This study reports
a simple one-step hydrothermal method for the
preparation of a Ni(OH)
2
and MnO
2
intercalated
rGO nanostructure as a potential supercapacitor electrode material.
Having highly amorphous rGO layers with turbostratic and integrated
wrinkled flower-like morphology, the as-prepared electrode material
showed a high specific capacitance of 420 F g
–1
and
an energy density of 14.58 Wh kg
–1
with 0.5 M Na
2
SO
4
as the electrolyte in a symmetric two-electrode.
With the successful intercalation of the γ-MnO
2
and
α-Ni(OH)
2
in between the surface of the as-prepared
rGO layers, the interlayer distance of the rGO nanosheets expanded
to 0.87 nm. The synergistic effect of γ-MnO
2
, α-Ni(OH)
2
, and rGO exhibited the satisfying high cyclic stability with
a capacitance retention of 82% even after 10 000 cycles. Thus,
the as-prepared Ni(OH)
2
and MnO
2
intercalated
rGO ternary hybrid is expected to contribute to the fabrication of
a real-time high-performing supercapacitor device.
We are reporting the preparation of a self-doped mesoporous activated carbon by the treatment of waste collected from car engine exhaust. The waste was pyrolyzed at 850°C in N 2 atmosphere using KOH activating agent. Highly porous activated carbon was obtained with the presence of N, O, S, and P as self-dopant. A high specific surface area of 410 m 2 g −1 with the pore volume of 0.5947 cm 3 g −1 was achieved. Electrode prepared with the activated carbon showed a high specific capacitance (280 Fg −1 ) using a 1-butyl-3-methylimidazolium chloride electrolyte. It retained 95% of initial capacitance after 10,000 cycles, demonstrated high cyclic stability and sustainability.
In this work, we reported a facile hydrothermal process to fabricate activated carbon (AC) from waste jute fibre. Sequential chemical and thermal activation have been introduced to form a highly functionalized and porous structure. The prepared AC was characterized by Field Emission Scanning Electron Microscopy (FESEM), X-ray Powder Diffraction (XRD), and Raman Spectroscopy. A hierarchical porous 3D cage-like microstructure was observed from FESEM. Non-linear highly disordered structure and low crystallinity were confirmed by XRD and Raman Spectroscopy. The synthesized AC was then used for batch adsorption study for the removal of an industrial toxic dye, basic blue 41 (BB41). The dependence of the adsorption process on different factors e.g., pH, contact time, and initial concentration has been investigated to find the optimum process conditions. At pH 8, maximum removal of 90 % was achieved. The adsorption was rapid for the first 30 minutes and reaches equilibrium at 70 minutes. Adsorption kinetics were interpreted by pseudo 1st and 2nd order kinetics, and it was best demonstrated by the later one. Langmuir and Freundlich isotherm models were linearized with experimental data; maximum adsorption capacity of 161.30 mg/g was calculated from the Langmuir model, which depicts the actual adsorption capacity.
Adsorbents based on nanocrystalline cellulose (NCC) were synthesized by two steps selective functionalization at C-2, C-3 position of glucose moiety/structure resulting in an intermediate product, di-aldehyde nanocrystalline cellulose (DANC) and final product, di-carboxylate nanocrystalline cellulose (DCNC). The success of functionalization reaction was confirmed by FTIR and SEM. The removal of basic blue 41 was then investigated by varying process parameters such as initial solution pH, contact time and initial dye concentration. The adsorption kinetics were investigated using pseudo 1 st and pseudo 2 nd -order model; which fitted well to the later one. Meanwhile, adsorption isotherm study predicted monolayer adsorption mechanism following the Langmuir model with a calculated maximum adsorption capacity of 446.19 mg/L for DCNC, which was much higher compared to DANC and NCC. The reusability studies configured that DCNC can be reused at least 5 cycles without losing significant efficiency. These findings prefigure that DCNC is an excellent biodegradable adsorbent.
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