Salt Concentration Of Seawater Research Articles

Effect of chloride binding and sulfate ion attack on the chloride diffusion in calcium sulfoaluminate-based material under seawater environment

The diffusion of chloride ions in reinforced concrete under the seawater environment will affect the physical or mechanical properties and durability. Sulfate ions also influence the diffusion of chloride ions by generating expansion products through physical and chemical reactions. Further research on the effects of chloride binding and sulfate ion attack on chloride ion diffusion will deepen the understanding of concrete failure mechanism. In this paper, a quaternary blend based on calcium sulfoaluminate (CSA) cement was prepared and laboratory immersion tests were conducted in artificial seawater with varying salt concentrations. Initially, chloride ion concentration measurements and XRD tests were conducted at different corrosion ages and salt concentrations. Subsequently, the chloride binding properties of CSA-based materials was quantified through the analysis of chloride ion concentration and the phases of hydration products. Meanwhile, the corrosive effect of sulfate ions on chloride ion diffusion was determined corresponds to the content of expansive hydration products. Furthermore, numerical simulations were employed to evaluate the impact of sulfate ion corrosion, chloride binding, and their combined effects on chloride ion diffusion, and the results were compared with free chloride ion concentration (Cf). The results indicate that the total chloride ion concentration (Ct) exhibits a linear relationship with increasing salt concentrations of seawater in CSA-based materials. Meanwhile, the bound chloride ion concentration (Cb) follows a logarithmic growth pattern. The chloride binding rate experiences a linear decline with the increase of chloride ion concentration in the artificial seawater. Additionally, the relationship between Cf and Cb or Ct can be described using different isothermal adsorption models for the CSA-based materials. Among these models, the Langmuir model is suitable for characterizing the relationship between Cf and Cb, while the Freundlich model is suitable for describing the relationship between Cf and Ct. Furthermore, it is noteworthy that sulfate ion attack and chloride binding exert nearly equivalent effects on the diffusion of chloride ions in CSA-based materials at short corrosion age and low chloride ion concentration. However, the corrosive impact of sulfate ions gradually evolves into the dominant factor in the progression of corrosion over time and the increase in seawater salt concentration.

Regulation effects of indoleacetic acid on lipid production and nutrient removal of Chlorella pyrenoidosa in seawater-containing wastewater

The utilization of seawater supplemented with wastewater nutrients for microalgae cultivation represents a promising and cost-effective approach that combines the benefits of wastewater treatment and microalgal resource recovery. However, the high salt content in seawater poses a significant challenge, hindering microalgal growth and reducing the removal of nitrogen and phosphorus on a large scale. The phytohormone indoleacetic acid (IAA) was used in this study to enhance stress resistance and lipid production of Chlorella pyrenoidosa grown in seawater-wastewater medium. Compared to the control groups involving regular wastewater and seawater-containing wastewater without IAA, Chlorella pyrenoidosa cultivated in the seawater-containing wastewater supplemented with IAA exhibited remarkable outcomes. Specifically, microalgae in IAA-enhanced seawater-containing wastewater achieved the highest lipid productivity (22.67 mg L−1 d−1) along with impressive nitrogen (99.3 %) and phosphorus (97.3 %) removal rates. Moreover, their cell sedimentation ratio reached 76.6 %, indicating enhanced settling properties. Additionally, the physiological mechanism changes after exposure to seawater stress and IAA were revealed based on the changes in antioxidant enzymes, endogenous hormones, and fatty acid saturation. Furthermore, the transcriptomic analysis elucidated the molecular mechanisms underlying microalgal lipid synthesis and their response to antioxidant stress when exposed to seawater. The supplementation of IAA under seawater stress stimulated energy metabolism and the antioxidant response in microalgal cells, effectively mitigating the adverse effects of seawater stress and promoting overall algal lipid productivity. Overall, this study unveiled the potential of exogenous plant hormones, particularly IAA, in enhancing stress resistance and lipid productivity of microalgae grown in seawater-wastewater medium, which significantly contributed towards the efficient use of seawater resources for microalgae cultivation and biofuel production.

Desain Eksperimen TUF Dalam Peningkatan Kualitas Garam Olahan Limbah Produksi Es dengan Metode Taguchi di PT. Putra Maesa Persada

Indonesia has salt resources in seawater along the Java Sea coast. However, the high salt content in seawater causes difficulties for various industries that use seawater as their raw material. A Taguchi experimental design using TUF filters was carried out to determine the best TUF filter composition in producing high-quality salt. The factors considered were the compositions of three materials, namely crushed coral, charcoal, and palm fibers. The results obtained for the sample filters were analyzed using one-way ANOVA, Minitab, and the Signal-to-Noise Ratio (SNR) method. The optimal TUF filter composition was found to be 450g finely crushed coral, 350g finely crushed charcoal, and 30g palm fibers. The study results revealed that the best factor for improving salt quality was crushed coral, with a contribution of 65.63842% and an F-value of 109.3333. Charcoal also provided a significant contribution of 24.40453% with an F-value of 40.65041. However, palm fibers did not contribute significantly to improving salt quality. The optimal TUF filter composition can help improve salt quality and increase productivity while reducing costs for various industries such as food production and preservation. The optimal composition of 450g of crushed coral, 350g of charcoal, and 30g of palm fibers can significantly improve the quality of salt production. In conclusion, the use of TUF filters with the optimal composition of 450g crushed coral, 350g charcoal, and 30g palm fibers can significantly improve salt quality. This study provides insight into the potential applications of TUF filters and should encourage further exploration of the technology's potential in various industries.

User Acceptance for Multitask IoT Monitoring and Controlling System for Salt Ponds

The process of making salt is still done manually by filling water into reservoirs and plots which require salt farmers to visit their farms periodically. This is mainly because the speed of the salt crystalization process is always inconsistent due to salt concentration in seawater and the weather. This study aims to build a new prototype of a water level monitoring system in reservoirs and plots in salt ponds then measure the water's salinity value, which will be reported to the farmers. The method used in this research is prototyping, which includes system requirement analysis, rapid design, prototype building, system evaluation, and system improvement. The system was tested using the black box method, namely testing all system functionality and determining user satisfaction with questionnaires. The functionality test results, including monitoring the water level and the pump control, show that the prototype functions correctly. The designed system can send information in the form of water level values in reservoirs, water levels in plots, and salinity values with linear sensor accuracy with measurement results with conventional measuring instruments with standard error values of 0.485, 0.44, and 0.72, respectively. Applying this system will ease farmers’ monitoring of water levels and controlling irrigation in reservoirs and plots.

CA/PEG/chitosan membrane incorporated with TiO2 nanoparticles for strengthening and permselectivity membrane for reverse osmosis desalination

In this paper, we describe the fabrication, characterization, and performance tests of CA/PEG/Chitosan membrane incorporated TiO2nanoparticlesin a ROD system to reduce salt content in seawater. The preparation of CA/PEG/Chitosan-TiO2-NPs was conducted by blending method under various masses of TiO2-NPs (0.5 g; 0.75 g; and 1.0 g). Based on our experiment, we report the presence functional group of Ti-O-Ti bonds shown under the wavenumber range of 671–711 cm−1. Several wavenumbers have also indicated the presence of functional groups from CA/PEG/chitosan such as –OH, C = O, C-H, and NH2. Uniquely, morphological analysis shows that the pore size formed is 10 nm-1000 nm (0.01 µm-1.00 µm) after adding TiO2-NPs to the CA/PEG/Chitosan membrane. This is evidenced by the XRD pattern, which shows an increased XRD pattern with a high crystallinity phase. Strengthening tests on the fabricated membranes were successfully evaluated and showed that the addition of TiO2 affected the strength of the membrane. The evaluation of the membrane performance test found that the addition of TiO2-NPs mass incorporated into the CA/PEG/Chitosan membrane decreased the value of water flux, pH, and salinity. Meanwhile, there was an increase in the percentage value of salt rejection. This proves that the performance of the CA/PEG/Chitosan-TiO2-NPs membrane increases durability and permselectivity as filter materials for the ROD system.

Performance analysis of a novel solar cogeneration system for generating potable water and electricity

PurposeThe utilisation of renewable energy sources for generating electricity and potable water is one of the most sustainable approaches in the current scenario. Therefore, the current research aims to design and develop a novel co-generation system to address the electricity and potable water needs of rural areas.Design/methodology/approachThe cogeneration system mainly consists of a solar parabolic dish concentrator (SPDC) system with a concentrated photo-voltaic module at the receiver for electricity generation. It is further integrated with a low-temperature thermal desalination (LTTD) system for generating potable water. Also, a novel corn cob filtration system is introduced for the pre-treatment to reduce the salt content in seawater before circulating it into the receiver of the SPDC system. The designed novel co-generation system has been numerically and experimentally tested to analyse the performance at Karaikal, U.T. of Puducherry, India.FindingsBecause of the pre-treatment with a corn cob, the scale formation in the pipes of the SPDC system is significantly reduced, which enhances the efficiency of the system. It is observed that the conductivity, pH and TDS of seawater are reduced significantly after the pre-treatment by the corncob filtration system. Also, the integrated system is capable of generating 6–8 litres of potable water per day.Originality/valueThe integration of the corncob filtration system reduced the scaling formation compared to the general circulation of water in the hoses. Also, the integrated SPDC and LTTD systems are comparatively economical to generate higher yields of clean water than solar stills.

Changes in the salt concentration distribution in surface water (seawater) due to seawater recirculation in a porous medium under tidal fluctuations

Many studies have used numerical simulations and experiments to simulate saltwater intrusion in a nearshore aquifer. Thus, it is known that seawater recirculation occurs in a porous medium just below a sloping beach, and a saltwater wedge occurs in the medium below where the slope intersects the water level at low tide. This study investigated the salt distribution in the surface water when subterranean recirculation of seawater is occurring and there is a saltwater wedge in an underlying porous medium, along with the relationships between the seawater recirculation and the tidal amplitude and beach gradient. The salt distribution in a subterranean aquifer and in surface seawater where the shore sloped gently seaward with a constant slope of 1/10 or 1/5 under tidal amplitudes of 0.5, 1.0, or 2.0 m was numerically simulated by the ASGMF method, which couples water pressure and water flow in a porous medium with those in the overlying surface water and can simulate variable-density flows and the salt concentration distribution in both the porous medium and the surface water. The results showed that the recirculation of seawater depended on the tidal amplitude, being greater when the amplitude exceeded 1.0 m, but that it was unlikely to occur when the beach gradient was steep. Thus, the aspect ratio (width to depth) of the seawater recirculation decreased as the tidal amplitude increased above 1.0 m. Furthermore, the simulated surface water level was often lower than the tidal water level; thus, the surface water level was not consistent with the tidal water level imposed at the right boundary of the simulation domain but varied slightly under the influence of water flow in the surface water and gas flow in the atmosphere. The salt concentration in the surface water was not always the same as the seawater salt concentration because a thin freshwater layer and a brackish water layer of mixed freshwater and saltwater overlay the seawater.

Energy, exergy, and economic analyses of a novel biomass-based multigeneration system integrated with multi-effect distillation, electrodialysis, and LNG tank

In this study, a novel multigeneration system is considered from energy, exergy, and economic points of view. The combined system composed of biomass gasifier, CO2 cycle, cooling system, multi-effect distillation (MED), and electrodialysis was assessed. This integrated system produces electricity, cooling, distilled water, sodium hydroxide (NaOH), and hydrogen chloride (HCl). A parametric study regarding moisture content of biomass, the efficiency of expander I, LHV of biomass, the salt concentration of seawater, and a number of MED effects on system performance was conducted. The obtained energy and exergy efficiencies of modeled MGS are 75.1% and 88.4%. The highest and lowest exergy destruction rates (EDR) belong to the liquefied natural gas line and electrodialysis, respectively. The proposed MGS produces 73.17 GWh of cooling, 103 GWh of electrical energy, 1223 Ton of NaOH, 1114 Ton of HCl, and 212.6 m3 of potable water annually. The influence of expander I on energy and exergy efficiencies of the CO2 cycle was investigated. Results revealed that increasing the LHV of the biomass results in a decrement of both energy and exergy efficiencies of MGS and recovery ratio. When considering the biomass moisture content, the efficiencies of exergy and exergy of MGS diminished with a rise in moisture amount.

Morphological, biochemical and physiological responses of a tropical coastal plant Guettarda speciosa to salt stress

Selection and utilization of plants with high salt tolerance can be efficient to rapidly construct or restore the vegetation of the tropical coral islands. Here, we investigated the response of Guettarda speciosa , a typical tropical coastal plant, to salt stress. Different morphological, physiological and biochemical changes in G. speciosa plants after being subjected to NaCl stress based on the salt content of the reference seawater were studied. The results showed that G. speciosa can be tolerant to 25 g L −1 NaCl which corresponds to 2.5% salt content of seawater. A series of adaptive mechanisms were triggered to cope with salt-stress, including the increase in the thickness of leaf epidermis and palisade tissue to limit water loss, changes in photosynthetic pigments, and antioxidant defense mechanisms. Osmoregulatory substances and antioxidant enzymes worked together to cope with membrane lipid peroxidation caused by the accumulation of reactive oxygen species under salt stress and maintain the stability of osmotic potentials. Our findings indicated that G. speciosa has a strong salt tolerance but probably could not tolerate prolonged seawater immersion, which limit its coastal distribution. Therefore, G. speciosa can be considered for vegetation construction and ecological restoration in tropical coral islands such as those in South China Sea.

Performance and parameter optimization of a capacitive salinity/heat engine for harvesting salinity difference energy and low grade heat

A novel cycle model of the capacitive salinity/heat engine mainly consisting of nano-porous super-capacitors is established for harvesting mixed free energy caused by salinity difference between the river water and the seawater, and the thermal energy due to the temperature difference. The heat engine is charged and discharged in the cycle of a low temperature brine and a high temperature fresh water, respectively. The analytical expressions of the cyclic work output and efficiency are given. General performance characteristics of the capacitive salinity/heat engine are analyzed. The temperature of the heat reservoir and salt concentration of seawater are optimized to improve the efficiency of the capacitive salinity/heat engine. The optimal selection ranges of several main parameters are provided. When the Stern distance is equal to 1 nm and the charging voltage is equal to 3.5V, the energy conversion efficiency of the capacitive salinity/heat engine is about 40%, while the pure thermal efficiency in the cycle is about 16.9%. The energy conversion efficiency of the capacitive salinity/heat engine is significantly larger than that of the capacitive heat engine. The results obtained can facilitate the application of this technology to real life, which can reduce the consumption of fossil fuels.

Development of a non-invasive method for monitoring variations in salt concentrations of seawater using nuclear technique and Monte Carlo simulation

In the oil production industry, water is used as a fluid injected into the well to raise the oil when the well is depressurized. Water thus produced presents variations in the concentrations of dissolved salts, as there is a mixture of different types of water, related to its origin (such as connate water, sea water). Because it is reused in oil production, water needs to be monitored to maintain the standard suitable for its use as it can be hypersaline, contributing to the encrustation of pipes and contamination of underground water reservoirs. In this study, a noninvasive method was developed to determine the salt concentration in seawater. The method uses a detection system that contains a NaI(Tl) detector, a241Am source, and a sample holder to measure the mass attenuation coefficient of saltwater samples. For validation, the same setup was also simulated using the MCNPX code. Saltwater samples with different concentrations of NaCl and KBr were used as a proxy for seawater. The mass attenuation coefficients for the simulation exhibited the smallest relative errors (up to 6.2%), and the experimental ones exhibited the highest relative errors (up to 25%) when compared with theoretical values.

Development of the design and determination of the mode characteristics of the demineralizer for sea water

The object of research is block low-temperature installations for obtaining fresh water.
 Investigated problem: obtaining fresh water from sea using low-temperature technologies.
 Main scientific results: the design is developed and the operating characteristics of the demineralizer for sea water are determined.
 The influence of the initial salt content of sea water on the ice formation rate is determined. With an increase in the salinity of 3.5 times, productivity on ice decreases 2.3 times.
 The kinetics of the salt content in the freezing solution depends on the initial concentration. With an initial salt content of 6.74 g/l, the process rate is 0.4 g/h, with a salt content of 1 g/l – 0.14 g/h
 With an initial salt content of 6.74 g/l, the process of separating wastewater from the ice block is more intensive. The salt content of the first portion of the effluent is 3.2 times higher than the initial concentration of the solution.
 A cryoscopic curve was obtained for seawater in the concentration range from 0 to 6.74 g/l.
 The area of practical use of the research results: studies of the quality of the obtained water showed that the content of nitrates decreases 5 times, the hardness decreases by 2 mg/dm³. The salt content is reduced from 858 mg/dm³ to 560 mg/dm³.
 Plants for the concentration of food liquids by the block freezing method are designed to produce environmentally friendly products that preserve the bioactive complex of raw materials as much as possible with minimal energy consumption.
 An innovative technological product: design and operating modes of a block freezing plant for seawater desalination.
 Scope of application of the innovative technological product: industrial enterprises, the technological process of which requires small volumes of fresh water; to obtain fresh water on oil platforms in the oceans; small hotels, boarding houses on the seaside.

Vivivary Tests on Mangrove Plants Species Rhizophora apiculata and Avicennia alba Against the Level of Salt Salinity and Tide

Indonesia's coastal areas have a large area and potential for mangrove ecosystems. Of the approximately 15,900 million ha of mangrove forests in the world. 27% or 4,293 million ha are in Indonesia. The Sicanang Medan Belawan mangrove forest, North Sumatra Province, is a wetland area which mostly consists of mangrove forests. In the mangrove forest, there are Rhizophora apiculata and Avicennia alba species. Mangroves have unique morphological characters as a form of adaptation to the environment, one of which is the salinity of sea water which is the level of salinity or salt content in seawater. In the mangrove forest of Sicanang Medan Belawan, there are Rhizophora apiculata and Avicennia alba species which have the characteristics of vivivar culture development. From the results of test 1 on the species Rhizopora apiculata, it was found that the highest salinity level at the muddy and sandy station was 30 ppm, and the highest pH was at 7.79, and at a temperature of 29 C. While for Avicennia alba the highest salinity value was obtained at 30.6 ppm, the highest pH was at 7.82. , and temperature at 29.5 C. Based on the results that different zoning could affect yield, the vivivary shape of mangroves also had an effect on yield. salinity affects mangroves to develop, the higher the salinity, the more difficult it is for the seeds to develop

Identifikasi Keberadaan Air pada Proses Penyaluran Fluida Produksi di Lapangan Minyak Lepas Pantai

Oil production that flows from the Platform to the FSO (Floating Storage and Offloading) "A" is derived from PT. "B" and the "C" Oil Company in the Madura Strait. The total oil production flowing from the Platform to the "A" FSO is currently around 6000 BOPD. As a result of the delivery system using the same channel, a problem arises, namely oil losses between the Platform as a delivery point and FSO "A" as a receiving point. Besides that, the water that is involved in the oil distribution process will be a deduction factor that will be used as a correction for oil shipments, the more water the less amount of oil will be received at FSO "A". The oil samples that have been taken are then observed for their characteristics, namely density, composition (%-mole), BS&W, emulsion, flash, shrinkage at PPPTMGB "Lemigas" Laboratory Jakarta. The specific gravity of samples is around 1,018. While the characteristics of the two are different from the characteristics of sea water; this difference is shown by the results of SG (1,018 vs 1,025) and the salt content of sea water is much higher than the water formation of PT "B" and PT "C". The oil samples of PT "B" and PT "C" have almost the same SG, which is 0.79. BS&W oil in both ships is quite low; this shows that the separation of oil and water on the Platform went quite well. However, BS&W samples in incoming FSO "A" are very high, at 5%; this indicates an off-set at the water-oil interface level settling time on the Platform separator so that water can be joined with the oil flow from the Platform to the FSO "A"

Optimalisasi Tingkat Kevakuman Pada Fresh Water Generator di MV. Glovis Daylight

A freshwater generator is one of the auxiliary machines onboard which functions to convert seawater into freshwater by distilling it in a vacuum. Fresh water on the ship is very important for crew accommodation and also for the smooth work of machinery on ships that use freshwater for cooling media or for other purposes. The working principle of a freshwater generator is to separate the salt content in seawater by evaporating it in a vacuum so that the boiling point decreases and the water can evaporate below a temperature of 100oC. Problems and disturbances in the freshwater generator will affect the amount of freshwater production, therefore the condition of the auxiliary machine must be maintained. In this study, the authors used the fishbone analysis method to describe the factors that caused the vacuum that was not optimal and to find out the causes, impacts, and efforts made to overcome these problems. Based on the results of research that the author has done in MV. During the practice, Glovis Daylight concluded that the inadequate vacuum in the freshwater generator was caused by low ejector pump pressure, broken mechanical seal on the ejector pump, dirty strainer, and crust on the condenser and evaporator plates. The resulting impact is that the resulting freshwater production will decrease. Efforts to overcome this require routine maintenance according to the manual book, replacement of mechanical seals, cleaning strainer, and descaling of the condenser and evaporator plates.

Rheological properties, compressive strength, hydration products and microstructure of seawater-mixed cement pastes

The application of seawater as the mixing water in concrete production could mitigate the increasing demand for fresh water in concrete production associated with the continuously increasing offshore infrastructures. Understanding the key factors that influence the properties of seawater-mixed cementitious materials could promote the application of seawater during concrete preparation. A comprehensive investigation was carried out to assess the effects of the water/cement ratio (w/c), the partial replacement of ordinary Portland cement (OPC) with supplementary cementitious materials, and the salt concentration in seawater on the rheological properties (plastic viscosity (η), dynamic yield stress (τd), thixotropic area (Athix)), compressive strength (fc), hydration products and microstructure of cement pastes. The results show that there was an increase in η, τd, Athix and fc in all seawater mixes compared to deionized (DI) water mixes, and the increase in strength was more significant in the pastes with a lower w/c. The increase in salt concentration in the seawater did not linearly increase fc; instead, the early age strength increased initially and then decreased. This result was due to the combined effects of the increased chloride and Na+ ions on the strength development with the increase in salt concentration in the seawater. Interestingly, it was found that there was a good correlation between the results of η and fc for the seawater mixes in this study, and the same η value indicated a higher fc in the seawater mix than in the DI water mix.

In silico identification and functional validation of linear cationic \u03b1-helical antimicrobial peptides in the ascidian Ciona intestinalis

We developed a computing method to identify linear cationic α-helical antimicrobial peptides (LCAMPs) in the genome of Ciona intestinalis based on its structural and physicochemical features. Using this method, 22 candidates of Ciona LCAMPs, including well-known antimicrobial peptides, were identified from 21,975 non-redundant amino acid sequences in Ciona genome database, Ghost database. We also experimentally confirmed the antimicrobial activities of five LCAMP candidates, and three of them were found to be active in the presence of 500 mM NaCl, nearly equivalent to the salt concentration of seawater. Membrane topology prediction suggested that salt resistance of Ciona LCAMPs might be influenced by hydrophobic interactions between the peptide and membrane. Further, we applied our method to Xenopus tropicalis genome and found 11 LCAMP candidates. Thus, our method may serve as an effective and powerful tool for searching LCAMPs that are difficult to find using conventional homology-based methods.

Modeling variable density flow in subsurface and surface water in the vicinity of the boundary between a surface water–atmosphere system and the subsurface

When seawater intrudes into a subterranean estuary, there is interaction between groundwater and surface water, and ocean tides and waves can influence the salt concentration distribution in subsurface of the estuary. However, numerical simulations of seawater intrusion into a subterranean estuary often neglect the atmosphere and surface water and simply specify hydrostatic pressure and a constant seawater salt concentration. This study examined the influence of fluid flow and pressure in a surface water-atmosphere system consisting of both atmosphere and surface water on the salt distribution in subsurface and in the surface water by a numerical simulation that couples fluid flows in the surface water-atmosphere system and groundwater. This study first confirmed the precision of the simulation method by comparing experimentally determined salt concentration distributions in silica beads unsaturated with water. This study then conducted an experiment in a two-dimensional tank filled with seawater and glass beads (mean diameter 0.2 mm) and carried out two simulations of this tank experiment: one of a limited system consisting of the porous medium and surface water only, and the other of a full system, consisting of the porous medium, surface water, and atmosphere. Darcy's law has frequently been applied in limited system simulations by assigning extremely high permeability to the surface water. This study therefore also conducted a third, simpler numerical simulation of the limited system that used only Darcy's law. The salt concentration distribution obtained by the full system simulation was closer to the experimental distribution than that obtained by the limited system simulation. This result implies that fluid flow and pressure in both the atmosphere and surface water influence water flow and water pressure in the porous medium. Furthermore, the third simulation using Darcy's law only could not precisely reproduce flow in the surface water. Therefore, when variable-density flow in surface water and a shallow subsurface are numerically simulated, the simulation system needs to include atmosphere and surface water to take account of the influence of fluid flow and fluid pressure in both the atmosphere and surface water on the fluid flow and transport of salt in a shallow subsurface.

Chitosan Film as Eco-Friendly and Recyclable Bio-Adsorbent to Remove/Recover Diclofenac, Ketoprofen, and their Mixture from Wastewater.

This paper reported the first example on the use of chitosan films, without further modification, to remove and recover, through bio-sorption processes, the emerging pollutant Diclofenac from water. The latter was adopted as a model, among non-steroidal anti-inflammatory drugs, by obtaining a maximum adsorption capacity, qmax, on chitosan of about 10 mg/g, under the applied experimental conditions of work. The literature gap about the use of chitosan films, which was already used for dyes and heavy metals removal, to adsorb emerging pollutants from water was covered, claiming the wide range application of chitosan films to remove a different class of pollutants. Several parameters affecting the Diclofenac adsorption process, such as the pH and ionic strength of solutions containing Diclofenac, the amount of the bio-sorbent and pollutant, and the temperature values, were investigated. The kinetics and the adsorption isotherms, along with the thermodynamic parameters (ΔG°, ΔH°, and ΔS°) were also evaluated. The process occurred very efficiently, and Chitosan/Diclofenac amounts dependent, remove about the 90% of the pollutant, in 2 h, from the tested solutions, through electrostatic interaction involving the carboxylic moiety of Diclofenac and Chitosan amino groups. This finding was confirmed by the pH and salt effects on the bio-sorption process, including swelling measurements of Chitosan films and by FTIR-ATR analysis. In detail, the maximum adsorption was observed at pH 5, when pollutant and Chitosan were negatively and positively charged, respectively. By reducing or increasing the pH around this value, a reduced affinity was observed. Accordingly, the presence of salts retarded the Diclofenac removal screening its charges, which hinders the interaction with Chitosan. The sorption was spontaneous (ΔG° < 0) and endothermic (ΔH° > 0) following the pseudo-second order kinetic model. The process was Diclofenac and Chitosan amount dependent. In addition, the Freundlich and Temkin isotherms well described the process, which showed the heterogeneous character of the process. Experiments of the complete desorption were also performed by using NaCl solutions 0.25 M (like sea water salt concentration) proposing the reuse of the pollutant and the recycling of the bio-sorbent lowering the associated costs. The versatility of the adsorbent was reported by exploring the possibility to induce the Diclofenac light-induced degradation after the adsorption and by-products adsorption onto chitosan films. To emphasize the chitosan capacity of treating water, the removal of another pollutant such as Ketoprofen and the mixture of Diclofenac and Ketoprofen were investigated. In this way, a green and eco-friendly production-pollution prevention technology for removing emerging pollutants from water was presented, which reduced the overall environmental impact. This illustrated experiments both in static and dynamic conditions for potential industrial applications.

Flexural and Impact Properties of Stainless Steel based Glass Fibre Reinforced Fibre Metal Laminate under Hygrothermal Conditioning

Fibre metal laminates (FMLs) have appeared as the most suitable materials for shipbuilding, aeronautical and aerospace applications due to their superior mechanical properties over traditional materials. In this paper, degradation in flexural and impact properties of glass fibre/epoxy composite (GF/E composite) and stainless steel glass fibre/epoxy fibre metal laminate (SS FML) due to hygrothermal conditioning has been investigated for marine applications. Hand lay-up process was used for specimen preparation according to ASTM standards. Distilled water and seawater were used for hygrothermal conditioning at 40°C and 70°C for three months. The three point bend test was performed on universal testing machine using a three point bend fixture. The pendulum type impact testing machine was used to perform Izod impact test. Due to the preventive action of outer stainless steel layers against moisture ingestion, the reduction in mechanical properties of SS FML was less as compared to GF/E composite. SS FML and GF/E composite exhibited low moisture absorption rate in seawater at both temperatures as high salt content in seawater reduces the moisture diffusion process into the composite matrix.