Papers by Keyword: Seawater

Abstract: During cavitation investigations with manganese-aluminum-bronzes (MAB) in seawater using ultrasound (US), it was found that the microstructure of the bronze was developed by etching. To investigate this phenomenon in more detail, metallographically polished MAB samples were US-treated in synthetic seawater. On the one hand, pulsed ultrasound was used with a sonotrode in order to be able to observe the effects of cavitation. On the other hand, an ultrasonic bath with less power than the sonotrode was used to investigate the influence of ultrasound on the electrochemical response of the MAB. It was found that the k-phase is attacked most severely by cavitation, followed by β-phase and the α-phase. Potentiostatic measurements indicated that the transport of oxygen to, and of metal ions from the metal surface is enhanced by the ultrasound, which then leads to increased corrosion rates.

Abstract: Seawater desalination can be applied in Malaysia to overcome water supply issues which majorly due to water pollution. The desalination using membrane technology highly depends on the design of the membrane, operating conditions of the process, and the feed characteristics of the seawater. The aim of this research is to identify the effect of these factors on the performance of the reverse osmosis membrane in desalinating seawater in Malaysia. The simulation study is conducted by using the IMS Design program. The reverse osmosis (RO) membrane process that consists of three membrane stages arranged in series is designed accordingly. The effect of operating temperature, feed concentration, feed pH, and membrane stages on the salt rejection and permeate flux are evaluated. As a result, an increase in temperature and feed concentration reduces the salt rejection percentage, while increasing the permeate flux. However, there is no significant effect of feed pH on the salt rejection percentage and permeate flux since the type of membrane used is able to operate in a wide pH range. Lastly, the four stages membrane increases the permeate recovery and permeate flux but reduces the percentage of salt rejection.

Abstract: Представлен оригинальный метод получения композиционных сорбционных материалов на основе смешанных ферроцианидов Ni-K и Zn-K в композиции с силоксан-акрилатной эмульсией и полиэтиленом. Оригинальность метода заключается в гидрофобизации материала за счет введения полиэтиленовых волокон в структуру ферроцианидов. Изучены особенности извлечения микро- и микроконцентраций катионов Cs ⁺ , а также радионуклидов Cs-137 из морской воды в статических и динамических условиях. Экспериментальные значения сорбции аппроксимируются согласно уравнениям Фрейндлиха, Ленгмюра, Ленгмюра-Фрейндлиха, а значения максимальной сорбции G _max и константы адсорбционного равновесия K _lрассчитаны. Установлено, что сорбенты, синтезированные с использованием полиэтилена, при степени очистки морской воды от ионов цезия до 99% обладают наилучшими сорбционными характеристиками. Значения K _p для цезия при использовании исследуемых сорбентов могут достигать 10 ⁵ мл / г, что свидетельствует об их перспективности для очистки морской воды от радиоактивного цезия. Описанный подход является примером простого и доступного технологического синтеза эффективных и востребованных на практике сорбентов высокого эксплуатационного качества.

Abstract: The study aims to determine Total Petroleum Hydrocarbon (TPH) status in seawater from Teluk Batik beach seawater. In July 2018, fishing vessel sunk two nautical miles off Pematang Damar Laut, a coastal village within the town of George Town, Penang Malaysia, which also impacted the coastline of Perak State. Approximately six tons of diesel and hundreds of liters of fuel oil drifted from the Penang sea to the Perak coast. On further subsequent wave action the TPH concentrations in seawater fluctuated over time. In the coastal water of Teluk Batik Beach, Perak, Malaysia, grab samples were taken from surface seawater for determining the TPH concentrations in November and December 2019. The TPH in seawater was determined by the extractable solvent (Hexane) and the additional petroleum hydrocarbons by the Infrared (IR) method. The values of TPH ranged from 91 to 503 mg/L. Compared to the standards in Malaysian waters, the TPH levels found in this study were high, indicating serious pollution of TPH in the area under study.

Abstract: Titanium-Nickel pre-alloyed powder was reinforced with Nano-Silica in 2%, 4% , 6% and 8 wt. % due to effectiveness of Nanoscale ceramic Reinforcement in improving the properties of Metals and Alloys. The compositions of the Pre-Alloyed powders and Nano Silica Approximately 50 nm in diameter and spherical in shape were weighed and mixed in Planetary Ball Mill followed by compaction at 50 MPa using a Uniaxial Compaction machine The green pellets obtained were sintered in Argon Environment for 5 hrs and allowed to furnace cool. The pellets were then sectioned through their cross-section for slices 3 mm thick followed by Cold-mounting and Soldering followed by cold mounting additionally. The Samples were analyzed via X-Ray Diffraction (XRD) for phase distribution as a function of variation in nano-Silica reinforcements and Microstructural analysis was performed via Optical Microscope. The effect of Volume percentage on the densification was determined via Archimedes principle and Micro-Vickers hardness was used for mechanical Evaluation. The Electrochemical Properties were evaluated using Potentio-Dynamic Polarization and Electrochemical Impedance Spectroscopy (EIS) in neutral salt solution (3.5% NaCl). The results indicated increasing dissolution of the TiNi phase into intermetallic Titanium-rich and Ni-rich phases in the matrix and hardening due to the Nano-Silica effect of Grain Boundary impingement and phase dissolution of Equiatomic phase and mixed behavior in Corrosion properties as determined by the electrochemical techniques whereas densification decreased due to poor plasticity of Nano-Silica and hinderance in diffusion during the sintering process.

Abstract: In this paper, an experimental work studies the principal operating parameters of a proposed desalination process using air humidification-dehumidification method. The major objective of this work is to determine the humid air behavior through the desalination system. Different operating conditions including the effect of the water temperature at the entry to the humidifier, the ratio of the mass of water to the air, the air/water flow rate, and cooling water at entry the dehumidifier on the desalination performance were studied. The results show that the freshwater increases with increasing the water temperature at the inlet of the humidifier, the ratio of the mass of water to air, and cooling water flow rate in the dehumidifier. Cooling water outlet temperature at the condenser increases with increasing the water temperature at humidifier inlet. Also, it decreases as increasing cooling water flow rate while the ratio of the mass of water to air achieves the highest productivity and gained output ratio (GOR). The achieved mass ratio (MR) is 4.5 and the mass flow rate of air is 0.8 kg/min.

Abstract: The paper is aimed to the study of the corrosion-fatigue behavior of high strength steels for offshore pipelines. Tests have been performed in order to study fatigue crack growth in synthetic seawater under cathodic protection. The tests have been carried out on three different steel grades from 65 to 85 ksi with tempered martensite and ferrite-bainite microstructures. The effect of stress intensity factor, cathodic protection potential and cyclic loading frequency is shown.

Abstract: This paper illustrates a special investigation on geopolymer concrete synthesized from fly ash, sand, coarse aggregates (solid phases) in conditions of sodium silicate solution and seawater (liquid phases). The mixtures of geopolymer concrete were designed with proportion changes of among materials to evaluate effects of the proportions to engineering properties of products. The specimens were molded into cylinder with 200 mm in length and 100 mm in diameter, and then cured at room condition (28 °C, 80 % of humidity) for testing engineering properties for 7 days, 28 days, 90 days, and 180 days. The engineering properties of geopolymer concrete samples included compressive strength (MPa), water absorption (kg/m³), and volumetric weight (kg/m³). The results showed that the fly ash-based geopolymer concrete using sodium silicate solution and seawater was very good performance with value of 180 day-compressive strength at 58 MPa, water absorption and volumetric weight were at 180 kg/m³ and 2200 kg/m³, respectively.

Abstract: Tensile residual stress can cause a reduction in the fatigue strength of steel not only in air but also in corrosive environments. In air, for example, the effect of residual stress on fatigue strength can be estimated by using relations between fatigue strength and mean stress such as the modified Goodman diagram. However, it is not clear whether a sort of fatigue strength estimation can be applicable to corrosion fatigue properties. This paper presents an experimental method to evaluate the effect of welding residual stress on corrosion fatigue properties quantitatively, where corrosion fatigue tests were conducted in synthetic seawater by using characteristic fatigue specimens that have two parts, a tensile residual stress part and the other supporting part. Bead-on-plate welding was performed for applying welding residual stress in the tensile residual stress part. Residual stress relaxation was measured using the X-ray diffraction method in the midst of fatigue testing. Effects of tensile residual stress on corrosion pit growth and S-N curves were discussed.

Abstract: Desalination can be carried out in water to remove any salt. The process takes place after tertiary treatment of municipal and industrial waste water as a final treatment before discharge to the recipient. The desalination of seawater using Reverse Osmosis (R.O.) technique is now a tried and proven technology that can provide high-quality water supply. The resulting from R.O. water is not suitable for drinking. The method proposed in this paper is selected desalination via zeolitic micro-particles. The method exhibits some significant advantages such as the easy recovery and reuse of powders (with negligible losses during the release process of trapped ions in liquid solution), the selective removal of ions and the ability of producing directly potable water without the need for further enrichment.