexation for bone tissue engineering

Bone tissue engineering aims to design mechanically improved macroporous hydrogels with fibrous topologies using polysaccharides that can provide an appropriate microenvironment in bone defects in order to enhance bone regeneration similar to the native bone extracellular matrix. Herein, we developed hydrogels by intercalation of chitosan (CS) and sodium alginate (SA)-based polyelectrolyte complexes (PECs) (in situ formation using glucuronic acid delta-galactone as an acidifying agent (GDL)) within the poly(acrylamide) (PAM)-crosslinked network (PEC-PAM) during free radical polymerization. The structure and interactions of PEC-PAM were confirmed by FTIR and XRD experiments. The PEC greatly influenced the porosity, pore size, and mechanical properties of hydrogels. Importantly, the PEC within the hydrogels possessed a macroporous structure with a ladder-like fibrous topology, which may provide better cell growth and adhesion. Moreover, the hydrogels showed good bio-mineralization capacity in simulated body fluid solutions as confirmed by FTIR, XRD, FE-SEM, and SEM-EDX. The in vitro performance of the PEC-PAM hydrogels was assessed towards human bone osteoblasts cells in terms of cell proliferation, biocompatibility, and cell adhesion. All of the results suggest that PEC-PAM hydrogels have good potential in bone tissue engineering.

Chitosan/Ag-Bentonite Nanocomposites: Preparation, Characterization, Swelling and Biological Properties

In the present work, Chitosan/bentonite, Chitosan/Ag-bentonite and Chitosan/AgNPs-bentonite composite materials were prepared and shaped in form of beads, and characterized using several methods. After that, their thermal stability, swelling properties and antibacterial and antifungal activity were evaluated. In the case of Chitosan/AgNPs-bentonite, the XRD analysis confirms the partial intercalation of chitosan in the interlayer of bentonite and the formation of silver nanoparticles, AgNPs, with an average diameter between 10 and 25 nm. The latter is confirmed by UV–Visible diffuse reflectance spectroscopy by the apparition of the large absorption band at 442 nm. For all prepared materials, the FTIR analysis shows the presence of strong interaction between chitosan reactive groups and bentonite interlayer materials. This result is confirmed by thermal analysis where it is observed that these composite materials exhibit a higher thermal stability than the biopolymer alone. The composite materials present also a very good swelling capacity. Indeed, the swelling rate carried out in water media at pH 7 and a temperature of 30 °C is 160% higher than that of the corresponding dried material. Otherwise, Chitosan/AgNPs-bentonite sample displays a very high antibacteriaPseudomonas aeruginosal activity against pathogen bacteria strains such as Staphylococcus aureus ATCC 25923 and ATCC 27853. This activity is less important for S. aureus ATCC 43300 and no activity is observed for Escherichia coli ATCC 25922 and Candida albicans ATCC 10231. Since the starting chitosan and bentonite materials showed no antibacterial or antifungal activity, the antibacterial activity of Chitosan/AgNPs-bentonite sample is attributed to loaded AgNPs species.

Hexavalent chromium removal by chitosan modified-bioreduced nontronite

Recent efforts have focused on structural Fe(II) in chemically or biologically reduced clay minerals to immobilize Cr(VI) from aqueous solution, but the coulombic repulsion between the negatively charged clay surface and the polyanionic form of Cr(VI), e.g., dichromate, can hinder the effectiveness of this process. The purpose of this study was to investigate the efficiency and mechanism of Cr(VI) removal by a charge-reversed nontronite (NAu-2), an Fe-rich smectite. Chitosan, a linear polysaccharide derived from chitin found in soil and groundwater, was used to reverse the charge of NAu-2. Intercalation of chitosan into NAu-2 interlayer increased the basal d-spacing of NAu-2 from 1.23nm to 1.83nm and zeta potential from −27.17 to +34.13mV, with the amount of increase depending on chitosan/NAu-2 ratio. Structural Fe(III) in chitosan-exchanged NAu-2 was then biologically reduced by an iron-reducing bacterium Shewanella putrefaciens CN32 in bicarbonate buffer with lactate as the sole electron donor, with and without electron shuttle, AQDS. Without AQDS, the extent of Fe(III) reduction increased from the lowest (∼9%) for the chitosan-free NAu-2 to the highest (∼12%) for the highest chitosan loaded NAu-2 (3:1 ratio). This enhancement of Fe(III) reduction was likely due to the attachment of negatively charged bacterial cells to charge-reversed (e.g., positively charged) NAu-2 surfaces, facilitating the electron transfer between cells and structural Fe(III). With AQDS, Fe(III) reduction extent doubled relative to those without AQDS, but the enhancement effect was similar across all chitosan loadings, suggesting that AQDS was more important than chitosan in enhancing Fe(III) bioreduction. Chitosan-exchanged, biologically reduced NAu-2 was then utilized for removing Cr(VI) in batch experiments with three consecutive spikes of 50µM Cr. With the first Cr spike, the rate of Cr(VI) removal by charged-reversed NAu-2 that was bioreduced without and with AQDS was ∼1.5 and ∼6µmolg−1h−1, respectively. However, the capacity of these clays to remove Cr(VI) was progressively exhausted upon addition of subsequent Cr spikes. X-ray photoelectron spectroscopy (XPS) revealed that the reduction product of Cr(VI) by chitosan-exchanged-bioreduced NAu-2 was Cr(III), possibly in the form of Cr(OH)3. In summary, our results demonstrated that the combined effects of sorption and redox reactions by charge-reversed bioreduced nontronite may offer a feasible in-situ approach for remediating Cr(VI) polluted soil and groundwater.

Ecologically friendly chitosan-montmorillonite bio-nanocomposite as adsorbent for textile dyes from aqueous solutions

The bio-nanocomposite of montmorillonite and natural biopolymer chitosan (C-MM) was synthesized. Intercalation of chitosan in form of monolayer into the interlamellar space of montmorillonite was confirmed by XRD and IR analysis. The adsorption of textile dyes: Acid Yellow 99 (AY99), Acid Orange 10 (AO10) and Reactive Black 5 (RB5) onto C-MM was investigated. The adsorption was performed with the respect to adsorption time, pH and initial dye concentration. The kinetics of adsorption obeyed pseudo-second-order of kinetics and was the most efficient in acidic pH. Langmuir model best described the adsorption of AY99 and AO10 , while RB5 adsorption isotherm was best fitted with Freundlich model.

Adsorption of Cu2+ on Montmorillonite and Chitosan-Montmorillonite Composite Toward Acetate Ligand and the pH Dependence

Chitosan-montmorillonite composite was extensively used for the removal of heavy metals from wastewater. In wastewater, copper (Cu2+) usually coexist with the organic ligands, which had unknown effect on Cu2+ adsorption by the composite materials. In order to understand further on that, the adsorption of copper by the composite materials must be studied. In the present study, montmorillonite was coated with chitosan, and X-ray diffraction (XRD) patterns of the composite proved the intercalation of chitosan in the montmorillonite. Fourier transform infrared (FTIR) spectra of the composite identified the presence of amino group on the composite, and that of the composite saturated with metals identified the interaction between the amino groups and metals. Langmuir adsorption isotherm indicated that the composite had more capacity to adsorb Cu2+ from wastewater than montmorillonite. The adsorption capacity of Cu2+ by montmorillonite and chitosan-montmorillonite composite was studied, respectively, as a function of pH and in the presence of acetate. Compared to the montmorillonite at low ligand concentration (0.08 mmol/L) or low pH ( 4.5). Therefore, the composite is more suitable for removing Cu2+ than montmorillonite in acid aqueous medium.

Ultrasound assisted preparation of chitosan–vermiculite bionanocomposite foams for cadmium uptake

The objective of this work was the development of functional bionanocomposites based on the intercalation of the cationic biopolymer chitosan in natural or in organically modified vermiculite samples under experimental conditions involving ultrasound irradiation. The resulting materials were processed as macroporous foams with the aim to apply them in the removal of Cd(II) ions from aqueous solution. Physicochemical characterization confirmed the intercalation of chitosan into the interlayer space of vermiculite, causing the exfoliation of VU layers in those bionanocomposites. They were processed as foams by means of freeze-drying resulting in materials that show interconnected elongated macropores with average diameter around 150–200μm, and the material in the cell walls exhibited a tendency to organize in parallel planes. The adsorption equilibrium data of Cd(II) on the bionanocomposite foams, carried out in batch mode, was interpreted with the Langmuir, Freundlich and Prausnitz–Radke (P–R) isotherm models, and the P-R isotherm showed the best fit to the experimental data. The adsorption capacity was increased by raising the solution pH, which most likely favors a chelation mechanism between the chitosan chains and the Cd(II) cations. The chitosan–vermiculite bionanocomposites with the highest chitosan content showed exceptionally high adsorption capacity values, at least three times higher than those of the individual components.

Structure-Property Relationship of Layered Metal Oxide Phosphonate/Chitosan Nanohybrids for Transducer in Biosensing Device

A candid approach to analyze the performance characteristics of phenyl phosphonate-functionalized zirconium oxide and pure zirconium oxide (ZrO2) fillers reinforced chitosan nanocomposites and their suitability as a potential biomaterial for the development of transducer surface in biosensing device has been investigated in this communication. Functionalization of ZrO2 has been carried out using sulfophenylphosphonate which was confirmed using Fourier transform infrared spectrographs. The electrostatic intercalation of chitosan with filler particles was monitored using electrochemical impedance analyzer which exhibits lowest bulk resistance which is highly effective for ionic switching. Incorporation of zirconium sulfophenylphosphonate (ZrSP) the ionic conductivity of the chitosan film attained a value of 1.2 × 10−6 S/cm as compared to the unmodified one which is a prefeasibility work for the fabrication of biosensing platform. Variation in performance characteristics has been evaluated through morphological and thermal characterization. TGA and DSC analysis reveal that the thermal stability and decomposition temperature of the nanocomposites were improved by the addition of reinforcing filler particles. XRD and SEM and TEM results support the above assumption. The continuous alignment of the proton transfer channels of the nanocomposites was thoroughly investigated by AFM analysis which revealed phase morphology for improved enzyme entrapment. Further, surface functionalized nanofillers result considerable increment of mechanical properties in terms of elastic modulus and tensile stress.

Adsorption of an anionic azo dye by cross-linked chitosan/bentonite composite

In this study, cross-linked chitosan (CCS)/bentonite (BT) composite was prepared by the intercalation of chitosan in bentonite and the cross-linking reaction between chitosan and glutaraldehyde. CCS/BT composite was characterized by using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermal gravimetric analyses (TGA). Their adsorption characteristics were assessed by using an azo dye (Amido Black 10B) as a model adsorbate. The adsorption of Amido Black 10B onto the CCS/BT composite was found to be optimal at pH 2. The adsorption isotherm was well described by the Langmuir model and the maximum adsorption capacity was 323.6mg/g at 293K and pH 2. Amido Black 10B adsorption kinetics followed a pseudo-second-order kinetic model. The calculated thermodynamic parameters showed that the adsorption of Amido Black 10B by CCS/BT composite was spontaneous and endothermic in nature.

Stability of chitosan/montmorillonite nanohybrid towards enzymatic degradation on grafting with poly(lactic acid)

Enzymatic degradation of nanohybrid based on intercalation of chitosan (CS) within the galleries of montmorillonite (MMT) clay and grafted with poly(lactic acid) (PLA) was studied using esterase enzyme in phosphate buffered solution. Chitosan was first intercalated between the galleries of natural unmodified sodium MMT clay and subsequently grafted with PLA to prepare nanohybrids of CS-g-PLA/MMT. The prepared membranes were characterised by X-ray diffraction, transmission electron microscopy and NMR spectroscopy. The specimens were then subjected to enzymatic degradation to understand the effect of copolymerisation with PLA and the effect of incorporation of MMT in the CS matrix. The presence of MMT clay provided stability towards degradation of polymer matrix because of nanoscale dispersibility, thereby acting as a barrier towards the permeation of water molecules to induce hydrolysis of PLA. Similarly, the grafting of CS with crystalline PLA stabilised the CS matrix towards degradation, rendering it suitable for tissue engineering applications.

MMT-supported Ag nanoparticles for chitosan nanocomposites: Structural properties and antibacterial activity

Multifunctional bionanocomposites have been prepared by loading chitosan matrix with silver-montmorillonite antimicrobial nanoparticles obtained by replacing Na+ ions of natural montmorillonite with silver ions. This filler has been chosen for its twofold advantage to serve as silver supporting material and to confer new and better performance to the obtained material. It has been proved that the achievement of the intercalation of chitosan into the silicate galleries of montomorillonite as well as the interaction between chitosan and Ag ions and silver particles lead to an enhancement of the thermal stability, to an improvement of mechanical strengths and to a reduction of the liquid water uptake of the obtained bionanocomposites. Results also show that silver ions are released in a steady and prolonged manner providing, after 24 h, a significant reduction in the microbial growth of Pseudomonas spp.