Adsorption of Lead on Gel Combustion Derived Nano ZnO

AbstractMany naturally available materials were used as adsorbents to remove heavy metal ions from water, which are not effective because of low surface area. Novel nano materials are used as adsorbents to remove metal ions to treat potable water. In the present work nano sized large surface area Zinc Oxide (ZnO) was synthesized by gel combustion method and used as an adsorbent to remove lead (II) (Pb2+) from aqueous solution. The nano ZnO was characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy Dispersive X-Ray analysis (EDAX) and surface area analysis. Effect of lead concentration, adsorbent dosage and pH on adsorption was studied. Increase in the initial concentration of Pb, decreases the percentage of adsorption, whereas increase in the adsorbent dosage and pH of the solution, increases the adsorption of Pb2+ on ZnO. Synthesized nano ZnO shows almost complete Pb adsorption at lower initial concentration. The equilibrium adsorption capacity of Pb on nano ZnO adsorbent were measured and extrapolated using Langmuir and Freundlich adsorption isotherm models and the experimental data perfectly fits both adsorption isotherms

Prediction of Acoustic Natural Frequencies for two dimensional simplified aircraft cabin by Impedance Mobility and Compact Matrix(IMCM) approach

Prediction of modal characteristics of acoustic cavities with irregular shapes is an important topic in vibro-acoustic analysis of systems. In this paper, proposed method of impedance and mobility compact matrix (IMCM) provided the approach of Integro Modal Method (IMM) in the matrix form for prediction of modal characteristics of acoustical cavities with irregular shape. This method, consists of discretizing the whole cavity into a series of sub cavities either regular or irregular cavities. Acoustic pressure in regular sub cavities has been decomposed over a modal basis and for irregular sub cavities over that of bounding surface. Continuity of both pressure and velocity between adjacent sub cavities is ensured using a membrane with zero mass and stiffness. This method aims to develop a physical basis rather than a numerical approach. Mathematical formulation of the method has been explained in detail. Coupling equations being in a matrix form, so, it is easily solved using numerical methods in computer. The current approach is demonstrated by considering two dimensional simplified aircraft cabin as an irregular cavity. Predicted natural frequencies of the simplified aircraft cabin based on the proposed method have been compared with the available results in the literature and are in good agreement

Influence of Duct Joint on Modal Parameters of Rectangular Duct

The present paper discusses influence of duct joint on structural dynamic characteristics (modal parameters) of a rectangular duct. An analytical model is developed to consider the effect of duct joint on modal parameters. The joint condition is modeled as a combination of linear and torsional spring’s stiffness. Developed analytical model is validated with experimental results for a rectangular duct with Pittsburgh lock joint. It is observed that both natural frequencies and mode shapes are in good agreement. For further understanding the influence of duct joint on modal parameters, current analytical model results are compared to duct without joints results and noticed that only antisymmetric mode shapes of duct with joint condition are deviating from ideal duc

Muffler Design for a Refrigerator Compressor

During its operation, a refrigerator compressor produces pulsating noise, primarily driven by the suction and discharge processes. Sound attenuating mufflers need to be designed without any additional pressure drop on both suction and discharge side. An additional pressure drop at the suction and discharge side will lead to lower charging and discharging of the compressor and hence reduces cooling capacity. Since a one dimensional formulation with plane wave assumption to calculate transmission loss is not applicable for small mufflers (ratio of length to diameter is less than 1), a numerical methodology was established and validated using an impedance tube. Detailed three dimensional Computational Fluid Dynamics (CFD) simulations were used to further study the pressure drop across the mufflers for a given flow and compressor operating frequency. In the proposed new methodology, the pressure distribution is observed as a function of frequency and an optimal position of inlet and outlet pipes is decided to improve transmission loss. Mufflers designed with this approach showed better acoustic performance on the suction and discharge side of refrigerator compressor. The effect of various refrigerants on acoustic frequencies is also studied, which would additionally help in tuning the muffler to improve its effectiveness

Chemical constituents and their biological activities of the sponge family <i>Aplysinellidae</i>: A review†

723-733Bromo tyrosine derived metabolites are a group of alkaloids, frequently encountered in the sponges of the order Verongida. Several bromotyrosine derived alkaloids have been isolated from the sponges family Aplysinellidae (order Verongida) with varied biological activities. A concise review of the family of the sponges Aplysinellidae has been summarized till June 1999 that have been abstracted in chemical abstracts

Influence of cadmium sulfide nanoparticles on structural and electrical properties of polyvinyl alcohol films

Cadmium sulfide (CdS) nanoparticles have been synthesized by hydrothermal method and dispersed in poly vinyl alcohol (PVA) matrix in varying amounts by weight. Subsequently, PVA/CdS nanocomposites have been synthesized with the objective of investigating the effect of CdS nanoparticles on structural and electrical properties of PVA films. Structural properties were analyzed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Differential scanning calorimetry (DSC) was used to investigate thermal properties of PVA/CdS nanocomposites. Electrical properties were measured by using high frequency LCR meter and were found to be strongly dependent on frequency and nano CdS content. Dielectric constant decreased with increase in frequency and with increase in nanofiller concentration. AC conductivity and dielectric loss increased with frequency and decreased with increase in nano CdS content