Concentrated NaCl Solutions Research Articles

Screening of Salinity Tolerance and Genome-Wide Association Study in 249 Peanut Accessions (Arachis hypogaea L.)

Salinity stress is one of the important abiotic stresses in crops. In this study, ten different concentrations of NaCl solutions were tested to determine the optimal level of NaCl concentration for salinity tolerance test at the germination stage in peanut, and 0.6% NaC1 was suitable for the test. A total of 249 peanut accessions were tested with 0.6% NaC1 and radical root lengths of the accessions were measured. The results showed that there were significant genetic variations on the tolerance to salinity stress among the tested accessions. Through a Genome-Wide Association Study (GWAS) using the Axiom_Arachis array with 58K SNPs, three putative SNPs with significant relation to radicle root length were identified on chromosomes Aradu.A03, Araip.B01, and Araip.B05.

Comparison of different methods for assessing effects of soil interparticle forces on aggregate stability

Soil interparticle forces, involving in van der Waalsattractive force, and surface hydration and electrostatic repulsive forces, greatly influence the soil aggregate stability. However, current studies on methods for evaluating the impact of soil interparticle forces in aggregate stability are scarce. This research was aimed to examine the impact of soil interparticle forces on aggregate stability using diverse methods for different soil types. Soil aggregate stability was tested through the pipette method, wet sieving, and rainfall simulation, respectively characterized by aggregate stability index (ASI), mean weight diameter (MWD), and splash erosion mass (SE). Soil interparticle forces were adjusted by the changing concentrations of NaCl solution. The results showed that all three approaches can be applied to study the impact of soil interparticle forces on aggregate stability. The ASI, MWD, and SE showed little change below 10−2 mol L−1 NaCl concentration and then ASI and MWD increased at a high rate above 10−2 mol L−1 concentration of NaCl, while the SE showed the opposite trend. These results were as expected for soil interparticle forces. Moreover, for a single soil, a substantial correlation existed between the aggregate stability indicators obtained from three methods. However, the order of soil aggregate stability, measured by three methods were varied among soil types. Our results suggest that a single method cannot be applied to determine the aggregate stability of all soil types even if the breakdown mechanism was identical, because organic matter content and particle size distribution of soil are important factors influencing aggregate stability. Hence, in order to compare the difference in aggregate stability between various soils, multiple methods should be considered to investigate the impact of interparticle forces of soil on its aggregate stability. If a single method was to be chosen, wet sieving may be a good choice as it was not only relatively simple and time-saving but also reflected more comprehensive information about sizes and amount of fragments released from soil aggregates.

Chitosan film as recyclable adsorbent membrane to remove/recover hazardous pharmaceutical pollutants from water: the case of the emerging pollutant Furosemide

Due to the negative effects of emerging contaminants on the environment, that can potentially induce deleterious effects in aquatic and human life, this paper focuses on the removal from the water of Furosemide, through the adsorption process. Indeed, only a few papers are available in the literature about the Furosemide adsorption and, chitosan films are thus proposed for this purpose as safe, sustainable, and recyclable adsorbent materials. In the present work, the effects on the adsorption process of several experimental parameters such as the pH values, ionic strength, amount of adsorbent/pollutant, and temperature values were investigated. The kinetics models, isotherms of adsorption, and the thermodynamic parameters were studied showing that the Furosemide physisorption occurred on the heterogeneous Chitosan surface, endothermically (ΔH° = +31.27 ± 3.40 kJ mol−1) and spontaneously (ΔS° = +150.00 ± 10.00 J mol−1 K−1), following a pseudo-second-order kinetic model. The 90% of the pollutant was adsorbed in 2 h, with a maximum adsorption capacity of 3.5 mg × g−1. Despite these relatively low adsorption capacities, experiments of desorption were performed and 100% of adsorbed Furosemide was recovered by using concentrated NaCl solutions, proposing a low-cost and green approach, with respect to the previous literature relative to the Furosemide adsorption, fundamental for the pollutant recovery and adsorbent reuse.

(Invited) Corrosion Process of Metals below the Freezing Point

Atmospheric corrosion has been intensively investigated using an acceleration test using a temperature/humidity cycling in a laboratory to investigate the corrosion mechanism and the outdoor exposure test to evaluate the actual corrosion progress in a real environment. Corrosion of metals in a cold district is recently paid attention because a considerable amount of anti-freezing agents are sparged to the driveway in the winter season and cause severer corrosion of vehicles and structures. Repetition of freezing/melting of water also induces physical stress to the material and influences, for example, the mass-transportation process related to the corrosion reaction. In this study, therefore, the corrosion behavior of metals in the freezing condition was investigated both the outdoor exposure test and the laboratory test. In the laboratory test, low-temperature cycling was applied to the galvanic couples of Zn-steel plate cold commercial (SPCC) pair. A pair was set in a sample holder with a gap distance of ca. 0.1 mm between two metal plates and placed in a small box to avoid the direct blowing in a temperature-controlled chamber. Basic temperature cycling was composed of 4-stages as (i) low temperature (T L = –20°C, 1 h), (ii) transition from T Lto T H (1 h) (iii) high temperature (e.g., T H = 0, 1 h), and (iv) transition from T H to T L (1 h),. Relative humidity (RH) in a chamber was not actively controlled. The T and RH presented in this paper were measured by using a T & RH sensor close to the sample. At T L, 0.1% NaCl solution of ca. 1 cm3 was dropped at the gap that was immediately frozen. Fig. 1(a) shows the typical galvanic current i g in a single T-cycle observed at the gap covered with ice. In this condition, the ice was not almost melted at T H. The i g increased with T but not dependent on RH because the current flowed mainly under or around the ice. The considerably large i g observed under the ice proposed that the ionic conductivity was maintained even at the freezing temperature as –20 °C. Probably a thin liquid layer of concentrated NaCl solution was formed at the interface between the metals and ice due to the exclusion of salt from the solid ice phase during the freezing process. The presence of the liquid phase was also investigated by the different experiments of the impedance measurement between two Pt electrodes in the freezing condition. After many T-cycles, T H was raised to 2 °C to accelerate the melting of ice and, thus, the evaporation of melted water. After the many cycling, the surface was almost dried and covered with a mixture of corrosion products and salt. Fig. 1(b) shows the i g in this condition. The i g flowed at T L where the RH was rather high at stage i, increased with increasing T at stage iv, and dropped with lowering RH at T H in stage iii. This behavior was similar to that observed in the ordinal wet, and dry test conducted higher than the melting point. From these results, the atmospheric corrosion process in the cold district includes the ordinal atmospheric corrosion on the dry area and wet-corrosion in the quasi-solution under the ice. Figure 1

Experimental Study on Corrosion of J55 Casing Steel and N80 Tubing Steel in High Pressure and High Temperature Solution Containing CO2 and NaCl

The downhole casing and tubing in thermal recovery wells are the main channels for fluid flow. The corrosion for casing and tubing in high pressure (5 MPa) and high temperature (200 °C) (HPHT) fluid can cause string failure due to wall thinning, deformation, and fracture. In order to study the corrosion characteristics of J55 casing steel and N80 tubing steel in HPHT environment containing CO2 and NaCl, corrosion and corrosion inhibition experiments were carried out using a rotating autoclave at a pressure of 5 MPa and 50–200 °C environment. Morphologies and compositions of corrosion products were analyzed by SEM and XRD. HPHT corrosion process was discussed by Arrhenius equation and the transition state equation. Results showed that the corrosion rates of the two materials increased with CO2 partial pressure while increased initially and then decreased with increasing temperature. In CO2–NaCl solution, the saturate NaCl decreased the CO2 corrosion rates at low temperature (inhibition) and increased CO2 corrosion rates at high temperature. Meanwhile, SEM results showed that the surfaces of CO2 corrosion became more dense and uniform at high temperature. The increase of NaCl leaded to pitting and high concentration NaCl solution causes granular products to appear on the CO2 corrosion surface. The carbon steel corrosion rate is mainly controlled by kinetic parameters of activation; the activation parameters were increased by the increase in temperature and NaCl concentration. Oil-soluble imidazoline acts as a good inhibitor for corrosion of J55 and N80 in this work.

Physiological, morphological and anatomical responses of Hibiscus moscheutos to non-uniform salinity stress

Plant growth in the heterogeneous salinity soil is better than that of in the uniform salinity soil, thus, planting salt tolerant plants in the partial zone desalinated soil of the saline land may reduce the revegetation costs. The swamp rose mallow (Hibiscus moscheutos, SRM), which is an important landscape plant that grows in coastal saline lands, may be an optional plant that can adapt to the non-uniform salinity soil. In this study, SRM seedlings grown in split-root pots irrigated with different concentration of NaCl solutions were studied. There were four treatments, a control (0 mM NaCl), uniform salinity (200 mM NaCl), and two non-uniform salinities (0/200 mM and 0/400 mM NaCl). We determined the growth, gas exchange properties of the leaves, morphological parameters of the leaves and roots, water potential and consumption, and ion accumulation of the seedlings. The aim was to reveal the physiological and anatomical responses of SRM to non-uniform salinity. Under non-uniform salinity, the total biomass, shoot height, and leaf area of SRM seedlings were significantly higher and the leaf Na+ and Cl− contents were significantly lower than under uniform salinity. The total biomass was negatively corelated with the mean root zone salinity. Once the parts of the roots were in the salt-free zone, the leaf water potential and the daily water consumption of the seedlings under non-uniform salinity were much higher than the uniform salinity treatment. The leaf gas exchange of SRM under non-uniform salinity was not significantly inhibited compared to the control, but was significantly higher than under uniform salinity. The leaf electron transport rate (ETR) and maximum quantum yield (Fv/Fm) of the PSII, leaf SOD activity, and the MDA content of the seedlings subjected to non-uniform salinity treatments were at unstressed level. In terms of leaf anatomical traits, that the palisade and spongy parenchyma was significantly thicker than the uniform salinity. Early senescence of the leaves was observed under both uniform and non-uniform salinity conditions. More roots, especially fine roots, were distributed in the non-saline zone. These results indicate that under non-uniform salinity, SRM seedling growth was significantly inhibited, however, the salt stress was alleviated by the partial salt-free root zone compared to uniform the salinity. Non-uniform salinity led to moderate Na+ accumulation in the leaves, which in turn caused slight oxidative and osmotic stress, but had little influence on the morphological or anatomical traits of the leaves. SRM could adapt to the saline soil where partial zone desalinated or partial zone replaced by the non-saline soil.

Highly efficient extraction separation of La3+ and Ce3+ with N, N, N′, N′-tetraisobutyl-3-oxadiglycolamide from mixed REEs

The extraction and selective separation of Ln3+ with N, N, N′, N′-tetraisobutyl-3-oxadiglycolamide (TiBDGA) from the aqueous HCl solution was studied. The extraction temperature, diluent, salting-out agent, hydrochloric acid concentration, and extractant concentration were investigated to evaluate the effect on the extraction distribution ratio. The extraction mechanism was established based on the FT-IR spectra, XPS analysis, and crystal structure, which ascertains that the stoichiometry of the complex is La(TiBDGA)2Cl3·4H2O. The complex crystallizes in the orthorhombic space group Pbca and La3+ ions coordinate with ten oxygen donor atoms. The extraction results showed that TiBDGA has good selectivity of La3+ and Ce3+ from the other Ln3+. The presence of both NaCl and HCl showed a significant enhancement of extraction and separation. When the concentrations of both HCl and NaCl solution were 2.0 M, the separation factors of La3+ and Ce3+ from adjacent Pr3+ were as high as 133.7 and 136.5, respectively.

Phase boundary of CH4, CO2, and binary CH4-CO2 hydrates formed in NaCl solutions

The equilibrium phase boundary of gas hydrates divides the phase diagram of the gas–water system into two zones, i.e., one with hydrates and the other without hydrates. Motivations to investigate the phase boundary of gas hydrates formed by CH4, CO2, and their mixture in saline water stem from its foundation roles in e.g., flow assurance, energy recovery, and CO2 sequestration. In this work, a thermodynamic model has been developed to improve the prediction accuracy of the equilibrium phase boundary of CH4, CO2, and binary CH4-CO2 hydrates in both pure and saline water. A different set of reference properties are employed in this newly developed model. A database collecting the most up to date measured phase boundary of gas hydrates have been newly generated, containing 728 data points with the temperature ranging from 261.8 K to 300 K, and the concentration of NaCl solutions up to 24.12 wt%, which is used for parameter regression and model validation. The impacts of temperature, NaCl, and gas composition on the phase boundary of gas hydrates are well captured by the developed model. A convergence trend of the phase boundary curves of the binary CH4-CO2 hydrates in the high-temperature range is observed and explained with the Clausius-Clapeyron equation. The overall average absolute relative deviation (AARD) of the calculated phase boundary pressure of the 728 points is 4.42%. The performance of the newly developed model is satisfactory considering the discrepancies among measured data from various sources.

Label-free biosensor array comprised of Vernier microring resonator and 3 × 3 optical coupler

A 3 × 3 linearly distributed optical coupler was used in a Vernier -based SOI microring resonator in order to design a label-free biosensor takes advantage of low loss and fully isolated reference unit from the measurand. The coupled mode theory was used to drive the optical transfer function of the system. The electric field propagation through the sensor’s waveguides and the normalized light transmission versus the wavelength spectrum were studied using variational finite-difference time domain (varFDTD) method. The sensor performance was characterized based on the refractive index variation of the optical waveguide superstrate by applying different concentrations of glucose and NaCl solutions. Then, three types of cancer cells, including MCF7, MDA-MB-231 and Hella cell line, were detected based on the antibody–antigen reaction. The sensitivity and the detection limit of the proposed sensor were measured to be 578 nm/RIU and 2.8 × 10−5 RIU, respectively. Results show the capability of the proposed sensor as a high-performance device for label-free sensing. The proposed sensor can potentially be used for measuring the sucrose concentration in food industries and accurate determination of seawater salinity.

Mineral Recovery Enhanced Desalination (MRED) process: An innovative technology for desalinating hard brackish water

Desalination of water containing high concentrations of calcium, dissolved carbon dioxide, sulfate, silica and other sparingly soluble salts is difficult because of the scaling potential. An innovative pre-treatment scheme was investigated at bench scale that selectively removes these constituents and produces a soft water to enable desalination with high feed water recovery. The process first removes dissolved carbon dioxide by air stripping at low pH. Magnesium is removed by precipitation at high pH. Calcium is removed by ion exchange (IX), and sulfate is removed by nanofiltration (NF). Cation regenerant from IX, containing calcium, and concentrate from NF, containing sulfate, is combined to precipitate gypsum. Concentrate from the desalination process consisting of a concentrated NaCl solution is used to regenerate the IX resins. The selective precipitation, IX, and NF processes were tested in laboratory experiments and produced magnesium hydroxide and gypsum at greater than 90% and 95% purity respectively. A process model was developed to calculate process performance, mass and liquid flow rates. The MRED process offers the following benefits: 1) greater recovery of brackish feedwater by a desalination process, 2) recovery of marketable commodities and 3) reduction in the volume and mass of waste products from the treatment process.

Rapid determination of propylthiouracil and methimazole by surface-enhanced Raman scattering based on sodium alginate-protected silver nanoparticles.

A rapid, ultrasensitive and selective method has been established to determine antithyroid drugs [propylthiouracil (PTU) and methimazole (MTZ)] by surface-enhanced Raman scattering (SERS). Silver nanoparticles (AgNPs) were synthesized by reduction of silver nitrate (AgNO3) with sodium alginate (SA) and were used as SERS substrates. Through optimization of the SERS conditions, including the volume of SA-protected AgNPs solution, pH of Britton-Robinson (BR) buffer solution and concentration of NaCl solution, linear responses were obtained for PTU and MTZ in the concentration ranges of 3.02 × 10-9-1.06 × 10-5molL-1 and 1.21 × 10-9-1.21 × 10-5molL-1, respectively. By the present method, the limits of detection (LODs) for the determination of PTU and MTZ were as low as 1.58 × 10-10molL-1 and 2.97 × 10-11molL-1. The method was successfully applied for the determination of PTU and MTZ in real samples. The recovery of PTU and MTZ from actual samples ranged between 97.20 and 104.80%, with relative standard deviations (RSDs) less than 3.63%.

Dimensionally Stable and Mechanically Adaptive Polyelectrolyte Hydrogel.

Mechanically adaptive hydrogels with reversible cross-links can change their mechanical characteristics to adapt to the external environment. However, inevitable swelling/shrinkage occurs with the mechanical property change, which impedes the applications of these hydrogels. In this study, mechanical adaptivity with high dimensional stability is achieved in alginate-based polyelectrolyte hydrogels by introducing an opposite swelling mechanism. The dually crosslinked alginate-polystyrene sulfonate (Alg-PSS) hydrogels are constructed through the copolymerization of alginate-methacrylate (Alg-MA) and sodium p-styrene sulfonate (NaSS), as well as Ca2+ crosslinking. In the Alg-PSS hydrogel network, the reversible Ca2+ -carboxylate and Ca2+ -sulfonate cross-links can be disrupted by Na+ and soften the hydrogels. Moreover, the PSS chains crosslinked in the hydrogel network undergo the coil-globule transition in concentrated NaCl solutions to suppress hydrogel swelling during softening. The optimized Alg-PSS hydrogel (Alg5 -PSS0.75 -MBAA2.5 ) shows a dramatic tensile modulus change from 191.3kPa in deionized water (DIW) to 15.1kPa in 2.0mol L-1 NaCl solution with a negligible volume increase ratio of only 0.6%. The Alg-PSS hydrogels may find applications in artificial valves or soft robotics, where high dimensional stability and invariable volume are required for smart hydrogels.

Effect of Ionic Strength on the Aggregation Propensity of Aβ1-42 Peptide: An In-silico Study

Background: Aggregation of misfolded proteins under stress conditions in the cell might lead to several neurodegenerative disorders. Amyloid-beta (Aβ1-42) peptide, the causative agent of Alzheimer’s disease, has the propensity to fold into β-sheets under stress, forming aggregated amyloid plaques. This is influenced by factors such as pH, temperature, metal ions, mutation of residues, and ionic strength of the solution. There are several studies that have highlighted the importance of ionic strength in affecting the folding and aggregation propensity of Aβ1-42 peptide. Objective: To understand the effect of ionic strength of the solution on the aggregation propensity of Aβ1-42 peptide, using computational approaches. Materials and Methods: In this study, Molecular Dynamics (MD) simulations were performed on Aβ1-42 peptide monomer placed in (i) 0 M, (ii) 0.15 M, and (iii) 0.30 M concentration of NaCl solution. To prepare the input files for the MD simulations, we have used the Amberff99SB force field. The conformational dynamics of Aβ1-42 peptide monomer in different ionic strengths of the solutions were illustrated from the analysis of the corresponding MD trajectory using the CPPtraj tool. Results: From the MD trajectory analysis, we observe that with an increase in the ionic strength of the solution, Aβ1-42 peptide monomer shows a lesser tendency to undergo aggregation. From RMSD and SASA analysis, we noticed that Aβ1-42 peptide monomer undergoes a rapid change in conformation with an increase in the ionic strength of the solution. In addition, from the radius of gyration (Rg) analysis, we observed Aβ1-42 peptide monomer to be more compact at moderate ionic strength of the solution. Aβ1-42 peptide was also found to hold its helical secondary structure at moderate and higher ionic strengths of the solution. The diffusion coefficient of Aβ1-42 peptide monomer was also found to vary with the ionic strength of the solution. We observed a relatively higher diffusion coefficient value for Aβ1-42 peptide at moderate ionic strength of the solution. Conclusion: Our findings from this computational study highlight the marked effect of ionic strength of the solution on the conformational dynamics and aggregation propensity of Aβ1-42 peptide monomer.

Computer Simulation of Electrochemical Studies of Al6061-Al2O3 Metal Matrix Composite: Effect of Heat Treatment

The aim of this work is to investigate the corrosion Studies of Aluminum Oxide (Al2O3) reinforced Aluminum 6061 metal matrix composites in Different Concentrations of HCl & NaCl solutions using weight loss method, Potentio-dynamic & EIS Technique. The composites have been prepared by Die- casting method. Aluminum 6061 / Al2O3 MMCs containing different sizes such as 40, 60, and 100 microns and 0, 4, and 8 weight percentages of Al2O3 particulates are casted. The corrosion characteristics of Aluminum 6061 / Al2O3 composite and the unreinforced alloy were experimentally assessed. The results indicated that corrosion rate of metal matrix composites is lower than that of matrix material Al 6061 under the corrosive atmosphere irrespective of exposure time and concentration of corrodent. Aluminum 6061 / Al2O3 composite become more corrosion resistant as the Al2O3 content is increased. This is because of the formation of stable oxide layer over the specimens. Scanning Electron Microscopy (SEM) shows the degree of attack of HCl & NaCl solution on the surface of the investigated material.

A comparison study on the natural and half-soaking galvanic accelerated corrosion of reinforced concrete based on an improved electrochemical model

In order to investigate the half-soaking galvanic accelerated corrosion and natural corrosion comparatively, an improved electrochemical model was established. Taking the diffusion of ions, potential distribution and polarization into consideration, the difference between two corrosion methods were essentially revealed. By changing the boundary conditions of the model, Finite Element Method (FEM) was applied to simulate corrosion potential distribution, ions concentration and current density both on the steel–concrete interface and within concrete. In natural corrosion, macrocell corrosion was coupled with microcell corrosion, and the anodic and cathodic current densities were self-balanced. To model the real corrosion under natural environment, the cathodic to anodic area ratio (Ac/Aa) of macrocell was assumed to be changing with the development of corrosion. In galvanic accelerated corrosion, the influence of external ions concentration on current density was considered, which eventually affected the distribution of rust layer of steel rebar. The simulation results agree well with the test data collected from literatures. A further discussion indicates that impressed current density significantly affects the time ratio of natural corrosion to galvanic accelerated corrosion, while the NaCl solution concentration shows no clear influence on time ratio. The bearing capacities of the corroded steel rebar under half-soaking method (HSM) and natural corrosion will show no clear difference, but the HSM method is not very appropriate for studying the corrosion cracking process of reinforced concrete.

Impact of ionic-electromagnetic field interaction on Maxwell-Wagner polarization in porous medium

The brine composition of porous media and its effect on the polarization properties of the sandstone reservoir is important for understanding the mechanism of oil detachment from the grain surfaces and its movement through the reservoir channel. The mechanisms by which aqueous ions interact with the reservoir minerals via interfacial, ionic, dipolar and electronic polarization has been the subject of many researches. Moreover, the differential effects of cations and anions (polarization mechanisms) on fluid mobility under the influence of EM field are not been fully elucidated. Also, the complexity of reservoir response with the presence of oil and saline water to electromagnetic wave is not well understood. This study employs the wide frequency window polarization model to determine the influence of the concentration of adsorbed ions on reservoir rock properties. Berea sandstone was saturated with crude oil and different concentrations of NaCl solutions (3000, 5000, 7000, 9000 and 11,000 ppm). The result reveals that at 11000 ppm, we have a strong wavelength shift with 6.8 nm at 11.2 GHz for Ionic and 6.1 nm at 11.8 GHz for electronic polarization. It was deduced that Impedance is frequency dependent, which indicates a positive effect of electromagnetic field interaction on oil mobility. The increased in concentration of the electrolyte (NaCl), the polarization in the diffuse layer is stronger than that of stern layers due to better ionic distribution, as well as the van der Waals and intramolecular forces of attraction contribute to more adsorption energy in the porous media. The additional negative ions enable better dispersion due to relaxation, resulting from dielectric polarization and electrophoretic mobility with frequency.

High pyrolysis temperature biochar reduced the transport of petroleum degradation bacteria Corynebacterium variabile HRJ4 in porous media

Biochar has been widely applied for the remediation of petroleum-contaminated soil. However, the effect of biochar on the transport of petroleum degradation bacteria has not been studied. A typical Gram-positive petroleum degradation bacteria-Corynebacterium variabile HRJ4 was used to study the effect of different biochars on bacterial transport and retention. Results indicated that the addition of biochar in sand was effective for reducing the transport of bacteria and poplar sawdust biochar (PSBC) had a stronger hinder effect than corn straw biochar (CSBC). The hindrance was more evident with pyrolysis temperature of biochar raised from 300°C to 600°C, which was attributed to the increase of specific surface area (309 times). The hindrance effect also enhanced with higher application rate of biochar. Furthermore, the reduction of HRJ4 transport was more obvious in higher (25 mmol/L) concentration of NaCl solution owing to electrostatic attraction enhancement. The adsorption of biochar to HRJ4 was defined to contribute to the hindrance of HRJ4 transport mainly. Combining the influence of feedstocks and pyrolysis temperature on HRJ4 transport, it suggested that specific surface area had the greatest effect on HRJ4 transport, and pore-filling, electrostatic force also contributed to HRJ4 retained in quartz sand column. At last, phenol transportation experiment indicated that the restriction of biochar on HRJ4 enhanced the phenol removal rate in the column. This study provides a theoretical basis for the interaction of biochar and bacteria, which is vital for the remediation of oil-contaminated soil and groundwater in the field.

Multistage osmotically assisted reverse osmosis process for concentrating solutions using hollow fiber membrane modules

Reverse osmosis (RO) is commonly used to concentrate solutions in food preparation and environmental applications among others. Limitations on the applied pressure, which must be higher than the osmotic pressure of the feed solution, determine the concentration that can be achieved by RO. Recently, an osmotically assisted reverse osmosis (OARO) system that can be operated even with low applied pressure has been suggested as a new concentration process. In this study, we performed concentration tests on a multistage OARO system that used two types of hollow fiber (HF) membrane modules made from cellulose triacetate with different numbers of HFs. Water permeated through the membrane and the concentration increased as it progressed through the modules, even when using concentrated NaCl solutions (1.0 and 2.0 M) with low applied pressures (10 and 15 bar). The concentration increased in each of ten stages in a multistage concentration test. Water flux and concentration ratio were strongly influenced by the internal concentration polarization in the modules.

Effects of bias voltage on coating structures and anticorrosion performances of PA-PVD Al coated NdFeB magnets

Al coated NdFeB magnets were prepared by plasma-assisted-physical-vapor-deposition (PA-PVD) method for enhancing the corrosion resistance. Morphologies and structures were characterized by an X-ray diffractometer and a scanning electron microscope. Corrosion behaviors of the samples with different bias voltages were studied by electrochemical methods and neutral salt spray test, respectively. The bias voltage during the deposition process was optimized according to the coating structures and corrosion resistances. The density and flatness of Al coating increase with increasing the bias voltage, and at the same time the thickness decreases. The coating density and thickness turn to be stable when bias voltage is 1800 V. Also, the corrosion behaviors of PA-PVD Al coatings in different media, such as NaOH, HNO3 and NaCl solutions, were studied. The self-corrosion potentials (Ecorr) of PA-PVD Al coatings almost keep constant in NaOH and HNO3 solutions with different concentrations. However, the self-corrosion current densities (Jcorr) decrease with the increasing concentrations. Ecorr shifts to negative potential and Jcorr decreases gradually when increasing the concentration of NaCl solution. The corrosion mechanisms of Al coatings are discussed based on the corrosion behaviors in different media.

Effects of cryoprotectants on Nostoc sphaeroides superchilled at low temperature (−3.0°C) and their action mechanisms

AbstractEffects of cryoprotectants (NaCl, sucrose and trehalose) on Nostoc sphaeroides (N. sphaeroides) superchilled at −3.0°C as well as their action mechanisms were studied. Prior to storage, N. sphaeroides were immersed into different concentrations (5% and 10%) of NaCl solutions, sucrose solutions, and trehalose solutions for 2 hr. The texture properties, drip loss and low field nuclear magnetic resonance (NMR)‐imaging of N. sphaeroides with different treatments were evaluated. The freezing point, solute absorption, water distribution and microscopic structure were also measured to illustrate the action mechanisms of cryoprotectants. Results suggested that cryoprotectants offered an effective method for keeping the texture properties, lowering drip loss, and maintaining the shape of N. sphaeroides. Among all the cryoprotectants used, 5% NaCl exhibited the best effect. The study of their action mechanisms showed that cryoprotectants were efficient in reducing the freezing point, the proportion of free water and microscopic structure destruction of N. sphaeroides.Practical ApplicationsConsidering the higher water content of N. sphaeroides, it is not suitable to be deeply frozen because the formation of numerous ice crystals can cause severe damages to the tissue. To suppress these undesirable changes in superchilling, cryoprotectants including NaCl, sucrose and trehalose are added to the food products. This research contributes to lay a theoretical foundation for the further study of superchilling storage of N. sphaeroides.