Efficient removal of metal ions from aqueous solutions using MoS2 functionalized chitosan Schiff base incorporated with Fe3O4 nanoparticle.

In the present work a novel pyrazole based chitosan Schiff base material was prepared using 5-azido-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde and functionalized using Fe3O4-MoS2, where the nanoparticles get embedded within the gel matrix. The composite material was characterized using various techniques such as XRD, SEM, FTIR, EDS and TGA. The adsorbent material was analysed for the adsorptive take up process from the aqueous solutions of metal ion concentration ranging 20-100 mgL-1. The maximum adsorption capacity obtained for the material was 200.00 and 125.00 mg/g for Cr(VI) and Cu(II) respectively. Adsorptive mechanism was found to have pseudo second order kinetics and the adsorption isotherm followed Langmuir adsorption model following the monolayer adsorptive process. Further the evaluated thermodynamic parameter showed the adsorption process to be spontaneous and endothermic in nature. Reusability of the composite material was achieved using suitable stripping solutions.

Studies on the effect of storage time and plasticizers on the structural variations in thermoplastic starch.

Starch was combined with plasticizers such as glycerol, sorbitol, glycerol/sorbitol and urea/ethanolamine blends by means of high shear extrusion process to prepare thermoplastic starch (TPS). Effect of storage time and plasticizers on the structural stability of melt processed TPS was investigated. Morphological observation, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy reveal that melt extrusion process is efficient in transforming granular starch into a plasticized starch for all plasticizer compositions. XRD analysis highlights major changes in the microstructure of plasticized starch, and dependence of crystalline type and degree of crystallinity mainly on the plasticizer composition and storage time. Dynamical mechanical analysis (DMA) yields a decrease of the peak intensity of loss factor with aging time. The effect of ageing on tensile strength also appears to be highly dependent on the plasticizer composition. Thus, through different plasticizer combinations and ageing, starch-based materials with significant differences in tensile properties can be obtained, which may be tuned to meet the requirements of a wide range of applications.

Preparation and properties of novel melt-blended halloysite nanotubes/wheat starch nanocomposites.

Novel bionanocomposites based on halloysite nanotubes as nanofillers and plasticized starch as polymeric matrix were successfully prepared by melt-extrusion for the first time. Both modified and non modified halloysites were added at different weight contents. The structural, morphological, thermal and mechanical properties of plasticized starch/halloysites nanocomposites were investigated. Melt-compounding appears to be a suitable process to uniformly disperse nanotubes in the plasticized starch matrix. Interactions between plasticized starch and halloysites in the nanocomposites and microstructure modifications were monitored using Fourier transfer infrared spectroscopy, X-ray diffraction and dynamic mechanical analysis. Addition of halloysite nanotubes slightly enhances the thermal stability of starch (onset temperature of degradation delayed to higher temperatures). The tensile mechanical properties of starch are also significantly improved (up to +144% for Young's modulus and up to +29% for strength) upon addition of both modified and unmodified halloysites, interestingly without loss of ductility. Modified halloysites lead to significantly higher Young's modulus than unmodified halloysites.

Spectral characterization of apatite formation on poly(2-hydroxyethylmethacrylate)-TiO2 nanocomposite film prepared by sol-gel process.

Poly(2-hydroxyethylmethacrylate) films incorporated with titanium dioxide nanoparticles were successfully synthesized by an in situ sol-gel process. The in vitro bioactive properties of the films were assessed after immersion in simulated body fluid for up to 21 days through biomimetic method. Hydroxyapatite formation was observed on the surfaces of nanocomposites. This indicates that prepared composites are bioactive. Fourier transforms infrared spectroscopy, X-ray diffraction patterns, X-ray photoelectron spectroscopy and scanning electron microscope images confirm the hydroxyapatite formation on nanocomposite. The present study provides an analytical method for the assessment of titanium dioxide nanoparticles filled poly(2-hydroxyethylmethacrylate) polymer nanocomposites for biomedical applications.