Papers by Keyword: NaCl

Abstract: Synthesis of calcium alginate silica gel based on coral skeleton and wedi awu beach sand has the potential to be used as a product to reduce NaCl levels in seawater. This research aims to maximize the potential of natural materials. The materials used in the manufacture of adsorbents are calcium from coral skeletons used as a constituent of CaCl2, silica extracted from Wedi Awu beach sand, and sodium alginate. The three materials were synthesized into a cross-linked calcium alginate silica gel. Silica extracted from beach sand was mixed with sodium alginate, and then the mixture was dripped into CaCl2 solution. The results obtained are white round-shaped adsorbent gel, which occurs because SiO2 reacts with-O-groups on sodium alginate to form a white mixture, and Ca2+ in CaCl2 will crosslink with sodium alginate when dripped, forming an adsorbent gel. In the FTIR analysis of silica calcium alginate adsorbent gel, there are-OH, C=O, C-O groups that can play an active role in NaCl adsorption. Calcium alginate silica adsorbent gel can produce the highest percent adsorption at a CaCl2 concentration of 0.5 M, with an optimum contact time of 60 minutes, namely for Na + obtained a percent adsorption of 95.24% and on Cl-of 99.19%. The results of concentration and time optimization were then tested with real seawater with a percent adsorption of Na + of 69.33% while on Cl-of 37.26%.

Abstract: Microbial fuel cells (MFCs) are considered as an economical and sustainable technology for various applications. This study has designed four single-chamber SCMFCs that composed of graphite plates as electrodes and used wastewater as a substrate for microorganisms. In order to evaluate the performance of SCMFC, the experiments were executed in a batch mode over 18 days at various types of salt bridge. Four salt bridges are used namely (KCl, NaCl, KNO₃, and Cotton Rope). It was found that KCl generated a maximum voltage of 989 mv. The following results were obtained for wastewater investigated parameters: COD = 94%, PO₄ = 88.4%, NO₃ = 88%, TSS = 80%, and Fe = 76%, respectively at 1 M KCl. The experiment was then carried out using different values of KCl (1, 1.5, 2, 3 M). It was found that at a molar concentration of 1.5, 1422 mv of maximum voltage has been generated. Results for wastewater treatment demonstrated that COD of 81%, PO4 of 78.2%, NO3 of 79%, TSS of 80%, and Fe of 84%.

Abstract: In its use, reefer containers require a lot of energy to operate to cool the cargo inside. Because the cooling system in the reefer container must operate continuously to maintain the temperature in the container. To reduce the operation of the cooling system, reefer containers are equipped with PCM (phase change material) as thermal energy storage which can store heat energy longer to create a lag time for the operation of the cooling system. In previous research, the use of PCM in cold storage can save the cost of using cold storage. From this research, the use of PCM in reefer containers was developed. The eutectic mixture used as PCM is NaCl-H2O with additional ingredients is propylene glycol. Before being applied to the reefer container, the mixture was tested using the cooling chamber methods to determine its thermophysics. The presence of additives in the PCM eutectic mixture is expected to reduce the supercooling phenomenon, reduce corrosive properties and increase the use of PCM based on NaCl-H2O.

Abstract: Developing Mg based implants for temporary applications based on their biodegradation in the physiological environment is a potential research area in the biomedical engineering. Assessing the bio-corrosion in simulated conditions helps to reduce the complexity of research studies associated with in-vivo experiments and can be used to assess the true behavior of the Mg implant in artificial solutions. On the other hand, assessing the corrosion behavior by using 3.5% NaCl solution is a standard ASTM protocol widely used in the industries. Hence, in the present work, degradation of pure Mg due to bio-corrosion in two different solutions i.e simulated body fluids (SBF) and 3.5% NaCl solution has been investigated. From the results, the weight loss measurements indicated higher degradation during the initial 24 h in SBF solution. However, with the increased immersion time to 72 h, due to the deposition of mineral phases from SBF as confirmed from the electron microscopy and X-Ray diffraction study, the degradation was observed as decreased in SBF compared with NaCl solution. Hence, the results demonstrate that the evaluation of degradation behavior of Mg based materials in simulated physiological environments is appropriate compared with the standard NaCl environment.

Abstract: The protection performance Aloe vulgaris (AV) and Nicotiana tabacum (NT) leaf extracts on 1070 aluminum (Al) were separately studied while the combined admixture of the extracts (AVNT) on mild steel (MS) was also studied in 3.5% NaCl solution by gravimetric analysis. Data output showed AV and NT effectively stifled the redox reaction process responsible for Al corrosion in NaCl with protection performance data above 98% throughout the exposure hours signifying strong resilience of the extract molecules withstanding the corrosive anions and thermodynamic stability with respect to exposure time. AVNT performed effective on mild steel at relatively lower efficiency, but with final values above 80% efficiency. Statistical data for standard deviation shows the degree of variation of protection performance data for AV, NT and AVNT extracts from mean value is minimal signifying consistent data value with respect to exposure time. Data also showed 100% of AV and NT protection performance data are above 98% efficiency value at +0% margin of error while 14.29% of AVNT protection performance data are above 95% efficiency at margin of error of +14.97%. Data from analysis of variance shows AV extract concentration and observation time strongly influences the performance out of AV at rated value of 42.06% and 29.41%. NT extract concentration solely dominated the performance output of NT at 95.37% while the performance of AVNT was independent of its concentration with values below threshold significance. However, AVNT performance varied significantly with observation time signifying progressive improvement in performance in over time.

Abstract: It is well known that the mechanical resistance of austenitic stainless steels can be increased considerably by cold rolling process.¶ The cold rolling effect on corrosion resistance of AISI 304L stainless steel in 3% Sodium Chloride solution was investigated by potentiodynamic polarisation and by Scanning Electronic Microscopy (SEM). The pitting corrosion in this environment is related to the rate of cold deformation. The cold rolling induces important changes in the microstructure and involves phase transformation (γ→a'). The AISI 304L developes martensitic structure after 16% cold working. The potentiodynamic results show a moderate variation of the passivity zone, a remarkable decrease in the pitting potential and a free potential. The results also show an increase in the current density. However, it seems that the critical deformation rate appears to start at approximately 50% of the rolling deformation where the passivation current is minimal. After the polarisation tests, metastable pits are observed using SEM and the most probable initiation causes are discussed

Abstract: It is known that heat treatment (HT) highly affects the properties of base metal (BM) and fusion zones (FZ) of duplex stainless steel (DSS). In fact, it may give unwanted structure changes. Duplex stainless steels SAF 2205 welded joint was subjected to thermal cycle at temperature of 850^◦C at holding times 1, 3, 5 and 7 hours. The influence of heating cycles and concentration of corrosive medium on the corrosion properties and microstructure of 2205 alloy was the objective of this work. It was found that process led to noticeable decrease in the corrosion resistance of BM and FZ specimens; moreover the decrease was large in BM than FZ. It was also found that sigma phase (σ) precipitated in the different zones of the structure. σ phase volume fraction was found to increase with increasing the holding time of HT, and its increase is larger in BM. Corrosion resistance was found to be oppositely related to σ phase formation. Secondary austenite phase (γ₂) was also precipitated and its volume fraction in FZ was found to increase with increasing the holding time of HT and decreased in BM.

Abstract: Corrosion behavior of Incoloy 825 was studied in high temperature vapor with high concentration of NaCl. After 80 h exposure, a bi-layer structure was formed on sample surface after exposure. The outer layer is consisted of loose and large-grain oxides, and the inner layer is composed of fine-grain oxide. The whole layer was identified to be CrOOH/Fe₃O₄/Cr₂O₃/Incoloy 825 from outer to inner.

Abstract: Chloride leaching is considered a promising alternative method to recover copper from chalcopyrite and other primary copper sulfides, because it favors the leaching kinetics and avoids passivation of minerals. Nevertheless, chloride ions are highly toxic for iron-oxidizing microorganisms that participate in the bioleaching process. A comparative genomic analysis was carried out based on the complete genomes of bacteria belonging to Nitrospirae, Firmicutes, Actinobacteria and Proteobacteria phyla, and of archaea belonging to Euryarchaeota and Crenarchaeota was carried out to identify molecular determinants involved in chloride tolerance of acidophilic iron-oxidizing microorganisms. The results obtained showed that representative Nitrospirae and Firmicutes harbor genes for the biosynthesis and uptake of compatible solutes such as ectoine, trehalose and potassium, which have been shown to have a role in salt tolerance. Microorganisms belonging to other phyla harbor genes for potassium transporters, but no genes for compatible solutes were detected. In agreement with the bioinformatic results, minimum inhibitory concentration (MIC) determinations and growth kinetics experiments showed that Leptospirillum ferriphilum (Nitrospirae) was more tolerant to NaCl than Acidithiobacillus ferrooxidans (Proteobacteria). Furthermore, it was observed that the addition of 0.5 mM ectoine to the L. ferriphilum culture stimulated growth in the presence of 100 mM NaCl. On the contrary, ectoine had no effect on the growth of At. ferrooxidans. These results suggest that ectoine and likely trehalose could play a key role in chloride tolerance in L. ferriphilum. conferring adaptative advantages compared to A. ferrooxidans and possibly other iron-oxidizing microorganisms.

Abstract: Investigation on structure and electronic structure under external electric field is a very interesting subject. To investigate the evolution of structure and properties from the perspective of electronic structure, the configuration of NaCl crystal has been calculated with the first principles in different external electric field. The system of energy, bond length, geometrical, radial distribution function, difference charge density, and density of states has been carefully examined. The analysis of the calculated results suggested that, with the increasing of external electric field, the system energy presents the roughly increases to a maximum value then begin to decrease, the long range structure become more disordered, the geometrical structure is significantly influenced, the iconicity of NaCl enhances.