Abhishek Kardam

Ultrafast thermal charging of inorganic nano-phase change material composites for solar thermal energy storage

The present research article reports the heat transfer characteristics of nano-phase change material (NPCM) composites: nanographite (NG)–PCM composites and multi-walled carbon nanotube (CNT)–PCM composites. For the preparation of NPCM composites, inorganic PCM, magnesium nitrate hexahydrate (Mg(NO3)2·6H2O) was used as the pristine PCM and nanocellulose was used as a stabilizing agent. NG–PCM composites were prepared by varying the concentration of NG from 0.1–0.6 wt%, whereas CNT–PCM composites were prepared using 0.1 and 0.2 wt% of CNT. The prepared NPCM composites exhibited enhanced thermal conductivity and a faster heating rate than pristine PCMs. Two different experimental setups were used for investigating the heat transfer characteristics of the prepared NPCM composites during the melting and solidification processes: (i) conventional heating and (ii) solar illumination. The experimental observations indicated a higher heat transfer rate in the NPCM composites as compared to pristine PCM for both experimental setups. It was observed that the heating melting and solidification rate using a conventional heating setup increased by 48% and 77%, respectively, for NG–PCM composites (at 0.6 wt%) & 24% and 15%, respectively for CNT–PCM composites (at 0.2 wt%). Upon solar illumination, both NG–PCM and CNT–PCM composites demonstrated an ultrafast heating rate (of the order of few seconds) and a higher heating temperature than the conventional heating based approach. The ultrafast heating of NPCM composites upon solar illumination was attributed to the plasmonic heating effect of carbon nanomaterials, which instantly convert optical energy into heat at nanometer scale in addition to conventional thermal diffusion based slow heating, the sole mechanism responsible for slow heating of PCM composites in a conventional heating setup. Out of the two carbon nanofillers used, CNTs were shown to have a better heat transfer performance than NGs to collect, convert and store the broad spectrum solar energy as thermal energy.

A novel reusable nanocomposite for complete removal of dyes, heavy metals and microbial load from water based on nanocellulose and silver nano-embedded pebbles

The present work proposed a nanocellulose (NC)–silver nanoparticles (AgNPs) embedded pebbles-based composite material as a novel reusable cost-effective water purification device for complete removal of dyes, heavy metals and microbes. NC was prepared using acid hydrolysis of cellulose. The AgNPs were generated in situ using glucose and embedded within the porous concrete pebbles by the technique of inter-diffusion of ion, providing a very strong binding of nanoparticles within the porous pebbles and thus preventing any nanomaterials leaching. Fabrication of a continual running water purifier was achieved by making different layering of NC and Ag nano-embedded pebbles in a glass column. The water purifier exhibited not only excellent dye and heavy metal adsorption capacity, but also long-term antibacterial activity against pathogenic and non-pathogenic bacterial strains. The adsorption mainly occurred through electrostatic interaction and pore diffusion also contributed to the process. The bed column purifier has shown 99.48% Pb(II) and 98.30% Cr(III) removal efficiency along with 99% decontamination of microbial load at an optimum working pH of 6.0. The high adsorption capacity and reusability, with complete removal of dyes, heavy metals and Escherichia coli from the simulated contaminated water of composite material, will provide new opportunities to develop a cost-effective and eco-friendly water purifier for commercial application.

Enhanced Removal of Cationic Dye Methylene Blue from Aqueous Solution Using Nanocellulose Prepared from Agricultural Waste Sugarcane Bagasse

In the present communication nanocellulose was prepared from agricultural waste sugarcane bagasse and used for the removal of cationic dye methylene blue . Nanocellulose was prepared using bleaching treatment of agricultural waste followed by acid hydrolysis . SEM, TEM and TGA techniques were used to characterize prepared nanocellulose particles. Adsorption studies were optimized using simple batch experiments. Maximum sorption efficiency obtained for the removal of methylene blue using nanocellulose is 35 mg/g. The adsorption process fitted well for both Langmuir and freundlich isotherms. Regeneration studies signify that nanocellulose can be used successively up to 6 cycles of adsorption/desorption.

A Review on Thermophysical Properties of Nanoparticle-Enhanced Phase Change Materials for Thermal Energy Storage

A review of current experimental studies on variations in thermophysical properties of phase change material (PCM) due to dispersion of highly-conductive nanoparticles , coined as nanoparticle-enhanced PCMs (NePCMs), is presented in this article. The NePCMs may be considered as a solution to improve latent heat thermal energy storage performance. Thermophysical properties such as thermal conductivity, latent heat, viscosity and super cooling of PCMs could be changed for different physical properties of dispersed nanoparticle such as size, shape, concentration and surface properties. The present review focuses on the studies that describe the effect of addition of nanoparticles on the thermophysical properties of PCM with the help of available explanations in the literature.

Thermal properties of nano-graphite-embedded magnesium chloride hexahydrate phase change composites

Phase change materials can provide large heat storage density with low volume. But their low thermal conductivity limits their heat transfer capabilities. Since carbonaceous nanoparticles have a good thermal conductivity they can be applied as an additive to phase change materials to increase their heat transfer rate. In this study, nano-graphite is used as an additive and the influences of its various concentrations on the thermal conductivity and melting and freezing rate for the nanoparticle-enhanced phase change materials is experimentally investigated. Experimental results indicates a reduction of 22% in melting time and a reduction of 75% in solidification time of 0.5% nano-graphite-embedded phase change material.

Solar thermal charging properties of graphene oxide embedded myristic acid composites phase change material

The present paper reports the heat transfer characteristics of graphene oxide (GO) embedded myristic acid based phase change material (GO-PCM) composites. By varying concentrations of GO (0.1-0.5 wt%), different GO-PCM composites were preapred. Two different experimental setups were used for investigating the heat transfer characteristics of the prepared GO-PCM composites during the melting and solidification processes: (i) conventional heating and (ii) solar illumination. The experimental observations indicated a higher heat transfer rate in the GO-PCM composites as compared to pristine PCM for both experimental setups. From the experimental results of conventional heating setup, it was observed that the melting and solidification rate for GO–PCM composites, at 0.5 wt% of GO, increased by 48% and 70%, respectively in comparison to pristine PCM. The experimental results using solar illumination setup demonstrated an ultrafast heating rate for GO-PCM composites than the conventional heating based approach.

Real Time Measurement of Biosorption Efficiency of Chemically Modified Coconut Powder for Pb(II) and Cd(II) Using Open Circuit Potential

Abstract The present communication reports a new method for the potentiometric determination of adsorbent efficiency of coconut shell powder for removal of lead and cadmium from water. A three-electrode system containing metal-coated copper wire electrode was used as a working electrode. At equilibrium Open Circuit Potential (OCP) values represents metal ion concentration in solution. With the addition of coconut powder an appreciable decrease in the OCP was observed, which is associated with the reduction of the metal ion concentration due to the uptake of metal ions by the coconut powder. Chemical modification of coconut biomass was carried out by graft co-polymerization of acrylic acid. Modified biopolymer has been characterized using FTIR technique. An increase in the adsorbent efficiency of the biomass was observed by graft-copolymerized biopolymer i.e. from 54.4 mg/g to 122.1 mg/g and 58.8 mg/g to 141 mg/g respectively for Pb (II) and Cd (II) ions. The OCP based method provides an easy and simple approach for real time measurement of adsorption efficiency, which is a low cost and less time consuming process.