Biosorption of chromium onto Erythrina Variegata Orientalis leaf powder

The biosorption of chromium from an aqueous solution onto Erythrina Variegata Orientalis leaf powder was investigated in batch operations. The equilibrium agitation time was 180 min. The extent of chromium biosorption increased from 74.2% to 86.4% with decrease in biosorbent size from 150 to 45 μm for a dosage of 30 g/L. The biosorption decreased from 99.1 (0.45 mg/g) to 45.5% (1.64 mg/g) with an increase in chromium initial concentration (C _o ) from 22.5 to 180 mg/L. The extent of biosorption was maximum at pH=3. The experimental data were well explained by Langmuir and Redlich-Peterson isotherm models. The biosorption data followed second-order kinetics with a rate constant of 0.078 g/mg-min for 50 g/L of 45 μm size biosorbent. The biosorption was exothermic and feasible. The biosorption was tending towards irreversibility with increasing temperature.     

Influence of size-classified and slightly soluble mineral additives on hydration of tricalcium silicate

Early-age hydration of cement is enhanced by slightly soluble mineral additives (ie, fillers, such as quartz and limestone). However, few studies have attempted to systematically compare the effects of different fillers on cementitious hydration rates, and none have quantified such effects using fillers with comparable, size-classified particle size distributions (PSDs). This study examines the influence of size-classified fillers [ie, limestone (CaCO₃), quartz (SiO₂), corundum (Al₂O₃), and rutile (TiO₂)] on early-age hydration kinetics of tricalcium silicate (C₃S) using a combination of experimental methods, while also employing a modified phase boundary and nucleation and growth model. In prior studies, wherein fillers with broad PSDs were used, it has been reported that between quartz and limestone, the latter is a superior filler due to its ability to partake in anion-exchange reactions with C-S-H. Contrary to prior investigations, this study shows that when size-classified and area matched fillers are used—which, essentially, eliminate degrees of freedom associated with surface area and agglomeration of filler particulates—the filler effect of quartz is broadly similar to that of limestone as well as rutile. Results also show that unlike quartz, limestone, and rutile—which enhance C₃S hydration kinetics—corundum suppresses hydration of C₃S during the first several hours after mixing. Such deceleration in C₃S hydration kinetics is attributed to the adsorption of aluminate anions—released from corundum's dissolution—onto anhydrous particulates’ surfaces, which impedes both the dissolution of C₃S and heterogeneous nucleation of C-S-H.     

Phase behaviour modelling of Athabasca bitumen for in situ combustion applications

Phase behaviour modelling of reservoir fluid is a fundamental step for reservoir simulation. Furthermore, as the complexity of the recovery process increases, the fluid model plays a more important role in the reliability of the simulation outputs. Although the in situ combustion enhanced oil recovery method (ISC) is one of the most complex recovery techniques available in the petroleum engineering literature, for most of the simulation jobs related to this elaborate process only simple and rudimentary fluid characterization layouts are considered. In this work, the principal fluid properties of Athabasca bitumen with regard to the ISC process are recognized, extracted from the literature, validated for consistency, and used for the development of an inclusive and accurate fluid model. Then the fluid model is fully developed while considering the ISC reaction kinetics so that the model has both accuracy, indispensable for phase behaviour modelling, and consistency, essential for the reactions definitions.     

Ionic conductivity and interfacial properties of polymer electrolytes based on PEO and boroxine ring polymer

Blended polymer electrolytes based on poly(ethylene oxide) (PEO) and boroxine ring polymer (BP) solvated with lithium triflate were formulated and evaluated. Compared to PEO–salt polymer electrolyte, ionic conductivities of blended polymer electrolytes were two orders of magnitude higher in a low‐temperature range; as well, lithium transference numbers were increased to ～ 0.4. These were due to the increased mobility and anion trapping of boroxine rings. BP also exhibited the stabilizing effect on lithium–polymer electrolyte interface, and a reduced interfacial resistance between lithium metal and the polymer electrolyte was found with increasing of BP content. Polymer electrolytes based on PEO and BP are suitable for use in lithium secondary battery. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 17–21, 2002; DOI 10.1002/app.10090     

The outlook of zeolite-Y hampered metal–ligand framework as heterogeneous catalysts: synthesis,spectral account and catalytic features

Zeolite-Y enslaved complexes were prepared by the Flexible ligand method. Synthesized materials were characterized by various spectral tools like powder X-ray diffraction, spectral studies (UV–Vis and FT-IR), chemical analysis (ICP-OES and elemental), scanning electron microscopy, AAS and ¹H-NMR techniques. Further, BET and thermogravimetric (TG) analysis were also done for characterization of surface area, pore volume, thermal behavior, and related parameters. Baeyer–Villiger oxidation of cyclohexanone was carried out over Zeolite-Y enslaved complexes using hydrogen peroxide (H₂O₂) as an oxidant. The performance of the heterogeneous system with the homogeneous system was compared to determine the protection effect of the zeolitic matrix over the active center on the catalytic properties. In addition, the effect of experimental variables (various solvents, amount of catalyst, the mole ratio of substrate and oxidant, temperature, and reaction time) was examined in order to get absolute reaction conditions. Under the optimized reaction conditions, [Fe(nbab)₂]-Y was found to be a potential candidate, achieving 70 % ?-caprolactone selectivity.     

Design and assessment of delay timer alarm systems for nonlinear chemical processes

In process and manufacturing industries, alarm systems play a critical role in ensuring safe and efficient operations. The objective of a standard industrial alarm system is to detect undesirable deviations in process variables as soon as they occur. Fault detection and diagnosis systems often need to be alerted by an industrial alarm system; however, poorly designed alarms often lead to alarm flooding and other undesirable events. In this article, we consider the problem of industrial alarm design for processes represented by stochastic nonlinear time‐series models. The alarm design for such complex processes faces three important challenges: (1) industrial processes exhibit highly nonlinear behavior; (2) state variables are not precisely known (modeling error); and (3) process signals are not necessarily Gaussian, stationary or uncorrelated. In this article, a procedure for designing a delay timer alarm configuration is proposed for the process states. The proposed design is based on minimization of the rate of false and missed alarm rates—two common performance measures for alarm systems. To ensure the alarm design is robust to any non‐stationary process behavior, an expected‐case and a worst‐case alarm designs are proposed. Finally, the efficacy of the proposed alarm design is illustrated on a non‐stationary chemical reactor problem. © 2017 American Institute of Chemical Engineers AIChE J, 63: 77–90, 2018     

Relative Genotoxicities of PAH of Molecular Weight 252 AMU in Coal Tar-Contaminated Sediment

Bioassay-directed chemical fractionation methodology was used to calculate relative mutagenic potencies of polycyclic aromatic hydrocarbons (PAH) of molecular weight 252 amu in coal tarcontaminated sediment from Sydney Harbour, Nova Scotia. A normal phase HPLC technique was used to separate organic solvent extracts into fractions containing isomeric PAH of a single benzologue class. Bioassays with Salmonella typhimurium strain YG1025 with the addition of oxidative metabolism (S9) showed that approximately 50% of the mutagenic activity observed in the sediment extract was associated with PAH of molecular weight 252 amu. Further separation of the 252 PAH fraction using reversed phase HPLC yielded subfractions containing individual compounds; bioassay dose-response curves for these subfractions showed that benzo[a]pyrene was responsible for approximately 75% of the activity of the 252 PAH fraction.     

Mechanical,Electrical and Water Absorption Study of Jute/Glass/Jute-bamboo/Glass-bamboo-bisphenol-C-formaldehyde-acrylate a Value Added Composites

Bisphenol-C-formaldehyde-acrylate (BCFA) resin was synthesized by reacting 0.1 mol bisphenol-C-formaldehyde resin, 0.4 mol acrylic acid in 25 ml 1,4-dioxane and 1.5 g phenothiazine catalyst at 80°C for 6 h. Jute, glass, jute-bamboo, and glass-bamboo composites were prepared by compression molding technique at 150°C for 2 h under 30.4 MPa pressure. Jute-BCFA, Glass-BCFA, Jute-bamboo-BCFA, Glass-Bamboo-BCFA possess 50, 114, 49, and 65 MPa tensile strength; 58, 185, 69, and 70 MPa flexural strength; 1.2, 3.3, 1.3, and 1.9 kV/mm electric strength and 6.2 × 10¹², 2.5 × 10¹³, 6.6 × 10¹², and 1.5 × 10¹³ ohm cm volume resistivity. The data are interpreted in terms of nature of fibers and resin and fiber loading and orientation. Water absorption behavior of composites is tested in pure water, 10% NaCl and 10% Hcl solutions at room temperature as well as in boiling water. Observed diffusivity order for each of composite is H₂O < NaCl < HCl. Sandwich composites shown high water absorption in all media due to high bamboo fiber loading and fiber agglomeration. The presence of HCl and NaCl affected the water structure and hence diffusivity. Jute-bamboo-BCFA and Glass-Bamboo-BCFA delaminated in boiling water within half an hour. Mechanical and electrical properties and water absorption behavior are affected by the nature of fibers and matrix, fiber loading and fiber arrangement. Fairly good mechanical and electrical properties of Jute-BCFA and Glass-BCFA and their low water absorption behavior signify their usefulness as low load bearing applications. Composites signify their use for low load bearing applications in construction, electrical and marine industries.     

Physicochemical Study of CPOL-701–Glass/Jute Composites

Glass and jute composites (CPOL-701-G and CPOL-701-J) have been fabricated by hand lay-up technique at 50°C under 27.6 MPa pressure for 3–4 h using MEKP and cobalt naphthenate. Both composites possess excellent tensile, flexural and dielectric strengths, volume resistivity and dielectric constant as well as hydrolytic stability against water, 10% aq. HCl and 10% aq. NaCl at 35°C. Cured CPOL-701 appears to be having good thermal stability (206°C) and high values of kinetic parameters. Excellent physicochemical properties of the composites signify their industrial importance.     

Preparation and Physico-Chemical Study of Sandwich Glass-Jute-Bisphenol-C-Formaldehyde Resin Composites

Glass-Jute-bisphenol-C-formaldehyde (Glass-Jute-BCF) sandwich composites were prepared by hand lay-up technique at 150°C under 30.4 MPa pressure for 2 h. The resin, glass and jute fiber content in the sandwich composite were 33.3, 10.4 and 56.3 wt%, respectively. 10 prepregs containing 8 inner prepregs of jute mats sandwiched between 2 outer prepregs of glass mats. Glass-Jute-BCF sandwich composite has 23 MPa tensile strength, 119 MPa flexural strength, 1.72 kV/mm electric strength and 1.25 × 10¹² ohm cm volume resistivity. Tensile strength and volume resistivity both decreased, while flexural strength and electrical strength both improved upon hybridization. Sandwich composite showed high diffusivity in water, 10% NaCl and 10% HCl solutions as compared to Glass-BCF composite. Equilibrium water absorption time is found to be 72 h in all 3 environments. Comparatively low diffusivity is observed due to silane treated glass fibers. No effect of boiling water is observed on stability of composite. Saturation time in boiling water reduced 18 times without any damage to the composite. Glass-Jute-BCF sandwich composite may be useful for low load bearing applications in construction, electrical and electronic industries as well as in harsh acidic and saline environments.