Adsorption Of Chloride Research Articles

Modeling of mercuric chloride removal in ductwork and fabric filter by raw activated carbon injection

Based on previous experimental adsorption kinetic and equilibrium data for mercuric chloride (HgCl2) adsorption onto raw activated carbon (AC), a comprehensive model was formulated for its removal in the ductwork and fabric filter by raw AC injection in coal combustion flue gas. Various factors that can impact the performance and sorbent utilization were investigated, including inlet HgCl2 concentration, sorbent loading, particle size, external and internal mass-transfer considerations, residence time, filtration time, injection mode, and pressure drop. Despite these considerations, in-flight removal of HgCl2 in the ductwork was found to be almost negligible. For the removal in fabric filter, the effect of particle size was found to be significant, particularly for continuous sorbent injection. On the other hand, a discontinuous injection mode delivering the same amount of sorbent in 10% of a cleaning cycle resulted in higher removal performance and sorbent utilization. However, at the end of the cleaning cycle, most of the sorbent capacity was not used (<0.2%). The pressure drop across the filter cake built by fly ash and sorbent was found to be manageable within typical operating limits.

Interactions between calcium silicate hydrate (C-S-H) and calcium chloride, bromide and nitrate

The interaction between C-S-H and anions, especially chloride, is already well documented. However, the conclusions vary from one author to another and a comparison of the obtained data is not always possible. Thus, this study aims to clarify this phenomenon and extend it to the case of bromide and nitrate. For this matter, a new analytical method has been developed in order to make the measurement directly in synthetic C-S-H suspensions, i.e. without any filtration, after calcium salt addition. Various parameters have been taken into account: the anion type and concentration, the Ca/Si of the C-S-H particles (ranging from 0.8 to 1.42) and the incorporation of aluminum inside the C-S-H structure. It has been found that there is no specific adsorption of chloride, bromide or nitrate by C-S-H. Calcium adsorption, which has been detected and measured, is limited, whatever the initial Ca/Si, and the presence of aluminum does not have any influence on it.

Direct AFM measurements of morphology and interaction force at solid-liquid interfaces between DTAC/CTAC and mica

The adsorption of dedecyltrimethylammoium chloride (DTAC) and hexadecyltrimethylammoium chloride (CTAC) on muscovite mica substrates was examined using atomic force microscopy (AFM). Adsorption morphology images and interaction forces of cationic surfactants at solid-solution interfaces were measured in tapping mode and PicoForce mode, respectively. The images demonstrated that the adsorbed structure was varied by a variety of surfactant concentrations. The adsorbed layer on mica was monolayer at first, and then became bilayer. A striped adsorbed structure was observed in a higher concentration of CTAC, which could not be found in any other concentrations of DTAC. For force measurements, the repulsive force was exponentially decreasing with the concentration increasing till a net attractive force appeared. A largest attractive force could be observed at a certain concentration, which was close to the point of charge neutralization. The results also showed a significant impact of hydrocarbon chain length on adsorption. An adsorption simulation was established to give a clear understanding of the interaction between cationic surfactants and mica.

The role of boron nitride nanotube as a new chemical sensor and potential reservoir for hydrogen halides environmental pollutants

Density functional theory (DFT) studies on the interaction of hydrogen halides (HX) environmental pollutants and the boron nitride nanotubes (BNNTs) have been reported. To exploit the possibility of BNNTs as gas sensors, the adsorption of hydrogen fluoride (HF), hydrogen chloride (HCl) and hydrogen bromide (HBr) on the side wall of armchair (5,5) boron nitride nanotubes have been investigated. B3LYP/6-31G (d) level were used to analyze the structural and electronic properties of investigate sensor. The adsorption process were interpreted by highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO), quantum theory of atoms in molecules (QTAIM), natural bond orbital (NBO) and molecular electrostatic potential (MEP) analysis. Topological parameters of bond critical points have been used to calculate as measure of hydrogen bond (HB) strength. Stronger binding energy, larger charge transfer and charge density illustrate that HF gas possesses chemisorbed adsorption process. The obtained results also show the strongest HB in HF/BNNT complex. We expect that results could provide helpful information for the design of new BNNTs based sensing devices.

Restraining Na-Montmorillonite Delamination in Water by Adsorption of Sodium Dodecyl Sulfate or Octadecyl Trimethyl Ammonium Chloride on the Edges

The delamination of montmorillonite in water leads to sliming in ore slurry, which is detrimental to mineral flotation and solid/water separation. In this work, the delamination of Na-montmorillonite (Na-MMT) has been restrained by sodium dodecyl sulfate (SDS) or octadecyl trimethyl ammonium chloride (1831) through the adsorption on the edge of the mineral. The experimental results have shown that the pretreatment by adding SDS and 1831 could greatly reduce the Stokes size percentage of −1.1 µm particles in the aqueous Na-MMT suspension. From the X-ray diffractometer (XRD) results, the interlayer spacing of the MMT pre-treated by SDS and 1831 is smaller than that of original MMT particles. Adsorption position of SDS and 1831 on MMT surfaces was analyzed by the measurements of adsorption capacity of SDS and 1831, inductively-coupled plasma spectra, and zeta potential before and after the plane surface of MMT was covered with tetraethylenepentaminecopper ([Cu(tetren)]2+). The results indicated that SDS and 1831 are adsorbed on the edge and the whole surface of Na-MMT, respectively. Delamination of MMT could be well restrained by the adsorption of SDS and 1831 on the edges of MMT.

Effect of Salt Concentration on the Corrosion Behavior of Carbon Steel in CO2Environment

Effect of salt (NaCl) concentration on the corrosion rate of carbon steel in CO2-saturated solutions was explored in a wide range from 0.001 wt% to 10 wt%. Electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR) were utilized to determine the instantaneous corrosion rate of C1018 carbon steel under freely corroding condition. Both EIS and LPR results indicated that corrosion rate decreases with increasing salt concentration, and the highest corrosion rate was found at the lowest salt concentration (0.001 wt%). Potentiodynamic polarization and potentiostatic hold experiments were performed to study anodic and cathodic kinetics using microelectrode technique. Cathodic polarization results showed that the cathodic reaction is under diffusion or mixed control and the limiting current increases with decreasing salt concentration. Anodic polarization results suggested that chloride adsorption prevails at high salt concentration, while hydroxyl adsorption prevails at low salt concen...

Infrared Spectroscopic Study of the Adsorption Forms of Cyanuric Acid and Cyanuric Chloride on TiO2

Cyanuric acid is often found to be the end product in the hydrolysis of waste melamine and in the TiO2-mediated photocatalytic decomposition of s-triazine-containing compounds used as herbicides or dyes. The photocatalytically recalcitrant nature of cyanuric acid on TiO2 may be closely related to its adsorption properties, including the tautomeric forms present on the surfaces and their bonding structures, which remain to be determined. In this paper, we present the optimized adsorption structures of the four tautomeric isomers (triketo, diketo, monoketo, and triol) of cyanuric acid on a model rutile-TiO2(110) surface and their vibrational absorptions. Experimentally, the adsorption structures of cyanuric acid and chloride on powdered TiO2 are analyzed on the basis of the theoretically obtained, characteristic infrared information. Cyanuric acid on TiO2 at 35 °C exists in triketo and hydroxylated forms, but the diketo becomes the predominant form on the surface at 250 °C, being bonded to a titanium site via one of its carbonyl groups and with a N-H···O hydrogen bonding interaction. Hydroxylation of cyanuric chloride occurs as it is adsorbed on TiO2 at 35 °C. Upon being heated to 200 °C, the surface is mainly covered with the diketo form of cyanuric acid after the adsorption of cyanuric chloride.

Evaluation of polymer composites based on core/shell polystyrene/Mg–Al–NO3 layered double hydroxides for chloride entrapment

This study demonstrates the synthesis and characterisation of core–shell particles for the removal of chlorides from water. The evaluation of their efficiency was conducted under a variety of experimental conditions. The core–shell particles consist of an organic template coated with Mg–Al–NO3 layered double hydroxides (LDH). The characterisation of the LDH traps in terms of their morphology, structure and composition was accomplished with a variety of techniques such as SEM, energy dispersive X-ray analysis, Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis. The LDH trap chloride adsorption loading was evaluated in respect of several parameters such as temperature, pH, contact time and dosage of traps. The experimental data fitting on kinetics models indicated that the adsorption's rate determining step was the chemisorption mechanism.

Adsorption and desorption behaviors of cetylpyridinium chloride on hydroxyapatite nanoparticles with different morphologies.

Application of hydroxyapatite (HAp) nanoparticles to repair damaged enamel has attracted recent attention. In this study, HAp nanoparticles with various morphologies (spherical, short-rod, long-rod and fiber morphologies) were synthesized via chemical precipitation methods without the addition of template molecules, and the adsorption/desorption behaviors of a cationic antibacterial agent, cetylpyridinium chloride (CPC), on the HAp nanoparticles were evaluated. The adsorption of CPC on each HAp nanoparticle showed Langmuir-type adsorption, and the short-rod/long-rod HAp nanoparticles showed thermodynamically more stable adsorption of CPC than that with the spherical/fiber HAp nanoparticles. The desorption rate of CPC from the short-rod/long-rod HAp nanoparticles was slower than that of the spherical/fiber HAp nanoparticles. The HAp nanoparticles with different CPC release profiles presented here have potential applications as nanoparticulate enamel repair agents with antibacterial properties.

In situRaman monitoring of single-walled carbon nanotube filling with copper chloride

<italic<In situ</italic< characterization of single-walled carbon nanotubes during their gas-phase filling with copper chloride (CuCl) was performed with Raman spectroscopy. The time dependence of positions and intensities of G, 2D, and radial breathing modes was investigated. It was demonstrated that the adsorption of copper chloride from gas phase on the external and internal surfaces of nanotubes leads to the Raman mode shifting. However, this effect is weaker than in case of formation of one-dimensional CuCl crystals inside nanotubes.

Macromolecular Structure of Dodecyltrimethylammonium Chloride at the Silica/Water Interface Studied by Sum Frequency Generation Spectroscopy

Adsorption of the cationic surfactant dodecyltrimethylammonium chloride at the silica/water interface was studied using sum frequency generation (SFG) spectroscopy under high ionic strength (100 mM NaCl) and at pH values ranging from 3 to 11, which are conditions relevant to hydraulic fracturing in enhanced oil recovery operations. At surfactant concentrations above the critical micelle concentration, SFG spectra of the CH stretching region indicate a more noncentrosymmetric structure for the surfactant aggregate is formed at the interface under acidic or basic conditions compared to neutral conditions. The SFG spectra also indicate a change in the packing/ordering of the surfactant hydrophobic tails with pH as well. In addition, the observed changes in the SFG spectra of water upon the addition of surfactant vary depending on the pH. At pH 7 and 11, the SFG intensity decreases in the OH stretching region, indicating a decrease in the magnitude of the electrostatic potential at the interface when the cati...

Comparative studies of flotation and adsorption with cetyl pyridinium chloride on molybdite and fluorapatite

In this study, flotation and adsorption of cetyl pyridinium chloride (CPC), a novel cationic collector for molybdite and fluorapatite, were comparatively investigated by flotation tests, zeta potential measurements, adsorption tests and fluorescence spectroscopic analysis. The flotation results demonstrated a large difference in molybdite and fluorapatite recovery, from 33.5% at pH2 to 40.7% at 8, showing a possibility for the separation of molybdite from fluorapatite in the range of pH2–8. A higher amount of adsorbed CPC on molybdite than on fluorapatite was dramatically revealed by Zeta potential measurements as well as adsorption tests, which can explain the better floatability of molybdite than fluorapatite with CPC as the collector. Adsorption isotherm showed the adsorption of CPC on both minerals are mainly attributed to polar group-surface electrostatic attraction at lower CPC concentration and chain–chain hydrophobic interaction at CPC concentrations above its critical hemimicelle concentration (CHC, 6.47×10−4mol/L). The four region model for adsorbed layer microstructure of CPC on both minerals is also acquired from adsorption isotherm, in addition, further determined from fluorescence emission spectroscopy measurements.

Adsorption of acetyl halide molecules on the surface of pristine and Al-doped graphene: Ab initio study

We have scrutinized the adsorption energy, electronic structure, natural bond analysis (NBO), density of state (DOS) and global indices for adsorption of acetyl chloride (AC) and acetyl fluoride (AF) on the surface of pristine graphene as well as Al-doped graphene. The adsorption energies have been calculated for the most stable configurations of the molecules on the surface of pristine and Al-doped graphene. According to the calculated parameters, there is very weak physical adsorption of AC and AF on pristine graphene while strong adsorption takes place in the case of Al-doped graphene. The charge transfer from adsorbed molecules to Al-doped graphene surface was confirmed by the natural bond orbital as well as the Mulliken population analysis while there is no charge transfer with pristine graphene. Additionally, the density of states results reveal that orbital hybridization takes place between above-mentioned molecules and Al-doped graphene sheet, whereas there is no hybridization between the molecules and the pristine graphene. Our calculated adsorption energies for the most stable position configurations of AC and AF on Al-doped graphene were −68.8kJmol−1 (−52.6kJmol−1 BSSE corrected energy) and −78.4kJmol−1 (−64.3kJmol−1 BSSE corrected energy) which are correspond to chemisorptions process respectively. These results point to the appropriateness of Al-doped graphene as a powerful adsorbent for practical applications.

Adsorption of Methylene Fluoride and Methylene Chloride at the Surface of Ice under Tropospheric Conditions: A Grand Canonical Monte Carlo Simulation Study

The adsorption of two halogenated methane derivatives, namely, methylene fluoride and methylene chloride, at the surface of Ih ice is studied by grand canonical Monte Carlo simulations under tropospheric conditions. The adsorption isotherms of the two molecules, differing only in the halogen atom type, are found to be markedly different from each other. Thus, while methylene fluoride exhibits multilayer adsorption and its adsorption isotherm belongs to class II according to the IUPAC convention, methylene chloride does not show considerable adsorption at the ice surface, as its condensation well precedes the saturation of even the first adsorbed molecular layer. Interestingly, both the surface orientation and the binding energy of the two types of adsorbed molecules are rather similar to each other; first layer molecules form one single hydrogen bond with the dangling OH groups of the ice surface. The strong differences in the adsorption behavior of methylene fluoride and methylene chloride are traced bac...

Interaction of CNCl molecule and single-walled AlN nanotubes using DFT and TD-DFT calculations

Density functional theory (DFT) calculations are used to study the influence of cyanogen chloride (CNCl) adsorption over the geometrical and electronic properties of single-walled (5, 0), (8, 0), and (10, 0) AlN nanotubes as an adsorbent for adsorbate. It has been found that, the CNCl can be adsorbed on (5, 0), (8, 0), and (10, 0) AlN nanotubes with the energy values of −0.645, −0.493, −0.470eV, respectively. In addition, the effect of nanotube diameter over the charge transfer between the molecule and nanotube has been studied. Based on the DOS plots, interaction of CNCl over AlN nanotubes has slightly changed the electronic properties of the nanotubes, being insensitive to the adsorption of the CNCl molecule.

Avaliação do Processo de Salinização da Água na Microbacia do Rio Doce, São João da Barra-RJ, em Decorrência do Acidente Ambiental no Superporto do AçuRJ

The use of irrigation in agricultural crops is critical to ensure adequate productivity, especially in regions with water shortage and climate with well-defined rainy and dry seasons. This study aimed at analyzing the environmental accident in Deposit 4 of LLX Acu Operacoes Portuarias S.A., in November 2012, and assess the quality of water used for irrigation of farms in the Doce River watershed, Sao Joao da Barra, RJ, in March 2013. The samples were collected from 13 to 16 March 2013, and the analyses were performed at Laboratorio Campo, located in Paracatu-MG. The following parameters were analyzed: electrical conductivity (EC), chloride, sodium, calcium, magnesium and sodium adsorption ratio (SAR). During the environmental accident in Deposit 4, in November 2012, the EC of the Quitingute Water Channel reached the level of 42,000 µS/cm. However, in March 2013, the water of this channel showed no restrictions as to use in irrigation. The results of analyses of groundwater wells showed that approximately 11% of the samples were above the ideal EC and that none had restrictions on sodium danger according to the SAR classification.

In Situ Coherent Surface x-Ray Scattering Study of the Au (111) Surface Dynamics in Electrolytes: The Effect of Surface Reconstruction and Chloride Adsorption

It has long been conceived that in equilibrium electrode surfaces in contact with electrolytes remain highly dynamic, exhibiting steady processes such as detachment and adsorption of surface atoms. Importantly, some of those microstate fluctuations play an essential role on formation of surface structure and composition, and ultimately affect the functionality of electrodes. Surface-sensitive techniques, like STM and surface x-ray scattering (SXS), have become invaluable to unraveling electrode surface structures under changing electrochemical environments. Measurements on surface dynamics, however, remain challenging for electrochemical systems [[1]]. In this talk, we will report on the study of Au (111) surface dynamics by coherent surface x-ray scattering (CSXS). A brief introduction will be given for implementation of CSXS and ISXS for electrochemical studies. Time-resolved capability of CSXS will be highlighted. To elucidate factors that could influence surface dynamics, Au (111) electrode surfaces are systemically tailored by varying electrochemical conditions. Phase transition in Au (111) electrode surface had been well characterized by SXS, with structural changes that were shown to be both dependent on potentials and solution chemistry [[2]]. A sharp drop in x-ray scattering intensity around 0.12 V, shown in Fig. 1 (black curve), marks phase transition from (p x√3) to (1x1), which then can be reconstructed back to form a (p x√3) structure in a reverse potential scan. A similar potential dependence is found with increasing chloride concentration as shown in Fig. 1 (red curve). Careful comparison of the hysteresis loops, presented in Fig. 1, additionally reveals that chloride concentration influences the kinetics of phase transition in Au (111) surfaces. In additional to structural details, we have also attained some preliminary results on the dynamics of Au (111) surfaces from CSXS experiments. In the present work, surface dynamics are quantified in terms of correlation time, a parameter that describes the temporal separation between two configurations that are no longer resemble each other due to microstate fluctuations. Correlation time in relation to surface structure will be shown and discussed as a function of applied potential and chloride concentration. A comprehensive analysis on surface dynamics will be performed to help establish its relations with surface structure and solution chemistry. [1] M. Pierce, V. Komanicky, A. Barbour, D. C. Hennessy, C. Zhu, A. Sandy, H. You, Phys. Rev. B 86, 085410 (2012). [2] J. Wang, B.M. Ocko, A. J. Davenport, H. S. Isaacs, Phys. Rev. B 46 10321 (1992). Figure 1

On the Effects of Halides on the Hydrogen Peroxide Reduction Reaction in Aqueous Electrolytes

The influence of adsorbed species on the kinetics and mechanism of a number of redox reactions has been recognized for decades1. In particular, the adsorption of both chloride and bromide on Pt electrodes in acidic electrolytes, is known to promote the two-electron reduction of oxygen to peroxide instead of the desired four-electron reduction to water 2,3. This contribution seeks to gain insights into the reduction of H2O2 on a polycrystalline Pt electrode in 0.1 M HClO4 solutions containing a few ppm of either Cl- or Br-. The strategy employed makes use of a chronoamperometric method recently developed in our laboratories to determine independently, the effects of potential, E, and coverage of the adsorbate, q, on the peroxide reduction reaction on a Pt rotating disk electrode, RDE EXPERIMENTAL All measurements were performed in an all-glass, three-compartment cell in a 1 mM H2O2 in 0.1 M HClO4 solution either neat or containing 10 µM NaCl or 10 µM KBr. Experiments were performed with a rotating Pt ring-Pt disk electrode, Pt|Pt RRDE, (Pine Instruments, (A = 0.164 cm2) using a bipotentiostat (Pine Instruments). A Pt foil and a reversible hydrogenelectrode in the same solution (RHE) were used as counter and reference electrodes, respectively. RESULTS AND DISCUSSION Shown in Fig.1 are polarization curves recorded at a scan rate, ν = 10 mV/s for a Pt disk electrode in 0.1 M HClO4 containing 1 mM H2O2in the absence (black curve) and in the presence of either 10 mM NaCl or 10 μM KBr (red curve). In contrast to the rather subtle effects of chloride, the presence of bromide gives rise to a substantial, ca. 0.3 V, shift in the onset for peroxide reduction. Chronoamperometric curves, i.e. disk current, idisk vs time, obtained in upon stepping the potential from a value Eo, at which its coverage q is negligible 0, to a value Eads at which q attains a finite value are displayed in Fig. 2. The results of these experiments make it possible to correlate the disk current, i, as a function of Eads at fixed q, or as a function of q for a fixed Eadsas illustrated in Panels A and B in Fig. 3, respectively. Implications of these results on the effects of these impurities on the oxygen reduction reaction (ORR) will be discussed. ACKNOWLEDGEMENTS This work was supported by a grant from NSF (CHE-0911621). REFERENCES Marković, N. M.; Ross Jr, P. N., Surf. Sci. Reports 2002, 45, 117-229.Stamenkovic, V.; M. Markovic, N.; Ross Jr, P. N., J. Electroanal. Chem. 2001, 500, 44-51.Schmidt, T. J.; Paulus, U. A.; Gasteiger, H. A.; Behm, R. J., J. Electroanal. Chem. 2001, 508, 41-47. Figure 1

The impact of rice husk, activated carbon, almond shell, and sand filters on some physical and chemical properties of aqueous salt solution

In this study, the impact of rice husk, activated carbon, almond shell, and sand filters on some physical and chemical properties of saline water was investigated and compared. Salt solutions were collected downstream of columns filled with pure sand, sand plus rice husk, sand plus activated carbon, and sand plus almond shell, all with similar weights. The turbidity, water hardness, and the concentrations of chloride, sodium, potassium, magnesium, and calcium ions were measured over time. The results showed no effect of the pure sand on the adsorption of chloride (Cl−), calcium (Ca+), and magnesium (Mg+) ions. However, the highest adsorption of Ca+ (30.5%), Cl− (20%), and Mg+ (17.5%) ions and the maximum reduction of water hardness (23%) were achieved by passing saline water throughout a mixture of sand plus rice shell filters. The minimum adsorption of the ions was obtained with a mixture of sand plus almond shell filters. None of the filters had a significant impact on electrical conductivity of the saline water. In conclusion, combining sand filter with rice and almond shell filters were more effective in the desalinization of saline water.

Mechanisms of the hydration of A-300 aerosol with adsorbed chlorides of alkali metals in an organic medium

The hydration of systems obtained via the adsorption of alkali metal chlorides on A-300 nanosilica is studied by means of low-temperature 1H NMR spectroscopy. It is shown that in weakly polar organic media, adsorbed water is present in the form of weakly and strongly associated water. A reduction in the differentiation of adsorbed water in the SiO2/NaCl > SiO2/KCl > SiO2/LiCl series of composites is established that could be due to changes in the lattice parameters of SiO2. Quantum-chemical calculations are performed for the 1H NMR spectra of complexes containing clusters of Si8O12(OH)8 and hydrated ion pairs of alkali metal chlorides. These calculations allow us to explain the displacement in the chemical shifts of water protons.