D.K. Kohli

Enhanced salt-adsorption capacity of ambient pressure dried carbon aerogel activated by CO2 for capacitive deionization application

AbstractCarbon aerogels (CAs) were prepared by polycondensation of resorcinol and formaldehyde using ambient drying technique and were further activated by CO2. These were investigated for capacitive deionization (CDI) application. The gel parameters were optimized to obtain mesoporous CA with pore size distribution in 8–10 nm. The CA was further subjected to CO2 activation at 950°C for different time durations and its effect on surface properties was studied. The surface area of the activated CA increased from 698 to 2057 m2/g with corresponding increase in mesopore area from 289 to 644 m2/g. The pore volume also increased from 0.79 to 1.72 cm3/g. Cyclic voltammetry was performed on the test electrodes and specific capacitance values of 108 F/g was measured at scan rate of 10 mV/s in 1 M NaCl. Electrodes of size 200 × 200 mm were synthesized with an active material loading of ~15 mg/cm2 and their CDI performance was evaluated in batch mode experiment. Salt-adsorption capacity as high as 8.4 mg/g for CO2 ...

Study of carbon aerogel-activated carbon composite electrodes for capacitive deionization application

Abstract Electrodes synthesized using mesoporous carbon aerogel (CA), microporous-activated carbon (AC), and different combinations of the two were evaluated for capacitive deionization application. Composite electrodes with CA and AC in the ratio of 75:25 provided the highest specific capacitance value (90 F/g at scan rate of 2 mV/s). Further, it was observed that on increasing the scan rates to up to 10 mV/s, the reduction in specific capacitance values for the electrodes with 75:25 CA/AC composition was only 5%, whereas the reduction for pure CA and pure AC electrodes were 23 and 52%, respectively. The test cell made using 75:25 CA/AC composite electrodes (size 10 cm × 10 cm with material loading of 15 mg/cm2) showed fast adsorption and desorption cycle of ∼15 min and salt removal efficiency of 51% was obtained.

Preparation and characterization of hydrophobic platinum-doped carbon aerogel catalyst for hydrogen isotope separation

We report preparation of hydrophobic platinum-doped carbon aerogel (PtCA) catalyst and its characterization for catalytic exchange reactions between hydrogen isotopes. The PtCA powder was synthesized by sol-gel polymerization method, mixed with colloidal PTFE solution, and coated on Dixon rings to obtain hydrophobic catalyst. The Pt cluster size in PtCA powder was observed to vary from 3 to 5 nm for a change in resorcinol to alkali molar ratio in synthesis solution from 20 to 200. Transmission electron microscopy of powder showed that the Pt clusters were uniformally dispersed and Pt0 metallic content estimated by X-ray photoelectron spectroscopy (XPS) was found to be of ~70%. The catalytic activity was found to depend on Pt cluster size and was higher for smaller cluster size. For the smallest achieved Pt cluster size of 3 nm, catalytic activity of ~0.8 m3 (STP) s−1 m−3 was obtained for hydrogen isotope exchange in atmospheric pressure conditions.