Seawater System Research Articles

Mild construction of robust FeS-based electrode for pH-universal hydrogen evolution at industrial current density

The development of fast and mild preparation of transition metal electrocatalysts for efficient and ultra-stable water electrolysis in wide pH range electrolytes is essential for hydrogen energy supply. Herein, ultrathin and metastable FeS nanolayer self-supported on 3D porous iron foam (IF) substrate is fabricated via one-step mild sulfurization etching for only 2 h to obtain FeS@IF electrode, which achieves efficient and long-term hydrogen evolution in alkaline simulated seawater (1.0 M KOH + 0.5 M NaCl), neutral electrolyte (1.0 M PBS) and other corrosive systems. The overpotentials are only 63 mV and 78 mV to drive 10 mA cm−2 during hydrogen evolution in 1.0 M KOH + 0.5 M NaCl and 1.0 M PBS, respectively. Additionally, the FeS@IF electrode continuously catalyzes for over 600 h at 0.2–0.4 A cm−2 in 1.0 M PBS with negligible performance loss, partly attributed to FeS nanolayer firmly etching on the surface and the formation of corrosion-resistant ultrathin nano fan-like iron sulfide oxide (FeOxSy). This uniformly-distributed morphology helps to facilitate the interfacial electron transmission between active species and substrate, expose more active sites, and provide moderate channels for the rapid liberation of gas bubbles and mass transfer. This work proposes a novel strategy for developing efficient and stable catalysts for hydrogen production in wide pH range systems.

Giant Osmotic Energy Conversion through Vertical-Aligned Ion-Permselective Nanochannels in Covalent Organic Framework Membranes.

Nanofluidic membranes have been demonstrated as promising candidates for osmotic energy harvesting. However, it remains a long-standing challenge to fabricate high-efficiency ion-permselective membranes with well-defined channel architectures. Here, we demonstrate high-performance osmotic energy conversion membranes based on oriented two-dimensional covalent organic frameworks (COFs) with ultrashort vertically aligned nanofluidic channels that enabled efficient and selective ion transport. Experiments combined with molecular dynamics simulations revealed that exquisite control over channel orientation, charge polarity, and charge density contributed to high ion selectivity and permeability. When applied to osmotic energy conversion, a pair of 100 nm thick oppositely charged COF membranes achieved an ultrahigh output power density of 43.2 W m-2 at a 50-fold salinity gradient and up to 228.9 W m-2 for the Dead Sea and river water system. The achieved power density outperforms the state-of-the-art nanofluidic membranes, suggesting the great potential of oriented COF membranes in the fields of advanced membrane technology and energy conversion.

Derivation of copper water quality criteria in the Bohai Sea of China considering the effects of multiple environmental factors on copper toxicity

Copper has become one of the most important heavy metal pollutants in the environment because of its wide application and high toxicity, but research on water quality criteria (WQCs) on copper is limited, especially the derivation of seawater WQC. In addition, the toxicity of copper in the seawater system is affected by various environmental factors. Therefore, establishing a WQC that meets the characteristics of the regional environment is a top priority. The correlations between four factors of temperature, salinity, pH, dissolved organic carbon (DOC) and the toxic effect values of copper were analyzed in this study, and the temperature was determined as the most influential factor among the four factors in the Bohai Sea. A specific correlation between temperature and the toxic effects of copper was identified, and WQCs were derived based on the identified correlation and the variations of the Bohai Sea's temperature in different seasons by species sensitivity distribution (SSD) method. Under the condition of the winter, spring, autumn, and summer with an average water temperature of 0.09, 15.96, 17.83, and 24.87 °C, the obtained short-term water quality criteria (SWQCs) were 44.29, 4.70, 4.31, and 3.33 μg/L; the long-term water quality criteria (LWQCs) were 18.14, 1.93, 1.77 and 1.36 μg/L. The findings indicated the importance of introducing specific environmental conditions during the derivation process. This work could provide valuable information for pollution prevention and aquatic life protection in the Bohai Sea and provide a valuable reference for the derivation of criteria in other regions alike.

Chlorella vulgaris Extracts as Modulators of the Health Status and the Inflammatory Response of Gilthead Seabream Juveniles (Sparus aurata).

This study aimed to evaluate the effects of short-term supplementation, with 2% Chlorella vulgaris (C. vulgaris) biomass and two 0.1% C. vulgaris extracts, on the health status (experiment one) and on the inflammatory response (experiment two) of gilthead seabream (Sparus aurata). The trial comprised four isoproteic (50% crude protein) and isolipidic (17% crude fat) diets. A fishmeal-based (FM), practical diet was used as a control (CTR), whereas three experimental diets based on CTR were further supplemented with a 2% inclusion of C. vulgaris biomass (Diet D1); 0.1% inclusion of C. vulgaris peptide-enriched extract (Diet D2) and finally a 0.1% inclusion of C. vulgaris insoluble fraction (Diet D3). Diets were randomly assigned to quadruplicate groups of 97 fish/tank (IBW: 33.4 ± 4.1 g), fed to satiation three times a day in a recirculation seawater system. In experiment one, seabream juveniles were fed for 2 weeks and sampled for tissues at 1 week and at the end of the feeding period. Afterwards, randomly selected fish from each group were subjected to an inflammatory insult (experiment two) by intraperitoneal injection of inactivated gram-negative bacteria, following 24 and 48 h fish were sampled for tissues. Blood was withdrawn for haematological procedures, whereas plasma and gut tissue were sampled for immune and oxidative stress parameters. The anterior gut was also collected for gene expression measurements. After 1 and 2 weeks of feeding, fish fed D2 showed higher circulating neutrophils than seabream fed CTR. In contrast, dietary treatments induced mild effects on the innate immune and antioxidant functions of gilthead seabream juveniles fed for 2 weeks. In the inflammatory response following the inflammatory insult, mild effects could be attributed to C. vulgaris supplementation either in biomass form or extract. However, the C. vulgaris soluble peptide-enriched extract seems to confer a protective, anti-stress effect in the gut at the molecular level, which should be further explored in future studies.

Experimental Investigation of Transfer Characteristics of Midrange Underwater Wireless Power Transfer

The transfer characteristics of an underwater Wireless Power Transfer (WPT) system with a resonant frequency of 460kHz are studied experimentally. The coils have an outer diameter of 22.5 cm. Through this study, it was found that when the transfer distance is small, the transmission effect of WPT system in seawater is similar to that in air; when the transfer distance is larger than 20 cm, the load voltage of the WPT system in seawater is 4 times higher than that in air, and the transmission efficiency in seawater can reach 17 times of that in air on average. The experimental results in this paper are compared with studies published, and a circuit model is proposed to explain and predict the experimental phenomena, but the specific model still needs further work. Finally, the underwater WPT system has a low transfer efficiency of only 20% at midrange, so the findings of this research may be used for distance first scenarios.

Sustainable and efficient reduction of pollutants by immobilized PEG-P/Ag/Ag2O/Ag3PO4/TiO2 photocatalyst for purification of saline wastewater

In this study, we have reported an efficient and stable degradation of pollutants at salinity condition using newly developed solar-light-driven silicone-TiO2 based photocatalytic immobilized system. The interfacial layer of Silicone-PEG-P/Ag/Ag2O/Ag3PO4/TiO2 (S-PEG/PAgT) photocatalyst exhibited higher surface roughness, hydrophobicity, better light absorption, and narrow band gap than S-TiO2. The Rh B degradation by S-PEG/PAgT (91.2%) was 1.71 folds higher than S-TiO2 (53.5%) under simulated solar light irradiation. The reduction rate was significantly higher in S-PEG/PAgT (0.0792 min−1) than S-TiO2 (0.0229 min−1). The S-PEG/PAgT demonstrated high TOC removal (>80%), high repeatability (10 cycles) and excellent activity after 30 days of incubation in aqueous NaCl. The mechanism analysis revealed the synergistic effect of surface morphology with irregular chamfered edges and photoinduced reactive species (O2−) with successive formation of free chlorine radicals (Cl) contributed to the removal of pollutants in saline wastewater. Therefore, considering the above advantages of high efficiency and effective elimination of organics illustrates the potential of newly developed S-PEG/PAgT immobilized system in long-term practical treatment real seawater and ballast water.

Fe-doped CoNiP@N-doped carbon nanosheet arrays for hydrazine oxidation assisting energy-saving seawater splitting

Hydrazine oxidation assisting seawater splitting is a promising strategy to achieve chlorine-free energy-saving hydrogen production. Herein, Fe-doped Ni2P/CoP encapsulated by ultrathin nitrogen-doped carbon layers (Fe-CoNiP@NC) with unique nanosheet structure grown on Ni foam are synthesized, which was used as highly efficient and durable bifunctional catalyst for both hydrazine oxidation reaction (HzOR) and hydrogen evolution reaction (HER). For the two-electrode system toward overall hydrazine splitting (OHzS) in alkaline seawater, Fe-CoNiP@NC reveals a low cell voltage of 0.56 V at 1000 mA cm−2, stable operation for 100 h to keep ∼500 mA cm−2, and nearly 100% Faraday efficiency. Compared to the N2H4-free seawater system, the OHzS system can save 4.03 kWh for producing 1.0 m3 of H2, realizing energy-saving H2 production.

A systematic construction of water-electricity cogeneration and thermal membrane coupling desalination technology using the waste heat in steel industry

The widespread use of fossil energy emits a large amount of carbon dioxide, leading to the greenhouse effect and global warming. The essence of reducing carbon emissions is to achieve higher-quality sustainable development. The recycling of waste heat in the iron and steel industry is of great significance to reducing carbon emissions. Aiming at the problem of insufficient utilization of gas in iron and steel industry and the development of seawater desalination industry, a water-electricity cogeneration and thermal membrane coupling technology is established. Low-temperature multi-effect distillation seawater desalination device is directly connected with steam turbine generator, which uses gas to generate electricity. After generating electricity, negative pressure exhaust at the end of steam turbine is used for seawater desalination. The thermal efficiency of the system is increased to over 80%, the waste heat is effectively utilized, and the carbon emission in the thermal desalination process is reduced. At the same time, the high-efficiency removal and resource utilization of salt in concentrated seawater are realized. The recovery ratio of freshwater is over 55%, the salt content of freshwater is below 500 mg/L, and the salt content of seawater concentrated by membrane method can reach 79,450 mg/L. A new comprehensive utilization and recycling system of seawater has been constructed to realize efficient recycling of energy resources and promote the development process of carbon emission reduction.

A dynamic intercalation mechanism in pre-intercalation carbon nanosheets for capacitive deionization cells

Given that carbon-based electrodes suffer from poor long-term stabilities and limited desalination capacity, the optimized charge storage mechanism used for improving desalination performance remains requisite. In this work, the KC-pre-intercalated carbon nanosheets (PCNs) with abundant conjugated carbonyl groups were designed via a one-step smelting method for the first time as a novel intercalation electrode in the symmetric capacitive deionization. Interestingly, below 500 mg/L, the physical electrical double-layer mechanism is mainly influential. Benefitting from the proposed dynamic intercalation mechanism, a remarkable ion removal capacity of 1.65 g g−1 and impressive cyclability of 300 cycles (97.96%) were observed in the high salt concentrations (>1000 mg/L) and simulated seawater system rather than pure NaCl solution. The ultrahigh adsorption capacity and prominent cycling stability make the PCNs-based device rank top three among these of all the symmetric CDI systems reported in the literatures so far. The Na+ ions are intercalated in the enlarged interlayer spacing without a host structure deformation, thus offering a high ion removal rate (2.04 mg g−1 min−1) and a low energy consumption (0.28 Wh g−1). Our work exemplifies the importance of engineering conjugated carbonyl groups and pre-intercalated structure to capacitive deionization for brine.

Effect of Different Natural Substrates on Periphyton Production under Earthen Lined Seawater Pond for Periphyton based Aquaculture

Background: Periphyton-based aquaculture improves water quality, provides a natural food supplement, limits harmful bacteria, provides a safe haven for shrimp to escape, and adds living space. The impacts of diverse natural substrates on periphyton formation were examined under earthen lined pond seawater systems as a first step in analysing the sustainability of periphyton-based shrimp production. Methods: Natural substrates such as coconut coir, coconut shell and split bamboo pole were placed inside the earthen lined pond filled with seawater for duration of 45 days. Periphyton samples were obtained from each type of substrate on the 15th, 30th and 45th days of the experiment. For all substrates, periphyton biomass and chlorophyll ‘a’ pigment in the periphyton were measured at depths of 0 to 40 cm, 40 to 80 cm and 80 to 120 cm. Physico-chemical parameters of experiment pond water were recorded during periphyton samplings. Result: During the experiment, coconut coir showed higher periphyton biomass in terms of dry matter (DM) (3.4995 0.31201 mg/cm2) and chlorophyll ‘a’ pigment (3.2949 0. 27076 mg/cm2). Duncan’s Multiple Range Test and One Way ANOVA of diverse data reveal a significant difference (P 0.05) between the substrates in periphyton biomass and chlorophyll ‘a’ pigment. In all three substrates, a Student’s ‘t’ test analysis shows that the upper 0 to 40 cm depth yields more periphyton biomass and chlorophyll ‘a’ content than the other levels. Coconut coir was the best natural substrate for periphyton growth among the three.

Promoting the reduction of CO2 to formate and formaldehyde via gas–liquid interface dielectric barrier discharge using a Zn0.5Cd0.5S/CoP/multiwalled carbon nanotubes catalyst

A Zn0.5Cd0.5S (ZCS) solid solution was prepared using a hydrothermal method, in which CoP nanowires were added as a co-catalyst and co-deposited with multiwalled carbon nanotubes (MWNTs) on sponge to prepare a series of ZCS/CoP/MWNTs/sponge electrodes. The microstructures of catalysts were analyzed to confirm ZCS and CoP were successfully loaded in MWNTs/sponge. The CO2 reduction products (formate and formaldehyde) produced via dielectric barrier discharge (DBD) using the different catalysts proved that the introduction of the CoP nanowires co-catalyst can enhance the catalytic activity of ZCS/MWNTs/sponge in the DBD system. Using 10% CoP and a ZCS/CoP concentration of 2.5 g·L−1, the resulting ZCS/CoP/MWNTs/sponge catalyst exhibited the best catalytic of CO2 reduction ability toward formate (7894.6 μmol·L−1) and formaldehyde (308.5 μmol·L−1) after 60 min of discharge, respectively. The proposed DBD catalytic mechanism for the reduction of CO2 was analyzed according to the Tafel slope, density functional theory calculations, photocurrent density and plasma reaction process. Furthermore, the application of the DBD catalytic technology for CO2 capture and reduction was shown to be efficient in a seawater system, and as such, it could be useful for marine CO2 storage and conversion.

Comparative study on the esterification of gymnodimine in different shellfish exposed to the dissolved toxin in seawater

Some lipophilic phycotoxins dissolved in seawater can be accumulated by bivalves via the filtering process. To explore the relationship between the bioaccumulation of gymnodimine-A (GYM-A) and free fatty acids (FFAs) of shellfish, three species of bivalves (venus clam Meretrix meretrix, mussel Mytilus galloprovincialis, and ark shell Anadara kagoshimensis) were exposed to dissolved GYM-A for 7 days in the same seawater system. Results indicated that GYM-A can be accumulated by these bivalves from the dissolved phase and esterified with FFAs reaching over 90% in most tissues of bivalves. Gymnodimine-A and its esters mainly distributed in the gills of shellfish, and the highest concentration of toxins occurred in mussel, followed by ark shell and venus clam. Similar percent of different fatty acid esters occurred in the experimental shellfish, in which the C16:0, C17:0, C18:0, C18:1, C20:1, C20:2, C22:2, and C22:6-GYM-A esters were the main metabolites of GYM-A. The binding capacity of fatty acids and GYM-A varied in different FFAs, which can explain why the C20:1-GYM-A ester dominated the ester profile while C16:0 was the most abundant fatty acid in all samples. Comparing with the FFA profile of shellfish in the control groups, overexpression of some FFAs occurred in the tissues of shellfish exposed to GYM-A in the experimental groups, which suggested that biosynthesis of FFAs was affected by the accumulation and metabolism of GYM-A in bivalves. Multiple fatty acids including some valuably nutritional FFAs such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were consumed in the esterification metabolism of GYM-A, which hinted that the lipid metabolism and nutritional quality of shellfish affected by the contamination of GYMs should be explored and assessed in future works.

Stress Corrosion Cracking of Austenitic Cast Iron in Chloride-Containing Waters

Austenitic cast iron has been used for many years for pump cases, column pipes, and valves in seawater systems, particularly in the Middle East. Since the 1970s, failures have occurred by stress corrosion cracking, and there have been a number of research efforts to understand the problem and suggest means of preventing it. Cracking failures have continued and further research has been undertaken to try and understand the problem more thoroughly. This paper reviews the data from the early research, and presents the results of previously unpublished work, and its implications for the further use of austenitic cast iron in seawater and alternative alloys.

Coproduction of xylo-oligosaccharides and glucose from sugarcane bagasse in subcritical CO2-assisted seawater system

Abundant seawater resources can replace the shortage of freshwater resources. The co-production of xylo-oligosaccharides and glucose from sugarcane bagasse by subcritical CO2-assisted seawater pretreatment was studied in this paper. We investigated the effects of pretreatment conditions of temperature, CO2 pressure and reaction time on the yield of xylo-oligosaccharides in subcritical CO2-assisted seawater systems. The maximum xylo-oligosaccharide yield of 68.23% was obtained at 165 °C/2 MPa/5 min. After further enzymatic hydrolysis of the solid residue, the highest glucose yield of 94.45% was obtained. In this system, there is a synergistic effect of mixed ions in seawater and CO2 to depolymerize xylan into xylo-oligosaccharides with a lower degree of polymerization. At the same time, the addition of CO2 increased the pore size and porosity of sugarcane bagasse, improved the efficiency of enzymatic hydrolysis and increased the yield of glucose. Therefore, this study provides a more environmentally friendly and sustainable process for the co-production of xylo-oligosaccharides and glucose from sugarcane bagasse, and improves the utilization of seawater resources.Graphical

Predicting the corrosion properties of cast and hot isostatic pressed CoCrMo/W alloys in seawater by machine learning

PurposeCobalt-based alloys exhibit a unique combination of wear resistance, strength and corrosion resistance. Localized corrosion of such alloys in seawater system can be several orders of magnitude faster than general corrosion, and direct experimental evidence of the local activation process is still lacking, which makes the accurate prediction for properties difficult, especially for long-term corrosion. The purpose of this study is revealing the relationship between multiple environments and corrosion properties to predict the corrosion of cobalt-based alloys.Design/methodology/approachA data-driven method for the prediction of the corrosion behavior of cast and hot isostatic-pressed CoCrMo/W alloys in seawater is proposed. The gradient boosting regression models calculate mean relative errors (MREs) of 0.160 and 0.435 by evaluating a hold-out set for breakdown potential (Eb) and maximum current density (imax), respectively, considering various compositions, synthesis methods and corrosion environments.FindingsThe models can be used to estimate the “unseen” cobalt-based alloy after immersion in 3.5 Wt.% NaCl solution for one, two, four and eight months to obtain high precision with MREs of 7.8% and 9.8% for Eb and imax, respectively.Originality/valueMachine learning method provides novel and promising insights for the prediction of localized corrosion properties.

Retention of the Tulane virus, a norovirus surrogate, by ultrafiltration in seawater and production systems

Shellfish as a foodstuff must meet sanitary quality objectives for the protection of consumers and this quality is closely linked to the water. The oyster industry considered this challenge related to contaminations and currently, the major risk of disease is due to the presence of norovirus (NoV) since all oyster-consuming countries report outbreaks of gastroenteritis linked to the presence of this microorganism. Ultrafiltration has already demonstrated to be efficient for viral protection of oyster farms in previous studies. In this work, retention by ultrafiltration of Tulane virus, a NoV surrogate, was evaluated. The effect of virus concentration in the feed on the ultrafiltration efficiency has been assessed. Low retentions of about 1 log were observed at the lowest viral concentrations. At higher concentrations, an increase of retention up to 5 log was obtained. These results highlight the potential overestimation of UF efficiency during laboratory experiments realized at high concentrations, compared to low concentrations found in environmental resources. In agreement with other studies, higher retentions at high concentrations could be explained by formation of viral aggregates, which could facilitate the steric exclusion but also modify the electrostatic and hydrophobic interactions between isolated viruses/aggregates and membrane. Virus retentions with a fresh mineral water (Evian water) and seawater were compared. Seawater achieved higher retention rates for Tulane virus due to the membrane fouling.

Dual-strategy of hetero-engineering and cation doping to boost energy-saving hydrogen production via hydrazine-assisted seawater electrolysis

When compared with pure water, hydrogen produced by seawater electrolysis has a better practical application potential. By replacing the oxygen evolution reaction (OER) and competitive chlorine evolution reaction (ClER) with the thermodynamically favorable anodic hydrazine oxidation reaction (HzOR) in alkaline seawater, energy-saving hydrogen production can be achieved. In this study, Fe/Co dual-doped Ni2P and MIL-FeCoNi heterostructures (FeCo-Ni2P@MIL-FeCoNi) arrays with simultaneous cation doping and hetero-engineering provide excellent bifunctional electrocatalytic performance for HzOR and hydrogen evolution reaction (HER) in alkaline seawater electrolyte. Overall hydrazine splitting (OHzS) in seawater is impressive, with a low cell voltage of only 400 mV required to reach 1000 mA cm−2 and stable operation for 1000 h to maintain above 500 mA cm−2. As a proof-of-concept, the OHzS system can save 3.03 kW h when producing 1.0 L of H2 when compared with the N2H4-free seawater system, resulting in energy-saving H2 production. Density functional theory calculations show that the combination of Co-doping and the fabrication of FeCo-Ni2P and MIL-FeCoNi heterointerfaces can result in a low water dissociation barrier, optimized hydrogen adsorption free energy toward HER, and favorable adsorbed dehydrogenation kinetics for HzOR. This processing route paves the way for a practical approach to the efficient utilization of hydrogen, which is abundant in the ocean energy field, to achieve a carbon-neutral hydrogen economy.

Effects of Dietary Lysophosphatidylcholine on Growth Performance and Lipid Metabolism of Juvenile Turbot

A 56-day feeding trial was conducted in a flow-through seawater system to investigate the effects of lysophosphatidylcholine (LPC) on growth performance and lipid metabolism of turbot. Four experimental diets were prepared, differing only in the LPC supplementation, namely, 0 (LPC-0, control), 0.1 (LPC-0.1), 0.25 (LPC-0.25), and 0.5% (LPC-0.5) of dry matter. Each diet was randomly fed to triplicate tanks. LPC-0.1 and LPC-0.25 led to significantly higher weight gain than the control diet, and the highest weight gain was observed in LPC-0.1. Compared to the control group, the LPC-supplemented groups had higher survival and lower hepatosomatic index and viscerosomatic index. LPC-0.25 led to significantly lower contents of crude lipid and ash in whole fish. Dietary LPC supplementation led to a basic decrease in the lipid metabolism-related biochemical parameters in serum but had only very minor influence on the fatty acid composition in the liver and subcutaneous tissue around the fin (STF). High LPC levels upregulated the mRNA expression of BSAL and ApoEα in both the liver and STF. In conclusion, dietary LPC supplementation (0.1-0.25%) enhanced the growth, lowered the lipid accumulation in juvenile turbot, and significantly regulated the lipid metabolism. However, it seldom influenced the fatty acid composition.

Simulation and optimisation of a SWRO system in Cape Town, South Africa

Seawater reverse osmosis (SWRO) system is popular in most islands and coastal areas around the world with limited fresh water resources. A SWRO system was designed to fulfil 50% of the population water demand in Cape Town, South Africa, which can lead up to 383,353 m3/day in the next 15 years. The total dissolved solid (TDS) within the product (i.e. drinking water) was lowered to 600 ppm by referring to standard guideline stated by the World Health Organization (WHO). Design flowrate was set at 766,704 m3/day and the parameters such as feed, permeate, concentrate flowrate, number of vessels, number of membrane elements, number of stages, seawater chemical composition, temperature, pressure, and system configuration were considered in this study. Reverse Osmosis System Analysis (ROSA) 2017 software was integrated the design with simulation to further understand how different parameters affect one another in SWRO system. The TDS standard value of 600 ppm in the products were 73.76 ppm and 181.13 ppm after further optimisation. The efficiency of the SWRO system recovery rate was 75.87% and specific energy consumption (SEC) was 6.18 kwh/m3, greater than the previous value of 50% and 9.7 kwh/m3 in terms of recovery percentage and SEC respectively. The findings indicate that a lower amount of feed and energy is needed to achieve the desired production value. Hence, it is also resulting in major savings in terms of operating cost for SWRO system.

Sprečavanje korozije ploča od mekog čelika potopljenih u morsku vodu ekstraktom ulja nekih prirodnih proizvoda

The hull plates of the ship made of mild steel (MS) are always in contact with seawater are always in contact with aggressive ions such as chloride ions present in seawater.The corrosion resistance of the hull plates of the ship made of mild steel has been investigated by polarization study. Sandalwood oil extract containing 5 g each of Cardamom (disambiguation), Clove (disambiguation), Nutmeg, India Sambrani (loban), Chrysopogon zizanioides, commonly known as vetiver and Camphor was used as corrosion inhibitor along with Trisodium citrate (TSC), sodium dihydrogen phosphate (SDP) and Zn2+. The corrosion resistance was measured in the absence and presence of various inhibitor systems: Trisodium citrate (TSC) 100 ppm+ Zn2+ 50ppm system, sodium dihydrogen phosphate (SDP) 100 ppm+ Zn2+ 50ppm system, Oil coated (3days) MS, Oil coated (3days) MS +TSC 100 ppm+ Zn2+ 50 ppm system and Oil coated (3days) MS +SDP100 ppm+ Zn2+ 50 ppm system were used. It is observed that when mild steel is immersed in SW+TSC 100 ppm+ Zn2+ 50ppm system , the corrosion resistance of MS increases. When mild steel is immersed in SW+ SDP 100 ppm+ Zn2+ 50ppm system , the corrosion resistance of MS increases. When mild steel is immersed in Oil coated (3days) MS in Sea water system , the corrosion resistance of MS increases. When mild steel is immersed in Oil coated (3days) MS in SW+TSC 100 ppm+ Zn2+ 50ppm system , the corrosion resistance of MS increases. When mild steel is immersed in Oil coated (3 days) MS in SW+ SDP 100 ppm+ Zn2+ 50ppm system , the corrosion resistance of MS increases. This is revealed by the fact that there is increase in LPR value and decrease in corrosion current value. The corrosion potential is shifted to anodic side. This indicates that in this inhibitor system, the anodic reaction of metal dissolution is controlled predominantly. This implies that these inhibitor systems may be coated on mild steel surface used as hull plates to prevent corrosion of mild steel in sea water.