Electro-Fenton treatment of synthetic organic dyes: Influence of operational parameters and kinetic study

This work investigates oxidative decolorization of two different dyes, Methylene blue and Titan yellow in aqueous solution using an environmentally friendly advanced electro-chemical oxidation (electro-Fenton) process. The effect of operating conditions like H₂O₂ concentration, current density, initial dye concentration was studied in a batch stirred cell. Individual decolorization decay kinetics for both dyes was investigated. The second-order absolute rate constants (L mol^?1 s^?1) between hydroxyl radical and dye have been calculated from experimental data by fitting it to the decolorization model. The apparent kinetic constants, k _app (s^?1) for Methylene blue and Titan yellow dye decolorization were also determined. The experimental data showed a good fit to the theoretical model, which can predict data in a wide range of % dye decolorization. This process also reduces COD of the dye solution, and the unit energy demand (UED) in kWh/kg COD removed for different electrical current has been reported.     

Separation of acid–water mixtures by pervaporation using nanoparticle filled mixed matrix copolymer membranes

BACKGROUND: Low energy and less expensive membrane based separation of acetic acid‐water mixtures would be a better alternative to conventional separation processes. However, suitable acid resistant membranes are still lacking. Thus, the objective of the present study was to develop mixed matrix membrane (MMM) which would allow high flux and water selectivity over a wide range of feed concentrations of acid in water. RESULTS: Three MMMs, namely PANBA0.5, PANBA1.5 and PANBA3 were made by emulsion copolymerization of acrylonitrile (AN) and butyl acrylate (BA) with 5.5:1 comonomer ratio and in situ incorporation of 0.5, 1.5 and 3 wt%, sodium montmorilonite (Na‐MMT) nanofillers, respectively. For a feed concentration of 99.5 wt% of acid in water the membranes show good permeation flux (2.61, 3.19, 3.97 kg m^?2 h^?1 µm^?1, for PANBA0.5, PANBA1.5 and PANBA3 membrane, respectively) and very high separation factors for water (1473, 1370, 1292 for PANBA0.5, PANBA1.5 and PANBA3 membrane, respectively) at 30 °C. Similarly for a dilute acid–water solution, i.e. for 71.6 wt% acid the membrane showed a very high thickness normalize flux (8.67, 9.44, 11.56 kg m^?2 h^?1 µm^?1, for PANBA0.5, PANBA1.5 and PANBA3 membrane, respectively) and good water selectivity (101.7, 95.3, 79 for PANBA0.5, PANBA1.5 and PANBA3 membrane, respectively) at the same feed temperature. The permeation ratio, permeability, diffusion coefficient and activation energy for permeation of the membranes were also estimated. CONCLUSION: Unlike most of the reported membranes, the present MMMs allowed high flux and selectivity over a wide range of feed concentrations. These membranes may also be effective for separating other similar organic‐water mixtures. Copyright © 2012 Society of Chemical Industry     

ENGAGE compatibilized HDPE/EPDM blends: Modification of some industrially pertinent properties and morphology upon incorporation of Mg(OH)2 filler and electron beam crosslinked network

To observe the effect of ENGAGE (a poly‐olefin elastomer) on compatibilization of industrially important incompatible blend, high‐density polyethylene (HDPE)/ethylene‐propylene diene elastomer (EPDM), 15 wt % ENGAGE is incorporated into the system and the latter is found satisfactorily efficient as compatibilizer for the above system. To improve some industrially pertinent properties another strategies are also followed in addition, incorporation of magnesium hydroxide [Mg(OH)₂] and electron beam (EB) crosslinking into the system. The gel content was found to increase with radiation dose, EPDM content and Mg(OH)₂ dispersion. ENGAGE interestingly increases the gel content that is, promotes crosslinking. It is unique that filler dispersion and crosslinked network formation maintain the compatibility of the ternary system, which is confirmed by X‐ray diffraction, differential scanning calorimetry, mechanical properties, and scanning electron microscope. The compatibilization, Mg(OH)₂ dispersion, and EB crosslinking improve the mechanical, thermo mechanical, flame retardant properties, and phase morphology considerably. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44922.     

SiC–YAG sintered composites from hydroxy hydrogel powder precursors

Yttrium hydroxide and aluminium hydroxide hydrogel were derived from yttrium nitrate and aluminium nitrate through hydroxy hydrogel route in which SiC particles were kept dispersed. The gel-like mass was heat treated at 900°C in ambient atmosphere followed by heat treatment at 1400°C in Ar atmosphere. The specimens were then sintered in the temperature range of 1800–1950°C in Ar atmosphere with 30 min soaking. The phases were identified by XRD analysis. Microstructure of the sintered materials were analysed by scanning electron micrograph. With this new method of preparation of powder precursors, the process of sintering was easier and almost theoretical density was achieved with moderate hardness. The mechanism of densification was postulated to be a solid-state initiated liquid phase sintering and the overall process of which was activated by the reactive species formed from hydroxy hydrogel powder precursors.     

Evaluation of Non-Ambiguous Critical Micelle Concentration of Surfactants in Relation to Solution Behaviors of Pure and Mixed Surfactant Systems: A Physicochemical Documentary and Analysis

Critical micelle concentration (CMC) is a fundamental physical parameter of surfactant aggregation in solution. The CMC is determined by different methods, tensiometry, conductometry, microcalorimetry, fluorimetry, and so on. However, it is known that though CMC is reported as a single value, in reality, micelle formation occurs over a narrow range of concentration for different experimental procedures produce different results. We shall discuss about a unique procedure of measuring correct CMC applicable to all potential methods used in practice. This is essential for the evaluation of thermodynamic properties of the micelle forming process in pure and mixed states in terms of solution theories. As we in this short documentary want to deal with various aspects of Milton Rosen's research—wherein we have also worked—a few other facets of surfactant chemistry research, besides the micelle formation, are also briefly discussed. In mixed surfactant systems, synergistic effects in various surfactant properties like detergency, foaming, solubilization, and so on are found whereas in some others non-synergistic effects are observed. Dehydration of micelles with an increase in temperature or by the addition of hydrophilic substances may cause clouding to the system. Soluble amphiphilic systems produce Gibbs monolayer at the air/water interface; insoluble amphiphiles form Langmuir monolayers. A documentary of the above aspects will be herein presented and discussed. We mention that this article is neither an original research article nor a review article. This is a mixture of the two: a documentary of both original research and some review of our works presented in memory of Prof. Milton Rosen.     

Design of Alkaline/Surfactant/Polymer (ASP) Slug and its use in Enhanced Oil Recovery

Abstract

Studies have been done to design an optimum composition of alkali/surfactant/polymer (ASP) slug and its application in flooding to increase the additional recovery of oil. A very low concentration of alkali and surfactant is used to achieve ultra-low interfacial tension between the trapped oil and the injection water, and polymer is used to increase the viscosity of the injection water for mobility control. Based on the experimental results of physico-chemical properties of polymer, surfactant, and alkali and their mutual interaction in solution, an ASP slug of composition SDS: 0.1 wt%, SDBS: 0.075 wt%, polyacrylamide: 2,000 ppm, and NaOH: 0.7 wt% has been recommended for flooding. Two sets of core-flooding experiments have been conducted using the designed ASP slug in a tri-axial core holder to measure the additional recovery of oil. The average additional oil recovery over conventional water flooding was found to be more than 20% of the original oil in place (OOIP).     

Efficient processing of oil–water emulsions confined within 2D cylinders with various microwave irradiations: Role of metallic annulus

Extensive studies have been carried out to investigate the role of metallic annulus on efficient microwave processing of oil–water emulsions confined within 2D cylinders in the presence of lateral/radial irradiations. A preliminary study has been carried out via average power within a sample vs. sample diameter to estimate microwave power absorptions for various o/w and w/o emulsions with specific fractions of the dispersed phase (?) in the absence of metallic annulus. Based on those studies, various regimes (sample dimension) have been identified for each emulsion (o/w or w/o) based on appropriate length scales. Two types of metallic annular configurations have been considered such as circular and square annuli for further analysis via average power vs. aspect ratio (a) distribution for each regime. Based on that study, suitable aspect ratios have been chosen to carry out detailed analysis on spatial power and temperature distributions for each regime with metallic annuli. Finally, optimal heating strategies have been recommended based on two significant factors such as ‘large heating rate’ with ‘minimal thermal runaway’ for various regimes of o/w and w/o emulsions. It is observed that average power absorptions show greater intensification due to metallic annulus for most of the regimes of o/w emulsions than that for corresponding regimes of w/o emulsions due to lateral and/or radial irradiations. However, in general, for regimes with smaller diameters (for both o/w and w/o samples) radial irradiation is favored, whereas for large regimes, lateral irradiation is favored as the optimal heating strategies.     

Application of single and mixtures of red sandalwood and other natural dyes for dyeing of jute fabric: studies on colour parameters/colour fastness and compatibility

Single and binary mixtures of aqueous extracts of red sandalwood (RSW) with aqueous extract of other natural dyes like manjistha (MJ), jackfruit wood (JFW), marigold (MG), sappan wood (SW) and babool (BL) in different proportions are applied on bleached jute fabric for its dyeing after double pre-mordanted with myrobolan and aluminium sulphate applied in sequence under optimised conditions of mordanting with effects of use of different proportions of binary mixture of selective natural dyes on colour strength and other colour. Parameters and colour fastness properties have been investigated. Compatibility of selective binary mixture of dyes was also judged by a relatively newer colour index parameter established earlier from this laboratory. Binary of mixture of RSW and MJ is found to be most compatible with rating 4 (in 0–5 scale), and mixture of RSW:MG and RSW:JFW is found to have average compatibility having rating 3. Dyed fabric samples have also been further treated with cationic dye-fixing agents namely N-cetyl-N-trimethylammonium bromide (CTAB), cetrimide and Sandofix-HCF to improve wash fastness. Treatment with 2% CTAB or Sandofix-HCF improves the wash fastness to nearly 1 unit. Treatment with 1% benztriazole improves the light fastness of natural dyed jute textiles nearly half to one unit. The possible chemistry and mechanisms for such improvement in wash fastness by CTAB and improvement of light fastness by benztriazole for jute have also been discussed to explain the observed effects.     

Investigation on germanium oxide-based glasses for infrared optical fibre development

We demonstrate the suitability of GeO₂ for fibre engineering by compositional modifications of core and cladding glasses using the rod-in-tube technique, which have been matched for fibre drawing. The methods adopted for identifying the core–clad combination (56GeO₂–31PbO–9Na₂O–4Ga₂O₃ and 55GeO₂–30PbO–11Na₂O–4Ga₂O₃) are explained, based on the thermal, viscosity, and optical properties. We specially point out to the relatively high transformation temperature range (T_g > 380 °C) of the glass, which is suitable for chemical sensing and metrological applications in the 150–200 °C. The total intrinsic loss is compared with the measured loss in multi- and single-mode fibres from 0.532 to 2.02 μm, with loss less than 2.5 dB m⁻¹ in the 1000–1600 nm range. The origin of larger loss outside this region is explained.     

Inventory model with two rates of production for deteriorating items with permissible delay in payments

Some decentralized smoothing problems are solved by applying a forward-pass fixed-interval smoother formula in discrete-time systems. It is assumed that a simple estimation structure consists of a global processor and of two local processors. Two cases are considered for the problems of decentralized smoothing and smoothing update: when the local backward-pass information filtered estimates are available, and when the local-smoothed estimates are available. Some features of present algorithms are discussed from the point of view of data transmissions and numerical computations, etc.