Improvement in galvannealed coating of IF-HS steel strips by combined GDOES and colour-etching method

Galvannealed coating of high strength interstitial free (IF-HS) steel was characterised by Glow Discharge Optical Emission Spectroscopy (GDOES) and colour-etching techniques. Overalloyed galvannealed coatings with considerably high amount of Γ and Γ1 phases were detected in the first set of experiments. Necessary process modifications in galvannealing furnace were made to maximise the ä phase in the galvannealed coating, which was confirmed through GDOES and colour-etching techniques. As a result, an improvement in galvannealed product quality with a better powdering resistance property during forming has been achieved.     

Electro-conductive Palmyra Fibers By In Situ Polymerization of Pyrrole

Palmyra (Borassus flabellifer L.) is one of the natural fruit fibers that are available in plenty. This fiber has many advantages, such as biodegradability, renewability, low density, and low cost, which offer greater opportunities to develop new applications. Imparting electrical conductivity to this fiber may open up avenues for various novel applications. In the present study, Palmyra fibers are made electro-conductive by in situ chemical polymerization of pyrrole with FeCl₃ oxidant and PTSA dopant. Prepared electro-conductive fibers show average electrical resistivity 2.96 kΩ cm^?1. A positive correlation is found between fiber-length and electrical resistance, whereas a negative correlation is found in between fiber-diameter and electrical resistance. FTIR study is conducted to understand the chemical interaction between lingo-cellulose and polypyrrole. Tensile properties and thermal degradation behavior of the prepared electro-conductive fibers are evaluated, and significant deterioration of both tensile properties and thermal stability is observed. Due to this reason, these electro-conductive fibers are unsuitable for mechanical processing and high-tech applications. But the response of these fibers in different pH solution is investigated, and their possible application as a pH sensor has been explored.     

Polypyrrole based electro-conductive textiles for heat generation

This work deals with the preparation and characterization of electrically conductive textiles for heat generation. Needlepunched nonwoven, spunlace nonwoven, and woven fabrics, all made of 100% polyester fibers, were made electrically conductive by in situ chemical polymerization of pyrrole with p-toluene sulfonic acid dopant. Alkali hydrolysis of polyester fabrics was done before in situ polymerization for better fixation of polypyrrole on polyester. The average surface resistivities were found to be 1013.08, 1099.72, and 1434.12?Ω/□, respectively, for needlepunched, spunlace, and woven fabrics. The electro-conductive fabrics displayed exponential rise of surface temperature on application of voltage and the rise of temperature was found to be related to the time duration of applied voltage. The electro-conductive fabrics exhibited linear voltage–current relationship at low voltage range. The surface resistivity of the electro-conductive fabrics was increased substantially on prolong exposure to atmosphere.     

Casein based biogenic‐synthesized zinc oxide nanoparticles simultaneously decontaminate heavy metals,dyes, and pathogenic microbes: a rational strategy for wastewater treatment

BACKGROUND

Wastewater management has become a great concern recently due to industrial and domestic discharges containing metals, organic pollutants and pathogenic microbes that contaminate water bodies and also cause waterborne diseases. Although there have been multiple conventional processes for removing contaminants, nanomaterials have recently gained importance for wastewater treatments.

RESULTS

Here, ZnONP_CS with an average size of 10 nm was successfully synthesized by using casein as biogenic reducing and capping agent. Removal of three metals and two dyes was investigated and it was found that nearly 90% was removed. Adsorption isotherm data were best fitted with the Langmuir model, and the maximum adsorption capacity (mg g^?1) was found to be 156.74 for Cd(II), 194.93 for Pd(II), 67.93 for Co(II), 115.47 for methylene blue and 62.19 for congo red. Repeated cycles of regeneration and reuse showed a drop in removal efficiency of 10–13%. Further, nanoparticles also showed efficient photo‐degradation of dyes within 240 min. Moreover, ZnONP_CS demonstrated high antibacterial potential for Escherichia coli in the presence of metals and dyes.

CONCLUSION

Biogenic synthesized ZnONP_CS demonstrated simultaneous removal of metals, dyes as well as pathogenic microbes, and could be used as a cost‐effective and reusable system in various industrial effluent treatments. © 2018 Society of Chemical Industry     

Active layer modification of commercial nanofiltration membrane using CuBTC/PVA matrix for improved surface and separation characteristics

The present study proposes a facile route for the modification of commercial nanofiltration (NF) polymeric membrane by embedding metal organic framework (MOF) via dip coating. A mixed membrane matrix comprising of copper benzene-1,3,5-tricarboxylate (CuBTC) and polyvinyl alcohol (PVA) served as the new active layer. The obtained topography, functional group, and surface elemental analysis elucidated the presence of heterogeneous phase and the distribution of the MOF on the membrane. The dip coating well supported the modification through excellent adhesion. The water wettability of the modified membrane displayed a positive correlation with CuBTC loading in the PVA polymer matrix. Permeation and separation characteristics of the resultant membranes were investigated by retaining protein and carbohydrates from synthetic dairy wastewater (SDWW). The permeability rate of modified samples increased to 43% as compared to the commercial NF membrane. A significant improvement in the rejection rate of carbohydrate from 61% to 87% and protein from 88% to 94% was achieved. Membrane Fouling was found to be much lesser for the modified samples. The study highlights the potential of CuBTC as filler material for enhancing the separation characteristic of established NF membrane.     

A Sinusoidal Pulsewidth Modulated Three-Phase AC to DC Converter-Fed DC Motor Drive

The external performances such as power factor, displacement factor, harmonic factor, and ripple factor of a three-phase ac to dc converter-fed separately excited dc motor drive employing sinusoidal pulsewidth modulation (SPWM) control technique are obtained for different speeds and modulation indexes. Since separately excited dc motors with armature voltage control provide constant torque operation, the external performance is also determined for the drive motor operating at different values of constant load torque. Motoring and regenerating operations of the dc drive machine are considered. The three-phase PWM converter-motor drive system is analyzed, taking commutation effects into account in motoring and regenerating operations. The analysis has revealed 27 common modes in one repetitive period of the output voltage. The sequence of modes for all pulses in one period of the output voltage is established. Experimental oscillograms of typical waveforms from a laboratory-sized dc motor are illustrated to verify the basic principles of operation. Although the converter circuit requires some additional components in comparison with the commonly used phase-controlled converter, the improved performance characteristics make it attractive for industrial applications involving large power ratings.     

Constructing special k-dominating sets using variations on the greedy algorithm

This paper focuses on the efficient selection of a special type of subset of network nodes, which we call a $k$-SPR set, for the purpose of coordinating the routing of messages through a network. Such a set is a special $k$-hop-connected $k$-dominating set that has an additional property that promotes the regular occurrence of routers in all directions. The distributed algorithms introduced here for obtaining a $k$-SPR set require that each node broadcast at most three messages to its $k$-hop neighbors. These transmissions can be made asynchronously. The time required to send these messages and the sizes of the resulting sets are compared by means of data collected from simulations.The main contribution is the adaptation of some variations of the distributed greedy algorithms to the problem of generating a small $k$-SPR set. These variations are much faster than the standard distributed greedy algorithm. Yet, when used with a sensible choice for a certain parameter, our empirical evidence strongly suggests that the resulting set size will generally be very close to the set size for the standard greedy algorithms.     

Assessment of wastewater treatment technologies: life cycle approach

Four municipal wastewater treatment plants (WWTPs) in India based on different technologies are compared by conducting Life Cycle Assessment (LCA) using field data. CML 2 baseline 2000 methodology is adopted in which eight impact categories are considered. SBRs ranked highest in energy consumption and global warming potential (GWP) but also produced the best effluent with respect to organics and nutrients. Constructed wetlands have negligible energy consumption and negative GWP because of carbon sequestration in the macrophytes. Emissions associated with electricity production required to operate the WWTPs, emissions to water from treated effluent and heavy metal emissions from waste sludge applied to land are identified as main contributors for overall environmental impacts of WWTPs. This comparison of technologies suggests that results from LCA can be used as indicators in a multicriteria decision‐making framework along with other sustainability indicators.     

Numerical study on heat transfer and pressure drop characteristics of fluid flow in an inserted coiled tube type three fluid heat exchanger

The paper presents numerical investigations of a three fluid heat exchanger (TFHE), which is an improvement on the double pipe heat exchanger, where a helical tube is inserted in the annular space between two straight pipes. The helical tube side fluid, that is, hot water continuously transfers heat to the outer annulus side fluid and innermost tube side fluid. The heat transfer and pressure drop characteristics of the TFHE are assessed for different flow rates and inlet temperatures. With an increment in the volumetric flow rate of the helical tube side fluid and outer annulus side fluid, the overall heat transfer coefficient increases, and the effectiveness decreases for heat transfer from the helical tube side fluid to outer annulus side fluid in both parallel flow and counter flow configurations. It is also observed that with increment in the helical tube side fluid inlet temperature, the overall heat transfer coefficient and effectiveness increases for heat transfer from the helical tube side fluid to outer annulus side fluid in both flow configurations. The parameter, JF factor, has been proposed to evaluate the thermohydraulic behavior of the TFHE, where it is obtained that the behavior of the TFHE is better at a lower helical tube side fluid velocity and higher outer annulus side fluid velocity.