Sulfite Research Articles

Effect of organic acid additives on sulfite oxidation in a calcium-based slurry

The forced oxidation of sulfite ions was conducted to obtain high-quality gypsum in the flue gas desulfurization system. The effects of formic, lactic, acrylic, acetic, propionic, and hexanoic acids added to calcium-based slurry on sulfite oxidation were investigated in this study. Sulfite oxidation was inhibited when the pKa value of organic acids was small or the carbon chain was long. In the identical slurry pH 6, the SO4 2- fractions of slurries with formic and lactic acids, which have the smallest pKa values, were lower than half that of the additive-free slurry. The addition of hexanoic acid with the longest carbon chain showed a similar SO4 2- fraction to that of additive-free slurry. These results indicate that the inhibitory effect on sulfite oxidation is more expressed by the acidity of organic acids. The SO4 2- fraction in the slurry affects the growth and quality of gypsum crystals. The slurry with acetic acid presented the highest SO4 2- fraction and resulted in the formation of high-quality gypsum crystals. The findings of this study can contribute to the selection of organic acid additives with high desulfurization efficiency and the production of high-quality gypsum.

Modulating the intrinsic fluorescence properties of amoxicillin by sulfur nanodot-based nanoreactor for its direct fluorescence detection

Direct fluorescence detection of amoxicillin (AMX) is highly desired for food and environment safety but remains a formidable challenge because of its low conjugation degree and stabilization effects on excitons. In this work, we proposed a direct fluorometry for AMX through modulating its fluorescence properties by utilizing sulfur nanodots (S-dots) as nanoreactors. S-dots provided both confined carrier and reactants (polyethylene glycol (PEG) and sulfite ions) to modulate the fluorescence properties of AMX, achieving a 277-fold increase on the fluorescence intensities. PEG and SO32- interacted with AMX through both covalent and hydrogen bounds, which stabilized the excited states, decreased the chances of nonradiative path and activated the radiative decay. The ultrasmall sized S-dots also provided confinement carries for promoting the reactivity between AMX and surface function groups. Quantitative detection of AMX in commercial milk samples was realized through direct recording the fluorescence signals, achieving a limit of detection of 159 nM. The reported results provided a new idea to design fluorescence assays for extremely weak emissive molecules, showing great potential in food safety analysis, environmental and healthy monitoring.

Facile, sustainable, and innovative inclusion of a highly fluorescent isoindole-sulfonate-based probe for the quantification of fluvoxamine, a CNS antidepressant drug; comprehensive method sustainability evaluation

The suggested study employs a specific technique to ensure the sustainability and ecological friendliness of an analyte evaluation procedure. The utilization of various recently developed methodologies as potential indicators of ecological sustainability and feasibility necessitates attention and consideration. The established analytical methodology employs a novel reagent mixture composed of phthalic dialdehyde and sulfite ion. This reagent is used to create a new fluorescent core that can be monitored using fluorimetric techniques at a wavelength of 385 nm after being excited at 320 nm. Condensation of the amino group of fluvoxamine can occur in a pH-controlled solution containing phthalaldehyde/sulfite. The present investigation presents a new, environmentally sustainable, and accurate fluorometric technique for identifying the medication. A linear relationship was detected for fluvoxamine over the 0.06–1.50 μg mL−1 concentration range. The method's validation and quantum yield determination were assessed following the International Council for Harmonization's (I.C.H.) established guidelines. The results exhibit remarkable precision and accuracy, consistent with the different methodologies published in the literature. Subsequently, an assessment was conducted to evaluate the environmental sustainability of the suggested technique, employing a range of contemporary indicators for determining environmental safety. The WAC concept, which combines ecological and operational elements and makes use of the Green/Red/Blue (RGB 12) scheme, interestingly identifies the current analytical method as white. Finally, BAGI, a novel tool for evaluating the method's applicability, was used in this study and showed that the planned method achieved a high applicability score.

304L Austenitic Stainless Steel Corrosion Studies in Neutral Environment in Presence of Sulfite Ions

Abstract This paper examined the influence of the sulfite concentration introduced in the electrolyte added to the neutral solution (1 mol L-1 Na2SO4) on the corrosion process of 304L stainless steel material. 304L. The accelerated effect of sulfite ions under corrosion rate of 304L austenitic stainless steel was demonstrated using electrochemical techniques such as linear sweep voltammetry at a low scan rate −1 mV s−1, the Tafel slope method, chronoamperometry, and electrochemical impedance spectroscopy. Electrochemical studies were conducted using a BioLogic SP150 potentiostat/galvanostat. Stainless steels are the most varied and intricate group among all steels. Among them, 304L austenitic stainless steel is one of the most commonly utilized alloys, prized for its excellent corrosion resistance and strength, hygienic and aesthetic properties, affordability, good formability, and effective weldability. [1-3]. In modern industry, the amount of austenitic stainless steel represents only about 2% of the total steel production manufactured globally. This type of steel is commonly employed in chemical engineering, metal extraction, desalination and wastewater treatment plants, the oil and gas sector, transportation and aerospace industries, the food and beverage sector, as well as in architecture and construction engineering. [1].

53074 The usefulness of skin prick and patch testing for local anesthetics in clinical practice for patients with sulfite allergy

53074 The usefulness of skin prick and patch testing for local anesthetics in clinical practice for patients with sulfite allergy

A simple and efficient chemodosimeter for colorimetric and “turn-on” fluorescent detection of sulphite in aqueous solution

Described in this article the design and synthesis of a simple fluorogenic and chromogenic chemodosimeter C for sensitive and selective detection of sulphite via the 1,4-Michael addition reaction. This chemodosimeter demonstrated high SO32− selectivity over other twenty-three competitive analytes in ∼100 % aqueous solution. Chemodosimeter C revealed a 35-fold “turn-on” fluorescence enhancement towards sulphite ions, as well as fluorometric color change from colorless to cyan. The chemodosimeters’ detection limit for sulphite ions was determined to be 0.782 µM. The sensing mechanism was established using 1H NMR titration, HRMS, and theoretical calculations. Additionally, convenient chemodosimeter C-based test strips and C-treated silica gel were developed for rapid on-site visual detection of sulphite ions.

Electrochemical detection of sulfite using gold nanoparticles decorated poly[2-(methacryloyloxy) ethyl] trimethylammonium chloride: kinetic and mechanistic studies

Abstract Given the widespread use of sulfites in various industries and their potential environmental and health impacts, accurate and efficient detection is crucial. The deployment of positively charged poly [2-(methacryloyloxy) ethyl] trimethylammonium chloride (PMTC) decorated with gold nanoparticles (AuNPs) offers a novel approach, enhancing sensitivity and specificity in the electrochemical detection of negatively charged sulfite ions (SO32-). A sensor for detecting SO32- was developed using PMTC decorated with AuNPs on a glassy carbon electrode (GCE). Transmission electron microscopy (TEM) was employed to examine the structural morphology of the composite material, and the formation of AuNPs was confirmed through ultraviolet-visible spectroscopy. Zeta potential analysis affirmed the positive charge of the PMTC composite, highlighting its effective coordination with the negatively charged SO32-. The surface conductivity of the modified GCE was studied using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Kinetic analyses, focusing on scan rate and pH dependencies, elucidated the SO32- oxidation dynamics and the interaction between the positively charged PMTC and negatively charged SO32-. Quantitative evaluation was performed using the current-time (I-t) technique, achieving a limit of detection of 0.41 ± 0.003 µM (S/N = 3) within a linear range of 6.66 µM to 1020 µM. The modified electrode demonstrated remarkable stability, repeatability, and resistance to common interferents. Real sample analysis using laboratory tap water with a fixed SO32- concentration exhibited excellent recovery. The oxidation of SO32- on the AuNPs-PMTC-GCE proceeded via first-order kinetics and followed a stepwise pathway facilitated by the charge interactions.

Enhanced Electrocatalysis on Copper Nanostructures: Role of the Oxidation State in Sulfite Oxidation.

The influence of surface morphology and the oxidation state on the electrocatalytic activity of nanostructured electrodes is well recognized, yet disentangling their individual roles in specific reactions remains challenging. Here, we investigated the electrooxidation of sulfite ions in an alkaline environment using cyclic voltammetry on copper oxide nanostructured electrodes with different oxidation states and morphologies but with similar active areas. To this aim, we synthesized nanostructured Cu films made of nanoparticles or nanorods on top of glassy carbon electrodes. Our findings showed an enhanced sensitivity and a lower detection threshold when utilizing Cu(I) over Cu(II). Density functional theory-based thermochemical analysis revealed the underlying oxidation mechanism, indicating that while the energy gain associated with the process is comparable for both oxide surfaces, the desorption energy barrier for the resulting sulfate molecules is three times higher on Cu(II). This becomes the limiting step of the reaction kinetics and diminishes the overall electrooxidation efficiency. Our proposed mechanism relies on the tautomerization of hydroxyl groups confined on the surface of Cu-based electrodes. This mechanism might be applicable to electrochemical reactions involving other sulfur compounds that hold technological significance.

Sulfite ion and gold (111) surface interaction mechanism

The interaction of a sulfite ion (SO32−) with the Au (111) surface has been studied using density functional theory. The results of the geometry optimization, the charge density distribution, and the density of states showed that sulfite ions exhibit a strong interaction with the Au (111) surface atoms, and they are adsorbed by forming a strong ionic bond that leads to the rearrangement of Au surface atoms. Consequently, this interaction leads to a charge transfer from the sulfite ion to Au surface atoms. The results proved a change in the geometry of the adsorbed sulfite ion, but it is not degraded on the gold surface because of the covalent bonds between sulfur and oxygen atoms.

Synthesis study of size-controlled rhenium nanoparticle systems using reverse micelle-based methodologies

In this study, rhenium nanoparticles were successfully synthesized with precise size control using a water-in-oil microemulsion method under an ambient atmosphere. Spectroscopic characterization using UV-Vis and ESI-MS techniques was used to study the stability of the rhenium(IV) precursor and verify its reduction into rhenium-based nanoparticles. The morphology and size of the rhenium nanoparticles were examined using HR-TEM. The results indicate formation of amorphous rhenium nanoparticles with an average size of 2.2 nm at a water-to-surfactant concentration ratio (W factor) of 10. These rhenium nanoparticles also have good size-stability compared to rhenium colloids generated in water alone. After one week, the particle diameter increased by only 0.6 nm with no evidence of aggregation. An investigation into the effect of various factors on the size and size distribution of the rhenium nanoparticles indicate that the W factor is the most influential parameter (among the considered factors) for size tuning, given that increases in W led to bigger and more polydisperse particles. Additionally, the microemulsion surfactant (AOT) protects the rhenium nanoparticles from their natural tendency to oxidize to perrhenate ion under an air atmosphere. However, a significant consideration in the use of AOT is the previously unreported presence of a chemical impurity which is able to reduce the rhenium(IV) precursor salt and generate rhenium nanoparticles within these microemulsion systems. Our investigation found that this impurity is the sulfite ion which is most likely introduced during manufacturing.

UV/Sulfite reduction kinetics of perfluorobutane sulfonic acid (PFBS), perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA)

Reduction of persistent perfluorinated compounds (PFCs) by UV-activated sulfite (SF) has been recognized as one of the most effective advanced reduction processes (ARPs). With the UV/SF ARP, PFBS degradation reached 66.6 % at 25 °C after 6 h, while PFOS and PFOA were completely degraded within 80 and 20 mins, respectively. PFOA has the largest defluorination efficiency of 77.5 %, greater than 57.8 % for PFOS and 42.7 % for PFBS after 6 h. With the UV/SF system operated at 15, 25, 35 and 45 °C, activation energy (Ea) of PFBS defluorination was determined to be 360.8 kJ/mol, larger than those of PFOS and PFOA (319.4 and 67.3 kJ/mol, respectively), which implies that PFBS is more persistent and difficult to be degraded in the natural environment. Based on the consumption of SF, secondary-order kinetics models were developed to describe the degradation and defluorination of PFBS, PFOS, and PFOA at various reaction times. Concentrations of various intermediate species were determined by liquid chromatography quadrupole time-of-flight mass spectrometry (LC/QTOF-MS) during the PFBS degradation to investigate the reaction pathways in the UV/SF ARP. The proposed reaction mechanisms for PFBS degradation include desulfonation, H/F exchange, and chain shortening via direct C − C bond cleavage.

Spatial Confinement of Co Nanoparticles in N-Doped Carbon Nanorods for Wastewater Purification via CaSO3 Activation.

Spatial confinement of organic pollutants and reactive oxygen species (e.g., SO4•- and •OH) with ultrashort lifetime inside the scale of chemical theoretical diffusion could provide a greatly promising strategy to overcome the limitation of mass transfer in the heterogeneous Fenton-like oxidation process. Herein, we first reported spatial confinement of cobalt nanoparticles in N-doped carbon nanorods (Co-NCNRs), by encapsulating Co nanoparticles into N-doped carbon nanorods, in activating CaSO3 for antibiotic degradation. Compared to Na2SO3 and NaHSO3, CaSO3 could slowly and persistently discharge SO32- due to its low solubility, thus avoiding the depletion of the generated SO3•- and •OH under the high concentration of sulfite ions. Fully physical characterizations confirmed that the 3D hydrogel was mostly transformed into the nanorod structure of Co-NCNRs at 550 °C. Co atoms were successfully nanoconfined into N-doped carbon nanorods, which contributes to mass transfer and prevents the agglomeration of Co nanoparticles, thus enhancing its catalytic activity and stability in activating CaSO3 for water decontamination. The catalytic performance, kinetic research, influences of inorganic anions, pH, and degradation mechanism of chlortetracycline degradation catalyzed by the Co-NCNRs/CaSO3 system have been studied in detail. This work not only proposed a facile method for synthesis of nanoconfined catalyst but also provided an excellent Co-NCNRs/CaSO3 system for wastewater treatment.

Dual detection and quantification of hypochlorite and sulfite ions via SERS spectroscopy by utilizing the redox reaction of tetramethylbenzidine

We developed a highly efficient, ultra-sensitive, and selective dual detection sensor for hypochlorite (ClO–) and sulfite (SO32–) ions based on surface-enhanced Raman scattering (SERS) spectroscopy. 3,3′,5,5′-Tetramethylbenzidine (TMB) is oxidized by ClO– under acidic conditions to diazotized oxTMB that, when electrostatically adsorbed onto Au nanoparticles (NPs), produces a strong Raman signal at 1605 cm−1. Meanwhile, oxTMB is reduced to TMB by SO32–, which significantly reduces the Raman signal. The linear detection range of the proposed sensor is 10–10 to 10–6 M with a detection limit of 59 pM for ClO– and 10–9 to 10–5 M with a detection limit of 5.4 nM for SO32–. In addition, the sensor was successfully applied to detect ClO– and SO32– in water samples.

Background-Free and Reversible Upconversion Hydrogel Sensing Platform for Visual Monitoring of Sulfite.

Excessive sulfite usage in food and pharmaceutical production causes respiratory and neurological diseases, underscoring the need for a sensitive and rapid quantification strategy. The portable sensing platform based on a luminescent hydrogel sensor is a powerful tool for the on-site, real-time detection of sulfite ions. However, the lack of recyclability in almost all reaction-based hydrogel sensors increases the application cost. This study constructed a reversible and upconversion nanoprobe combining upconversion nanoparticles (UCNPs) and pararosaniline (PAR) for sulfite detection. The upconversion nanoprobe was further encapsulated in a three-dimensional polyacrylamide hydrogel matrix to create a background-free, reversible hydrogel sensor. The near-infrared excitation of UCNPs avoids the autofluorescence in the hydrogel and real samples. Meanwhile, PAR serves as a specific recognition unit for sulfite ions. After the addition of sulfites, a specific reaction occurs between PAR and sulfites, leading to the recovery of characteristic emission at 540 nm, achieving sensitive detection of sulfite ions. Importantly, this specific reaction is reversible under thermal treatment, allowing the hydrogel sensor to return to its initial state and thus enabling reversible detection of sulfite ions. Furthermore, a portable sensing platform is developed to realize point-of-care, real-time quantitative detection of sulfite ions. The proposed upconversion reversible hydrogel sensor provides a new sensing strategy for the detection of hazardous substances in food and offers new insights into the preparation of reversible, highly sensitive hydrogel sensors.

Detection of TNP and sulfite ions in an aqueous medium using a pyrazinium-based chemosensor

A pyrazinium-based fluorescent chemosensor exhibited effecient detection of TNP and sulfite ions in aqueous medium. The chemosensor with a visually detectable color change in the presence of sulfite was integrated with a smartphone.

A Kumujian-C based highly selective fluorescence turn-on probe enables the detection of sulfite in real samples and living cells

Kumujian-C as a small molecular fluorescent probe as a turn-on sensor for sulfite ions.

Hydrogen sulfite ion functionalized cationic covalent organic framework nanosheets as a separator boosted the energy storage performance of Li–S batteries

EB-COF:HSO3 was prepared by solvothermal and ion-exchange methods to enhance Li–S battery separators, suppressing the “shuttle effect” of soluble polysulfides and improving charge/discharge efficiencies with excellent electrochemical performance.

Determination of the efficiency of oxygen removal from water from the ratio of the concentrations of sodium sulfite and the iron catalyst

The main issue of corrosion activity is the removal of oxygen from water. Under certain conditions, inhibitors-passivators are effective. Other methods based on thermal and vacuum deaeration of water. These methods are energy-consuming and do not provide the necessary quality of water, so chemical reagents are used for deep deoxidation of water regardless of secondary pollution.
 In this work, distilled water with a certain concentration of oxygen was placed in a hermetic container. The calculated amount of sodium sulfite solution (sodium metabisulfite) was added to the water and after certain intervals the oxygen concentration in the water was recorded using an oxygen meter, the sensor of which was placed in the container before. In another series of experiments, calculated amounts of sodium sulfite and iron sulfate solutions were added to the water, the container was quickly closed and the oxygen concentration in the water was recorded at certain intervals.
 It has been shown that in distilled water at room temperature, sodium sulfite interacts very slowly with oxygen. In 1 hour, the rate of oxygen recovery increases from 27.7 % to 56.9 % when the sulfite concentration increases from 50 to 300 mg/dm3. It was established that iron (II) ions significantly accelerate the rate of oxygen reduction by sulfite already at an iron concentration of 0.1 mg/dm3 at a sulfite concentration of 50-300 mg/dm3. According to the integral kinetic curves of the 0th, 1st, 2nd, and 3rd orders, kinetic models of sulfite oxidation in distilled water with oxygen in the presence of iron ions were determined.
 It is shown that when the concentration of sulfite increases to 200, 300 mg/dm3, with an iron concentration of 0.5‑1.0 mg/dm3, the oxidation processes follow first-order reactions and their speed is determined by the oxygen concentration. When the concentration of iron and sulfite is reduced, the realization of oxidation processes according to the reactions of the 2nd and 3rd orders was noted, when the speed of the process depends not only on the concentration of oxygen, but also on the concentration of sulfite (2nd order) and iron ions (3rd order) .
 This work is aimed at solving the relevance of the problem of water deoxidation for water preparation in cooling systems. The direction of the research is very promising considering the satisfactory and effective results obtained and the inexpensive chemical reagents used. Further research will be aimed at finding ideal conditions for the reaction and finding optimal concentrations of reagents while ensuring maximum efficiency of the process, which in turn will bring mankind a solution to the problem of spending large amounts of money, chemical reagents and environmental pollution.

Smooth nickel - a suitable anodic material in new alkaline fuel cells sulphite/oxygen

<p>The anodic oxidation of sulphite ions was studied by voltammetric techniques on a nickel electrode in alkaline solution at various concentration of sulphite and polarization rate. The kinetic parameters of the electrode process have been determined using Tafel plots method and a mechanism of the electrochemical oxidation reaction of sulphite has been proposed. Current density, potential range of sulphite electro-oxidation and transformation degree of sulphite ions in the test solutions have been obtained by chronoamperometry and chronocoulometry. The sulphite oxidation mechanism on nickel electrode has been sustained by electrochemical impedance spectroscopy.</p>

Effect of Additions of Mixtures of Sodium Sulfite and Formic and Acetic Acid on the Photocatalytic Reduction of Water with Cadmium Sulfide Suspensions

The photochemical reduction of water with cadmium sulfide suspensions containing mixtures of sodium sulfite and formic and acetic acid solutions has been studied by electromotive force measurements and gasometry. The sulfite ions are oxidized on the anode in the sulfite–acetate suspensions; the sulfite ions and formic acid, in the sulfite–formate solutions. Hydrogen peroxide was found among the products of the photochemical reaction; it is involved in the oxidation of the radicals of sulfite ions and molecular sulfur of CdS particles and prevents the reduction of water.