Dielectric behaviour of plasma hydrogenated TiO2/cyanoethylated cellulose nanocomposites.

The interface between the polymer and nanoparticle has a vital role in determining the overall dielectric properties of a dielectric polymer nanocomposite. In this study, a novel dielectric nanocomposite containing a high permittivity polymer, cyanoethylated cellulose (CRS) and TiO2 nanoparticles surface modified by hydrogen plasma treatments was successfully prepared with different weight percentages (10%, 20% and 30%) of hydrogenated TiO2. Internal structure of H plasma treated TiO2 nanoparticles (H-TiO2) and the intermolecular interactions and morphology within the polymer nanocomposites were analysed. H-TiO2/CRS thin films on SiO2/Si wafers were used to form metal-insulator-metal (MIM) type capacitors. Capacitances and loss factors in the frequency range of 1 kHz to 1 MHz were measured. At 1 kHz H-TiO2/CRS nanocomposites exhibited ultra-high dielectric constants of 80, 118 and 131 for nanocomposites with 10%, 20% and 30% weight of hydrogenated TiO2 respectively, significantly higher than values of pure CRS (21) and TiO2 (41). Furthermore, all three H-TiO2 /CRS nanocomposites show a loss factor <0.3 at 1 kHz and low leakage current densities (10-6 A cm-2-10-7 A cm-2). Leakage was studied using conductive atomic force microscopy (C-AFM) and it was observed that the leakage is associated with H-TiO2 nanoparticles embedded in the CRS polymer matrix. Although, modified interface slightly reduces energy densities compared to pristine TiO2/CRS system, the capacitance values for H-TiO2/CRS-in the voltage range of -2 V to 2 V are very stable. Whilst H-TiO2/CRS possesses ultra-high dielectric constants (>100), this study reveals that the polymer nanoparticle interface has a potential influence on dielectric behaviour of the composite.

Mechanochemical Synthesis of Polymorphic Urea ⋠Adipic Acid Cocrystal as a Sustained-Release Nitrogen Source.

A 2 : 1 urea ⋅ adipic acid cocrystal was obtained in two polymorphic forms (Form I reported earlier, and Form II synthesized in this study) using mechanochemistry as well as solution crystallization. Lower solubility and leaching study showed the newly synthesized urea ⋅ adipic acid 2 : 1 cocrystal to be an efficient sustained-release nitrogen fertilizer compared to commercially available urea.

Assessing the Carboxymethylcellulose Copper-Montmorillonite Nanocomposite for Controlling the Infection of Erwinia carotovora in Potato (Solanum tuberosum L.).

A novel antimicrobial formulation based on carboxymethylcellulose (CMC) spray-coated Cu2+ intercalated montmorillonite (MMT) nanocomposite material was prepared and its morphology, internal structure, and bonding interactions were studied. Meanwhile, the antibacterial efficacy and release behavior of Cu2+ was also determined. PXRD patterns indicated the intercalation of Cu2+, while FTIR spectra and TGA traces confirmed the association of Cu-MMT with CMC. SEM study revealed the improvement of nanocomposites by CMC, without disturbing the clay structure. TEM and EDAX studies indicated the distribution of Cu (copper) throughout the composite. In vitro antibacterial assays performed with Erwinia carotovora revealed effective bacterial growth suppression, indicating the potential of this material in controlling soft rot of potatoes (Solanum tuberosum); also observed was a connection between growth inhibition and concentration of CMC spray coats indicating a positive relationship between Cu2+ release and concentration of the CMC coatings. The activity pattern of the nanocomposite displayed a significant degree of sustained-release behavior.

Municipal solid waste biochar-bentonite composite for the removal of antibiotic ciprofloxacin from aqueous media.

This study investigates the adsorption of ciprofloxacin (CPX) onto a municipal solid waste derived biochar (MSW-BC) and a composite material developed by combining the biochar with bentonite clay. A bentonite-MSW slurry was first prepared at 1:5 ratio (w/w), and then pyrolyzed at 450 °C for 30 min. The composite was characterized by scanning electron microscopy (SEM), Powder X-ray diffraction (PXRD) and Fourier transform infrared (FTIR) spectroscopy before and after CPX adsorption. Batch experiments were conducted to assess the effect of pH, reaction time and adsorbate dosage. The SEM images confirmed successful modification of the biochar with bentonite showing plate like structures. The PXRD patterns showed changes in the crystalline lattice of both MSW-BC and the composite before and after CPX adsorption whereas the FTIR spectra indicated merging and widening of specific bands after CPX adsorption. The optimum CPX adsorption was achieved at pH 6, and the maximum adsorption capacity of the composite calculated via isotherm modeling was 190 mg/g, which was about 40% higher than the pristine MSW-BC. The Hill isotherm model along with pseudo-second order and Elovich kinetic models showed the best fit to the adsorption data. The most plausible mechanism for increased adsorption capacity is the increased active sites of the composites for CPX adsorption through induced electrostatic interactions between the functional groups of the composite and CPX molecules. The added reactive surfaces in the composite because of bentonite incorporation, and the intercalation of CPX in the clay interlayers improved the adsorption of CPX by the biochar-bentonite composite compared to the pristine biochar. Thus, MSW-BC-bentonite composites could be considered as a potential material for remediating pharmaceuticals in aqueous media.