Presence Of NaNO3 Research Articles

Enhancement mechanisms behind exclusive removal and selective recovery of copper from salt solutions with an aminothiazole-functionalized adsorbent

The aminothiazole-functionalized adsorbent (CEAD) could exclusively remove and to selectively recover copper. The adsorption and separation properties of Cu(II) onto CEAD from aqueous media, with or without salts such as NaNO3, Ca(NO3)2 and Ni(NO3)2, were systematically compared by carrying out single, binary and multiple component static and dynamic experiments. In binary systems, the adsorption capacities of Cu(II) were obviously increased by 39.47%, 47.37% and 57.89% with Ni(NO3)2, NaNO3 and Ca(NO3)2, respectively. Besides, simulation study was performed to selectively recover Cu(II) from multi-component aqueous media, with the separation factor of only 54.91 in aqueous media without salts. The separation factor became infinite in the presence of NaNO3 and the enhancement ratio for Cu(II) was raised by 126.31%. Dynamic adsorption could separate Cu(II) and Ni(II) completely and the amount of effluent for pure Ni(II) increased to 127 BV with the help of NaNO3. In the predominant chelating mode simulated by density functional theory calculation, a metal ion coordinated with three nitrogen atoms and formed a chelating complex with two five-membered rings, and Cu(II) showed stronger coordinating ability than Ni(II) did. Meanwhile, anions exerted significant beneficial effects by electrostatic screening, and thus strengthened the exclusive removal and selective recovery of Cu(II).

Quantifying the kinetics of olivine dissolution in partially closed and closed batch reactor systems

This study quantified the rates of olivine dissolution under constant air injection, in partially closed batch reactors and in control closed batch reactors (in the absence of air flow), in the presence of 4g of olivine, and 0, 0.001 and 0.01M NaNO3. Experiments were performed for 40,440 and 36,048min in partially closed and closed reactors respectively. Under constant air injection, the solution pH ranged from 6.8 and 7.3 for all conditions at the start of the experiments, to 7.5 and 7.8 at 40,440min. In the absence of air flow, an alkaline pH of 9.6 to 9.3 was observed for 36,048min. This pH difference is attributed to the constant buffering the solution through the formation of dissolved carbonate species (H2CO3/HCO3−). The alkaline pH, measured in the presence of olivine, implied a mechanism of pH control caused by the presence of Si(OH)4 species from the mineral surface. This effect was suggested by a drop to near neutral pH of the same aliquots, upon filtration of the olivine through a N2 degassed filter. A decrease in total alkalinity was measured for experiments under constant air injection, as a function of increasing NaNO3, suggesting a mechanism of Na+/CO32− interaction is involved in the enhancement of olivine dissolution rates through proton/Mg exchange. In the absence of air flow, the total alkalinity reached a maximum of 0.25mM, compared to 0.9mM with air flow at 0.01M NaNO3. Magnesium concentration increased in the presence of NaNO3 and permanently dissolving CO2 in partially closed batch reactors. This strongly suggests a key role of Na+ (coupled to CO2 dissolution) for enhancing olivine dissolution. Mg/Si ratios for all conditions showed incongruent olivine dissolution, suggesting a combination of two dissolution mechanisms at alkaline and near neutral pH values, in closed and partially closed batch reactors. The rate of olivine dissolution (ROL) was calculated as a function of mineral surface area and forsterite equilibrium solution parameters. In the presence of constant air injection, highest log ROL values range from −11 to −10.7 at the acidic to near neutral conditions (pH=6.8 to 7.2). Slower dissolution rates, with log ROL values of −11.5 to −11.4 were determined for experiments in the absence of air flow at alkaline pH values (9.6 to 9.8). Constant air injection (i.e. constant dissolution of CO2 at atmospheric pressure) in the presence of Na+ has proven effective for enhancing olivine dissolution.

Competitive effects on mercury removal by an agricultural waste: application to synthetic and natural spiked waters

In this work, the efficiency of a local and highly available agricultural waste, the raw rice husk, was used to remove mercury (Hg) from synthetic and natural waters, spiked with concentrations that reflect the contamination problems found in the environment. Different operating conditions were tested, including initial pH, ionic strength, the presence of co-ions (cadmium) and organic matter. The sorption efficiency of rice husk was slightly affected by the presence H+ ions (pH range between 3 and 9), but in the presence of NaNO3 and NaCl electrolytes and in binary solutions containing Cd2+ and Hg2+, the sorption efficiency was dependent on the nature and levels of the interfering ion and on the initial concentration of Hg2+ used. Nevertheless, in a situation of equilibrium the effect of those ions was negligible and the removal efficiency ranged between 82% and 94% and between 90% and 96% for an initial Hg2+ concentration of 0.05 mg L−1 and 0.50 mg L−1, respectively. In more complex matrices, i.e. in the presence of humic substances and in natural river waters, the speciation and dynamics of Hg was changed and a fraction of the metal becomes unavailable in solution. Even then, the values obtained for Hg removal were satisfactory, i.e. between 59% and 76% and 81% and 85% for an initial concentration of Hg2+ of 0.05 and 0.50 mg L−1, respectively.

Cu-catalytic generation of reactive oxidizing species from H2 and O2 produced by water electrolysis for electro-fenton degradation of organic contaminants

A novel Pd-based electro-Fenton process has recently been developed to degrade organic contaminants in wastewaters and groundwater. However, the high cost of Pd catalyst limits the application of this process. In this study, Cu supported on bamboo charcoal (Cu/C) was synthesized to evaluate the feasibility of substituting Pd catalysts. Using phenol as a probe organic contaminant, the performance of Cu/C catalyst was evaluated for the electro-Fenton degradation of phenol in a typical undivided electrolytic system. The electrochemical degradation of phenol in the presence of Cu/C was significant, following a pseudo-first-order kinetics with rate constant (k1) of 0.008min−1. The addition of Fe2+ remarkably enhanced the degradation (k1=0.012min−1). H2O2 and OH were validated as the reactive oxidizing species (ROSs), and OH was the main ROS contributing to phenol degradation. The as-synthesized Cu/C consisting of Cu, CuO and Cu2O could catalyze the production of H2O2 from chemisorbed H2 and O2 as well as the decomposition of H2O2 to OH. Particularly, the addition of Fe2+ facilitated the transformation of H2O2 to OH. Phenol degradation increased with increasing the current from 5 to 50mA and decreased with the further increase to 100mA. The degradation improved with the increase in Cu loadings and the decrease in solution pH. The presence of NaNO3, Na2SO3 or Na2S inhibited the degradation, while the presence of NaCl increased the degradation. Although the activity of Cu/C is much lower than that of Pd/C for phenol degradation, the cost of Cu/C is much lower.

The Fission-Based 99Mo Production Process ROMOL-99 and Its Application to PINSTECH Islamabad

An innovative process for fission based99Mo production has been developed under Isotope Technologies Dresden (ITD) GmbH (former Hans Wälischmiller GmbH (HWM), Branch Office Dresden), and its functionality has been tested and proved at the Pakistan Institute of Nuclear Science and Technology (PINSTECH), Islamabad. Targets made from uranium aluminum alloy clad with aluminum were irradiated in the core of Pakistan Research Reactor-1 (PARR-1). In the mean time more than 50 batches of fission molybdenum-99 (99Mo) have been produced meeting the international purity/pharmacopoeia specifications using this ROMOL-99 process. The process is based on alkaline dissolution of the neutron irradiated targets in presence of NaNO3, chemically extracting the99Mo from various fission products and purifying the product by column chromatography. This ROMOL-99 process will be described in some detail.

Effects of organic acids on Cd adsorption and desorption by two anthropic soils

The objective of this experiment was to study the effects of malic, tartaric, oxalic, and citric acid on the adsorption and desorption characteristics of Cd by two typical anthropic soils (lou soil and irrigation-silted soil) in North-west China. Cadmium adsorption and desorption were studied under a range of temperatures (25°C, 30°C, 35°C, 40°C), organic acid concentrations (0.5–5.0 mmol·L−1), and pH values (2–8). The results showed that the Cd adsorption capacity of the lou soil was significantly greater than that of the irrigation-silted soil. Generally, Cd adsorption increased as the temperature increased. In the presence of NaNO3, the adsorption of Cd was endothermic with ΔH values of 31.365 kJ·mol−1 for lou soil and 28.278 kJ·mol−1 for irrigation-silted soil. The endothermic reaction indicated that H bonds were the main driving force for Cd adsorption in both soils. However, different concentrations of organic acids showed various influences on the two soils. In the presence of citric acid, chemical adsorption and van der Waals interactions were the main driving forces for Cd adsorption rather than H bonds. Although the types of organic acids and soil properties were different, the effects of the organic acids on the adsorption and desorption of Cd were similar in the two soils. The adsorption percentage of Cd generally decreased as organic acid concentrations increased. In contrast, the adsorption percentage increased as the pH of the initial solution increased. The exception was that adsorption percentage of Cd increased slightly as oxalic acid concentrations increased. In contrast, the desorption percentage of Cd increased with increasing concentrations of organic acids but decreased as the initial solution pH increased.

Studies on electrochemical detoxification of trichloroethene (TCE) on Ti/IrO2–Ta2O5 electrode from aqueous solution

Anodic oxidation of trichloroethene (TCE), a toxic chlorinated water contaminant, is carried out using Ti/IrO2–Ta2O5 electrode. The redox behaviour of TCE molecule, fouling of electrodes and generation of oxygen was studied by cyclic voltammetry. The studies on cyclic voltammetry reveals that the TCE oxidation takes place directly on electrode surface at the potential region above 0.3V vs. SCE by direct electron transformation and oxygen evolution from anode. The effect of the electrolyte, pH of the aqueous medium and applied current density on the mineralization behaviour of TCE is also investigated. The degradation of TCE is monitored in terms of TOC and TCE concentration with electrolysis time and corresponding chloride evolution. The complete mineralization of TCE is achieved using Na2SO4 as supporting electrolyte. Conversely, the mineralization of the TCE molecule was observed to be poor because of the electrode fouling in the presence of NaNO3. The dechlorination of TCE is found to increase with electrolysis time and the complete dechlorination is observed at all Iappl studied. The kinetics of TCE degradation was found to follow pseudo-first order reaction whose rate constant was calculated to be 0.0081cms−1 at Iappl value of 13.39mAcm−2. The performance of Ti/IrO2–Ta2O5 anode was proved to be better compared to Pt under similar experimental conditions.

The impact of stabilization mechanism on the aggregation kinetics of silver nanoparticles

The use of silver nanoparticles (AgNPs) for various applications is growing drastically. The increase in use will eventually lead to their release into the environment. The tendency of AgNPs to aggregate and the kinetics of aggregation are major factors that govern their fate in the environment. Dynamic light scattering (DLS) was utilized to investigate the electrolyte-induced aggregation kinetics (NaNO3, NaCl and Ca(NO3)2) of coated and uncoated AgNPs which are electrostatically (H2-AgNPs and Citrate-AgNPs), sterically (polyvinylpyrrolidone (PVP)-AgNPs) and electrosterically (branched polyethyleneimine (BPEI)-AgNPs) stabilized. The aggregation kinetics of the electrostatically stabilized AgNPs was in agreement with the classical Derjaguin–Landau–Verwey–Overbeek (DLVO) theory and the AgNPs exhibited both reaction-limited and diffusion-limited regimes. The H2-AgNPs had critical coagulation concentrations (CCC) of 25, 30 and 3mM in the presence of NaNO3, NaCl and Ca(NO3)2 salts, respectively. The Citrate-AgNPs had CCC of 70, 70 and 5mM in the presence of NaNO3, NaCl and Ca(NO3)2 salts, respectively. The values of the Hamaker constant for the electrostatically stabilized AgNPs were also determined and the values were in agreement with the reported values for metallic particles. The aggregation kinetics for both the sterically and electrosterically stabilized AgNPs (PVP-AgNPs and BPEI-AgNPs) was not in agreement with the DLVO theory and the particles were resistant to aggregation even at high ionic strength and electrolyte valence. The PVP-AgNPs and the BPEI-AgNPs had no critical aggregation concentration value at the investigated ionic strength values.

Flame atomic absorption spectrometry determination of trace amount of gold after separation and preconcentration onto ion-exchange polyethylenimine coated on Al2O3

The object of this work is to develop a simple and selective method for efficient extraction of Au(III) ions in aqueous solution using a new solid-phase extraction sorbent. Polyethylenimine (PEI) ion-exchange polymer was coated on alumina in the presence of NaNO3. The method is based on sorption of Au3+ ions on 50mg PEI/Al2O3. A solution of 0.5M thiourea, then 1.0M HCl effectively eluted the gold ion and then aspirated into flame atomic absorption spectroscopy (FAAS). The influence of flow rate of sample solution and eluent, the pH effect, eluent type and sorption capacity was investigated. The effects of various diverse ions for preconcentration and separation of the gold ion were investigated. Relative standard deviation of 4.0μgmL−1 of gold was 1.46% (n=10). The detection limit was 26.2ngL−1 in original solution. The method has been applied successfully for the recovery of trace amount of Au(III) ions from water samples.

Removal of heavy metal ions by iron oxide coated sewage sludge

The municipal sewage sludge was modified with iron oxide employed in metal ions removal. The surface modification method was proposed and the effect of parameters in the preparation was studied. The iron oxide coated sludge had higher surface area, pore volume and iron content, compared to uncoated sludge. The suitable conditions for removal of Cu(II), Cd(II), Ni(II) and Pb(II) ions from solutions were investigated using batch method. The suitable pH value in the extraction was 7 for adsorption of Cd(II) and Ni(II), 6 for Cu(II) and 5 for Pb(II) ions. The presence of NaNO3, Ca(NO3)2 and Na2SO4 in metal solution in the concentration of 0.01M and 0.50M could reduce the removal efficiency. The adsorption isotherms for the adsorption of the metal ions were defined by Langmuir relation. The maximum adsorption capacity of the iron oxide coated sludge for Cu(II), Cd(II), Ni(II) and Pb(II) was 17.3, 14.7, 7.8 and 42.4mgg−1, respectively. The adsorption kinetics for every metal ions followed pseudo-second order model. The metal removal from wastewater by iron oxide coated sludge was also demonstrated.

Immunological properties of 60Co gamma-rays irradiated bothropstoxin-I

We investigated the immunological behavior of BTHX-1, before and after irradiation. SDS-PAGE showed that BTHX-1 irradiated in the presence of NaNO3, had its structure preserved. Animals’ plasma immunized with native BTHX-1 had high IgG1 titers. The irradiated protein induced high titers of IgG2b. When the toxin was irradiated with t-butanol, there was a slight decrease in the production of IgG2b. Real-time PCR showed that both the IL-2 as for IL4 was more expression from the cells of the animals immunized with BTHX-1 irradiated. These results indicate that irradiation of proteins leads to significant structural modifications.

A Novel Spectrophotometric Method for the Determination of Isoniazid Using Cu(II) as Spectroscopic Probe Ion

Abstract A novel method to determine isoniazid with high sensitivity and good selectivity has been established by using Cu(II) as a spectroscopic probe ion. The experiment indicated that Cu(II) was reduced to Cu(I) by isoniazid at pH 6.0, then the resulting Cu(I) was precipitated with SCN− to form CuSCN that could be stayed upon the surface of water phase in the presence of NaNO3. By determining the residual amount of Cu(II) in the water phase, the indirect determination of isoniazid could be achieved. Good linear relationship between the amount of the reacted Cu(II) and the concentration of isoniazid was observed, with the linear range being 0.050–4.50 µg·mL−1, and the detection limit being 0.048 µg·mL−1. This method has been successfully applied to determining isoniazid among pharmaceutical samples and patient urine samples.

The influence of the nature of the background electrolyte on the heat effects of dissociation of succinic acid

The results of calorimetric measurements were used to determine the heat effects of dissociation of succinic acid at 298.15 K and several ionic strength values in the presence of NaNO3. The thermodynamic characteristics of dissociation at fixed ionic strength values and I = 0 were calculated.

The solubility and kinetics of decomposition of ozone in aqueous solutions of nitrates

The influence of the concentration of NaNO3 on the solubility of ozone in water was studied at 20, 30, and 40°C. The solubility coefficients of ozone were calculated, and the Henry constants and Sechenov coefficients determined. The Sechenov coefficients (Kc) were found to decrease insignificantly as the temperature increased. The kinetics of dissolved O3 transformations was analyzed. The decomposition of ozone was described by a pseudofirst-order equation with respect to salt concentration. The rate constant (kc) for the decomposition of ozone in the presence of NaNO3 was found to be 3.5 × 10−4 l mol−1 s−1.

Sorption Removal of Pb(II) from Solution by Uncalcined and Calcined MgAl‐Layered Double Hydroxides

Abstract Layered double hydroxide (LDH) with a Mg/Al molar ratio of 1:1 was synthesized by using a co‐precipitation method and its calcined product (CLDH) was obtained by calcination of the MgAl‐LDH at 500 °C. The sorption removal of Pb2+ from solution was investigated, finding that both LDH and CLDH show good sorption ability and they could be used as a new type of environmental sorbent for the removal of Pb2+ from water. The sorption kinetics and the sorption isotherms of Pb2+ on both LDH and CLDH can be described by the pseudo‐second order kinetics and Freundlich isotherm, respectively, under the studied conditions. The sorption amounts of Pb2+ on LDH and CLDH are independent of pH in a pH range of about 3–10. The presence of NaNO3 may inhibit the sorption ofPb2+ on LDH while hardly affect that on CLDH. The sorption mechanism of Pb2+ on LDH and CLDH may be attributed to the surface precipitation and the surface complex adsorption. The surface complex adsorption may be further distinguished to the chemical binding adsorption forming the inner‐sphere surface complexes and the electrostatic binding adsorption forming the outer‐sphere surface complexes. The sorption mechanism of Pb2+ on LDH may be attributed to the surface precipitation and the electrostatic binding adsorption, while that on CLDH may be attributed to the surface precipitation and the chemical binding adsorption.

The heat effects of dissociation of maleic and fumaric acids

The heat effects of dissociation of maleic and fumaric acids at 298.15 K and several ionic strength values were determined calorimetrically in the presence of NaNO3. The thermodynamic characteristics of dissociation at fixed ionic strengths and under standard conditions were calculated.

Gordonia polyisoprenivorans from groundwater contaminated with landfill leachate in a subtropical area: characterization of the isolate and exopolysaccharide production

A strain of Gordonia sp. (strain Lc), from landfill leachate-contaminated groundwater was characterized by polyphasic taxonomy and studied for exopolysaccharide (EPS) production. The cells were Gram-positive, catalase-positive, oxidase-negative and non-motile. The organism grew both aerobically and, in anoxic environment, in the presence of NaNO3. Rods occured singly, in pairs or in a typical coryneform V-shaped. The organism had morphological, physiological and chemical properties consistent with its assignment to the genus Gordonia and mycolic and fatty acid pattern that corresponded to those of G. polyisoprenivorans DSM 44302T. The comparison of the sequence of the first 500 bases of the 16S rDNA of strain Lc gave 100% similarity with the type strain of Gordonia polyisoprenivorans DSM 44302T. Experiments conducted in anaerobic conditions in liquid E medium with either glucose or sucrose as the main carbon source showed that sucrose did not support the growth of Lc strain and that on glucose the maximum specific growth rate was 0.17h-1, representing a generation time of approximately 4 hours. On glucose, a maximum of total EPS was produced during the exponential phase (126.17 ± 15.63 g l-1). The production of free EPS exceeded that of capsular and the free/capsular EPS ratio increased from 1.9 during the exponential phase to 7.8 during the stationary phase. At present, six strains of G. polyisoprenivorans have been isolated from various environments. Lc is the sixth strain of G. polyisoprenivorans described, the second strain detected in the landfill leachate-contaminated groundwater and the first that is being studied for EPS production.

High Temperature Oxidation Behaviour of Nimonic - 115 Alloy in Presence of Sodium Salts at 850OC

The high temperature oxidation behaviour of Nimonic-115 industrial alloy has been investigated in presence of NaNO3, Na2CO3 and Na2O2 at 850oC in flowing air. The oxidation kinetics and effect of salt deposition for the period of 48 h were studied. The scale morphologies were determined on the basis of X-ray diffraction analysis and Scanning electron microscopic techniques. It has been shown that the alloy corrodes at different rate in presence of different sodium salts although each salt contains the same amount of sodium equivalent to Na2O.

Radiolysis of an aqueous [11C]iomazenil solution

Summary Radiolysis of [11C]iomazenil was investigated in an aqueous solution. Preparation of [11C]iomazenil with [11C]CH3I produced a good radiochemical yield, however, its radiochemical purity was always less than 90 without additives. This poor radiochemical purity was attributed to radiolysis of [11C]iomazenil. The degradation of [11C]iomazenil via radiolysis was markedly facilitated in the presence of HCOONa (strong selective hydroxyl radical and hydrogen atom scavenger). On the other hand, the radiolysis was suppressed effectively in the presence of NaNO3 (selective hydrated electron scavenger), suggesting participation of hydrated electrons in the radiolysis of [11C]iomazenil. LC/MS analysis of the degradation product suggested that the major degradation product by radiolysis had a molecular weight of 285 corresponding to the deiodinated compound. The present study showed that a decrease in the radiochemical purity of [11C]iomazenil was attributed to the radiolysis via the deiodination reaction by hydrated electron.

Cesium and Strontium Ion Exchange on the Framework Titanium Silicate M2Ti2O3SiO4·nH2O (M = H, Na)

The ion exchange properties of the titanium silicate, M2Ti2O3SiO4.nH2O (M = H, Na), toward stable and radioactive 137Cs+ and 89Sr2+, have been examined. By studying the cesium and strontium uptake in the presence of NaNO3, CaCl2, NaOH, and HNO3 (in the range of 0.01-6 M) the sodium titanium silicate was found to be an efficient Cs+ ion exchanger in acid, neutral, and alkaline media and an efficient Sr2+ ion exchanger in neutral and alkaline media, which makes it promising for treatment of contaminated environmental media and biological systems.