Ion Concentration In Solution Research Articles

Ion exchange isotherms in solid: electrolyte solution systems

It is shown show that the ion exchange isotherms and the law of mass action are equivalent, the c/a versus c functions can be derived from the law of mass action (c and a: the concentration of ions in ion exchanger and solution, respectively). The equations are applied for cation exchange processes of bentonite clay (cobalt, manganese, mercury ions with calcium-bentonite; strontium ions with sodium-bentonite; cesium ions with lanthanide bentonite; lutetium ion with calcium-bentonite). The linear or non-linear shape of the isotherms does not prove the heterogeneity of the ion exchanger or the interaction among the sorbed cations.

Features of the content of carbonates in the ordinary chernozem improved by forest under plantings of false acacia (Robinia pseudoacacia L.)

Carbonate neoplasms are the characteristic feature of the black soil profile. The study of morphological and micromorphological characteristics and chemical composition gives an idea of the black soil genesis and serves as the diagnostic feature of classification units of them. The study of migration carbonate in the chernozem are of great scientific and practical interest (Afanasyeva, 1996). Nowadays the issues of migration carbonates, as well as the extent of the manifestation of this process in the soil profile need further researching, which is important as carbonates has one of the main role in basic soil processes, in particular, they affect the concentration and activity of calcium ions in the soil solution, the composition of the soil absorbing complex and pH in the soil solution. Carbonate neoplasms contribute to the formation of strong coagulation structures, which increases soil fertility and harvest agricultural crops, provides resistance against the wind, prevents reduction of the upper fertile soil layer, increases mobility of some chemical elements and improves such physical characteristics of soil as density, permeability and porosity (Goncharova, 1983). The aim of our work was to study the content of calcium carbonate in the soil profile of the test section 201–L under of the acacia plantations crops of forest ecosystems and to determine of their distribution in the soil genetic horizons. According to the aim of our work of we has the following tasks: to give a general characterization of carbonates of calcium in Chernozem usual, to perform sampling of the genetic horizons of the soil profile of test section 201–L, to determine the content of carbonates by conventional gravimetric methods; to study the features of the content of carbonates in soil profiles of test section 201–L; to conduct statistical processing of the obtained data; to formulate conclusions of the performed research. Soil samples were selected according to the standard technique in genetic horizons of the soil profile on three times (Fedorets, 2009). Determination of the percentage content of carbonates in the soil was performed by the gravimetric method, which is based on weight loss of soil due to discharge of CO2 during the destruction of carbonates with acid. It should be noted that the method can be applied in the case of the carbonates content up to 70 % (Travleev et al., 2009). The average coefficient of variation of carbonates of calcium content in genetic horizons of the soil profile is 77.5 %. This is quite a high rate, so as General it is considered that if the value of the coefficient of variation is less than 33 %, the result is considered homogeneous if more than 33 %, it is inhomogeneous. Based on this observation, we conclude that carbonate calcium has inhomogeneous redistribution of genetic horizons of test section 201–L. Regarding the reliability of the obtained data, we can see that the standard error calculations for each of the horizons does not exceed 0,34, which in turn confirms the accuracy of the our data. According to our calculations the lowest content of calcium carbonate is 1.47 % in the first horizon, and biggest – 16,07 % in the genetic horizon Ph (70–90 cm). These results are extending the current understanding of the processes of formation and distribution of calcium carbonate in the genetic horizons of the soil profile of the Chernozem ordinary. The data of percentage of calcium carbonate may be used in the solution of the question of the genesis, evolution and classification of soils, the obtained data can serve as the basis of the research the conditions of pedogenesis under the influence of natural climatic fluctuations and anthropogenic factors.

Effective removal of heavy metal ions from aqueous solutions using a new chelating resin poly [2,5-(1,3,4-thiadiazole)-benzalimine]: kinetic and thermodynamic study

A novel poly [2,5-(1,3,4-thiadiazole)-benzalimine] abbreviated as TDPI adsorbent was synthesized using simple polycondensation technique. The synthetic route involves the preparation of 2,5-diamino-1,3,4-thiadiazole from 2,5-dithiourea and subsequent condensation with terephthalaldehyde. The resin was chemically characterized using Fourier transform infrared (FT-IR), 1H-NMR, and 13C-NMR spectroscopic analysis. Surface morphology and thermal stability were analyzed using scanning electron microscopy (SEM) and thermo-gravimetric analysis (TGA). The effect of the pH value of solution, contact time, adsorbent dose, and initial metal ion concentration were investigated by batch equilibrium adsorption experiments. Kinetic studies show that the adsorption of metal ions onto the resin proceeds according to the pseudo-second-order model and the equilibrium data were best interpreted by the Redlich–Peterson isotherm. The experimental values of the adsorption capacities of Pb2+, Cu2+, Ni2+, and Cd2+ on to TDPI could reach up to 437.2, 491.6, 493.7, and 481.9 mg.g−1 respectively. The exothermic nature of the process, the affinity of the adsorbent towards the metal ions and the feasibility of the process are explained in the thermodynamic parameters. The resin stability and re-usability studies suggest that the resin is chemically stable (0.3 N HCl and H2SO4) and could be regenerated without any serious decline in performance.

Effects of Chlorine Ions on the Dissolution Mechanism of Cu Thin Film in Phosphoric Acid Based Solution.

The dissolution mechanisms of Cu thin film were studied with a focus on the effect of chlorine ion concentrations in mixture solutions of phosphoric and nitric acid. The dissolution behaviors of Cu thin film were investigated by using potentio-dynamic curves and impedance spectroscopy with varying chlorine ion concentrations. The copper dissolution rate decreased and as a result of this change, CuCl, salt films formed on the Cu surface in the presence of chlorine ions in the mixture solution. Such behavior was interpreted as being competitive adsorption between chlorine and nitrate ions on the copper surface. The passive oxide film on the Cu surface was further investigated in detail using X-ray photoelectron spectroscopy in both the absence and presence of differing chlorine ion concentrations.

Utilizing Reversible Interactions in Polymeric Nanoparticles To Generate Hollow Metal–Organic Nanoparticles

AbstractThe use of reversible linkers in polymers has been of interest mainly for biomedical applications. Herein, we present a novel strategy to utilize reversible interactions in polymeric nanoparticles to generate hollow metal–organic nanoparticles (MOPs). These hollow MOPs are synthesized from self‐assembled polymeric nanoparticles using a simple metal–comonomer exchange process in a single step. The control over the size of the polymer precursor particles translates into a straightforward opportunity for controlling MOP sizes. The shell thickness of the MOPs could be easily tuned by the concentration of metal ions in solution. The underlying mechanism for the formation of these hollow MOPs has been proposed. Evidence for the generality of the method is provided by its application to a variety of metal ions with different coordination geometries.

Utilizing Reversible Interactions in Polymeric Nanoparticles To Generate Hollow Metal-Organic Nanoparticles.

The use of reversible linkers in polymers has been of interest mainly for biomedical applications. Herein, we present a novel strategy to utilize reversible interactions in polymeric nanoparticles to generate hollow metal-organic nanoparticles (MOPs). These hollow MOPs are synthesized from self-assembled polymeric nanoparticles using a simple metal-comonomer exchange process in a single step. The control over the size of the polymer precursor particles translates into a straightforward opportunity for controlling MOP sizes. The shell thickness of the MOPs could be easily tuned by the concentration of metal ions in solution. The underlying mechanism for the formation of these hollow MOPs has been proposed. Evidence for the generality of the method is provided by its application to a variety of metal ions with different coordination geometries.

Rejection of nutrients contained in an anaerobic digestion effluent using a forward osmosis membrane

The possibility of applying a forward osmosis (FO) membrane filtration process for the post-treatment of an anaerobic membrane bioreactor (AnMBR) was investigated in this study. The FO membrane filtration test, using a surrogate AnMBR effluent prepared by supernatant obtained from a real anaerobic digester, demonstrated excellent rejection of phosphate ions. On the other hand, the rejection of ammonium ions was moderately effective and depended heavily on the operating conditions of the FO membrane (e.g. orientation of the FO membrane) solute concentration in the draw solution (DS) and ammonium ion concentration in the feed solution (FS). The flux of ammonium ions across the FO membrane decreased as the solute concentration in the FS increased. The reverse solute flux from the DS to FS also increased as the solute concentration in the DS increased. The above-mentioned trend was particularly remarkable in the FO filtration with an active layer facing DS (AL-DS) orientation, in which the reverse solute flux was higher than that in the active layer facing FS (AL-FS) orientation. The relationship between the degree of reverse solute flux and flux of ammonium ion was further explained by the FO filtration test using different solute species in the DS. When we used the solutes with higher reverse solute flux than sodium chloride as DS, the flux of ammonium ion became smaller. On the basis of the results obtained in this study, it can be concluded that the reverse solute flux would have a positive influence on the rejection of ammonium ions.

Natural zeolite for nickel ions removal from aqueous solutions: optimization and modeling using response surface methodology based on central composite design

Natural zeolite was tested as a low-cost adsorbent for Ni(II) removal from aqueous solutions. In order to reduce the total number of experiments necessary for achieving the best conditions of the batch sorption procedure, response surface methodology based on central composite design was carried out for the natural zeolite. Four independent variables, viz. initial nickel ion concentration (10–200 mg/L), adsorbent dose (0.1–0.7 g/L), contact time (5–120 min), and initial pH of solution (2–8) were transformed to coded values and the quadratic model was built to predict the responses. Very high regression coefficients between the variables and the response indicate excellent evaluation of experimental data using a second-order polynomial regression model. Three-dimensional plots demonstrate relationships between the nickel ion uptake with the paired factors (as the fourth factor was kept at its optimal level), which illustrate the behavior of the sorption system in a batch process. The model showed that nickel uptake in aqueous solution was affected by all four factors studied. An optimum nickel uptake was achieved at an initial nickel ion concentration of 10–15 mg/L, clinoptilolite dosage of 0.37–0.43 g/L, a contact time of 56–68 min, and a pH of 4.8–6. On the basis of experimental results and model parameters, it can be inferred that the adsorbent, which exhibits a relatively high adsorption capacity, can be utilized for the removal of nickel from aqueous solution.

Fenton-Like Oxidation of 4-Chlorophenol: Homogeneous or Heterogeneous?

Heterogeneous Fenton-like catalysts have received considerable research attention because they could potentially be attractive for oxidative removal of organic contaminants from tertiary wastewater. However, process design is still hampered by insufficient understanding of the chemical pathways involved, and especially whether oxidation activity stems from heterogeneous surface chemistry or minute concentrations of dissolved metal ions in the homogeneous phase. Using inductively coupled plasma-optical emission spectroscopy (ICP-OES) in combination with pH monitoring and ultraviolet–visible spectroscopy (UV–vis) we have monitored the degradation of 4-chlorophenol (4-CP) over two Fenton-like heterogeneous systems, namely FeOx supported on TiO2 and CuFe2O4. We show conclusively that these systems proceed predominantly through a homogeneous route via dissolved metal ions from the solid phase catalysts. Control experiments with homogeneous Fe3+ or Cu2+ systems reveal that even minute concentrations (μM/subppm) of dissolved metal ions leached from the solid phases account for the observed 4-CP degradation rates in the heterogeneous systems. ICP-OES revealed that metal leaching was time-dependent and variable because of pH variations associated with changing acid release rates. Buffering solutions at pH 7.4 suppressed metal leaching (and hence 4-CP degradation) in the FeOx/TiO2 system, but not in others. For example, pH buffering did not entirely suppress metal leaching from CuFe2O4, for which 4-CP degradation was retained through small concentrations of Fe and Cu ions in solution. Our results highlight the importance of careful monitoring of metal content in the aqueous phase, certainly with analytical sensitivity below ppm concentrations of the dissolved metals, and also the crucial influence of time-dependent pH variations on the reaction process. Recyclability of catalysts, pH buffering of solutions or monitoring of metal content in the solid phase by less sensitive analytical methods, for example, chemical analysis, gravimetry, X-ray fluorescence, or energy dispersive X-ray analysis in electron microscopes, cannot exclude the homogeneous Fenton route in the presence of solid catalysts.

Understanding the removal and regeneration potentials of biogenic wastes for toxic metals and organic dyes

This work highlights the removal dynamics of some industrial dyes, such as Congo Red (CR) and Methylene Blue (MB), Cd2+ and Pb2+ by two low-cost and readily available tree wastes (Pentaclethra macrophylla tree bark (PMTB biosorbent) and Malacantha alnifolia tree bark (MATB biosorbent). In this research work, experimental variables such as pH, biomass dose, initial solute ion concentration, agitation time and temperature were optimised. The surface textures of PMTB and MATB biosorbents were characterised using pH of Point of Zero Charge (pHPZC), Fourier Transform Infra Red Spectroscopy (FTIR), X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) respectively. Proximate Analysis (PA) and Bulk Density (BD) of these biosorbents were also determined. The highest Langmuir saturation monolayer adsorption capacity, qmaxLfor the removal of CR by MATB biosorbent was obtained as 800.00 mg/g. The pseudo-second order model provided the best fit for the kinetic data obtained for the removal of CR, MB, Cd2+ and Pb2+ by PMTB and MATB biosorbents. This implied that chemisorption might be the mechanism of the solute ions–biosorbents interaction in this study. Weber–Morris intraparticle diffusion model showed that intraparticle diffusion was not the only rate limiting step of the adsorption processes. Film/pore diffusion process might have played an important role in the rate limiting step of the adsorption processes. Thermodynamic data indicated that (ΔG°) for the removal of CR, MB, Cd2+ and Pb2+ onto PMTB and MATB biosorbents were non spontaneous at all temperatures. Also, (ΔH°) and (ΔS°) for the removal of CR, MB, Cd2+ and Pb2+ onto the biosorbents depicted the adsorption processes being exothermic with decreasing of the chaos.

Development of a new passive sampler based on diffusive milligel beads for copper analysis in water

A new passive sampler was designed and characterized for the determination of free copper ion (Cu2+) concentration in aqueous solution. Each sampling device was composed of a set of about 30 diffusive milligel (DMG) beads. Milligel beads with incorporated cation exchange resin (Chelex) particles were synthetized using an adapted droplet-based millifluidic process. Beads were assumed to be prolate spheroids, with a diameter of 1.6 mm and an anisotropic factor of 1.4. The milligel was controlled in chemical composition of hydrogel (monomer, cross-linker, initiator and Chelex concentration) and characterized in pore size. Two types of sampling devices were developed containing 7.5% and 15% of Chelex, respectively, and 6 nm pore size. The kinetic curves obtained demonstrated the accumulation of copper in the DMG according to the process described in the literature as absorption (and/or adsorption) and release following the Fick's first law of diffusion. For their use in water monitoring, the typical physico-chemical characteristics of the samplers, i.e. the mass-transfer coefficient (k0) and the sampler-water partition coefficient (Ksw), were determined based on a static exposure design. In order to determine the copper concentration in the samplers after their exposure, a method using DMG bead digestion combined to Inductively Coupled Plasma – Atomic Emission Spectrometry (ICP-AES) analysis was developed and optimized. The DMG devices proved to be capable to absorb free copper ions from an aqueous solution, which could be accurately quantified with a mean recovery of 99% and a repeatability of 7% (mean relative uncertainty).

Encapsulation of Cs/Sr contaminated clinoptilolite in geopolymers produced from metakaolin

The encapsulation of caesium (Cs) and strontium (Sr) contaminated clinoptilolite in Na and K based metakaolin geopolymers is reported. When Cs or Sr loaded clinoptilolite is mixed with a metakaolin geopolymer paste, the high pH of the activating solution and the high concentration of ions in solution cause ion exchange reactions and dissolution of clinoptilolite with release of Cs and Sr into the geopolymer matrix. The leaching of Cs and Sr from metakaolin-based geopolymer has therefore been investigated. It was found that Na-based geopolymers reduce leaching of Cs compared to K-based geopolymers and the results are in agreement with the hard and soft acids and bases (HSAB) theory. Cs ions are weak Lewis acids and aluminates are a weak Lewis base. During the formation of the geopolymer matrix Cs ions are preferentially bound to aluminate phases and replace Na in the geopolymer structure. Sr uptake by Na-geopolymers is limited to 0.4 mol Sr per mole of Al and any additional Sr is immobilised by the high pH which causes precipitation of Sr as low solubility hydroxide and carbonate phases. There was no evidence of any other phases being formed when Sr or Cs are added to metakaolin geopolymers.

Buffering or non-buffering; an action of pit-and-fissure sealants

ObjectivesThe aim of this study was to evaluate the buffering capacity of glass-ionomer material in vitro. The null hypothesis tested was that there is no effect of cured glass-ionomer pit-and-fissure sealant (PFS) pastes on the environmental acidity as well as the tooth substrate. MethodFor each material, a cured PFS disk and a section of human enamel were simultaneously soaked in lactic acid solution in a conical tube, and the pH of the solution was measured daily for one week. Subsequently, the total amount of calcium leached out in solution was also measured with ICP-AES. ResultsThe results showed that the acidity of the solutions changed over time. Significant differences of calcium ion concentration in solution were observed as a result of decalcification. As the PFS products tested did not include calcium, the concentration of calcium ion released indicated acidic erosion of the tooth enamel. ConclusionsThe glass-ionomer countered the acid of the solution rapidly and preserved the structure of human tooth enamel.

Nondestructive radioactive tracer technique in performance evaluation of organic based ion exchange materials Purolite NRW-4000 and Duolite A-378

Abstract The present paper demonstrates nondestructive application of the 131I and 82Br radioisotopes in performance evaluation of organic base anion exchange resins Purolite NRW-4000 and Duolite A-378. The evaluation was based on kinetics of iodide and bromide ion-isotopic exchange reactions taking place between the external ionic solution and the resin surface. It was observed that at a constant temperature of 35.0 °C when the concentration of bromide ions in solution increases from 0.001 mol/L to 0.004 mol/L, the specific reaction rate values for bromide ion-isotopic exchange increases from 0.228 to 0.266 min−1 using Purolite NRW-4000 resins and from 0.160 to 0.185 min−1 using Duolite A-378 resins. Also it was observed that under the same experimental conditions, the percentage of bromide ions exchanged increases from 60.67 % to 67.00 % using Purolite NRW-4000 resin, while for Duolite A-378 resin it increases from 49.30 % to 52.00%. The identical trend was observed for the two resins during iodide ion-isotopic exchange reaction. The overall results indicate that under identical experimental conditions, as compared to Duolite A-378 resins, Purolite NRW-4000 resins shows superior performance. It is expected that the present nondestructive radiotracer technique can be extended further for characterization of series of nuclear as well as non-nuclear grade ion exchange resins. The results of such study will be immensely useful in proper selection of the ion exchange resins in various industrial applications.

Electrochemical synthesis and characterization of zinc carbonate and zinc oxide nanoparticles

Zinc oxide and its precursor i.e., zinc carbonate is widely utilized in various fields of industry, especially in solar energy conversion, optical, and inorganic pigments. In this work, a facile and clean electrodeposition method was utilized for the synthesis of zinc carbonate nanoparticles. Also, zinc oxide nanoparticles were produced by calcination of the prepared zinc carbonate powder. Zinc carbonate nanoparticles with different sizes were electrodeposited by electrolysis of a zinc plate as anode in the solution of sodium carbonate. It was found that the particle size of zinc carbonate might be tuned by process parameters, i.e., electrolysis voltage, carbonate ion concentration, solvent composition and stirring rate of the electrolyte solution. An orthogonal array design was utilized to identify the optimum experimental conditions. The experimental results showed that the minimum size of the electrodeposited ZnCO3 particles is about 24 nm whereas the maximum particle size is around 40 nm. The TG-DSC studies of the nanoparticles indicated that the main thermal degradation of ZnCO3 occurs in two steps over the temperature ranges of 150–250 and 350–400 °C. The electrosynthesized ZnCO3 nanoparticles were calcined at the temperature of 600 °C to prepare ZnO nanoparticles. The prepared ZnCO3 and ZnO nanoparticles were characterized by SEM, X-ray diffraction (XRD), and FT-IR techniques.

Effect of sulfur on the ion concentration of pore solution and the hydration of calcium aluminate cement

The ion concentration, PH value of pore solution and the hydration of two low iron calcium aluminate cements based on bauxite (BCACs) with different sulfur content were investigated by XRD, ICP-OES, PH meter and SEM. The results indicate that the sulfur in the bauxite and coal results in the formation of ye’elimite (C4A3Š) in BCAC. The more the sulfur content in BCAC the more the C4A3Š formed. The hydration of C4A3Š decreases the ion concentrations of Ca, Al and the PH values but increases the concentration of S. Hydration and hydrates of CA are influenced by the hydration of C4A3Š in BCAC. CAH10 is found in the hydration of both BCAC samples, but C2AH8 is only found in the hydrates of the BCAC with lower SO3 content.

Novel therapeutic core–shell hydrogel scaffolds with sequential delivery of cobalt and bone morphogenetic protein-2 for synergistic bone regeneration

Enabling early angiogenesis is a crucial issue in the success of bone tissue engineering. Designing scaffolds with therapeutic potential to stimulate angiogenesis as well as osteogenesis is thus considered a promising strategy. Here, we propose a novel scaffold designed to deliver angiogenic and osteogenic factors in a sequential manner to synergize the bone regeneration event. Hydrogel fibrous scaffolds comprised of a collagen-based core and an alginate-based shell were constructed. Bone morphogenetic protein 2 (BMP2) was loaded in the core, while the shell incorporated Co ions, enabled by the alginate crosslinking in CoCl2/CaCl2 solution. The incorporation of Co ions was tunable by altering the concentration of Co ions in the crosslinking solution. The incorporated Co ions, that are known to play a role in angiogenesis, were released rapidly within a week, while the BMP2, acting as an osteogenic factor, was released in a highly sustainable manner over several weeks to months. The release of Co ions significantly up-regulated the in vitro angiogenic properties of cells, including the expression of angiogenic genes (CD31, VEGF, and HIF-1α), secretion of VEGF, and the formation of tubule-like networks. However, BMP2 did not activate the angiogenic processes. Osteogenesis was also significantly enhanced by the release of Co ions as well as BMP2, characterized by higher expression of osteogenic genes (OPN, ALP, BSP, and OCN), and OCN protein secretion. An in vivo study on the designed scaffolds implanted in rat calvarium defect demonstrated significantly enhanced bone formation, evidenced by new bone volume and bone density, due to the release of BMP2 and Co ions. This is the first study using Co ions as an angiogenic element together with the osteogenic factor BMP2 within scaffolds, and the results demonstrated the possible synergistic role of Co ions with BMP2 in the bone regeneration process, suggesting a novel potential therapeutic scaffold system. Statement of SignificanceThis is the first report that utilizes Co ion as a pro-angiogenic factor in concert with osteogenic factor BMP-2 in the fine-tuned core-shell hydrogel fiber scaffolds, and ultimately achieves osteo/angiogenesis of MSCs and bone regeneration through the sequential delivery of both biofactors. This novel approach facilitates a new class of therapeutic scaffolds, aiming at successful bone regeneration with the help of angiogenesis.

METHOD FOR RAPID ASSESSMENT OF ALUMINUM TOLERANCE OF PEA (Pisum sativum L.)

Abstract Crops vary considerably in their resistance to acidic soils, and many legumes, including pea (Pisum sativum L.), considered to be sensitive or moderately sensitive crops compared to cereals. The main factor determining the phytotoxicity of acidic soils is the increased concentration of mo-bile aluminum ions in the soil solution. Accumulation of aluminum in root tissues interferes with cell division, initiation of growth of lateral roots and uptake of minerals and water by plants. Under labo-ratory conditions the resistance of plants to aluminum is estimated by the degree of damage to the roots by aluminum using dyes (hematoxylin, eriochrome cyanine R) and the ability of roots to re-store growth after toxic effect of this metal. This work dedicated to the development of rapid assess-ment of aluminum tolerance especially for peas, which is as follows: the seeds were germinated in the growth chamber in the nutrient solution for 3 days (7000 lx illumination, temperature of 19 С at night and 21 С during the day, photoperiod 16 h), treated with a toxic concentration of aluminum chloride (3 mg Al/l) for 24 hours, incubated in fresh nutrient solution without aluminum for 2 days and stained with 0.1 % eriochrome cyanine R for 10 min. Zone of root tissue damage by aluminum painted in the color purple. Plant resistance to aluminum was determined by the length of the root re-growth area after exposure to the toxicant. Using 19 varieties of pea from the N.I. Vavilov Re-search Institute of Plant Industry collection (VIR collection) it was shown that pea has high variabil-ity in tolerance to aluminum. Varieties with a minimum (1.01.5 mm) length of the root re-growth (k-2759, k-3654 and k-3283) were characterized by intense purple color of the root, but varieties with a maximum (14.014.5 mm) length of the root re-growth (k-4376, k-9504 and k-7307) had a faint but detectable staining. The proposed method makes it possible to identify genotypes contrast-ing in aluminum tolerance, is highly reproducible and can be used for screening and study of intra-specific variability in this trait of pea plants at very early developing stage. Keywords: aluminum, hematoxylin, peas, soil acidification, acid tolerance, eriochrome cyanine R.

Design and model parameters estimation for fixed–bed column adsorption of Cu(II) and Ni(II) ions using magnetized saw dust

Fixed-bed column studies were performed using magnetized sawdust (Fe3O4–SD) as adsorbent for removal of Cu(II) and Ni(II) ions form aqueous solutions. Breakthrough curves were obtained by performing experiments in order to evaluate the influence of adsorbent bed height (2, 4, 8 cm), metal ion concentration in feed solution (10, 20, 30 mg/L), and feed flow rate (15, 20, 25 mL/min) for adsorption of Cu(II) and Ni(II) ions onto Fe3O4–SD adsorbent. Adsorption kinetics was analyzed using Bohart–Adams, Thomas, and Yoon–Nelson models. Kinetic data correlated well with both Thomas and Yoon–Nelson models, while Bohart–Adams model poorly predicted the model operation. Saturation loading capacity of adsorbent bed decreased with increase in adsorbent bed height, metal concentration in feed, and feed flow rate. Both mass transfer zone (MTZ) height and height of unused bed (HUNB) noticeably increased with increase in the values of the parameter studied. The results showed that reduced MTZ height and lowest HUNB are suitable for operating the column satisfactorily.

Effect of ionic-strength adjusters on the detection of silver ion using ion-selective electrode

Ion-selective electrodes (ISEs) are used in a wide variety of applications for determining the concentrations of various ions in aqueous solutions. When compared to many other analytical techniques, ISEs are relatively inexpensive, simple to use, and have an extremely wide range of applications and concentrations. In recent reports, cytotoxicity of silver nanoparticles (AgNPs) showed that AgNPs were ionized in the cells and led to causing cell-death. Thus, the measurement of silver ions in aqueous phase is important. In this work, several sodium and potassium salts were considered as ionic-strength adjusters (ISA) and were used in the calibration step to enhance sensitivity of detection the target ion. The result showed that potassium iodine (0.05M KI) acted as a very effective ISA, compared to conventional ISA (5M NaNO3).