Increase In Ion Concentration Research Articles

Lepidium perfoliatum seed gum: investigation of monosaccharide composition, antioxidant activity and rheological behavior in presence of salts

BackgroundIn the present study, the effects of NaCl and CaCl2 (0–200 mM) on the rheological properties of Lepidium perfoliatum seed gum (LPSG) as a novel potential source of hydrocolloid were investigated. Sugar composition and FTIR analysis were measured to supply more structural information.ResultsThe results illustrated that LPSG had small amounts of uronic acids (6.65%) and it is likely an arabinoxylan-type polysaccharide (it has 44.66% and 31.99% xylose and arabinose, respectively). The FTIR spectra also revealed that LPSG behaved like a typical polyelectrolyte due to the presence of carboxyl and hydroxyl groups. It was observed that the gum solutions exhibited viscoelastic properties in the presence of NaCl and CaCl2 salts. The tan δ values for all samples were less than 1 but greater than 0.1, exposing the weak gel-like behavior at different ion types and ionic strengths. With increasing salts concentrations, the limiting values of strain mostly increased due to the interchain interactions (from 1.46 to 4.61 and from 0.99 to 2.13 for NaCl and CaCl2, respectively). Therefore, the addition of salts increased the stiffness of mucilage solutions in the concentrated regime. The results of frequency sweep tests revealed that storage and loss moduli were increased with increasing ion concentration. This effect was more pronounced for LPSG solutions containing Ca2+. Among various models, the model of Higiro1 showed a higher efficiency to evaluate the intrinsic viscosity of LPSG for all co-solutes (R2 ≥ 0.98). With increasing the concentration of salts, the intrinsic viscosity of LPSG decreased. Calcium ions had a more diminution effect on intrinsic viscosity than sodium ions.ConclusionsTrying to adjust the salt concentration could modify the rheological properties of food products. Because food contains a variety of additives, further research should look into the rheological properties of LPSG at different pHs, as well as the presence of other salts and sugars often employed in the food industry. LPSG has the potential to be used in biomedical, pharmaceutical, food industries, tissue engineering, and cosmetic applications due to its biocompatibility, rheological properties, and antioxidant activities.Graphical

Effects of heavy metal ions Cu2+/Pb2+/Zn2+ on kinetic rate constants of struvite crystallization

Struvite (MAP) crystallization technology is widely used to treat ammonia nitrogen in waste effluents of its simple operation and good removal efficiency. However, the presence of heavy metal ions in the waste effluents causes problems such as slow crystallization rate and small crystal size, limiting the recovery rate and economic value of the MAP. The present study was conducted to investigate the effects of concentrations of three heavy metal ions (Cu2+, Zn2+, and Pb2+) on the crystal morphology, crystal size, average growth rate, and crystallization kinetics of MAP. A relationship was established between the kinetic rate constant Kt calculated by the chemical gradient model and the concentrations of heavy metal ions. The results showed that low concentrations of heavy metal ions in the solution created pits on the MAP surface, and high level of heavy metal ions generated flocs on the MAP surface, which were composed of metal hydroxides, thus inhibiting crystal growth. The crystal size, average growth rate, MAP crystallization rate, and kinetic rate constant Kt decreased with the increase in heavy metal ion concentration. Moreover, the Kt demonstrated a linear relationship with the heavy metal concentration ln(C/C*), which provided a reference for the optimization of the MAP crystallization process in the presence of heavy metal ions.

Influence of impurities on adsorption of hydrated Y3+ ions on the kaolinite (001) surface

The adsorption behavior of hydrated Y3+ ions on the outer and inner layers of the kaolinite (001) aluminum hydroxyl surface is studied by density functional theory. The bonding mechanism and the effect of common impurities (Mg, Ca and Fe) on the inner layer adsorption behavior are investigated. The results shows that the hydrated Y3+ ions retain the original number of coordinated water molecules and adsorb on the outer layer of the surface of kaolinite through hydrogen bonding, with an adsorption energy of − 262.66 kJ·mol−1. When the inner layer is adsorbed, the number of coordinated water molecules of the hydrated Y3+ ions decreases obviously due to the steric hindrance effect and they are adsorbed on the Ou site of the surface mainly through Y-Os covalent bonds. The electrons are transferred from the 5 s and 4p orbitals of the Y ions to the 2p orbital of the Os ions on the surface. The adsorption energy (−744.52 kJ·mol−1) is much lower than that for the outer layer. These results indicate that the inner layer adsorption of hydrated Y3+ ions occurs preferentially on the kaolinite (001) aluminum hydroxyl surface. The internal adsorption configurations and adsorption energies of hydrated Y3+ ions on the kaolinite surface are significantly affected by Mg, Ca and Fe doped at the Al sites, respectively. The adsorption of hydrated Y3+ ions on kaolinite surface becomes stronger with the increase of doping ion concentration with Mg, Ca and Fe doping, respectively, and the Ca and Mg impurities therefore significantly promote the adsorption of hydrated Y3+ ions. These results are helpful in revealing the microscopic adsorption mechanism of rare earth elements on ion-adsorbed rare earth minerals.

Comparative Study of the Adsorption Effects of Activated Carbons from Coconut Shell and Groundnut Shell as Absorbents for Metal Ions

The main objective of this research was to compare the effect of contact time, concentration, and temperature in preparing activated carbon from coconut shells and groundnut shells. The research was carried out at a temperature range of 35 -65 and the maximum adsorption capacities for Pb(II) and Cd(II) ions were respectively 3.61 and 3.34 mg/g for coconut shell, 3.21 and 3.13 mg/g for groundnut shell at the optimum temperature of 35 . Thus the maximum ion adsorption capacities followed the trend: coconut shell>groundnut shell. These results were obtained using the following optimum conditions: initial metal ions concentration of 100 mg/dm3, adsorbents weight of 0.5g, time of 30 min, and pH of 6. The adsorption of the metal ions by the adsorbents was found to decrease with an increase in the initial concentration of the metal ions in an aqueous solution. Also, the adsorption rate increased with temperature. The result of the work revealed that activated carbons derived from coconut shells and groundnut shells can be used as a low-cost alternative to commercial adsorbents in the removal of Pb(II) and Cd(II) ions from water and wastewater.

Gelation–based visual detection of fluoride ion: Strategic use of silyl protection–deprotection chemistry

• A gelation-based visual detection of fluoride ion is reported. • Fluoride ion converted a triphenylsilyl group-containing gelator (gel) into a nongelator (gel degradation). • Quantitative and semi-quantitative detection methods are reported. • Fluoride ion detection limit is considerably better than many existing gelation-based methods. We describe the design, synthesis, and visual fluoride ion detection by a new small-molecule gelator in this work. This gelator contains a triphenylsilyl group which is easily removed in the presence of fluoride ion. The strategic use of silyl group protection-deprotection chemistry enabled the detection of fluoride ion visually. We investigated two different routes for this purpose. In the first route, gels were responsive to fluoride ion and degraded in its presence. Gels degraded faster with an increase in fluoride ion concentration. Fluoride ion quantification was possible by correlating fluoride ion concentrations with gel-degradation times. In the second route, when gelation tests were performed in the presence of fluoride ion, gel formation was suppressed, and multiple visually distinguishable states were obtained. A semi-quantitative analysis for fluoride ion was achieved in this case. The performance and detection limit of this new gelator is superior to many existing gelation-based methods. Furthermore, the gels were fully characterized using SEM, TEM, FTIR, XRD, contact angle, fluorescence, and UV–vis spectroscopy techniques.

The influence of yttrium and manganese additions on the degradation and biocompatibility of magnesium-zinc-based alloys: In vitro and in vivo studies

The repair and regeneration of bone defects are highly challenging orthopedic problems. Recently, Mg-based implants have gained popularity due to their unique biodegradation and elastic modulus similar to that of human bone. The aim of our study is to develop a magnesium alloy with a controllable degradation that can closely match bone tissue to help injuries heal in vivo and avoid cytotoxicity caused by a sudden increase in ion concentration. In this study, we prepared and modified Mg-3 Zn, Mg-3Zn-1Y, and Mg-2Zn-1Mn by hot extrusion, and used Mg-2.5Y-2.5Nd was as a control. We then investigated the effect of additions of Y and Mn on alloys’ properties. Our results show that Mn and Y can improve not only compression strength but also corrosion resistance. The alloy Mg-2Zn-1Mn demonstrated good cytocompatibility in vitro, and for this reason we selected it for implantation in vivo. The degraded Mg-2Zn-1Mn implanted a bone defect area did not cause obvious rejection and inflammatory reaction, and the degradation products left no signs of damage to the heart, liver, kidney, or brain. Furthermore, we find that Mg-2Zn-1Mn can promote an osteoinductive response in vivo and the formation of bone regeneration.

Effect of monovalent salts on molecular interactions of globular protein (BSA) above its isoelectric point

Protein-protein interactions study is crucial for understanding functions of proteins in the living system. Here, the molecular interactions of bovine serum albumin (BSA) with the addition of different monovalent (Li+, Na+, and K+) and one divalent (Mg2+) cations were studied above the isoelectric point of the protein. Small-angle neutron scattering study reveals that though short-range attractive interactions remain unchanged, long-range repulsion strength decreases with increasing ion concentration. The presence of ions and variation of their concentration also affect the diffusion coefficient of protein. The protein-protein interactions are ion-specific and modified according to the charge density of the cations.

Tuning Ionic Screening To Accelerate Electrochemical CO2 Reduction in Ionic Liquid Electrolytes

Electric double layer formation often governs the rate and selectivity of CO2 electrochemical reduction. Ionic correlations critically define double layer properties that are essential to electrocatalytic performance, including capacitance and localization of potential gradients. However, the influence of ionic correlations on CO2 electroreduction remains unexplored. Here, we use electrochemical conversion of CO2 to CO in ionic liquid-based electrolytes to investigate how the emergence of ionic correlations with increasing ion concentration influences reaction rates and selectivity. Remarkably, we find substantial acceleration of potential-dependent CO2 reduction rates and enhancement of faradaic efficiency to CO at intermediate concentrations of 0.9 M ionic liquid in acetonitrile, a concentration regime that has not been studied previously. We find that onset potentials for CO2 reduction remain relatively unchanged at −2.01 V vs Ag/Ag+ from 0.025 M up to 1.1 M and increase to −2.04 V vs Ag/Ag+ in the limit of neat ionic liquids. Hence, the acceleration of CO2 reduction we observe originates from the amplification of potential-dependent driving forces, as opposed to changes in onset potential. Importantly, our findings are general across cocatalytic and noncatalytic ions. We propose that concentrations of maximum reactivity correspond to conditions where electric double layers exhibit the strongest screening, which would localize electric fields to stabilize polar intermediates. Our study demonstrates that tuning bulk electrostatic screening lengths via modulation of ionic clustering provides a general approach to accelerating both inner-sphere and outer-sphere electrochemical reactions.

Morphological Changes, Antibacterial Activity, and Cytotoxicity Characterization of Hydrothermally Synthesized Metal Ions-Incorporated Nanoapatites for Biomedical Application.

The objective of this study was to prepare hydroxyapatite (HA) with potential antibacterial activity against gram-negative and gram-positive bacteria by incorporating different atomic ratios of Cu2+ (0.1–1.0%), Mg2+ (1.0–7.0%), and Zn2+ (1.0–7.0%) to theoretically replace Ca2+ ions during the hydrothermal synthesis of grown precipitated HA nanorods. This study highlights the role of comparing different metal ions on synthetic nanoapatite in regulating the antibacterial properties and toxicity. The comparisons between infrared spectra and between diffractograms have confirmed that metal ions do not affect the formation of HA phases. The results show that after doped Cu2+, Mg2+, and Zn2+ ions replace Ca2+, the ionic radius is almost the same, but significantly smaller than that of the original Ca2+ ions, and the substitution effect causes the lattice distance to change, resulting in crystal structure distortion and reducing crystallinity. The reduction in the length of the nanopatites after the incorporation of Cu2+, Mg2+, and Zn2+ ions confirmed that the metal ions were mainly substituted during the growth of the rod-shape nanoapatite Ca2+ distributed along the longitudinal site. The antibacterial results show that nanoapatite containing Cu2+ (0.1%), Mg2+ (3%), and Zn2+ (5–7%) has obvious and higher antibacterial activity against gram-positive bacteria Staphylococcus aureus within 2 days. The antibacterial effect against the gram-negative bacillus Escherichia coli is not as pronounced as against Staphylococcus aureus. The antibacterial effect of Cu2+ substituted Ca2+ with an atomic ratio of 0.1~1.0% is even better than that of Mg2+- and Zn2+- doped with 1~7% groups. In terms of cytotoxicity, nanoapatites with Cu2+ (~0.2%) exhibit cytotoxicity, whereas Mg2+- (1–5%) and Zn2+- (~1%) doped nanoapatites are biocompatible at low concentrations but become cytotoxic as ionic concentration increases. The results show that the hydrothermally synthesized nanoapatite combined with Cu2+ (0.2%), Mg2+ (3%), and Zn2+ (3%) exhibits low toxicity and high antibacterial activity, which provides a good prospect for bypassing antibiotics for future biomedical applications.

Structural and wavelength dependent optical properties of La1-xEuxCoO3 perovskite phosphor

The Eu2+/Eu3+ doped LaCoO3 (La1-xEuxCoO3) perovskite phosphors have been prepared using auto-combustion technique. Rietveld structural analysis of X-ray diffraction patterns for all compositions shows rhombohedral crystal structure with R3‾c space group. The lattice parameters and unit cell volume increase while the crystallite size and particles size decrease with the increase of Eu ion concentration. The HRSEM images indicate spherically shaped particles elongated to each other. The EDS analysis confirms the presence of La, Eu, Co and O elements in the phosphor with good compositional homogeneity. The XPS spectra reveal the presence of (Co2+, Co3+) and (Eu2+, Eu3+) ions along with the oxygen vacancies in the phosphor. The optical band gap of LaCoO3 phosphor decreases with the increase of Eu ion concentration. The photoluminescence excitation spectra of La1-xEuxCoO3 phosphors contain the excitation peaks at 338, 355, 374, 394, 450 and 467 nm. The La1-xEuxCoO3 phosphors give multicolor emissions in the green, yellow and red regions upon 355, 374, 394, 450 and 467 nm excitations. The photoluminescence intensity of La1-xEuxCoO3 perovskite phosphors is optimized at 1 mol% concentration of Eu ion. Due to existence of Co2+ and Co3+ ions in the La1-xEuxCoO3 perovskite phosphors, the Eu3+ ion converts into Eu2+ ion, which gives the blue, green and red emissions. The CIE diagram verifies the color tunability in La1-xEuxCoO3 perovskite phosphors. Therefore, the La1-xEuxCoO3 perovskite phosphors may be very useful in display devices, white light emitting diodes (LEDs) and solid state lighting.

Characterization of the remediation of chromium ion contamination with bentonite by terahertz time-domain spectroscopy

Heavy metal pollution of agricultural and urban soils limits economic progress in the rapidly developing society. Terahertz technology is applied to detect heavy metal pollutants under existence of multiple pathways of their dissemination. In this study, terahertz time-domain spectroscopy (THz-TDS) is employed as an advanced probing technique in combination with traditional detecting methods to measure the adsorption ability of trivalent chromium ions on bentonite. The concentration of chromium ions and the weight of bentonite are known to influence on the adsorption capacity of the latter. It is tested here by both qualitative and quantitative measurements of two mentioned parameters. The adsorption process of chromium ions by bentonite is monitored using THz-TDS. The adsorptions signal from samples at 0.5 THz gradually increases with the increase of bentonite weight or chromium ion concentration. It would appear to indicate that terahertz could be used for quantitative detection of metal ions. Secondly, the ratios of results obtained by inductively coupled plasma mass spectrometry (ICP-MS) and the THz-TDS ones are stabilized at 0.105 ± 0.014 as the bentonite weight or chromium ion concentration increase. Such finding confirms that terahertz technology can be used for the quantitative detection of metal ions. Using the relationship between the ICP-MS test results and the THz-TDS ones, the amplitude value of bentonite is obtained to be 13.925 at the concentration of chromium ions of 0.05 mol/L, the mass of bentonite sample involved in adsorption of 1.5 g, and the detection frequency in THz-TDS measurements of 0.5 THz. The adsorption coefficient of bentonite is calculated to be 1.44%. Increase of the chromium ion concentration to 0.2 mol/L, and the mass of bentonite involved in adsorption to 3 g leads to the increase of the amplitude corresponding to adsorbed chromium ions to about 19.463, and the adsorption coefficient to about 2.1%. Obtained results demonstrate that terahertz technology is promising to meet the ever-increasing requirements in mineral analyses for rapid detection of chemical contaminants and measurement of the adsorption efficiencies of materials.

Effect of ethanolic leaf extract of Macaranga spinosa Muell-Arg on selected biomarkers of toxicity in Wistar rats

In Nigeria, plant-based herbal medicines are vital component of traditional medicine (TM) and their use for the maintenance of health and wellbeing has been a common practice. These TMs are freely used without mandatory safety or toxicological evaluation. Thus, it is necessary to identify plants with toxicity potentials among the plants used for therapeutic purposes in the country. This study investigated effect of ethanolic leaf extract of Macaranga spinosa Muell-Arg on selected biomarkers of toxicity in Wistar rats. Fifteen Wistar rats of both sexes weighing 96.8 -250 g were divided into three groups comprising of group 1 (control 0.5ml distilled water); group 2 (500 mg/kg b.w Macaranga spinosa Muell-Arg leaf extract) and group 3 (1000 mg/kg b.w Macaranga spinosa Muell-Arg leaf extract). At the end of one week oral administration, animals were sacrificed; blood and tissues samples were taken for biochemical and histopatological investigations respectively. Phytochemicals present were alkaloids, flavonoids, tannins, triterpeneoid/steroids, carbohydrates, cardenolide, and saponins. Urea, sodium ion, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) concentration were significantly elevated in group 3; non-significant increase in creatinine, potassium, bicarbonate, chloride ion and alkaline phosphatase (ALP) concentration in group 2 and 3 compared to group 1. Total protein and triglyceride were significantly decreased in group 3 compared to group 1. Albumin, total and conjugated bilirubin were non-significantly decreased in group 2 and 3 when compared to control group 1. Histological examination of kidney tissue showed no change in kidney histology; liver tissue indicated vacuolar and cytoplasm degeneration, and fatty change. Hart tissues showed normal cardiac myocytes. This study has established that ethanolic leaf extract of Macaranga spinosa Muell-Arg can cause hepatoxicity, mild nephrotoxicity and no significant alteration of lipid profile in Wistar rats. Therefore, users of this plant in TM should avoid excessive and prolong use, as it can be toxic to the liver.

Nanocrystalline samarium doped nickel-zinc-bismuth ferrites: Investigation of structural, electrical and dielectric properties

A composition of rare earth Samarium doped Ni-Zn-Bi nanoferrite Ni0.5Zn0.5Bi0.04SmxFe1.96-xO4 with a step size of 0.02 was successfully synthesized using a citrate precursor technique. XRD data confirmed that the prepared nano samples have a cubic structure with crystallite size in the range of 18–26nm. Porosity value for the prepared nanoferrites was obtained in the range of 45–48%. Hopping lengths for the A and B sites and dislocation density have been computed with an increase in samarium ion concentration. A tensile strain was noticed in the range from 4.30 × 10−3 to 6.14 × 10−3. SEM imaging confirmed the agglomeration of the prepared nanoferrites. The prepared nano samples obtained high resistivity values ranging from 8.20 × 109 to 2.76 × 1010 Ω.cm from the current-voltage plot for different dopants of Sm3+ ions. The real value of the complex dielectric constant increased from 17 to 8.89 at 1 MHz as Sm content increased. The imaginary part value of the complex dielectric constant increased from 0.101 to 1.38 and the value of the tan δε was found to increase from 0.069 to 0.133at 1 MHz for different contents of samarium ions. These conclusions drawn at 1 MHz frequency build these nanoferrites better for high-frequency applications.

Pickering Emulsion Stabilized by Tea Seed Cake Protein Nanoparticles as Lutein Carrier.

To effectively deliver lutein, hydrothermally prepared tea seed cake protein nanoparticles (TSCPN) were used to fabricate Pickering emulsion, and the bioaccessibility of lutein encapsulated by Pickering emulsion and the conventional emulsion was evaluated in vitro. The results indicated that the average size and absolute value of zeta potential of TSCPN increased along with the increase in the protein concentration, and 2% protein concentration was adopted to prepare TSCPN. With the increase in the concentration of TSCPN, the size of Pickering emulsion decreased from 337.02 μm to 89.36 μm, and when the TSCPN concentration was greater than 0.6%, all emulsions exhibited good stability during the 14 days storage. Combined with the microstructure result, 1.2% TSCPN was used to stabilize Pickering emulsion. With the increase in ionic concentration (0–400 mM), the particle size of the emulsions increased while the absolute value of zeta potential decreased. TSCPN-based Pickering emulsion was superior to the conventional emulsion for both lutein encapsulation (96.6 ± 1.0% vs. 82.1 ± 1.4%) and bioaccessibility (56.0 ± 1.1% vs. 35.2 ± 1.2%). Thus, TSCPN-based Pickering emulsion in this study have the potential as an effective carrier for lutein.

Effect of HumicAcid-Heavy Metals on the Nitrogen Removal Performance of ANAMMOX Bacteria and Its Kinetic Analysis

The effects of two typical heavy metal ions[Cu(Ⅱ) and Ni(Ⅱ)] and humic acid on ANAMMOX nitrogen removal (SAA) were studied through batch experiments, and the kinetic model was analyzed. At the same time, the effects of humic acid-heavy metal on ANAMMOX nitrogen removal were discussed. The results showed that ANAMMOX was promoted when ρ[Cu(Ⅱ)] and ρ[Ni(Ⅱ)] were 3 mg·L-1, and SAA was increased by 8.64% and 7.78%, respectively; ANAMMOX was inhibited when the ρ[Cu(Ⅱ)] and ρ[Ni(Ⅱ)] were 20 mg·L-1 and 5 mg·L-1, respectively, and the inhibition effect was more significant with the increase in heavy metal ion concentration. The index fitting showed that the IC50 of Cu(Ⅱ) and Ni(Ⅱ) on ANAMMOX were 29.67 mg·L-1 and 28.75 mg·L-1, respectively. SAA was increased by 7.37% when the ρ(humic acid) was 1 mg·L-1, and the inhibition rate reached 36.80% when the humic acid concentration was 40 mg·L-1. The linear fitting showed that the IC50 of humic acid on ANAMMOX was 58.36 mg·L-1. The modified Michaelis-Menten model could better describe the inhibitory kinetic behavior of heavy metals and humic acid on ANAMMOX. The model fitting showed that the complete inhibition concentrations (I*) of Cu(Ⅱ), Ni(Ⅱ), and humic acid on ANAMMOX were 49.59, 74.46, and 84.27 mg·L-1, respectively. An appropriate amount of humic acid was beneficial to improve the inhibition of heavy metals on ANAMMOX bacteria activity, and excessive humic acid would cause inhibition on ANAMMOX bacteria again.

Models and Programs of the Gain and Noise Figure of the Nd-doped Fiber Amplifier in 1.7-1.8μm Band

This paper gives an introduction and research results on the Nd-doped fiber amplifier. We have constructed calculation models and programs of the Gain and Noise Figure with changing pump power, signal power, number of doped ions per unit volume, and fiber length using MATLAB. When the pump power or ion concentration increases, or the signal power decreases, the Gain has an increasing trend as presented in the research results. The Gain reaches a maximum when the fiber length is 1.35m. The Noise Figure decreases with increasing signal power or decreasing ion concentration. It reaches a minimum with a high pump power and a fiber length of 1.4m.

Effect of impurity ions on the coupling between zonal flow and local turbulent transport in HL-2A plasmas

The effect of impurity ions on the coupling between geodesic acoustic mode (GAM) zonal flow and local turbulent transport has been studied using a Langmuir probe array in HL-2A ohmically heated deuterium plasmas. The experimental results illustrate that both the frequency and amplitude level of the GAM zonal flow significantly reduce with increase in the carbon ion concentration, which is qualitatively consistent with theoretical predictions (Xie et al 2018 Plasma Phys. Control. Fusion 60 025015). Meanwhile less energy is transferred from turbulence to GAM zonal flow due to the reduction in tilting and stretching of the turbulent vortex. Consequently, the impurity ions enhance the turbulence and turbulent transport owing to the reduced GAM zonal flow, as demonstrated by experiment. The experimental results presented here therefore reveal the dual roles played by impurity ions in the dynamics of GAM zonal flow, which could contribute to the understanding of inherent mechanisms governing turbulent transport in the presence of impurity ions.

Kinetic and equilibrium study of pyrolyzed sugarcane bagesse as adsorbents for Pb2+ and Cd2+ in an aqueous medium

ABSTRACT Sugarcane bagesse was utilised as a low-cost adsorbent for the removal of metal ions. The study was done at a temperature of 35°C, and the maximum adsorption capacities for Pb(II) and Cd(II) ions were 3.02 and 2.90 mg/g, respectively, for sugarcane bagasse. These results were determined using the following optimum conditions: initial metal ion concentration of 100 mg/dm3, adsorbent weight of 0.5 g, time of 30 min and pH of 6. The adsorption of the metal ions by the adsorbents decreased with an increase in the initial concentration of the metal ions in an aqueous solution. The rate of adsorption also increased with temperature. The adsorption showed a good fit to the Langmuir model compared to the Freundlich adsorption model. The Langmuir dimensionless constant (RL) for the adsorption of Pb(II) ion and Cd(II) ion ranged from 0.081 to 0.123 and 0.115 to 0.172, respectively, which confirms favourable adsorption. The adsorption process showed that the pseudo-second-order kinetics was a better fit than the pseudo-first-order kinetics. The result of this work showed a low-cost and efficient potential of sugarcane bagasse to be employed as a good adsorbent for metal ion removal.

Molecular characteristics of salty ions in phospholipid bilayer under electric field

The diffusion of salty ions has a great impact on the motor ability of muscle, and revealing the diffusion properties of ions with different concentrations in phospholipid bilayer under electric field is of great significance to the study of ion loss on the skin. In this paper, the diffusion properties of charged ions under electric field are studied by molecular dynamics (MD) simulations. Mean square displacement (MSD) was studied to reveal the displacement of ions in phospholipid bilayer. In addition, the relative concentration is also utilized to reveal the local concentration of ions in the direction of the electric field. The data shows that the negatively charged ions (Cl[Formula: see text], HCO3 HCO[Formula: see text], SO[Formula: see text] have much stronger diffusion capacity, compared to the positive charged ions (Na[Formula: see text], K[Formula: see text], Mg[Formula: see text] in the simulation systems. Furthermore, the diffusion property of ions becomes stronger with the increase of ion concentration.

Absence of anomalous underscreening in highly concentrated aqueous electrolytes confined between smooth silica surfaces

Recent surface forces apparatus experiments that measured the forces between two mica surfaces and a series of subsequent theoretical studies suggest the occurrence of universal underscreening in highly concentrated electrolyte solutions. We performed a set of systematic Atomic Force Spectroscopy measurements for aqueous salt solutions in a concentration range from 1 mM to 5 M using chloride salts of various alkali metals as well as mixed concentrated salt solutions (involving both mono- and divalent cations and anions), that mimic concentrated brines typically encountered in geological formations. Experiments were carried out using flat substrates and submicrometer-sized colloidal probes made of smooth oxidized silicon immersed in salt solutions at pH values of 6 and 9 and temperatures of 25 °C and 45 °C. While strong repulsive forces were observed for the smallest tip-sample separations, none of the conditions explored displayed any indication of anomalous long range electrostatic forces as reported for mica surfaces. Instead, forces are universally dominated by attractive van der Waals interactions at tip-sample separations of ≈2 nm and beyond for salt concentrations of 1 M and higher. Complementary calculations based on classical density functional theory for the primitive model support these experimental observations and display a consistent decrease in screening length with increasing ion concentration.