Papers by Keyword: Water

Abstract: Iron is a major impurity in many water resources and leads to contamination in drinking water. One technology that can be used to reduce the iron content is adsorption using activated carbon. Activated carbon can be derived from biomass including forestry and agricultural waste. To produce an economic adsorbent, the researcher used bengkirai wood sawdust waste which contains 52.9% cellulose and 24% lignin. This material is treated by physical and chemical activation to produce activated carbon. However, there is no information on the effect of the type and concentration of activator on the performance of bengkirai wood activated carbon in reducing iron content. Thus, the purpose of this research is to understand the effect of activator type and concentration on the performance of activated carbon from bengkirai wood to adsorb iron content. There are five steps in this research which are preparation, carbonization, chemical activation, characterization and performance test. The raw material is prepared by screening to get an uniform size of bengkirai wood sawdust. Then, the uniformed bengkirai sawdust is physically activated in the carbonization step by heating it in the furnace at 600°C for 2 hours. After that, the carbon is activated using acid which are HCl, HNO₃, and H₂SO₄ with concentrations of 0.1 M, 0.3 M and 0.5 M. The characterization done in this study are iodine number test and functional group test using Fourier Transform Infrared Spectroscopy (FTIR). The final step is performance test of activated carbon to adsorb iron in the water by contacting the activated carbon into water containing iron for 1 hour. The concentration of iron in the water is measured using Uv vis spectofometry. The result shows that the carbon activation with H₂SO₄ 0.1 M produce activated carbon with the highest iodine number compared to the other type of activator and concentration. The iodine number for this activated carbon is 839.76 mg/g. However, the activated carbon treated using HNO₃ shows the best performance to adsorb iron in water.

Abstract: Enhanced treatment of river water was investigated by the modified coagulation-flocculation process for the application of self-cleaning filters (SCF’s) in the removal of turbidity using a combination of Alum and Sudfloc 3880. This study is aimed to improve the removal of iron and turbidity concentrations from river water and reduce water loss. This is achieved by piloting innovative water treatment technologies such as the SCF’s Plant. The new technology further assessed the effectiveness, efficiency, and operability of the SCF’s Plant by varying certain operational parameters such as water flow, differential pressures, coagulant, and flocculent dosages. The results established in this study critically analyze the feasibility of deploying water treatment technologies such as the SCF Plant in areas with similar environmental conditions and/or facing similar water treatment challenges. The removal efficiencies of turbidity were about 40 % and further optimization will be continued until 90 % to 100 % is achieved. The average removal efficiency of turbidity was 40 % and achieved at a 250 m³/h flow rate. The average removal across all flow rates was over 20 %. Further optimization of the RF14 will be carried out using other chemical combinations and formulations at various process settings while bypassing the PLF filters. The PLF elements will be brought into service to further reduce the turbidity after the optimization of the RF14. Keywords: Water, Treatment, Coagulation, Flocculation, Processes, Technologies, Filters ^*

Abstract: In this paper we present the current situation related to the legislative framework on the definition of generated waste by ships in the field of maritime navigation and inland waterway navigation, their management on board ships, handover to port facilities and results in the development of proposals to support participants in the shipping activity in the field of pollution prevention of the Romanian Danube sector. The purpose of the paper is to contribute to the improvement of the current measures that are applied in the field of prevention of pollution of the Romanian Danube sector by ships.

Abstract: Waterborne disease has changed a basic challenge in human population. recently, the use of nanotechnology and application of nanomaterials for the control of pathogens in water is widely increased in research. Common indicator for microbial quality of water are determine presence of total and fecal coliforms. The purpose of this study was to evaluate the effect of Silver (Ag) and zinc oxide (ZnO) nanoparticles (NPs) and combination of them in removing total and fecal coliform bacteria from contaminated water. In this experimental study a synthetic solution was made by adding effluent to distilled water. In each run, the nano silver (20-100 μg /L) and ZnO NPs (0.25-2 mg/L) were added to contaminated water. The samples were tested by 15-tube series method based on the instruction 9221-B of 21th edition of standard method book on water and wastewater experiments. Bacteria removal efficiency were examined in contact times (15, 30,60, 90 and 120) minutes. Our data indicate a decrease in the number of bacteria (MPN) in the presence of the nanoparticles. Results revealed that the removal percentage of coliform bacteria removal increased with increasing the contact time and concentrations of nanoparticles. Ag NPs at a concentration of 100 μg /L and ZnO NPs at a concentration of 2 mg/L showed the highest percentage of removal bacteria and the combination of ZnO and Ag NPs have been high synergistic behavior against coliform bacteria in contaminated water. therefore, using a combination of ZnO and Ag NPs can become a new and efficient method for the removal of indicator bacteria from contaminated water.

Abstract: Hydrogen and water adsorptions on the monolayer hexagonal boron nitride (h-BN) have been studied using the density functional theory. In this study, two configurations of monovacancy were modeled, i.e., monovacancy at the nitrogen site (V_N) and monovacancy at the boron site (V_B), by removing N and B atoms from the h-BN sheet, respectively. A supercell consisting of 32 atoms was used to analyze the adsorption of hydrogen and water (H₂O) by calculating formation and adsorption energies. From the calculated negative adsorption energies, we found that the involved reactions are exothermic, meaning that hydrogen and H₂O are easily adsorbed on the h-BN sheet. In addition, the hydrogen system at the V_B site was the most stable, as shown by the lowest formation energy of 2.78 eV.

Abstract: Carbon-free electrosynthesis of ammonia using water (H₂ source) and air (N₂ source) is promising technology to reduce the global CO₂ emission resulting from the industrial ammonia production process (Haber-Bosch). In this study, electrocatalysis activity of non-noble metal perovskite-based catalyst (La_0.75Sr_0.25Cr_0.5Fe_0.5O_3-δ-Ce_0.8Gd_0.18Ca_0.02O_2-δ, LSCrF-CGDC) for ammonia synthesis directly from air and water was explored. Ammonia was successfully from wet air (3%H₂O) synthesized in a single-chamber type reactor. The highest ammonia formation rate and Faradaic efficiency of about 1.94×10^-11 mol s^-1 cm^-2 and 2.01% were achieved at 375 oC and 1.2 V, respectively. The observed ammonia formation rate is higher than reported for an expensive noble metal-based catalyst (Ru/MgO). The obtained results indicated that the direct synthesis of ammonia from air and water is a promising technology for green and sustainable ammonia synthesis.

Abstract: Tetramethylammonium hydroxide (TMAH) is a metal-free strong alkaline solution which can etch poly-Si. The concentration of dissolved gas as well as the concentration of TMAH affects etching rate of poly-Si. The detailed kinetics of poly-Si etching in TMAH solution is investigated in this study. The effect of water and TMAH concentration on the etching kinetics of poly-Si was investigated by using various concentrations of TMAH solution. It is found that H₂O in TMAH solution plays an important role in etching poly-Si. Presence of dissolved CO₂ and O₂ in TMAH solution tends to inhibit etching of poly-Si. The concentration of dissolved CO₂ and O₂ in TMAH were reduced by Ar bubbling, thereby the poly-Si etching rate increased.

Abstract: The research objective is to assemble a convection test system which acts as a heat exchanger (HE) and test its applicability using ethylene glycol. A Double Pipe (DP)-type HE consists of an inner pipe surrounded by an outer pipe (annulus) whereas a Coil-type HE composed of a coil surrounded by an outer pipe. Water flows through the outer pipe in both types of HE, while ethylene glycol flows through the inner piper or coil. HE in combination with other components (such as) forms a convection test system. The applicability of the system was tested to determine the heat transfer coefficient of ethylene glycol in a DP-type and Coil-type HEs. After that, the heat transfer rate was calculated and compared. The results show that the heat transfer coefficient in the DP-type HE is the lowest at 12.2 W/m2 oC and the highest at 26.8 W/m2 oC; and the corresponding heat transfer rate is the lowest at 8.3 W and the highest is 56.3 W. In comparison, for Coil-type HE, the lowest heat transfer coefficient is 38.9 W/m2 oC and the highest is 66.2 W/m2 oC which correspond to the heat transfer rate 19.9 W at the lowest and 225 W at the highest.

Abstract: The electrocatalytic ammonia synthesis using water (along with nitrogen) as a hydrogen source is proposed as an alternative green and clean technology to the energy-intensive and CO₂-emitting process (Haber-Bosch) for ammonia production. Besides, a selective electrocatalyst for ammonia synthesis versus the competing hydrogen evolution remains elusive. This study aims to investigate the electrocatalytic activity of non-noble metal Co and Fe-free perovskite oxide-based composite cathode (La_0.75Sr_0.25Cr_0.5Mn_0.5O_3-δ-Ce_0.8Gd_0.18Ca_0.02O_2-δ) towards ammonia synthesis from H₂O and N₂. The electrocatalyst was synthesized via a sol-gel process and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Ammonia was successfully with a maximum formation rate of 2.5 × 10^-10 mol s^-1 cm^-2 and Faradaic efficiency of 0.52% at 400 oC and applied voltage of 1.4 V. The results demonstrated that the proposed non-noble metal-based electrocatalyst is a promising material for the carbon-free ammonia synthesis process.

Abstract: The process of producing a monolithic concrete structure on site is constructed out under different climatic conditions, which can often be unsuitable for setting and hardening of concrete. The necessary conditions for setting and hardening of concrete are ensured by various ways of its curing. In practice, concrete curing is carried out in most cases by water spraying. It is used mostly in reinforced concrete ceiling slabs, which are further discussed in the work. A common procedure is to cure the upper surface of reinforced concrete ceiling slabs. This work therefore deals with the effect of curing of a reinforced concrete slab, on its strength properties. Long-term curing would yield higher values of compressive strength, but it is also necessary to consider how effective it is. As a pilot research in this work is investigating the properties of concrete cubes in various curing. It further develops theoretical possibilities for continuing research.