N.B. Singh

Fly ash/Kaolin based geopolymer green concretes and their mechanical properties.

Geopolymer concrete mixes were cast using fly ash, kaolin, sodium hydroxide, potassium hydroxide, sodium silicate and aggregates. Portland cement concrete (M30) was used as a reference sample. The effect of silica fume, temperature (40 °C, 60 °C, 80 °C, 100 °C and 120 °C), sodium and potassium hydroxides and different superplasticizers on the compressive strength are reported [1]. Maximum strength was found at 100 °C and 14 M alkali solution [1].

Combined effect of sodium sulphate and superplasticizer on the hydration of fly ash blended Portland® cement

Combined effect of polycarboxylate type superplasticizer and sodium sulphate on the hydration of fly ash blended Portland® cement has been studied by using different techniques. Water consistency, setting times, non-evaporable water contents, water percolation, air contents, compressive strengths and expansion in corrosive atmosphere were determined. Hydration products were examined with the help of DTA and X-ray diffraction techniques. It is found that the superplasticizer reduces the pore size and its adsorption on cement surfaces is decreased in the presence of sodium sulphate. Mechanism of hydration is discussed.

Phase Diagram Study of Succinonitrile-Vanillin Organic Alloy System

Phase diagram studies of succinonitrile-vanillin system show the formation of 2:1 congruent melting type compound. Crystallization velocities of pure components, succinonitrile-vanillin complex, and two eutectics have been determined at different undercoolings. On the basis of heat of fusion measurements, excess thermodynamic functions have been calculated. Microstructural studies revealed that impurities modify the morphology. FTIR spectral studies and computer simulation have shown the existence of hydrogen bonding in the eutectics and the congruent melting compound. On the basis of experimental results, the mechanism of formation of eutectics and its solidification behavior are discussed.

Cu(II) ion removal from aqueous solution using different adsorbents

AbstractRemoval of Cu(II) ions from aqueous solution by different adsorbents such as Khangar, bangal gram husk (BGH), and orange mesocarp (OMS) was studied. The equilibrium adsorption level was determined as a function of pH, adsorbent dose, metal ion concentration, and contact time. The working conditions were optimized by using a Taguchi L16 (44) experimental design. Statistical tools viz. signal-to-noise ratio (S/N) and analysis of variance have been used at 95% confidence level for all considered parameters. It was found that pH is the most important parameter for removal of Cu(II) from aqueous solution. The maximum adsorption capacities for Cu(II) on Khangar, BGH and OMS adsorbents were found to be 92.14, 90.34, and 85.73%, respectively. Langmuir and Freundlich adsorption isotherms were used to model the equilibrium adsorption data and it was found that for Khangar both isotherms fit the data. The study revealed that out of three adsorbents Khangar was found to be the most promising adsorbent for the...

Crystallization and Simulation Studies in m-Dinitrobenzene–p-Chloroaniline Eutectic System

Thaw-melt method showed that the phase diagram of m-dinitrobenzene (m-DNB)–p-chloroaniline (p-CA) system belongs to simple eutectic type. The kinetics of solidification followed Hillig and Turnbull’s equation. Excess thermodynamic functions and FT-IR spectral studies indicated some weak interaction between the component molecules in the eutectic. The mechanical strength of the eutectic was found to be higher than those of its components. Molecular stability was predicted on the basis of frontier molecular orbital analysis. The value was found to be 0.06073 a.u. for eutectic, indicating. the possibility of charge transfer interaction during the eutectic formation. Results showed that the eutectic is stabilized by hydrogen-bond formation. Calculated interaction energy of reactants and eutectic was found to be–17.4 kJ mol–1.

Effects of dietary nano and macro iron oxide (Fe2O3) on the growth, biochemical, and hematological profiles of African catfish (Clarias gariepinus) fingerlings

ABSTRACT Effects of nano and macro iron oxide as dietary iron sources on the growth, hematological, and biochemical characteristics of African catfish, Clarias gariepinus, fingerlings have been studied. Conventional basal feed was supplemented with nFe2O3 and Fe2O3 as treatments T1 and T2 (each at 0.0, 0.2, 0.4, 0.8, 1.2, and 1.6 g/kg supplementation levels) and given to C. gariepinus fingerlings (initial average weight and length 5.01 ± 0.80 g and 7.0 ± 0.53 cm respectively) for 7 weeks. After 7 weeks, the highest percent weight gains of 395.6% for T1 and 767.4% for T2 occurred simultaneously at the supplementation level of 0.4 g Fe kg−1 dry feed of both treatments, while the highest value for the control was 332.5%. Iron accumulations in liver were 2.727, 1.443, and 1.225 ppm, and red blood cell counts were 2.3, 6.0, and 7.0 x 1012/l for the same treatments. Supplementation of iron oxide in both nano and macro forms significantly improved the growth and health indices of C. gariepinus up to a concentration of 0.4 g Fe kg−1 dry feed. Also macro iron oxide was more effective than the nano form in enhancing fish growth within the supplementation levels (0.2−1.6 g kg−1) considered.

The solidification behavior and phase equilibrium of o-Nitroaniline-β-Naphthol binary eutectic system

ABSTRACT Phase diagram studies of o-nitroaniline-β-naphthol system have been made by the thaw melt method. Simple eutectic type phase diagram was formed. Formation of eutectic mixture occurred at 0.7222 mole fractions of o-nitroaniline and melted at 326.85 K. The heat of fusion of components and eutectic mixtures were determined with the help of DSC technique and excess thermodynamic functions were calculated. Experiments were performed to study the undercooling, microstructure and linear velocities of crystallization. Flexural strength measurements were also made. Eutectic mixture showed higher flexural strength as compared to the components.