Papers by Keyword: Water

Abstract: Due to the lack of raining levels, accretion population growth and increasing pollution in the water resources, the world nowadays is facing a real challenge of providing enough drinking water supplies. Many common species of bacteria could be founded in the water resources like Escherichia coli and Pseudomonas aeruginosa. This paper is an attempt to find an effective agent to eliminate these bacteria. silver nanoparticles (AgNPs) have been tested against these bacteria. Sliver nanoparticles were synthesized by wet chemistry method and were dispersed in an aqueous suspension and prepared in different concentrations. Also, some common antibiotics have been tested against the selected bacteria including; gentamycin (GN), cephalexin (KF), erythromycin (E), ampicillin (AM) and amoxicillin (AMX). The results confirmed that silver nanoparticles had a good antibacterial effect against the selected bacteria in comparison with the tested antibiotics.

Abstract: Various national and international standards recommend potable water for mixing concrete; however, the availability of potable water is virtually a daunting task in some developing communities. Concrete workers in such environments tend to utilize any available water for mixing concrete, and this may be detrimental to the quality of the concrete being produced. This study investigates the rheological, mineralogical and strength variability of concrete due to construction water impurities. Water samples were collected from four different construction sites within Southwestern region of Nigeria for production of concrete. The physical and chemical properties of the waters were determined so as to measure their rate of contamination, prior to their use for mixing concrete. The rheological properties of the fresh concrete, compressive strength, split tensile strength, and microscale features of hardened concrete, that were produced with each water sample were determined. From the results, the rheological features of concrete were found not to be affected by water impurities, however, the mechanical test results revealed about 10% reduction in strength between concrete made with water having least and higher concentration of impurities. Also, it was evident from the microscale tests that the water impurities do alter the hydration rate of concrete, which results in strength reduction. The study suggests pretreatment of concrete mixing water before use in order to avoid its damaging effect on concrete life.

Abstract: We are focused to the numerical modelling of heat, contaminant and water transport in unsaturated porous media in 3D. The heat exchange between water and porous media matrix is taken into the account. The determination of heat energy transmission coefficient and matrix heat conductivity is solved by means of inverse problem methods. The mathematical model represents the conservation of heat, contaminant and water mass balance. It is expressed by coupled non-linear system of parabolic-elliptic equations. Mathematical model for water transport in unsaturated porous media is represented by Richard's type equation. Heat transport by water includes water flux, molecular diffusion and dispersion. A successful experiment scenario is suggested to determine the required parameters including heat transmission and matrix heat conductivity coefficients. Additionally we investigate contaminant transport with heat transmission and contaminant adsorption. The obtained experiments support our method suitable for solution of direct and inverse problems. This problem we have discussed previously in 1D model, but preferential streamlines in 1D thin tubes shadow accurate results in determination of required parameters. In our presented setting we consider a cylindrical sample which is suitable in laboratory experiments for inverse problems.

Abstract: During last 20-25 years in Armenia has been established new thermal insulation material’s production. This program in short is named “Developing of perlite insulation technology”. The perlite is a volcanic mineral in form of soft stone, which is extracted from perlite mines of Armenia. First of all, the perlite is a construction material, which traditionally has been used in building construction purposes. At the same time, it is a good row material for making thermal insulation goods. The technology of transformation of perlite stone into perlite insulation material is developed by Professor Zohrab Melikyan jointly with experts of “Yerevan Perlite Company” in the framework of the program “Development of Environmentally Safe, cost Effective and Sustainable Energy Sector of Armenia in the Situation of Shutting Down of the Armenian Nuclear Power Plant”. The project was targeted to compensate the energy deficit that could arise in Armenia, following to shutting down of the Nuclear Power Plant (ANPP).

Abstract: The temperature-time regimes of drying of polyetheretherketone were revealed, during which it is completely possible to get rid of sorption water. The upper limit of the drying temperature is established, above which the thermal stability of polymers deteriorates markedly.

Abstract: Textile waste is produced in the starch process, a starch removal process, coloring, and printing. The use of banana peel (Musa Paradisiaca) was an alternative that was being developed as an absorbent to remove the color content and metal ions in textile waste. The purpose of this study was to analyze the workings and effectiveness of heavy metal adsorption and textile dyes with banana peel waste. Banana peel particles that were ready to be used as adsorbents were characterized using Scanning Electron Microscopy (SEM) to obtain particle morphology. Absorbance curve of Cu²⁺ dan Cr⁶⁺ can be obtained using spectrophotometric UV-Vis analysis with a wavelength of 635 nm for copper (Cu) and 469 nm for chromium (Cr). The activated carbon of banana peel was applied to 50 ml industrial waste solution and observed changes in absorbance for 120 minutes. The activated carbon was directly in contact with the solution of metal ions but the adsorption power was still not seen effectively so that the Atomic Absorption Spectroscopy (AAS) test was performed. The results of AAS analysis, namely activated carbon can reduce copper and chromium ion content respectively by 55.5% and 61%. If this activated carbon was used as an adsorbent for dyes in textile waste, the average absorption capacity of dye ion was 12.21% during the contact time of adsorption 120 minutes.

Abstract: High-precision flanges are used in conjunction with O-rings, bolts, and nuts in a variety of pipe connections to prevent the leakage of harmful fluids. Flanges require good hermeticity; i.e., without pores, cavities, blow holes, or other shrinkage defects. This study employed mold flow analysis to predict where and how defects are likely to occur during the casting process. In this study, we soaked the bottom of the casting system in cold water to direct the direction of solidification from the bottom upward. Simulation results indicate that this method significantly reduces the probability of shrinkage defects in castings.

Abstract: In our research the influence of thermal heating on the release of plasticizers from plastics into the meat product and water was researched. The two most widely used plasticizers, dibutyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP), were detected. Both of the plasticizers have a negative effect on the health. And both are regulated by regulation of the European Union. In this study were researched phthalates in products prepared by sous-vide technology and it was studied effect of reheating on migration of phthalates. The average concentrations of both phthalate esters, DBP and DEHP, in heated water decreased. The average concentration of DBP in water before heating was detected 0.82 mg/100 ml and after heating 0.52 mg/100 ml, the average concentration of DEHP in water before heating was established 0.33 mg/100 ml and after heating 0.19 mg/100 ml. In plastic wraps, average DBP concentration with reheating increased and average DEHP concentration with reheating dropped. The average DBP concentration in plastic packaging, heating at 60 °C/12 h was determined of 9.87 mg/dm² after reheating 60 °C/1 h was detected of 15.40 mg/dm². The average concentration of DEHP in plastic packaging, heating at 60 °C/12 h was determined of 58.71 mg/dm² and after reheating 60 °C/1 h was detected of 28.28 mg/dm². The average DBP concentration in meat products due to reheating decreased, the average DEHP concentration in meat products increased. The average DBP concentration in meat products heating at 60 °C/12 h was detected of 8.39 mg/g dry matter and after reheating of 6.43 mg/g dry matter, the average DEHP concentration heating at 60 °C/12 h was determined of 25.37 mg/g dry matter and after reheating of 65.51 mg/g dry matter..

Abstract: The article deals with the mechanism of interaction of super-plasticizers and hyper-plasticizers additives with mixing water, the formation of micelles and organized water. The interaction of mixing water and additives with Portland cement particles, surface tension, specific surface of bindings and their significance in setting and hardening processes are considered. It is shown that a local effect plays a decisive role in micro-heterogeneous organized media associated with the dissolution of hydrophilic and hydrophobic molecules in the volume of the micellar system or the receptor molecule cavity. In this case, the change of dissolved substances properties is due to the change of the medium state only in the microenvironment, and not in the whole solvent - water. The surface energy of the dispersed material and the degree of dispersion are very important for the concrete technology. All dispersed materials of the system are unstable. The aggregation of powder particles of building materials spontaneously takes place in highly dispersed powders and if such powders get pressure, it is possible to get a hard and strong material without water and additives.

Abstract: Steel sheet pile wall corrosion in soils and water is a complex phenomenon. The deterioration of these structures is costly and difficult to predict. The aim of this paper was to deal some empirical corrosion models which are analyzed and compared to Eurocode 3, Part 5 to estimate corrosion rate and the loss of thickness of anchored steel sheet pile wall. The results show that care should be taken to ensure that the maximum bending moments do not occur at the same level as the main corrosion zones. Furthermore, it is possible to define an upper and a lower bound, corresponding respectively to the presence of sea water in low water and the undisturbed natural soils, in order to predict the loss of thickness due to corrosion.