Halide Concentration Research Articles

Biobased Polymers Enabling the Synthesis of Ultralong Silver Nanowires and Other Nanostructures.

Conventional polyol synthesis of silver nanowires has exclusively relied on polyvinylpyrrolidone (PVP), a nonbiodegradable polymer with no viable alternatives. The underlying reaction mechanism remains unclear. Herein, we discovered a new sustainable solution by employing biobased cellulose derivatives, including hydroxyethyl cellulose (HEC), as effective substitutes for PVP. Under mild reaction conditions (125 °C, ambient pressure), HEC facilitates the growth of ultralong silver nanowires (>100 μm) from penta-twinned silver seeds through a four-stage kinetic process. Theoretical calculations further reveal that HEC is physiosorbed onto the silver surfaces, while the presence of bromide ions (Br-) facilitates the evolution of seeds into nanowires. By varying halide ion concentrations and substitution in different cellulose derivatives, we successfully synthesized silver nanostructures with additional intriguing morphologies, including quasi-spherical nanoparticles, bipyramids, and nanocubes. Furthermore, transparent conductive films fabricated from ultralong silver nanowires synthesized with HEC demonstrated superior performance compared to those made with PVP-synthesized nanowires.

Geochemical Characteristics and Genesis of Brine Chemical Composition in Cambrian Carbonate-Dominated Succession in the Northeastern Region of Chongqing, Southwestern China

Deeply situated brine is abundant in rare metal minerals, possessing significant economic worth. To the authors’ knowledge, brine present within the Cambrian carbonate-dominated succession in the northeastern region of Chongqing, Southwestern China, has not been previously reported. In this investigation, brine samples were collected from an abandoned brine well, designated as Tianyi Well, for the purpose of analyzing the hydrochemical characteristics and geochemical evolution of the brine. Halide concentrations, associated ions, and their ionic ratios within the sampled brine were analyzed. The brine originating from the deep Cambrian aquifer was characterized by high salinity levels, with an average TDS value of 242 ± 11 g/L, and was dominated by a Na-Cl facies. The studied brine underwent a moderate degree of seawater evaporation, occurring between the saturation levels of gypsum and halite, accompanied by some halite dissolution. Compared to modern seawater evaporation, the depletion of Mg2+, HCO3−, and SO42− concentrations, along with the enrichment of Ca2+, Li+, K+, and Sr2+, is likely primarily attributed to water–rock interactions. These interactions include dolomitization, combination of halite dissolution, upwelling of lithium- and potassium-bearing groundwater, calcium sulfate precipitation, biological sulfate reduction (BSR), and the common ion effect within the brine system. This research offers valuable insights into the genesis of the brine within the Cambrian carbonate succession and provides theoretical backing for the development of brine resources in the future.

Superoxide radicals dominated hydrogen peroxide activation using BiOI for boosting Fenton-like catalytic degradation of bisphenol A

Herein, flower-like BiOI micro-spherulites were successfully prepared via a solvothermal method, and it exhibited a remarkably Fenton-like catalytic efficacy in the degradation of BPA under dark condition without additional energy input. BiOI can function as an electron-poor center, facilitating the activation of H2O2 into •O2−, while simultaneously serving as an electron-rich center to reduce dissolved O2 to •O2−. This electron-rich and electron-poor centers of BiOI synergistically enhance the •O2− generation for highly Fenton-like catalytic performance. Moreover, the removal performance of BPA demonstrated a significant pH dependency, and the presence of low concentrations of halide ions and humic acid did not exhibit noticeable inhibitory effect on the degradation of BPA. Additionally, several intermediates have been identified to propose a comprehensive degradation mechanism for BPA. This study presents a novel BiOI Fenton-like catalytic system for the purification of recalcitrant organic pollutants in wastewater.

Optimizing removal of elemental mercury from flue gas using halide‐impregnated red mud

AbstractMercury (Hg0) emission from coal‐fired industrial plants poses severe threats to ecosystem sustainability and human health, urging the development of novel and cost‐effective adsorbents to treat industrial flue gas. Herein, the modification of industrial residual red mud (RM) through the impregnation of hydrogen halides (HH) and its adsorption characteristics for removing elemental mercury from combustion flue gas was reported. Experimental investigation of HH‐modified RM reveals that the hydrogen iodide (HI)‐modified RM with a concentration of 1.5 M had a maximum Hg0 removal efficiency of 98%, whereas hydrogen bromide (HBr) 1.5 M modified RM had a maximum Hg0 removal efficiency of 90%. The effect of various parameters, such as reaction temperature and halide concentrations, were also found to be influential for the adsorption efficiency of the modified RM. Moreover, it is important to highlight the chemisorption characteristics of HI‐modified RM, which significantly enhances the efficiency of the removal process. The Hg0 removal efficiency increases with the increase in HI concentration (1.5 M @ 93%) with an optimal reaction temperature of 140°C. Furthermore, the maximum Hg0 removal attained with a change in NO concentration was 98% at 200 ppm. However, increasing the SO2 concentration reduces the efficiency of RM for removing Hg0 in simulated coal combustion flue gas. The pseudo‐second‐order model (R2 = 0.98) accurately describes the adsorption of in kinetic investigations, indicating a chemisorption mechanism. This analysis of the chemisorption mechanism highlights the efficiency of halide‐modified industrial solid waste, which has the potential to be used in the design of economical and innovative adsorbents for reducing environmental pollution. The present study employed specific reaction parameters such as reaction temperature, halide loading contents, and different flue gas compositions, which had not been extensively explored.

Unintended polyhalogenated carbazole production during advanced oxidation of coking wastewater

Polyhalogenated carbazoles (PHCZs) are emerging as dioxin-like global pollutants, yet their environmental origins are not fully understood. This study investigates the application of the Fenton process in coking wastewater treatment, focusing on its dual role in carbazole removal and unintended PHCZ formation. The common halide ions (Cl– and Br–) in coking wastewater, especially Br– ions, exerted a notable impact on carbazole removal. Particularly, the influence of Br– ions was more significant, not only enhancing carbazole removal but also shaping the congener composition of PHCZ formation. Elevated halide ion concentrations were associated with the heightened formation of higher halogenated carbazoles. The Fenton reagent dosage ratio was identified as a crucial factor affecting the congener composition of PHCZs and their toxic equivalency value. The coexisting organic substance (i.e., phenol) in coking wastewater was observed to inhibit PHCZ formation, likely through competitive reactions with carbazole. Intriguingly, ammonium (NH4+) facilitated the generation of higher and mixed halogenated carbazoles, possibly due to the generation of nitrogen-containing brominating agents with stronger bromination capacity. This study underscores the importance of a comprehensive assessment, considering both substrate removal and potential byproduct formation, when employing the Fenton process for saline wastewater treatment.

Halides doping in the shallow lattice of BiOBr nanosheets promoting photocatalytic degradation of organic contaminants

The Br− in crystal structure of BiOBr are easily doped by other halides. However, the effect of halides doping degree on the photocatalytic performances of BiOBr is barely known. Herein, the halides (X’=Cl, I) doping degree in BiOBr (X’-BiOBr) nanosheets were regulated by altering the molar concentration of doped halides. The lower concentration of halides was doped into the shallow lattice of BiOBr, while excessive halides were doped into its deep lattices. The doped halides in shallow lattices of BiOBr modified band structure, contributing to efficient charge separation for promoted photodegradation of organic contaminants. Particularly, X’-BiOBr with halides doping in the shallow lattice exhibited superior photocatalytic activities.

Ultrafast adsorption of hexavalent chromium from aqueous effluents using covalent triazine frameworks

We have synthesized low-cost high performance covalent triazine framework (CTF) through Schiff base reaction of melamine and terephthalaldehyde with different proportions of the reactants. The synthesized adsorbents showed excellent capacity for adsorption of Cr (VI) at acidic pH while almost negligible adsorption at higher pH. The adsorbent displays excellent reusability, with a little decrease in adsorption capacity with the increasing number of cycles. Moreover, Cr (VI) the adsorption is unaffected by the presence of 50–500 times higher concentration of alkali metal and halide ions in solution, while sulphate ions demonstrate shielding behavior decreasing the adsorption capacity. Mechanistic studies indicate electrostatic attractions, ion exchange and reduction being responsible for the adsorption mediated by abundant nitrogen sites that also imbibes the adsorbent with high capacity. The adsorbent was also utilized to recover chromium from an industrial electroplating effluent, which demonstrates applicability of material for practical applications.

Distinguishing between Linear and Non-Linear (Cooperative) Substrate Activation Mechanisms in the Sonogashira Reaction under “Ligand-Free” and “Copper-Free” Conditions

The results are presented on the comparative studies of the differential selectivity patterns in the Sonogashira reaction with a pair of competing aryl acetylenes in the “ligand-free” and “copper-free” conditions when varying the nature and concentration of aryl halides and base. The revealed sensitivity of the differential selectivity of competing aryl acetylenes to aryl halide nature unambiguously indicated that the substrates were activated through linear mechanism from kinetic view. An absence of any influence of the nature and concentration of the base on the differential selectivity of competing aryl acetylenes indicated the irreversible character of the step of their activation.

Influence of ionic size on the optical and thermodynamical properties of chitosan based polymer composites with different ammonium halides

The biopolymer chitosan has been dissolved with 1% of acetic acid and the same has been embedded with different salts of ammonium halides like NH4F, NH4Cl, NH4Br, and NH4I with different concentrations to make the composites. The density, refractive index, and ultrasonic velocity of the said composite materials were measured and the space-filling factor along with polarizability and dielectric constant is obtained from refractive index data. From the refractive index data, the parameters like dielectric constant(ε), polarizability(α), and space-filling factor are calculated and from the ultrasonic velocity, the thermodynamical properties like relaxation strength (r s), acoustic impedance (Z), adiabatic compressibility (βs), intermolecular free length (Lf) and surface tension (σ) were calculated. The ultrasonic velocity of chitosan solution is 1515 ms− 1. The addition of ammonium halides leads to increase in ultrasonic velocity. The intermolecular free length (Lf), adiabatic compressibility (βs), and relaxation strength (r s) are decreasing and all other parameters are increasing with respect to ionic size and concentration of ammonium halides. All the results are analyzed and discussed with respect to the ionic size of the ammonium salts and concentrations.

Migrating 1H NMR peaks in the benzylation of adenine reveal the disruptive Kornblum oxidation in DMSO

AbstractThe alkylation of adenine using alkyl halides under basic conditions in dimethyl sulfoxide (DMSO), a common reaction to achieve N9‐alkylated adenine derivatives, is often low yielding with unreacted adenine and complicated reaction mixtures. Herein, we report the reaction monitoring of the alkylation of adenine in DMSO in the presence of NaH using benzylic halides via real‐time 1H NMR spectroscopy. NMR analysis revealed that under these generally used reaction conditions, the adeninate anion starting material is protonated as the anionic nucleophile abstracts a labile proton from an alkoxy sulfonium ion intermediate formed via the Kornblum oxidation reaction. To prevent the protonation of the adeninate anion, the reaction was performed in the presence of a mop‐up base DBU. Simultaneously increasing the concentration of the alkyl halide and the mop‐up base in a 1:1 ratio resulted in a complete reaction; however, increasing the temperature of the reaction promoted depletion of the starting material by protonation and hence reduced conversion to products. This result implies that heating of such electrophiles in DMSO should be avoided. The addition of a mop‐up base can help resolve the complication of protonation arising from the Kornblum oxidation reaction in alkylation reactions under similar conditions.

Mechanistic Insight for Disinfection Byproduct Formation Potential of Peracetic Acid and Performic Acid in Halide-Containing Water.

Peracetic acid (PAA) and performic acid (PFA) are two major peroxyacid (POA) oxidants of growing usage. This study reports the first systematic evaluation of PAA, PFA, and chlorine for their disinfection byproduct (DBP) formation potential in wastewater with or without high halide (i.e., bromide or iodide) concentrations. Compared with chlorine, DBP formation by PAA and PFA was minimal in regular wastewater. However, during 24 h disinfection of saline wastewater, PAA surprisingly produced more brominated and iodinated DBPs than chlorine, while PFA effectively kept all tested DBPs at bay. To understand these phenomena, a kinetic model was developed based on the literature and an additional kinetic investigation of POA decay and DBP (e.g., bromate, iodate, and iodophenol) generation in the POA/halide systems. The results show that PFA not only oxidizes halides 4-5 times faster than PAA to the corresponding HOBr or HOI but also efficiently oxidizes HOI/IO- to IO3-, thereby mitigating iodinated DBP formation. Additionally, PFA's rapid self-decay and slow release of H2O2 limit the HOBr level over the long-term oxidation in bromide-containing water. For saline water, this paper reveals the DBP formation potential of PAA and identifies PFA as an alternative to minimize DBPs. The new kinetic model is useful to optimize oxidant selection and elucidate involved DBP chemistry.

Impact-sliding fretting tribocorrosion behavior of 316L stainless steel in solution with different halide concentrations

Impact-sliding caused by random vibrations between tubes and supports can affect the operation of heat exchangers. In addition, a corrosive environment can cause damage, accelerating the synergism of corrosion and wear. Therefore, the focus of this work was the impact-sliding fretting tribocorrosion behavior of 316L heat exchanger tubes at different halide concentrations. A device system incorporating the in situ electrochemical measurements of impact-sliding fretting corrosion wear was constructed, and experiments on 316L heat exchanger tubes in sodium chloride (NaCl) solution with different concentrations (0.0, 0.1, 0.5, 1.0, 3.5, and 5.0 wt%) were carried out. The synergism between wear and corrosion was also calculated and analyzed. The wear and damage mechanisms were elucidated by correlating the corrosion-wear synergism, morphologies, and material loss rates. The results indicated that the stable wear stage occurred at approximately 9–12 h, after which the corrosion current increased with the expansion of the wear area. As the halide concentration increased, the scale of damage on the wear scars gradually decreased, changing from being dominated by cracks, delaminations, and grooves to being dominated by scratches, microgrooves, and holes. There was an obvious positive synergism between wear and corrosion. The material loss was dominated by pure mechanical wear and wear enhanced by corrosion, but corrosion enhanced by wear contributed more than tangential sliding fretting corrosion. The total mass loss increased gradually in the range of 0.0–0.5 wt% and decreased in the range of 0.5–5.0 wt%. Large-scale damage enhanced by corrosivity and small-scale damage reduced by lubricity dominated the material loss at low and high concentrations, respectively.

Uranium(VI) adsorption from carbonate solutions using cetyltrimethylammonium bromide modified purified-bentonite-MOF composite

A novel cetyltrimethylammonium bromide (CTABr) modified purified-bentonite (p-Bent)-MOF composite (CTABr/p-Bent-Co2(OH)2BDC) was first prepared to study the uranium(VI) adsorption from a variety of carbonate solutions. The experiments showed that at pH 8.0, the high concentration of carbonates and halides significantly suppressed the UVI adsorption. Compared with Co2(OH)2BDC (4.3 ± 0.9 mg·g−1), p-Bent (47.2 ± 3.7 mg·g−1), and CTABr/p-Bent (104.8 ± 0.8 mg·g−1), this ternary composite achieved an improved adsorption capacity of 111.7 ± 1.4 mg·g−1. The XPS spectra and DFT calculations indicated that carbonates and halides can compete for free uranyl ions with the –COOH and –OH groups on the composite surface. Particularly, CO32− and F− can inhibit the UVI adsorption from carbonate solutions by forming uranyl carbonates and uranyl fluorides. The Br− anion exchange and electrostatic attraction were demonstrated to be the dominant mechanisms for UVI adsorption on the composite, together with the –COOH/–OH complexation. This work presents a feasible strategy to prepare new clay-based multicomponent composites for extracting uranium from carbonate solutions, and provides new insight into the understanding of uranium adsorption in natural waters.

Alkali Halide and MIBC Interaction at Typical Flotation Interfaces in Saline Water as Determined by Molecular Dynamics Simulations

The molecular structure of the liquid–vapor interfaces of aqueous solutions of alkali metal halides and methyl isobutyl carbinol (MIBC, (CH3)2CHCH2COCH3) is determined by using molecular dynamics simulations with polarizable force fields for the first time. The salts are chlorides, and iodides, some of which are found in raw and partially desalinated seawater increasingly used in flotation operations in regions affected by severe and prolonged drought. The density profiles at the interfaces show that all ions prefer the interface; however, with MIBC, non-polarizable ions, generally small ones, are increasingly pushed into the liquid bulk. A few ions of comparatively less ionic NaCl than KCl and CsCl, persist at the interface, consistent with spectroscopy observations. On the other hand, strongly polarizable ions such as I− always share the interface with MIBC. In the presence of chlorides, the frother chains at the interface stretch slightly more toward vapor than in freshwater; however, in the presence of iodides, the chains stretch so much that they become orthogonal to the interface, giving rise to a well-packed monolayer, which is the most effective configuration. The dominant water configurations at the interface are double donor and single donor, with hydrogen atoms pointing toward the liquid, consistent with studies with sum-frequency generation experiments and extensive ab initio simulations. This picture changes radically in the presence of MIBC and salts. Depending on the halide and MIBC concentration, the different molecular configurations at the interface lead to very different surface tensions. The structure and properties of these new salt-rich interfaces and their impact on the location and arrangement of frother molecules should serve the flotation practitioner, especially in the search for the best frother and dosing in poor-quality water.

Chrono-colorimetric sensor array for detection and discrimination of halide ions using an all-in-one plasmonic sensor element

Most nanoparticle based colorimetric sensor array utilize several sensor elements and static response for discrimination of target analytes. This approach can be complicated and costly to synthesize or functionalize different nanoparticles for providing wide color variation. Herein, triangular silver nanoparticles (TSNPs) were used to develop a colorimetric sensor array by time-dimension responses. The principle of this sensor array is based on the diverse etching process of TSNPs in the presence of three halide ions, including bromide (Br−), iodide (I−) and chloride (Cl−). Various etchings of TSNPs induced color changes at different reaction time intervals, which produced a colorimetric pattern for each ion. Therefore, using time dependent etching responses of TSNPs as a single sensing component can produce a wide color variation which can be distinguished by naked eyes. The colorimetric responses of TSNPs upon the addition of different concentrations of halide ions have been analyzed by PLS regression (PLS-R) and PLS discriminant analysis (PLS-DA). The analytical figures of merit confirmed that the developed chrono-colorimetric TSNPs -based sensor array is successful in both the discrimination and quantitative detection of halide ions. At the final step, the three halide ions were accurately determined in a real water sample, which verified the potential of the developed sensor in a real sample.

Technologies for Halide Removal in Water Treatment – A State-of-the-Art Review

Halides (X=Cl, Br, I) are naturally present in water, and halide concentrations can be high in water sources that are impacted by high salinity. Halides are also present in wastewater streams from various industrial operations such as pulp and paper, oil and gas, and mining. Drinking water guideline limits have been established for halides, and halide removal from water is important in several ways. Chloride concentration in water is more related to salinity, and its removal from water matters because of adverse health effects, water scarcity, corrosion, and industrial needs. In drinking water treatment, disinfection is essential to improve water quality and prevent the spread of water born pathogens. However, disinfectants also produce harmful disinfection by-products (DBPs) from precursors such as halides and natural organic matter (NOM) in the source water. Removing halides in the source water before disinfection is a preferred option to increase the disinfection efficiency and avoid forming more toxic DBPs. Some industrial-made isotopes are radioactive and carcinogenic, and iodide produces iodinated DBPs. Bromide removal is important because it produces brominated DBPs. Halides also affect AOPs and can cause more active radicals such as OH. and SO4-. to transform into less active radicals. This paper aims to comprehensively review the sources of halides, the chemistry, and interaction in forming DBPs, current regulatory limits and state-of-art removal technologies available, and their challenges.

Heterovalent Tin Alloying in Layered MA3Sb2I9 Thin Films: Assessing the Origin of Enhanced Absorption and Self-Stabilizing Charge States

Heteroatom alloying of lead-free perovskite derivatives is a highly promising route to tailor their optoelectronic properties and stability for multiple applications. Here, we demonstrate the facile solution-based synthesis of Sn-alloyed layered MA3Sb2I9 thin films by precursor engineering, combining acetate and halide salts. An increasing concentration of tin halides in different oxidation states leads to a strong boost in absorption over the whole visible spectrum. We demonstrate phase-pure synthesis and elucidate the heterovalent incorporation of Sn into the MA3Sb2I9 lattice, proving the formation of additional electronic states in the bandgap by theoretical calculations. On this basis, we dissect the strong absorption increase into three components that we attribute to intervalence and heteroatom-induced interband absorption. Finally, we show the charge-stabilizing effect of the system through robustness toward precursors in mixed oxidation states and trace the improved ambient stability of this material back to this feature.

Mineralogy optimization for immobilization of potentially toxic elements and halides in Co-disposed flue gas desulfurization brines and bituminous coal fly ash

• Co-disposal of flue gas desulfurization wastewater brine and bituminous coal fly ash. • Zero liquid discharge through solidification/stabilization. • Contaminants encapsulation through mineralogy optimization. • Aluminate addition enhances the formation of Friedel's salt. • Gypsum addition enhances the formation of ettringite. The flue gas desulfurization (FGD) wastewater and coal fly ash (CFA) are waste products containing potentially toxic elements (PTEs) and halides of environmental concerns. A novel co-disposal strategy for these two wastes is a zero-liquid-discharge (ZLD) method which treats the concentrated FGD brine via a solidification/stabilization (S/S) process using CFA and alkaline additives. The objective of this study was to improve PTE and halide immobilization of this ZLD method by optimizing the mineralogy of the S/S solids in co-disposed FGD brines and bituminous CFA. The formation of Friedel's salt, which is critical in binding oxyanions and halides, was specifically evaluated. Various mixtures of FGD brines, CFA, and alkaline additives were systematically tested and the formed S/S solids were evaluated by long-term leaching tests and quantitative X-ray diffraction (QXRD) analyses. Addition of reactive aluminate (2.5 % by weight) and lime (10% by weight) yielded S/S solids with enhanced formation of Friedel's salt by up to 23%, which were able to retain the majority of selenate (>90%), arsenate (>99%), chromate (>99%) and chloride (>50%) from the brine after nine weeks of leaching tests. Comparatively, addition of gypsum promoted the formation of ettringite, which only enhanced the immobilization of borate, but not selenate and chloride. The hydraulic conductivity of the S/S solids was another important factor for contaminant leaching, because it could affect the stability of Friedel's salt under the leaching conditions and governed the immobilization of halides since the halide concentration from the brine exceeded the binding capacity of formed Friedel's salt.

Large volume and oxygen tolerant photoinduced aqueous atom transfer radical polymerization

We scaled up the aqueous photoinduced ICAR (PICAR) ATRP of acrylamide (AAm), with a scale-up factor of 400, from Vi = 5.0 mL to Vf = 2.0 L. Relatively large mixtures can be polymerized by 395 nm light, up to very high conversions while maintaining a narrow molecular weight distributions, in the presence of sodium pyruvate, which acts as both reactive oxygen species scavenger and exciter for [CuIL]+ (re)generation. The best reactions conditions were determined by analyzing the buffer strength, halide source nature and concentration, light wavelength, catalyst concentration, sodium pyruvate concentration, and initiator type. PICAR ATRP was successfully applied as well to other hydrophilic monomers besides AAm. The reaction progress could be monitored online via electrochemical methods. The best small-scale reaction was then scaled up with AAm to 40, 250, 500, 1000 and 2000 mL. The estimated crude cost of polyacrylamide (PAAm) and the reagent cost of the reaction mixture revealed that PICAR ATRP is feasible at large scale.

Lead Halide Perovskite Cube Coupled Star Nanocrystal Photocatalysts

Ligand dynamics on the surface of nanocrystals plays a major role in controlling their successive layers growth. This has been widely established for chalcogenide nanomaterials but less explored for recently emerged halide perovskite nanocrystals. However, with the introduction of different non-lead metal (Cd and Mn) acetates/oxides to limit surface halide concentration and alkylammonium ion ligands, herein, star shaped cube coupled nanocrystals are reported, and their growth from less than 50 nm to nearly 500 nm is monitored. These acetates/oxides helped in inducing secondary growth along one of the {200} facets of parent orthorhombic CsPbBr3 cube nanocrystals and led to the unique star shaped nanocrystals which consumed smaller size cube nanocrystals and continued to grow further. The method is also extended to CsPbCl3 nanocrystals. Due to complex shapes, these are further explored as photocatalysts for CH4 and CO evolution under purging CO2 gas in ethyl acetate/water medium, and their catalytic activities are compared with cube nanocrystals.