Catalytic effect of carbon nanostructures on the hydrogen storage properties of MgH2–NaAlH4 composite

The present investigation describes the hydrogen storage properties of 2:1 molar ratio of MgH₂–NaAlH₄ composite. De/rehydrogenation study reveals that MgH₂–NaAlH₄ composite offers beneficial hydrogen storage characteristics as compared to pristine NaAlH₄ and MgH₂. To investigate the effect of carbon nanostructures (CNS) on the de/rehydrogenation behavior of MgH₂–NaAlH₄ composite, we have employed 2 wt.% CNS namely, single wall carbon nanotubes (SWCNT) and graphene nano sheets (GNS). It is found that the hydrogen storage behavior of composite gets improved by the addition of 2 wt.% CNS. In particular, catalytic effect of GNS + SWCNT improves the hydrogen storage behavior and cyclability of the composite. De/rehydrogenation experiments performed up to six cycles show loss of 1.50 wt.% and 0.84 wt.% hydrogen capacity in MgH₂–NaAlH₄ catalyzed with 2 wt.% SWCNT and 2 wt.% GNS respectively. On the other hand, the loss of hydrogen capacity after six rehydrogenation cycles in GNS + SWCNT (1.5 + 0.5) wt.% catalyzed MgH₂–NaAlH₄ is diminished to 0.45 wt.%.     

Effect of Chemical Treatment on the Tensile Strength Behavior of Coir Geotextiles

ABSTRACT

The present study investigates the effects of chemical treatment on the tensile strength behavior of the two woven and two nonwoven coir geotextiles. The results reveal that tensile elongation at failure for the untreated and treated woven and nonwoven coir geotextiles was higher in the warp direction in comparison to the weft direction. The tensile elongation at failure for the untreated and treated woven coir geotextiles were influenced by the stiffness and the opening of kinks in the coir yarn whereas the tensile elongation at failure of the untreated/treated nonwoven coir geotextiles was influenced by the presence of the polyethylene (PE) yarn used in stitching along with PE netting and diameter of the yarn used in PE netting. The chemical treatment decreased and increased the tensile strength of both the woven and nonwoven coir geotextiles, respectively. The mass per unit area of woven coir geotextile decreased whereas it increased for both the nonwoven coir geotextiles after the chemical treatment. The chemical treatment modifies the surface characteristics of both the untreated woven and nonwoven coir geotextiles due the removal of impurities and filling up the voids present on the surface.     

A novel moment generating function based performance analysis over correlated Nakagami-m fading channels

The bit-error rate and channel capacity have been regarded as fundamental information theoretic performance measure to predict the maximum information rate of a communication system. In contrast, with the analysis of other important performance measures of the wireless communication systems, a novel and unified general approach for computing the bit-error-rate and channel capacity over the correlated Nakagam-m fading channels have been proposed. In this paper, we have analyzed and numerically simulated the bit-error-rate and channel capacity of the correlated Nakagami-m fading channel by using the moment generating function (MGF) based approach. The derived mathematical expression for the channel capacity is in terms of the Meijer G function which is valid for both integer and non-integer values of the fading parameters.     

Flame synthesis of carbon nano onions using liquefied petroleum gas without catalyst

Densely agglomerated, high specific surface area carbon nano onions with diameter of 30–40 nm have been synthesized. Liquefied petroleum gas and air mixtures produced carbon nano onions in diffusion flames without catalyst. The optimized oxidant to fuel ratio which produces carbon nano onions has been found to be 0.1 slpm/slpm. The experiment yielded 70% pure carbon nano onions with a rate of 5 g/h. X-ray diffraction, high-resolution electron microscopy and Raman spectrum reveal the densely packed sp² hybridized carbon with (002) semi-crystalline hexagonal graphite reflection. The carbon nano onions are thermally stable up to 600 °C.     

Recycling of bleach plant effluent of an Indian paper mill using water cascade analysis technique

A systematic approach to optimizing water network has traditionally been utilized to examine and plan water conservation in industrial processes. In the present case study, water cascade analysis was used to analyze and optimize the water network of a bleaching section of an Indian paper mill. Water system integration can minimize both the freshwater consumption and wastewater discharge of a paper mill. Three limiting constraints, i.e., Chemical oxygen demand, Total dissolved solids, and Adsorbable organic halides (AOX), were considered for the study; after analysis, AOX was found to be a critical limiting constraint. A nearest neighbor algorithm (NNA) was used to distribute the fresh water and recycled water among the plant operations. After the application of WCA and NNA in the bleaching section, 41.75% of fresh water consumption and 70.67% of wastewater generation could be reduced.     

Hybrid Electrolyte Design for High-Performance Zinc–Sulfur Battery

Rechargeable aqueous Zn/S batteries exhibit high capacity and energy density. However, the long-term battery performance is bottlenecked by the sulfur side reactions and serious Zn anode dendritic growth in the aqueous electrolyte medium. This work addresses the problem of sulfur side reactions and zinc dendrite growth simultaneously by developing a unique hybrid aqueous electrolyte using ethylene glycol as a co-solvent. The designed hybrid electrolyte enables the fabricated Zn/S battery to deliver an unprecedented capacity of 1435 mAh g⁻¹ and an excellent energy density of 730 Wh kg⁻¹ at 0.1 Ag⁻¹. In addition, the battery exhibits capacity retention of 70% after 250 cycles even at 3 Ag⁻¹. Moreover, the cathode charge–discharge mechanism studies demonstrate a multi-step conversion reaction. During discharge, the elemental sulfur is sequentially reduced by Zn to S²⁻ (${\mathrm{S}}_8\to {\mathrm{S}}_{\mathrm{x}}^{2-}\to {\mathrm{S}}_2^{2-}+{\mathrm{S}}^{2-})$, forming ZnS. On charging, the ZnS and short-chain polysulfides will oxidize back to elemental sulfur. This electrolyte design strategy and unique multi-step electrochemistry of the Zn/S system provide a new pathway in tackling both key issues of Zn dendritic growth and sulfur side reactions, and also in designing better Zn/S batteries in the future.