A laboratory study for the treatment of arsenic, iron, and manganese bearing ground water using Fe(3+) impregnated activated carbon: effects of shaking time, pH and temperature

This paper deals with the experimental investigation related to removal of arsenic from a simulated contaminated ground water by the adsorption onto Fe(3+) impregnated granular activated carbon (GAC-Fe) in presence of Fe(2+), Fe(3+), and Mn(2+). Similar study has also been done with granular activated carbon (GAC) for comparison. The effects of shaking time, pH, and temperature on the percentage removal of As(T), As(III), As(V), Fe(2+), Fe(3+), and Mn have been discussed. The shaking time for optimum removal of arsenic species has been noted as 8h for GAC-Fe and 12h for GAC, respectively. As(T) removal was less affected by the change in pH within the pH range of 2-11. Maximum removal of As(V) and As(III) was observed in the pH range of 5-7 and 9-11, respectively, for both the adsorbents. Under the experimental conditions at 30 degrees C, the optimum removal of As(T), As(III), As(V), Fe, and Mn are 95.5%, 93%, 98%, 100%, and 41%, respectively, when GAC-Fe is used. For GAC these values are 56%, 41%, 71%, 99%, and 98%. The adsorbent dose (AD) and its particle size (PS) for both GAC and GAC-Fe were 30 g/l and 125-150 mum, respectively. The initial arsenic concentration in the synthetic water sample was 200 ppb.     

Exploring the optical properties of exposed-core-based photonic-crystal fibers

Journal of Computational Electronics - A photonic-crystal fiber (PCF) based on the surface plasmon resonance (SPR) effect with low confinement loss and high sensitivity response is designed and its...     

Evaluation of Mechanical Properties of Solid Propellants in Rocket Motors by Indentation Technique

It is essential to evaluate the mechanical properties of propellants in a solid propellant rocket motor (SPRM) for structural integrity and its performance evaluation before the flight test. Conventionally, uni‐axial tensile testing on an universal testing machine (UTM) is used to evaluate the mechanical properties of solid propellant carton which is cast along with SPRM. Propellants in rocket motors experience various types of loading during storage, transportation, and environmental conditions over the period of time before actual flight whereas the propellant carton doesn’t experience the same as it is stored in magazine. At present, the mechanical properties of propellant cast in a carton are considered to be the mechanical properties of propellant in a rocket motor, which is not truly representative. Therefore, a non‐destructive indentation technique has been used to establish a method for evaluating the mechanical properties of solid propellants in rocket motors based on hydroxyl terminated polybutadiene. The test results obtained using the penetrometer indentation technique was analyzed comprehensively and compared with UTM results. The mathematical correlations were also developed using least square method and established by conducting the penetrometer indentation test on similar propellant composition. Further, the developed correlation was used to evaluate the mechanical properties of propellant in flight SPRM by penetrometer indentation technique.     

Synthesis of thermoplastic polyurethane nanocomposites of reactive nanoclay by bulk polymerization methods

This paper reports synthesis and characterization of thermoplastic polyurethane nanocomposites of reactive silicate clays. Pre-polymer (method I) and chain-extended polymer molecules (method II) with residual -NCO groups participated in tethering reactions with clay during clay-polymer mixing. It was found that both clay-polymer reactions and shear stress of mixing are responsible for clay exfoliation. In method I, more clay-tethered polymer chains were produced, but clay particles did not exfoliate due to low shear stress of mixing. Method II provided an order of magnitude higher shear stress of mixing and yielded exfoliated nanocomposites. Control experiments with high shear stress of mixing and no clay-polymer reactions resulted in only intercalated composites. It was found that clay particles deterred hydrogen bonding among hard segments. The exfoliated nanocomposites exhibited optical clarity and more than 100% increase in tensile strength and tensile modulus over pristine polyurethanes.     

High‐strength and low‐stiffness composites of nanoclay‐filled thermoplastic polyurethanes

In this study, bulk polymerized clay‐tethered thermoplastic polyurethane (TPU) composites were synthesized that offered much improved tensile strength with negligible changes in tensile modulus. These composites contained intercalated, tethered layered silicate particles and were synthesized by mixing low molecular weight prepolymer chains containing unreacted –NCO groups with reactive layered silicate clay followed by catalyzed chain extension reaction with butanediol. The molar ratio of –NCO and –OH functional groups in the composite was varied between 1.0 and 1.2. It was found that an appreciable amount of –NCO groups was consumed in reaction with moisture present in the clay and some in quaternary ammonium ion‐catalyzed dimerization and trimerization. Composites with –NCO to –OH molar ratio 1.1 provided the best improvement in mechanical properties—the composite with 5 wt% clay provided a 60% increase in tensile strength and 50% increase in strain at break, while the tensile modulus increased only by 15% over TPU. POLYM. ENG. SCI., 45:1532–1539, 2005. © 2005 Society of Plastics Engineers     

Effect of nanoclay on the mechanical and damping properties of aramid short fibre‐filled styrene butadiene rubber composites

The effect of nanoclay loading on the alteration of tensile and dynamic mechanical properties of aramid short fibre‐filled styrene butadiene rubber composites was investigated. In all the composites, 20 phr of N330 black was used. Dynamic mechanical thermal analysis was used to investigate the viscoelastic damping at lower dynamic strains. Compressive hysteresis was evaluated to characterize higher strain static damping properties. Matrix–fibre interaction and filler distribution were investigated using morphological analyses. Matrix–filler interface, estimated by the half height width of the tan δ peak, plays a major role in energy dissipation. The matrix–fibre interaction parameter shows a similar trend with low strain tensile stress values. Nanoclay addition to the composites leads to improved elongation at break and frequency damping properties. Compressive hysteresis reflects no improvement of hysteresis with nanoclay loading. Dynamic storage moduli, matrix–fibre interaction parameter and energy dissipation properties of the short fibre‐filled composites are negatively affected by nanoclay addition. However, ultimate elongation is improved markedly on nanoclay addition. In respect of tensile strength and elongation at break values, two composite samples (KF5NC10 and KF10NC10) offer optimum properties. Copyright © 2009 Society of Chemical Industry     

Condensation of R-134a Vapor over Single Horizontal Circular Integral-Fin Tubes with Trapezoidal Fins

An experimental investigation has been carried out for the condensation of R-134a vapor on four single horizontal circular integral-fin tubes (CIFTs) made of copper. The fins are of trapezoidal shape and the fin density of these tubes has been varied systematically from 934 fpm to 1,875 fpm. All the experimental data have been acquired at the saturation temperature of 312.4 +/- 0.5 K. The CIFT with 1,560 fpm fin density has been found to be the best-performing tube, as it has provided an enhancement factor (EF) of the order of 5.6. The experimental results are in the best agreement with Honda and Nozu model. This model has predicted 80% of the experimental results in a range of 0-30%.     

Inter-intra cellular pilot contamination mitigation for heterogeneous massive MIMO cellular systems

Telecommunication Systems - Massive multiple-input-multiple-output (MIMO) technology has been advocated as one of the most advanced and promising technologies for catering to the high data...