Dilute Cl Research Articles

Flue‐cured tobacco and Cl rates: Implications on yield, quality, and nutrient concentration

AbstractThe increase in flue‐cured tobacco (Nicotiana tabacum L.) yields in recent decades due to genetic improvements of new cultivars and management technologies may increase the plant demand for Cl, and the increased dry mass may dilute Cl concentration, thereby reducing negative effects. This study evaluated the effect of increasing doses of Cl on tobacco production, quality, and chemical composition of leaves, in four growing environments located at research stations where flue‐cured tobacco is produced in North Carolina. The treatments consisted of 11 rates of Cl (0, 11, 22, 34, 45, 56, 67, 78, 90, 101, and 112 kg ha−1) in each growing environment, with four replications in a randomized complete block design. The yield and visual quality, total alkaloids, and reducing sugars concentrations of cured leaf were determined. In addition, the concentration of selected nutrients (N, P, K, Ca, Mg, S, and Cl) and nitrate (NO3−) in tobacco leaves was measured in five different periods. Rates of Cl up to 112 kg ha−1 did not reduce the productivity or quality of flue‐cured tobacco in any environment. The Cl rate required to reach the threshold of 1.0% Cl content in cured leaf was site‐specific, being surpassed even in the control treatment at one location, or with Cl rates higher than 34 and 90 kg ha−1 in two environments. In one environment, the Cl rates increased tobacco yield, probably due the direct effect of Cl as a nutrient. Although the increasing Cl rates increased the reducing sugars concentration, visual quality was not attenuated.

Species fine structure of transition metal Cu(II) in aqueous chloride-bearing solutions: Insights from X-ray absorption spectroscopy and ab initio XANES calculations

Knowledge of the structure and speciation of aqueous Cu(II)-chloride complexes is important for understanding Cu(II) behavior in the deep removal technology of Cu impurity from nickel electrolysis anolytes containing chloride. In this paper, X-ray absorption spectroscopic measurements are reported for dissolved copper in lithium chloride (up to ~ 16 mol kg−1) solutions at room temperature. The speciation and structure of corresponding solutions has been probed by performing a combined ab initio XANES theoretical and experimental analysis. The EXAFS spectrum was analyzed as well within this approach. Our XAS data and ab initio XANES calculations favored the five-coordinated [Cu(H2O)5]2+ with square pyramidal configuration over the four-(square planar and tetrahedron, [Cu(H2O)4]2+) and six-coordinated (octahedron, [Cu(H2O)6]2+) structure in dilute Cl− solution (~ 0.55 mol kg−1). This is also supported by the EXAFS refinement with the [CuO5] model having the lowest statistical error. In the highest Cl− concentration solution, the results of both methods show that tetrahedral [CuCl4]2– complexes are predominant. Upon manually adjusting its geometric parameter to the distortion degree α of ~ 18° and average CuCl bond distance of 2.25 Å of a squashed tetrahedral model, not only does the calculated XANES spectrum well reproduce the experimental spectrum, but also the statistical error in the EXAFS refinements is lowest.

Fast response chlorine gas sensor based on mesoporous SnO 2

Mesoporous SnO 2 is obtained through a simple hydrothermal process by using tin chloride as a raw material, urea as a pore-forming agent and pH regulator. X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) nitrogen adsorption–desorption measurements are employed to characterize the obtained mesoporous structures. The results show that the as synthesized material after calcination can be well indexed to tetragonal phase SnO 2 with a mesoporous structure. The sensing properties of the sensor based on mesoporous SnO 2 are investigated. The results reveal that the response to dilute Cl 2 gas of the materials is very high and fast. The short recovery time mainly attributes to the bigger pore size of mesoporous SnO 2. Finally, the reaction mechanism is proposed.

Hyperfiltration of sodium chloride through kaolinite membranes under relatively low-heads – Implications for groundwater assessment

Abstract Three relatively low-head hyperfiltration experiments were conducted to investigate clay membrane behavior at lower hydraulic heads. Dilute Cl − solutions (187 and 336 mg/L) were forced through thin layers of kaolinite (0.67–1.62 mm) under heads ranging between 1.45 and 1.89 m. At the end of each experiment, there was a Cl − concentration increase (15–29%) within the cell. The concentration increase is attributable to solute-sieving by the kaolinite. Calculated final concentration increases at the membrane face ranged between 1.51 and 1.65 times the initial concentration and the calculated values of the reflection coefficient ranged between 0.35 and 0.40. These experiments show that clays are capable of significant hyperfiltration effects at lower pressure heads more typical of natural aquifers. Consequently, hyperfiltration effects may need to be considered in a broad spectrum of shallow subsurface processes in which these effects have been regarded as inconsequential; particularly in perched aquifers.

High sensitivity chlorine gas sensors using CdSnO 3 thick film prepared by co-precipitation method

This paper reports the gas-sensing properties to Cl 2 in CdSnO 3 thick film sensor. The raw powders of CdSnO 3 were prepared by co-precipitation method. The phase compositions and particle morphology were examined by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Effects of calcining temperature on gas-sensing properties, sensitivity ( R g/ R a) -operating temperature, and sensitivity-gas concentration were investigated. The results demonstrated that the CdSnO 3 sensor prepared by using the powder calcined at 900 °C showed high sensitivity to dilute Cl 2 at 250 °C. Especially, the CdSnO 3 sensor showed the sensitivity as high as 8 even to 0.1 ppm Cl 2.

High sensitivity chlorine gas sensors using CdIn 2O 4 thick film prepared by co-precipitation method

Gas-sensing properties to dilute Cl 2 have been investigated for CdIn 2O 4 thick film sensors prepared by co-precipitation method. Cadmium nitrate and indium nitrate were mixed in de-ionized water. The 0.1 M NaOH was added to the mixed solution. The co-precipitate obtained was washed, filtered, dried, and calcined at 600–900 °C for 4 h. The CdIn 2O 4 sensor prepared using the powder calcined at 600 °C showed high sensitivity ( S= R g/ R a) to dilute Cl 2 at 250 °C. In particular, the CdIn 2O 4 sensor showed the sensitivity as high as 1200 even to 0.2 ppm Cl 2. The crystal structure and surface morphology were examined by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively.

Rate and extent of ion-exchange process: the effect of physico-chemical characteristics of salicylate anions

Ten salicylate anions were used as model compounds in order to investigate systematically the impact of compound lipophilicity, valence, aqueous solubility and hydrogen bonding on binding into and release from a strong anion-exchange fiber, Smopex DS-218v. The release of salicylates from the fiber was studied at 1/10, 1/1 or 10/1 molar ratios of the external chloride-ions versus the salicylate bound in the fiber. The Donnan potential between the fiber and external solution (electrostatic interaction) appeared to be the main factor affecting the release of salicylates from the strong base anion-exchange fiber—an increase in the molar amount of the external chloride-ions resulted in a more effective release of all the salicylates from the fiber. The highest chloride-ion concentration (10/1) released the monovalent salicylates practically completely, while the lowest concentration (1/10) released only 10–35% of the loaded salicylates. The nature and strength of salicylate binding to the fiber by non-electrostatic interactions affected also the ion-exchange process, especially in dilute Cl − solutions. Hydrophobic interactions decreased the rate and amount of drug release from the fiber with the most lipophilic salicylates. Hydrogen bonding between the fiber and the compound restricted also the rate and extent of ion-exchange process of the hydrophilic 5-aminosalicylic acid and 5-hydroxysalicylic acid. The amount of divalent 5-carboxylsalicylic acid bound into and released from the fiber was clearly smaller as compared to the monovalent salicylates potentially due to cross-linking of the fiber chains.

Microstructure dependence of nanometre corrosion in Al-Ni-Y glassy alloys

In-situ scanning force microscopy was used to examine how corrosion at the nanometre scale depends on material microstructure. The results reveal an unusual porous corrosion morphology in partially nanocrystalline Al87Ni8.7Y4.3 alloys exposed to dilute Cl- solutions at various pH values. This nanometre-scale porosity is absent in the fully amorphous state of the same alloy. This difference is surprising because the macroscopic corrosion behaviours of the two materials are similar. This work shows that the partially nanocrystalline material sustains nanometre-scale corrosion damage in addition to localized corrosion pits. We propose a mechanism for porosity development based on acid-induced depassivation of protective oxides and two key microstructural differences between the fully amorphous and the partially nanocrystalline alloys.

Equilibrium characteristics of ion exchange between an OH-type strong anion exchange resin and dilute Cl- solution.

The equilibrium characteristics between the OH-type resin and NaCl or CaCl 2 aqueous solution at the various low concentrations were measured by a batch or column method. The experimental results obtained are discussed

F-Cl-OH partitioning between biotite and apatite

An assessment of F-C1-OH partitioning between natural apatite and biotite in a variety of rocks was used to evaluate reciprocal (Mg, Fe 2+, Al VI) (F, Cl, OH) mixing properties for biotite according to the reciprocal salt solution model of Wood and Nicholls (1978). Ideal mixing of F-C1-OH and Fe-Mg-Al VI in the hydroxyl and octahedral sites is assumed for biotites with dilute Cl concentrations. The reciprocal interaction parameters, in terms of Gibbs free energies, for the reactions KMg 3[ AlSi 3 O 10]( OH) 2 + KFe 3[ AlSi 3 O 10]( F) 2 = KMg 3[ AlSi 3 O 10]( F) 2 + KFe 3[ AlSi 3 O 10]( OH) 2 Phl Fann Fphl Ann and KMg 3[ AlSi 3 O 10]( Cl) 2 + KFe 3[ AlSi 3 O 10]( OH) 2 = KMg 3[ AlSi 3 O 10]( OH) 2 + KFe 3[ AlSi 3 O 10] ( Cl) 2 Clphl Ann Phl Clann are about −10 kcal/mol and −4.5 kcal/mol, respectively. These mixing properties are consistent with standard state thermodynamic properties for F and Cl endmember phases from Zhu and Sverjensky (1991). The approach of studying F-C1-OH partitioning between biotite and apatite permits distinguishing the reciprocal effects from the effects of temperature, pressure, and fluid composition. The resultant mixing properties are consistent with observations both in hydrothermal experiments and in natural mineral assemblages. The mixing properties presented in this study enable us now to predict F and Cl concentrations of hydrothermal fluids from the measured F and Cl concentrations in biotite with variable Fe-Mg-Al VI proportions. A case study of the Santa Rita porphyry copper deposits, New Mexico, shows that hydrothermal fluids responsible for the phyllic alteration had a salinity about 3 molal Cl −, in agreement with fluid inclusion studies. Our internally consistent standard thermodynamic properties and solid solution models also lead to recalibration of the apatite-biotite geothermometer. The revised geothermometer predicts temperatures that agree with those estimated from other independent geothermometers. The large reciprocal effects in biotite also point out the need to revise other geothermometers using biotite and to revise the ideal mixing model for biotite in petrologic studies.

PH and thermal stability of Mengo virus

At low temperatures Mengo virus retains a high level of infectivity over a wide range of pH when diluted in 0.1 M phosphate buffer. At 37°–56°C there is progressive loss of infectivity, particularly at extremes of the pH range. At 37° in the presence of dilute Cl − there is also a loss of infectivity between pH 5 and 7, giving a biphasic curve of pH stability. In phosphate-buffered hypertonic salt Mengo virus is inactivated at 0° at low pH, however it is relatively stable at 56° between pH 5 and 7.