Krishna Deb

Simple Chemical Route Synthesis of Fe2O3 Nanoparticles and its Application for Adsorptive Removal of Congo Red from Aqueous Media: Artificial Neural Network Modeling

Nanocrystalline Fe2O3 powder was synthesized by a simple chemical route involving FeCl3 and NaOH. The Fe2O3 powder thus prepared was characterized using x-ray diffraction study, scanning electron microscopy, and Fourier transform infrared spectroscopy. The adsorption properties of crystalline Fe2O3 powder have been investigated with an aim to explore a possible low cost and efficient way to remove Congo red (CR) from waste water. Fe2O3 powder was found as an excellent adsorbent for CR from aqueous medium. Adsorption capacity as much as 203.66 mg g−1 is reported at room temperature. Effect of different experimental parameters such as reaction pH, initial CR dye concentration, adsorbent dose, and reaction temperature were studied on adsorption capacity of Fe2O3 powder and modeled by artificial neural network (ANN). Optimal ANN structure (4–5–1) shows minimum mean squared error (MSE) of 0.00235 and determination coefficient (R2) of 0.991 with Levenberg–Marquardt algorithm. Isotherm analysis of experimental data exhibited better fit to the Langmuir isotherm. The adsorption process was found to follow second-order kinetics as depicted by the analysis of experimental results. Thermodynamic study shows that the adsorption process is endothermic, spontaneous, and thermodynamically favorable in the temperature range of 27°C to 60°C. GRAPHICAL ABSTRACT

Tuning of electrical and optical properties of polyaniline incorporated functional paper for flexible circuits through oxidative chemical polymerization

An organic semiconductor material made of polyaniline with outstanding physical properties was prepared on a flexible paper substrate. Oxidative chemical polymerization, a straightforward and cost effective technique for large scale synthesis has been employed for the preparation of the polymer on the paper substrate. CuCl2 has been chosen as a polymerizing agent for the oxidative chemical polymerization process. The prepared polymer semiconductor has become an ideal system to explore this outstanding recipe of chemistry and physics. Formation of polaron and bipolaron defect energy states in the polymer lattice facilitates exceptional electrical hole transport through the polymer chain, providing an electrical sheet resistance varying from 5.0 × 105 Ω □−1 to 2.8 × 107 Ω □−1. The optical band gap as obtained from the absorbance study was found to be in the range of 2.49 eV to 2.62 eV, which is suitable for the design of semiconductor devices. Most importantly, this article reports an effective way of tuning the optical and electrical properties of the prepared semiconductor, achieved through controlling the degree of oxidation during polymerization and thus bringing a control over the defect energy states. Along with the controllable electrical and optical properties, the flexibility of the paper substrates provides an extra merit to such polymer systems for designing paper based low cost flexible devices.