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Synthesis of high surface area activated carbon from eucalyptus bark for the removal of methylene blue

2021-03-09T09:25:42Z

Title: Synthesis of high surface area activated carbon from eucalyptus bark for the removal of methylene blue Authors: Yadav, Shailesh Kumar; Subhedar, Kiran Mahadeo; Dhakate, Sanjay Ranganth; Singh, Bhanu Pratap Abstract: In present study, high surface area (1852m²g⁻¹) activated carbon was synthesized by single step thermo chemical activation of agro-waste lignocellulose biomass (eucalyptus bark).The synthesized activated carbon has been characterized using scanning electron microscopy, energy-dispersive-X-ray spectroscopy and BET surface area analyser. The eucalyptus bark derived activated carbon (EBAC) was used to remove methylene blue (MB) from waste water. The pH, contact time and concentration of dye were optimized and it was found that at pH of 5.5-6.5 at the room temperature, maximum removal of dye was observed. The obtained time data follows the pseudo second order kinetics. The effect of concentration study was carried out with varying concentration at optimized pH and time. The maximum adsorption capacity is obtained to be 7.15 mg/g. To understand the adsorption process, the Dubinin–Radushkevich (D–R) isotherm and Freundlich isotherm were used for fitting of equilibrium data. The fitted data follows D-R isotherm which reveals the physisorption process during adsorption of dye. Page(s): 1059-1066

Development of conductive CFRPs using PANI-P-2M thermoset polymer matrix

2021-03-09T09:22:25Z

Title: Development of conductive CFRPs using PANI-P-2M thermoset polymer matrix Authors: Pati, Santwana; Das, Sukanta; Goto, Teruya; Takahashi, Tatsuhiro; Yokozeki, Tomohiro Abstract: This research article presents the analysis of a conductive carbon-fiber-reinforced plastic (CFRP) prepared using the new thermoset resin of polyaniline (PANI) applying 2-Methacryloyloxyethyl acid phosphate (P-2M) as a curable dopant. The results of this study established a conductive CFRP with easy synthesis route employing the prepreg technology. This work shows a successful fabrication of CFRP using the new resin developed using a curable dopant for PANI. This is a significant step forward at producing lightning strike protection (LSP) technologies with large scale manufacturing potential, and the future work aims at investigating this CFRP for lightning strike effectiveness. Page(s): 1067-1070

Stable ensemble brightness from nitrogen vacancy centers in nanodiamonds through optimized surface composition

2021-03-09T09:20:13Z

Title: Stable ensemble brightness from nitrogen vacancy centers in nanodiamonds through optimized surface composition Authors: Sandeep; Kumar, Ravi; Subhedar, Kiran Mahadeo; Kumar, Raj; Dhakate, Sanjay Rangnath Abstract: Stable ensemble emission from nitrogen vacancy (NV) centers in nanodiamonds (NDs) is highly desirable for diverse areas ranging from bio-imaging to quantum optics. The uniqueness of NV centers lies in their opto-spin properties like energy level structure, emission range (620-850 nm) and optical spin polarization. The host matrix (NDs), however, put some limitation on the photo-physical properties of these color centers. One of the major issues is surface proximity (where high concentration of defects are present) of NV centers. The NV centers being highly sensitive to the neighboring environment are unstable in such circumstances. The surface of NDs mainly exhibit non-diamond carbon which is well-known quencher of emission due to NV centers. The surface composition for desirable photo-physical properties of NV centers is still unknown. Here, we have systemically studied the effect of oxidation time at low oxidation temperature (450 ^oC) on the selective removal of sp² carbon, aqueous dispersion of NDs and emission collection due to NV centers at ensemble level. Among different air oxidations, heat treatment at 450 ^oC at residual time of 8 hours has been found to be suitable air oxidation conditions for the enhancement of brightness and ensemble photo-stability of NV centers. Page(s): 1071-1079

Fabrication of biowaste derived carbon-carbon based electrodes for high-performance supercapacitor applications

2021-03-09T09:17:39Z

Title: Fabrication of biowaste derived carbon-carbon based electrodes for high-performance supercapacitor applications Authors: Mitravinda, Tadepalli; Karthik, Mani; Anandan, Srinivasan; Sharma, Chandra Shekar; Rao, Tata Narasinga Abstract: The porous carbon is synthesised by chemical activation using cork dust bio-waste as carbon source and the electrochemical performance of the resulting carbon material is tested in even and uneven weight configuration using a two-electrode system. The obtained cork dust derived activated carbon (CDAC) shown a unique honeycomb structured morphology as confirmed by morphological analysis. X-ray diffraction (XRD) and Raman characterisation revealed the graphitic nature of the CDAC. Furthermore, the porous CDAC exhibited high specific surface area (1707 m²/g) and large pore volume (2.4 cc/g) with an average pore size of 4 nm. Even weight supercapacitor cell (SC) (positive and negative electrode with the same weight) and uneven weight SC cell (weight ratio of positive/negative electrodes:1.2) are assembled and tested in 1M TEABF₄/AN. Uneven weight SC cell delivers the highest specific capacitance value of 107 F/g at a current density of 1 A/g. The uneven weight device shows promising cyclic stability without significant changes in capacitance values after 10000 and 5000 charge-discharge cycles at the potential window of 3 V and 3.2 V, respectively. On the contrary, a less specific capacitance (87 F/g at a current density of 1 A/g) observed for the even weight SC cell though high-capacity retention is realised under the same experimental conditions. The enhanced supercapacitor performance of uneven weight configuration SC cell is attributed to the weight balancing of the electrode, high graphitic nature, and unique pore size distribution with interconnected morphology of CDAC. Page(s): 1080-1090