Nanoporous activated carbon materials derived from agro-wastes could be suitable low-cost electrode materials for high-rate performance electrochemical supercapacitors. Here we report high surface area nanoporous carbon materials derived from Lapsi seed agro-waste prepared by zinc chloride (ZnCl2) activation at 700 °C. Powder X-ray diffraction (pXRD) and Raman scattering confirmed the amorphous structure of the resulting carboniferous materials, which also incorporate oxygen-containing functional groups as confirmed by Fourier transform infrared (FTIR) spectroscopy. Scanning and transmission electron microscopy (SEM and TEM) analyses revealed the granular, nanoporous structures of the materials. High-resolution TEM (HR-TEM) confirmed a graphitic carbon structure containing interconnected mesopores. Surface areas and pore volumes of the materials were found, respectively, in the ranges from 931 to 2272 m2 g−1 and 0.998 to 2.845 cm3 g−1, and are thus superior to commercially available activated carbons. High surface areas, large pore volumes and interconnected mesopore structures of these Lapsi seed-derived nanoporous carbon materials lead to their excellent electrochemical supercapacitance performance in aqueous electrolyte (1 M H2SO4) with a maximum specific capacitance of 284 F g−1 at a current density of 1 A g−1. Furthermore, the electrodes showed high-rate capability sustaining 67.7% capacity retention even at high current density of 20 A g−1 with excellent cycle stability achieving 99% capacitance retention even after 10,000 charge–discharge cycles demonstrating the potential of Lapsi seed derived nanoporous carbons as suitable electrode materials in high-performance supercapacitor devices.
Activated carbons were prepared from Lapsi (Choerospondias axillaris) seed stone by zinc chloride (ZnCl2) activation at three different Lapsi seed powder (LSP):ZnCl2 ratios: 1:0.5 (AC-0.5), 1:1 (AC-1), and 1:2 (AC-2). The properties of these activated carbons (ACs), including effective surface areas, pore volumes, and pore size distributions were characterized from N2 adsorption-desorption isotherms. The ACs obtained were essentially nanoporous (including both micro- and mesoporous) with effective surface area ranging from 1167 to 1328 m2/g. Fourier-transform infrared (FTIR) spectroscopy showed the presence of functional groups on the surface of ACs. Scanning electron microscopy (SEM) images showed a high pore development in the ACs. X-ray diffraction (XRD) patterns showed that, in addition to the amorphous structure, ACs contains crystalline ZnO formed during the carbonization. Presence of amorphous carbon is further confirmed by Raman scattering, where we observed only D and G bands. Iron impregnated nanoporous AC has been found to be very effective for arsenic removal from ground water; amount of arsenic is decreased from ca. 200 ppb to 10 ppb. These experimental results indicate the potential use of Lapsi seed as a precursor material for the preparation of high surface area nanoporous activated carbons.
Abstract:In this paper, wool carpet dye adsorption properties of nanoporous activated carbon materials (NCMs) prepared from bamboo agro-product is reported. Bamboo cane powder was chemically activated with phosphoric acid at different temperatures (400, 500, and 600 • C) at an impregnation ratio of 1:1. We found that the specific surface area and the total pore volume of NCM increases with temperature giving the highest surface area and pore volume ca. 2130 m 2 ·g −1 and 2.69 cc·g −1 at 600 • C. Owing to superior surface textural properties, bamboo-derived NCM showed excellent adsorption capacity for wool carpet dyes Lanasyn orange (LO) and Lanasyn gray (LG). The adsorption phenomena could be described by Langmuir/Freundlich adsorption isotherm models. The maximum adsorption capacity was ca. 2.60 × 10 3 and 3.04 × 10 3 mg·g −1 for LO and LG, respectively. The adsorption followed pseudo second order kinetics with the second order rate constant of 1.24 × 10 −3 g·mg −1 ·min −1 (LO) and 7.69 × 10 −4 g·mg −1 ·min −1 (LG), respectively. This study demonstrated that the high surface area NCMs prepared from agro-product can be used as efficient and cost-effective adsorbent materials for the removal of dyes from industrial effluent.
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