Bisulfite Ion Research Articles

New insights into kinetics and mechanisms of acid sulphite delignification of Eucalyptus globulus wood

The kinetics of Eucalyptus globulus wood delignification in Mg-base acid sulphite pulping of dissolving pulp was studied using a pilot-scale batch digester simulating the industrial process. The behavior of lignin during impregnation, heating-up and bulk delignification at the final temperature was evaluated by the analysis of acid-insoluble lignin in wood and wood residue after pulping. The dynamics of lignin dissolution was followed by its structural analysis in solid residues and in solution by wet chemistry and 1D and 2D nuclear magnetic resonance (NMR) spectroscopy. About 30 % and 20 % of the lignin were removed in the impregnation and heating-up pulping steps, respectively. About 45 % of the lignin was removed at the final pulping temperature in bulk and 3 % in the residual delignification stages. The kinetics of bulk delignification followed a pseudo-first-order kinetics with an effective activation energy of 138.4 kJ/mol in the temperature range of 140–148 °C. Bulk delignification follows an undefined overall order in the hydrogen and bisulfite ions and depended on the partial pressure of SO2 at ca. 0.60 order within the range of combined SO2 in pulping acid of 1.14–1.66 % and total SO2 loads of 6.2–7.0 %. Minimum degree of lignin sulphonation to be dissolved in the pulping liquor was suggested to be about 0.35 sulphonic groups per one phenyl propane unit. Lignin removal during pulping showed dependence on its location in different morphological parts of the fibers and related structural characteristics, which were discussed accordingly. A role of the polysaccharide complex in the accessibility of lignin was highlighted. A noticeable cleavage of β-O-4 linkages occurred in lignin already dissolved in pulping liquor at the end of cooking.

A ferrocene-based probe for colourimetric/electrochemical detection of bisulfite ions and its practical application

A simple ferrocene-based organic probe (AK5) is described for selective and sensitive colourimetric/electrochemical detection of HSO3- ions in a 95 % aqueous solution. Upon adding HSO3− ions, the colour of the solution changes from brown to colourless instantaneously. The plausible mechanism of detection of HSO3− ions by AK5 was illustrated by 1H NMR, 13C NMR, HR-MS and DFT/TD-DFT analysis, which revealed nucleophilic addition of HSO3− ion to olefinic C-atom. The limits of detection (LOD) are determined to be 5.58 and 0.12 µM in colourimetric and electrochemical methods, respectively. The probe is successfully applied to estimate the levels of HSO3− ions in natural water and red wine samples.

An NIR-emissive AIEgen with dual sensing ability: An azine-based chemodosimeter for discriminative ppb-level detection of hydrazine and bisulfite ions

A new near-infrared (NIR) emissive aggregation-induced emission (AIE) active unsymmetrical azine (benzophenone-azine-phenyl-cyanovinyl-pyridinium chloride, BAPCP) with dual sensing ability is developed for discriminative detection of hydrazine (N2H4) and bisulfite (HSO3−) ions. The azine-based chemodosimeter, BAPCP was synthesized in a sustainable way adopting a solvent-free one-pot tandem mechanochemical route. The probe is nonfluorescent in organic solutions and displayed strong AIE at higher water fractions (upto 99% of H2O) with an emission maximum at 718 nm and a large Stokes shift of 333 nm. BAPCP could detect N2H4 by a ratiometric response at 525 nm by cleavage of the cyano-pyridinium ethylene group and showed a turn-off response against HSO3− by its nucleophilic addition across the olefinic bond of BAPCP. The probe showed excellent selectivity and low limit of detection (LOD) of 4 × 10−8 M (1.2 ppb) and 2.5 × 10−8 M (2 ppb) for N2H4 and HSO3−, respectively. The practical utility of the probe was demonstrated by solid-phase detection of these analytes on silica-coated TLC plates, followed by ImageJ analysis for on-site quantitation purposes. BAPCP is also capable of the detection of intracellular N2H4 and HSO3− in live cells.

Cationic Donor–Two-Acceptor Dye–Graphene Quantum Dot Nanoconjugate for the Ratiometric Detection of Bisulfite Ions and Monitoring of SO2 Levels in Heat-Stressed Cells

When the body temperature rises above 40.6 °C, heat stress in the cells causes mitochondrial damage. This damage can lead to apoptosis, multiple organ failure, and even death. The dysregulation of SO2 levels in the mitochondria is linked to this heat stress, and its detection may act as an early indicator of heat stroke. Graphene quantum dots (GQDs), a common class of zero-dimensional carbon-based fluorescent nanomaterials, have shown immense potential as sensory probes, and it is a prospective candidate for monitoring SO2 levels in living cells. Herein, we report a combination of a donor–two acceptor (D2A) red-emissive di-picolinium salt (PPy-Br) and hydroxy-functionalized graphene quantum dots (GQDs-OH) as the fluorescence resonance energy transfer (FRET)-based ratiometric sensor for bisulfite ions detection in aqueous media. The dye-GQD nanoconjugate displays excellent photostability and good aqueous dispersibility allowing the monitoring of SO2 levels in living cells during heat stress. The PPy-Br:GQD nanoconjugate is indifferent to a large number of cations, anions, or biologically relevant species and displays a detection limit of 36 nM for the solution phase detection of bisulfite. PPy-Br is biocompatible with human cell lines and endocytoses into the cells to ensure monitoring of SO2 levels in the mitochondrial milieu. PPy-Br-treated human breast cancer cells displayed a gradual decrease in fluorescence at temperatures above 40 °C, indicating an increase in SO2 levels in heat-stressed cells. The PPy-Br:GQDs sensing conjugate is efficient in the real-time monitoring of intracellular SO2 levels and demonstrates enough prospects for further explorations as a diagnostic kit for heat stroke monitoring.

Reductive dehalogenation and formation of sulfonated quinones in the aqueous reactions between various chloro-1,4-benzoquinones and sulfur(IV)

In this paper, the kinetic study of the reaction between substituted 1,4-benzoquinones (RBQs) and Na2SO3 (S(IV)) is presented in aqueous solutions at different pH values and reagent concentrations. The stoichiometry of the reaction is 1:2 RBQs:S(IV) and one equivalent of chloride ion was also detected as a product when using mono- (2-CBQ) or dichloro-benzoquinones (2,5-DCBQ; 2,6-DCBQ) as reactants. This shows that reductive dehalogenation occurs instead of simple reduction to the corresponding substituted 1,4-hydroquinones (RBQHs) and quinone bisulfites are formed, analogously to the addition of bisulfite ion to carbonyl compounds. Various sulfonated quinones have been identified as products by electrospray mass spectrometry. Kinetic traces at different wavelengths were obtained by the stopped-flow technique with spectrophotometric detection, a kinetic fitting program (ZiTa) was used to fit a multi-step model to the data. A detailed mathematical evaluation of the reaction scheme was carried out under non-pseudo-first order conditions showing that our model can be fitted with a double exponential function even when none of the reagents are in large excess.

Surfactant-induced excimer emission: A versatile platform for the design of fluorogenic probes

We report that the electrostatic association between a cyanovinylene (CV)-based cationic dye (CV–N+) and anionic surfactants rapidly induced the formation of self-assembled aggregates of CV-N+ molecules in an aqueous solution, displaying a red-shifted (Δλ = 100 nm), broad excimer emission at 650 nm. The anionic-surfactant-mediated excimer-forming properties of CV-N+ were further exploited as a versatile platform for the design of simple fluorescent “light-up” sensing systems for the specific and efficient detection of enzymatic activity (i.e., phospholipase D) and small molecules (i.e., bisulfite ions), respectively, without the complicated functionalization of fluorophores with suitable recognition groups. In these systems, which can be ensembled using various substrates, the cationic CV-N+ dye interacts with an anionic surfactant, which is the product of an analyte-induced specific reaction, thus triggering the formation of emissive aggregates.

Human peripheral blood mononuclear cells targeted multidimensional switch for selective detection of HSO3− anion

A new ratiometric π-conjugated luminophore with donor-acceptor (D- π- A) network CM {(E)-2-(4-(2-(9-butyl-9H-carbazol-3-yl)vinyl)benzylidine)malononitrile} has been synthesized by malononitrile conjugated carbazole dye with an intervening p-styryl spacer. Here, p-styryl conjugated malononitrile is used as a recognition site for the detection of HSO3− with a fast response time (within 50 s). In a mixed aqueous solution, CM reacts with HSO3− to give a new product 1-(9-butyl-9H-carbazol-3-yl)-2-(4-(2, 2-dicyanovinyl)phenyl)ethane-1-sulfonic acid. The probe exhibits positive solvatofluorochromism with solid state red fluorescence. The restriction of intermolecular rotation of p-styryl conjugated malononitrile unit enhances the typical solid state fluorescence properties. The probe (CM and its corresponding aldehyde CA) also demonstrates a strong solvent dependence yielding blue to green to pink and even red fluorescence in commonly used organic solvents like n-hexane, toluene, diethyl ether (DEE), THF, DCM, Dioxane, CH3CN and MeOH. The chemodosimetric approach of HSO3− selectively takes place at the olefinic carbon exhibiting a prominent chromogenic as well as ratiometric fluorescence change with a 147 nm blue-shift in the fluorescence spectrum. CM can detect HSO3− as low as 1.21 × 10−8 M. Moreover, the CM can be successfully applied to detect intrinsically generated intracellular HSO3− in human peripheral blood mononuclear cells (PBMCs). CM has shown sharp intensities (2628 ± 511.8) when the cells are HSO3− untreated. At green channel (at 486 nm) almost negligible fluorescence intensities are found (423 ± 127.5) for HSO3− untreated samples. However, the green fluorescence (2863 ± 427.5) increases significantly (p < 0.05), and simultaneously the red fluorescence gets significantly (p < 0.05) diminished (515 ± 113.2) after addition of HSO3−. The CM has been effectively utilized for evaluating the bisulfite ions in food samples as well. The concentrations of HSO3− in diluted sugar samples have been determined with the recovery of 97.6–9.12%.

A combination of experimental and TD-DFT investigations on the fluorescent detection of sulfite and bisulfite ions in aqueous solution via nucleophilic addition reaction

The selective detection of sulfite and bisulfite ions with anthracene-based compounds (CN1 and CN2) as chemo-dosimeters is reported using fluorescence changes in DMSO:HEPES (70:30%), v/v buffer solution (pH 7.4). Upon treatment with sulfite and bisulfite ions, the fluorescence of the probes gets enhanced significantly at 424 nm. The detection of these ions occurs through the nucleophilic addition at the vinylic C-atom of the probes, which terminates the photo-induced electron transfer (PET) process and consequently enhances the fluorescence. This detection mechanism is well supported by 1H NMR titration, HR-MS and DFT/TD-DFT calculations. The pseudo-first-order rate constants for the addition sulfite (at pH 7.4) and bisulfite (at pH 5) to CN1 are determined to be 3.22×10−3 and 5.02×10−3 s−1, respectively. The limits of detection for sulfite and bisulfite are found to be 1.85×10−7 and 1.56×10−7 M, respectively. The probe CN1 was successfully applied to the detection of bisulfite ion in real samples.

TD-DFT method of analysis of fluorescent detection of bisulphite ion in an aqueous solution by a pyrene-based chemodosimeter

A new pyrene-based chemodosimeter (RS3) has been designed and synthesized, which is found to be a promising fluorescent probe for detection of bisulphite ion in DMSO:Na2HPO4/citric acid buffer of pH 5. 1H NMR titration indicates that nucleophilic addition of HSO3− to vinylic C-atom of RS3 terminates the π-conjugation and consequently enhanced the fluorescence significantly. The sensing mechanism is further confirmed by density functional theory (DFT) and time dependent density functional theory (TD-DFT) methods. The binding constant of the 1:1 RS3-HSO3 adduct is found to be 0.7 × 103 M−1. The probe RS3 exhibits high selectivity towards bisulphite ion with a limit of detection of 0.15 µM, which is lower than the maximum permissible limit of bisulfite ion (1.25 µM) in food products required by the European Union Regulations. Further, the probe RS3 has been used for the determination of HSO3− in real samples such as distilled water, tap water, red wine, jaggery and white sugar and also successfully applied for the bio-imaging of HSO3− in live cells.

A photoswitchable “turn-on” fluorescent chemosensor: Quinoline-naphthalene duo for nanomolar detection of aluminum and bisulfite ions and its multifarious applications

A quinoline-naphthalene duo-based Schiff base probe (R) was synthesized and characterized by the usual spectroscopic and single-crystal X-ray crystallographic techniques. Probe R detects Al3+ and HSO3− ions via the fluorescent turn-on approach by dual pathways i.e., i) when probe R interacts with Al3+, the restriction of CN single bond rotation, blocking of both photoinduced electron transfer (PET) and CN isomerization were observed, and ii) when the sensor R interacts with HSO3−, imine (CH = N) bond was cleaved via hydrolysis and produced the respective aldehyde and amine behaving as a chemodosimeter. The binding stoichiometric ratio of R + Al3+ (1:1) was confirmed by Job’s plot, emission titration profile, NMR, and mass spectrometric analyses. This probe R is highly selective to both Al3+ -ions and HSO3− -ions, without any interference of other potentially competing cations and anions. Limit of detection (LOD) and quantification (LOQ) of R with Al3+ and HSO3− were downed to nanomolar concentrations, which is much lower than the recommended level of drinking water/food fixed by the World Health Organization (WHO). Furthermore, probe R was utilized in the detection of Al3+ and HSO3− ions in highly contaminated real samples, bioimaging in E. coli cells, multiple-targeting molecular logic gate, and in bovine serum albumin (BSA) binding.

A 1-Hydroxy-2,4-Diformylnaphthalene-Based Fluorescent Probe and Its Detection of Sulfites/Bisulfite.

A novel 1-hydroxy-2,4-diformylnaphthalene-based fluorescent probe L was synthesized by a Knoevenagel reaction and exhibited excellent sensitivity and selectivity towards sulfite ions (SO32−) and bisulfite ions (HSO3−). The detection limits of the probe L were 0.24 μM using UV-Vis spectroscopy and 9.93 nM using fluorescence spectroscopy, respectively. Furthermore, the fluorescent probe L could be utilized for detection in real water samples with satisfactory recoveries in the range 99.20%~104.30% in lake water and 100.00%~104.80% in tap water by UV-Vis absorption spectrometry, and in the range 100.50%~108.60% in lake water and 102.70%~103.80% in tap water by fluorescence spectrophotometry.

Simple aggregation-induced ratiometric emission active benzo[h]chromene derivative for detection of bisulfite in living cells

Monitoring levels of SO2 and its derivatives, including sulfite (SO32−) and bisulfite (HSO3−) ions, in biological systems is of great importance because their aberrant concentrations in cells may cause several diseases. Aggregation-induced-emission (AIE) active probes are exhibited good photophysical properties in aqueous solution, and have been applied in many fields. Herein, we report benzo[h]chromene aldehyde (1) with aggregation-induced ratiometric emission (AIRE) that showed a blue emission in a solution, whereas in an aggregate state, a green emission with 43-nm Stocks shift was observed. Furthermore, this green AIRE was specifically quenched using HSO3− under physiological conditions owing to the formation of a water-soluble and non-emissive product after the addition of bisulfite to the aldehyde group of 1. Finally, the imaging experiments indicated that probe 1 could be utilized to detect exogenous HSO3− in HeLa cells.

A lysosome specific ratiometric fluorescent probe for detection of bisulfite ion based on hybrid coumarin-benzimidazolium compounds

Hybrid 2-(2-(7-(diethylamino)-2-oxo-2H-chromen-3-yl)vinyl)-1,3-dimethyl-1H-benzo[d]imidazol-3-ium iodide compounds (LHZD-1 ∼ 3) were synthesized by Knoevenagel condensation reaction. Their structures were confirmed by 1H NMR, 13C NMR and HRMS spectroscopy. The fluorescence property of LHZD-1 ∼ 3 varied with the substituent groups such as -Br, -H and -OMe in the benzimidazolium skeleton. The probe LHZD-1 showed remarkable selectivity for the bisulfite ion over other common anions and biotins, which outputted the obvious color change in both absorption (462 nm to 400 nm) and emission (580 nm to 480 nm) spectra. The probe LHZD-1 showed the lysosome positioning action in Hela cells. This study not only provides a way for optimizing coumarin-benzimidazolium probes but also holds considerable promise in detection of bisulfite ion in organelles.

Surface lanthanide activator doping for constructing highly efficient energy transfer-based nanoprobes for the on-site monitoring of atmospheric sulfur dioxide.

The sensitive and on-site detection of sulfur dioxide (SO2) is in great demand in the fields of food safety and environmental protection. Here, we developed a novel upconversion nanoprobe based on the luminescence energy transfer mechanism for monitoring the atmospheric SO2 concentrations. The lanthanide emitters, Tm3+ ions, were optimized to be doped on the surface layer of the upconversion nanoparticles to improve their energy transfer efficiency by minimizing the distance between the emitters and the surface quencher, a cyanine dye. As a proof-of-concept, the optimal nanoprobe was utilized to detect SO2 water derivatives, bisulfite ions, exhibiting a linear luminescence increase in the range of 1 nM to 10 nM. Furthermore, we assembled the cyanine-modified upconversion nanoparticles onto a test paper, and used a smartphone-based detection platform to achieve portable and visual detection of SO2. The test paper showed a strong luminescence stability, homogeneity and good anti-interference. The limit of detection for SO2 gas was found to be 1 ng L-1. This novel upconversion test paper was also demonstrated to directly monitor the concentration of SO2 gas in atmosphere.

Sulfonate-Functionalized Mesoporous Silica Nanoparticles as Carriers for Controlled Herbicide Diquat Dibromide Release through Electrostatic Interaction.

Environmental stimuli-responsive pesticide release is desirable for enhanced efficiency and reduced side effects. In most cases, the loading and release of pesticides mainly depends on hydrophobic interactions and hydrogen bonding. Electrostatic interaction is less investigated as a weapon for achieving high loading content and controlled pesticide release. In this work, negative-charge decorated mesoporous silica nanoparticles (MSNs) were facilely fabricated by introducing sulfonate groups onto MSNs through a post-grafting method. Sulfonate-functionalized MSNs (MSN-SO3) were synthesized by conversion of epoxy group into sulfonate group using a bisulfite ion as a ring opening reagent. Diquat dibromide (DQ), one of the globally used quaternary ammonium herbicides, was efficiently loaded into these negatively charged MSN-SO3 nanoparticles. The loading content was increased to 12.73% compared to those using bare MSNs as carriers (5.31%). The release of DQ from DQ@MSN-SO3 nanoparticles was pH and ionic strength responsive, which was chiefly governed by the electrostatic interactions. Moreover, DQ@MSN-SO3 nanoparticles exhibited good herbicidal activity for the control of Datura stramonium L., and the bioactivity was affected by the ionic strength of the release medium. The strategy of cargo loading and release dependent on the electrostatic interactions could be generally used for charge-carrying pesticides using carriers possessing opposite charges to mitigate the potential negative impacts on the environment.

Benzo[e]indolium derivatives in aqueous solutions: Reaction with bisulfite and successive interaction with Cu2+ and Hg2+

A new benzo[e]indolium derivative 1 including pyridyl and thienyl groups was synthesized and characterized, which failed to response to Hg2+ or Cu2+ in aqueous system. However, it is interesting that when it reacted with bisulfite in HEPES buffer, the in situ generated ensemble as 1-SO3H displayed dramatic absorption and fluorescence changes after adding Cu2+ or Hg2+, which were contrary to the changes of 1 upon the addition of bisulfite ions. By contrast, the other two derivatives 2 and 3 showed the almost similar trends of spectral changes, which were short of ligating atoms N or S. The further investigation of 1HNMR spectra changes of 1 showed that C−SO3H bond may be interrupted because the good binding capacity of Hg2+ and Cu2+ with O of C−SO3H weaken the binding force of C−SO3H, which resulted in the recovery of ethylene with benzo[e]indolium block. The DFT calculations results further confirmed it.

Electrochemical behavior of valve steel in a CO2/sulfurous acid solution

Sulfur dioxide (SO2) is one of the principal impurities in carbon dioxide (CO2) streams captured from coal-fired power plants, and the synergistic effect of CO2/SO2 on the corrosion of steels has attracted significant recent attention. In this work, the corrosion mechanism of valve steel X80CrSiMoW152, in a mixed CO2/sulfurous acid aqueous environment, was investigated. Experiments were conducted by adding different concentrations of sulfurous acid to a CO2-saturated solution at 25 °C under different pH conditions. The effect of sulfurous acid on the corrosion mechanism was examined by potentiodynamic scanning. Results revealed that for the anodic reaction, the presence of 100 ppmw sulfurous acid promoted the dissolution of steel in CO2-saturated solutions. In the cathodic polarization curve, a “second-wave” phenomenon was observed before the second limiting current for cases with sulfurous acid at pH 3.0 and for the case with 1,000 ppmw sulfurous acid at pH 2.0. These new “waves” were potentially caused by the direct reduction of sulfurous acid or bisulfite ions on the steel surface. The adsorption of sulfurous acid or bisulfite could also impede the reduction of hydrogen by competitive adsorption, and by a decrease in the cathodic-reaction area for the reduction of hydrogen ions.

Use of Sodium Thiosulfate to Quench Hypochlorite Solutions Prior to Chlorate Analysis

Sodium thiosulfate is a commonly used quenching agent for sodium hypochlorite and has previously been deemed acceptable when quenching hypochlorite solutions before conducting chlorate analysis. However, using thiosulfate to quench hypochlorite solutions with compositions similar to those produced by electrolytic onsite generation process (OSG; free available chlorine content of 0.8% with a pH range of 8–10) can result in artificially low chlorate measurements. Reactions between thiosulfate and hypochlorite can result in a substantial decrease in pH that in turn causes the production of bisulfite ions from thiosulfate. In turn, these ions react with chlorate ions, resulting in artificially decreased measurements of chlorate in the initial hypochlorite solutions. Malonic acid does not cause a similar effect when used as a hypochlorite quenching agent and should therefore be used in place of thiosulfate when conducting chlorate analysis of hypochlorite solutions produced through electrolytic OSG processes.

Liquid–Liquid Extraction Protocol for the Removal of Aldehydes and Highly Reactive Ketones from Mixtures

The reaction of the bisulfite ion with aldehydes to form charged bisulfite adducts is a well-established method for the purification of aldehydes. This reaction has been modified to create a convenient liquid–liquid extraction method for the removal of aldehydes from mixtures. The use of a water-miscible solvent allows the reaction to occur during a simple 30 s shaking protocol by increasing the contact between the bisulfite ion and the aldehyde. The introduction of an immiscible solvent allows for the extraction of the uncharged organic components away from the bisulfite adduct. The developed protocol is applicable to a wide range of aldehydes, including sterically hindered neopentyl aldehydes. Sterically unhindered cyclic and linear ketones, as well as highly electrophilic ketones, are also removed using this protocol. The mild conditions tolerate a wide range of functional groups, allowing for excellent aldehyde contaminant removal rates with high levels of recovery of the desired component.

Efficacy of Bisulfite Ions as an Oxygen Scavenger in Monoethylene Glycol (At Least 20 wt%)/Water Mixtures

Summary This study investigates the oxygen-scavenging behavior of bisulfite ions in monoethylene glycol (MEG)/water mixtures at concentrations commonly found in gas-transportation pipelines. Temperatures and pH values were varied. The influence of transition-metal (TM) ions to catalyze the bisulfite oxygen scavenging was studied. Experimental results indicate that MEG significantly inhibits bisulfite oxygen removal, which is hindered at low pH values and, to some extent, temperature. TMs can accelerate the oxygen-scavenging reaction in pH-unadjusted solutions, although the rate was still lower than that of the pH-adjusted solutions. The possible mechanism for such behavior and industrial implications are discussed.