Recent Innovations in Chemical Engineering (Formerly Recent Patents on Chemical Engineering) - Volume 11, Issue 3, 2018

Background & Method: The incorporation of methacrylate capped zirconia nanocrystal (MZN) into an acrylic resin produced a UV curable hard-coat. The vinylfunctionalized surface of the nanoparticle improved its compatibility with the acrylate matrix, thus enabled an excellent dispersion even at 54 wt% zirconia leading to a transparent coating thicker than ten micrometers. The addition of nano-filler further improved the thermal stability and the mechanical strength of the composite. The thermal degradation temperature of the composite moved up by more than 100oC without altering the glass transition temperature. The nanoindentation hardness and the reduced modulus increased from 173 MPa and 1.36 GPa for the pure resin to 478 MPa and 6.7 GPa, respectively, for the composite film with 54 wt% zirconia. Results: The composite films showed a roughly linear increase of the refractive index with the volume fraction of zirconia. At 54 wt% loading, the index reached 1.6388. Conclusion: Furthermore, the transparent sol formed by dispersing MZN powder in a solvent also produced a transparent film on PMMA. However, the high inorganic content introduced some porosity into the film and made it vulnerable to creep and abrasion thus unsuitable for hard-coat.

Background: Se-based chalcogenide glasses have wide commercial applications such as switching, optical memory devices and xerography because of their behaviour as phase change material. Thermal characterisation behaviour of bulk chalcogenide glass In4Se84S12 has been studied by Differential Scanning Calorimetry (DSC) under nonisothermal conditions at four different heating rates 5°C/min, 10°C/min, 15°C/min and 20°C/min. The glass transition temperature (Tg), crystallisation temperature (Tc) and melting temperature (Tm) have been determined through DSC thermograms. Method: The activation energy for structural relaxation (ΔEt) is determined by Moynihan method. The activation energy of crystallization (ΔEc) is estimated by Kissinger and Ozawa equations under non-isothermal condition and order parameter (n) by using Johnson–Mehl– Arvami (JMA) model. Surface morphological analysis of thin film has been carried out by Scanning Electron Microscope (SEM) which depicts the development of grains. Results: Energy Dispersive Analysis by X-ray (EDX) analysis shows the perfect compositional elements in the alloy. X-ray Diffraction (XRD) of alloy sample has no sharp peaks which reflects that the alloy is amorphous. Conclusion: Based on thermal analysis, it is found that chalcogenide glass In4Se84S12 is thermally stable at 20°C /min and can be used in various solid state devices.

Background: Plasmonic light trapping in thin-film crystalline silicon solar cells is numerically investigated using finite-difference time-domain simulations. Method: Enhancement of optical absorption due to the excitation of localized surface plasmons in a periodic arrangement of aluminum nanostructures is analyzed. Result: Broadband photocurrent enhancement in a 1 μm thick silicon film can be observed over the 500-800 nm spectral range of interest. Conclusion: Photocurrent density under Air Mass 1.5 global solar irradiation has been found to be enhanced by up to 40% using aluminum nanostructures with 300 nm width and 100 nm thick. The present work offers a cost-effective plasmonic material for solar cell applications.

Background & Objective: A green one-pot synthesis of oleic acid (1) derivatives is promoted by Rare Earth Metal (REM) triflates and commercial Molybdenum dioxo dichloride (MoCl2O2) in the presence hydrogen peroxide as a green oxidant. Results: The protocol permits to govern the oxidation selectivity by simply choosing the proper combination of Mo and Sc catalysts. Conclusion: Methyl oleate epoxide 2a and azelaic acid 6 thus obtained are valuable industrial intermediates for synthesizing bio-compostable plastics, plasticizers of PVC, lubricating oils, cosmetics and pharmaceuticals (bactericides, anti-inflammatories, etc.).

Background: ZnO microstructures decorated with Ag nanoparticles (AgZnO) were synthesized by sol-gel method. Methodology: The samples were annealed at different annealing temperature ranging from 500 to 700°C, respectively. Results: The effect of different annealing temperature on the crystal structure and morphologies of prepared samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and energy dispersive X-ray spectrum (EDS). The photocatalytic degradation reaction is tested by the decomposition of methylene blue (MB) dye under ultra violet (UV) irradiation for 60 minutes. Conclusion: The EDS result demonstrated that the particle-like AgZnO samples consist of element Zn, O and Ag. XRD analysis shows that the AgZnO exhibited a hexagonal wurtzite crystal structure of ZnO and face-centered cubic (FCC) of Ag. The crystallite size was increased as annealing temperature was increased in the range of 84.14 nm – 103.89 nm. In particular, AgZnO annealed at 700°C exhibits the highest photocatalytic activity by degrading methylene blue (MB) solution by almost 92.99 % in 60 minutes compared to pure ZnO samples.

Background and Objective: This research investigated the application of three types of adsorbents derived from spent grated coconut (Cocos nucifera) powder; hexanewashed (HSGC), sulphuric acid treated (SSGC) and xanthated spent grated coconut (XSGC), to adsorb Pb(II) from aqueous solutions. The adsorbents were characterised by spectroscopic and quantitative analyses. Methodology: Different chemical treatments had changed the physicochemical characteristics of all adsorbents, namely the CHNOS content, pHslurry, and pHPZC. The morphology of SSGC had become spongy-like whereas XSGC had formed a flake-like structure. Elucidation of chemical characteristics of the adsorbent surface by Fourier transform infrared (FTIR) spectroscopy revealed the different types of functional groups. Result: The performances of all adsorbents were affected by pH and initial concentrations of Pb(II). The rate of Pb(II) uptake was rapid. The adsorption of Pb(II) on all adsorbents was best fitted to pseudo-second order kinetic models (R2 > 0.99) and Langmuir isotherm model (R2 > 0.99). The Langmuir adsorption capacities (qcal.max) for Pb(II) by HSGC, XSGC, and SSGC were 37.88, 49.02 and 172.41 mg/g, respectively. Conclusion: The thermodynamic study revealed that the adsorptions were endothermic with spontaneous and feasible process as the ΔGo values were negative. Ion exchange, ionic attraction and complexation were the dominant mechanisms involved in the Pb(II) adsorption.

Background: In this study, biogenic synthesis of silver nanoparticles (Ag-NPs) was done by using leaf extracts of Ocimum tenuiflorum and Tinospora cordifolia, Indian medicinal plants. An aqueous solution of silver nitrate was used as a precursor for Ag-NPs. Further, the washing of Ag-NPs was done with the help of centrifuge. Method: These biosynthesized nanoparticles were characterized with the help of UV-Vis spectroscopy, FTIR (Fourier-transform Infrared Spectroscopy), SEM (Scanning Electron Microscopy) with EDX (Energy Dispersive X-ray analysis) and TEM (Transmission Electron Microscopy). Conclusion: It was observed that the reduction of silver ions to silver nanoparticles occurs within 10 minutes of reaction time. Thus, this method can be used for the rapid and ecofriendly synthesis of silver nanoparticles.