Kinetics, thermodynamic and equilibrium study of Cr(VI) adsorption from aqueous solutions by NCL coal dust

The waste material NCL coal dust was used as adsorbent for removal of Cr(VI) from aqueous solutions under batch adsorption experiments. The maximum removal of 99.97% was recorded at pH 2. The time required to attain equilibrium was found to be 60 min. Adsorption kinetics was described by the Lagergren equation. The value of the rate constant of adsorption was found to be 0.0615 min^?1 at 16 mg dm^?3 initial concentration and 298 K. The applicability of the Langmuir and Freundlich equations for the present system was also tested at different temperatures: 298, 313, and 328 K. Both thermodynamic parameters and temperature dependence indicated the endothermic nature of Cr(VI) adsorption on coal dust. The results showed that NCL coal dust is a promising adsorbent for the removal of Cr(VI) from aqueous solutions.     

Electron‐Induced Reactive Processing of Poly(propylene)/Ethylene–Octene Copolymer Blends: A Novel Route to Prepare Thermoplastic Vulcanizates

TPVs are prepared by dynamic vulcanization in which crosslinking of an elastomeric polymer takes place during its melt mixing with a thermoplastic polymer under high‐shear conditions. 30:70 wt% blends of PP and ethylene–octene copolymer are vulcanized using electron‐induced reactive processing (EIReP) employing a range of absorbed doses (25, 50, and 100 kGy) while keeping the electron energy and treatment time fixed. The structure/property relationships of the prepared samples are studied using various characterization techniques such as DMA, DSC, SEM, and melt rheology. The results suggest that EIReP offers a novel route to prepare TPVs without any chemical crosslinking and coupling agents.

     

Protein-templated gold nanoclusters: size dependent inversion of fluorescence emission in the presence of molecular oxygen

Gold nanoclusters are promising candidates as biological markers without having toxic effects like fluorescent quantum dots. Herein, bovine serum albumin (BSA) protein stabilized gold nanoclusters of two different sizes emitting at 410 and 645 nm have been synthesized. These nanoclusters have been shown to interact with molecular oxygen differentially. Spectroscopic and chemical evidences show that dioxygen molecule gets adsorbed at two different orientations on the nanoclusters. The orientation motifs have been hypothesized to be superoxo and peroxo types on the smaller and the larger gold nanoclusters, respectively. Due to the difference in attachments, the oxygen molecule shows opposite changes in fluorescence intensity for the nanoclusters. The fluorescence intensity of the blue emitting nanocluster shows a profuse enhancement whereas the red emitting species shows quenching of emission. Superoxo type adsorption of the oxygen molecule on the blue emitting gold nanoclusters induce formation of singlet oxygen that in turn enhances the fluorescence intensity of the species. This could be verified by oxidation of diaminobenzidine (DAB) by singlet oxygen. Enhancement in fluorescence intensity of the blue emitting gold nanoclusters with an increase in concentration of molecular oxygen may enable them to be good candidates in bioimaging and detection.     

Anion-controlled morphologies and spectral features of cyanine-based nanoGUMBOS--an improved photosensitizer

The ability to control the morphologies and spectral properties of organic low-dimensional nanomaterials is of paramount importance. The research reported herein demonstrates a template-free approach to tailored morphological and optical properties for a novel class of pseudoisocyanine (PIC)-based fluorescent organic nanoparticles derived from a group of uniform materials based on organic salts (GUMBOS). The synthesized nanoscale PIC-based particles (termed nanoGUMBOS), [PIC][NTf(2)] and [PIC][BETI], exhibit interesting adaptability as a function of the associated anion. The diamond-shaped nanostructures of [PIC][NTf(2)] and [PIC][BETI] nanorods exhibit enhanced fluorescence quantum yields relative to the parent compound, [PIC][I]. As supported by fluorescence lifetime measurements, these enhanced spectral properties can be attributed to differences in molecular self-assembly ordering (e.g., H- vs. J-aggregation) and restricted molecular rotation leading to reduced twisted intramolecular charge transfer in the nanoGUMBOS. The electrochemical properties of the PIC-based GUMBOS suggest their potential use in dye-sensitized solar cells.     

Modeling of cross flow ultrafiltration of stevia extract in a rectangular cell

Prediction of ultrafiltration performance during clarification of pre-treated stevia extract by cross flow ultrafiltration in a rectangular cell is presented in this work. The steady state performance is modeled by using classical film theory. The transient state behaviour is quantified by using a model available in literature. In the model, higher molecular weight solutes are clubbed in one gel-forming component and Stevioside is assumed to be other component. In the process of modeling, the gel characteristics are estimated. Both total recycle and batch concentration mode of operations are modeled. The model results are in good agreement with the experimental data.     

Removal of Cd(II) from aqueous solution by kaolinite, montmorillonite and their poly(oxo zirconium) and tetrabutylammonium derivatives

Kaolinite, montmorillonite and their poly(oxo zirconium) and tetrabutylammonium derivatives have been used in this work for removing Cd(II) from aqueous solution. Batch adsorption studies were carried out under various Cd(II) concentrations, amount of clay adsorbents, pH, interaction time and temperature. The uptake of the metal was initially very fast, but gradually slowed down indicating diffusion into the interior of the adsorbent particles. The adsorption processes were more akin towards second order reaction mechanism. The suitability of the adsorbent was tested by fitting the adsorption data with Langmuir and Freundlich isotherms, which gave good fits with both isotherms. Adsorption was poor in strongly acidic solution but was improved in alkaline medium and continuously increased with rise in pH. The values of the thermodynamic parameters, DeltaH, DeltaS and DeltaG, indicated the interactions to be thermodynamically favourable.     

A strategic decision support system for logistics and supply chain network design

This paper aims to develop a strategic decision support system for logistics and supply chain network design of a multi-stage, multi-commodity, and multi-period distribution and transportation system. A mixed integer linear programming model is proposed to tackle the problem while minimizing the operating, transportation and handling cost through all tiers of the supply chain network. A genetic algorithm based method has been proposed to solve the problem in a large scale realistic environment. The efficacy of the developed strategic decision support model in achieving better utilization of network and resources to fulfil the customer demand is demonstrated using illustrative scenarios inspired from the real case of a logistics company.     

Effect of a thin prior-metallic coating on the morphology of hot-dip Zn coating

Copper has been investigated as a potential alloying element in the molten Zn bath and was found to have significant effects in phase formation kinetics as well as corrosion performance. In the present work, the effect of a prior-Cu coating process on hot-dip Zn coating morphology and thickness has been investigated. A thin layer of Cu was coated on steel by a displacement reaction having a thickness of 70–90?nm. The Cu and Zn coatings were characterised using glow discharge optical emission spectroscope, scanning electron microscope and confocal laser scanning microscope. The prior-Cu coating acted as a barrier to Fe dissolution and altered the substrate surface roughness as well as the interfacial energies resulting in modification of nucleation and growth of Fe–Zn intermetallic phases.