Sulfur Molecules Research Articles

Discovery of MgS and NaS in the Interstellar Medium and Tentative Detection of CaO

We report the first detection of the metal-bearing molecules sodium sulfide and magnesium sulfide and the tentative detection of calcium monoxide in the interstellar medium toward the Galactic center molecular cloud G+0.693-0.027. The derived column densities are (5.0 ± 1.1) × 1010 cm−2, (6.0 ± 0.6) × 1010 cm−2, and (2.0 ± 0.5) × 1010 cm−2, respectively. This translates into fractional abundances with respect to H2 of (3.7 ± 1.0) × 10−13, (4.4 ± 0.8) × 10−13, and (1.5 ± 0.4) × 10−13, respectively. We have also searched for other Na-, Mg-, and Ca-bearing species toward this source but none of them have been detected and thus we provide upper limits for their abundances. We discuss the possible chemical routes involved in the formation of these molecules containing metals under interstellar conditions. Finally, we compare the ratio between sulfur-bearing and oxygen-bearing molecules with and without metals, finding that metal-bearing sulfur molecules are much more abundant than metal-bearing oxygen ones, in contrast with the general trend found in the ratios between other nonmetal-oxygen- and sulfur-bearing molecules. This further strengthens the idea that sulfur may be a little depleted in G+0.693-0.027 as a result of the low-velocity shocks present in this source sputtering large amounts of material from dust grains.

Waste to Wealth: One-Step Exfoliating of Spent Graphite to Build a Low-Cost Cathode for Lithium-Sulfur Batteries.

With the booming development of Li-ion batteries (LIBs), the recycling and reusing of spent graphite (SG) from LIBs is becoming increasingly crucial. Meanwhile, developing low-cost and efficient carbon hosts for lithium-sulfur (Li-S) batteries has gained widespread attention in the past decade. Nevertheless, the processing of carbon materials as sulfur hosts is often energy-consuming and complex. Herein, a simple and environmental-friendly strategy is proposed to reuse the SG to prepare graphene/sulfur composite cathode for Li-S batteries. Due to expanded layer spacing and defects of SG, sulfur molecules can strip it into a graphene-type host via ball milling. By optimizing the S/SG ratio and ball milling time, the as-prepared graphene/sulfur composite cathode with 70 wt.% sulfur content exhibits a high capacity of 1000 mAh g-1. With a high sulfur loading of 4.68 mg cm-2, the graphene/sulfur cathode can maintain 526 mAh g-1 after 400 cycles. This work provides a novel waste-to-wealth perspective for recycling spent graphite from LIBs to reuse in Li-S batteries.

Potential of graphene as an adsorbent for HSSS· radical – A DFT investigation

The sulfane sulfur molecules are known to regulate many biological processes for the normal functioning of cells. Herein, the interactions of pristine, B-doped, N-doped, BN-codoped, monovacancy defected, and Stone-Wales (SW) defected graphene with HSSS· radical have been investigated theoretically in the framework of density functional theory (DFT) with an aim to understand if pristine or modified graphene can be used as an adsorbent for HSSS· radical. The analysis based on the structural details, Wiberg bond, ZPE-corrected adsorption energies, reaction enthalpies, reaction free energies and density of states (DOS) reveal that the pristine, BN-codoped, monovacancy defected and SW defected graphene would serve as potential adsorbents for adsorption of HSSS· radicals; the monovacancy defected graphene could be the best choice for this job. It is found that the B-doped graphene would act as a weak adsorbent but the N-doped graphene would not at all be suitable for adsorption of HSSS· radicals.

Understanding the charge transfer effects of single atoms for boosting the performance of Na-S batteries.

The effective flow of electrons through bulk electrodes is crucial for achieving high-performance batteries, although the poor conductivity of homocyclic sulfur molecules results in high barriers against the passage of electrons through electrode structures. This phenomenon causes incomplete reactions and the formation of metastable products. To enhance the performance of the electrode, it is important to place substitutable electrification units to accelerate the cleavage of sulfur molecules and increase the selectivity of stable products during charging and discharging. Herein, we develop a single-atom-charging strategy to address the electron transport issues in bulk sulfur electrodes. The establishment of the synergistic interaction between the adsorption model and electronic transfer helps us achieve a high level of selectivity towards the desirable short-chain sodium polysulfides during the practical battery test. These finding indicates that the atomic manganese sites have an enhanced ability to capture and donate electrons. Additionally, the charge transfer process facilitates the rearrangement of sodium ions, thereby accelerating the kinetics of the sodium ions through the electrostatic force. These combined effects improve pathway selectivity and conversion to stable products during the redox process, leading to superior electrochemical performance for room temperature sodium-sulfur batteries.

Short-Chain Sulfur Confined into Nitrogen-Doped Hollow Carbon Nanospheres for High-Capacity Potassium Storage.

Carbon-based materials are one of the ideal negative electrode materials for potassium ion batteries. However, the limited active sites and sluggish diffusion ion kinetics still hinder its commercialization process. To address these problems, we design a novel carbon composite anode, by confining highly reactive short-chain sulfur molecules into nitrogen-doped hollow carbon nanospheres (termed SHC-450). The formation process involves the controlled synthesis of hollow polyaniline (PANI) nanospheres as precursors via an Ostwald ripening mechanism and subsequent sulfuration treatment. The high content of constrained short-chain sulfur molecules (20.94 wt%) and considerable N (7.15 wt%) ensure sufficient active sites for K+ storage in SHC-450. Accordingly, the SHC-450 electrode exhibits a high reversible capacity of 472.05 mAh g-1 at 0.1 A g-1 and good rate capability (172 mAh g-1 at 2 A g-1). Thermogravimetric analysis shows that SHC-450 has impressive thermal stability to withstand a high temperature of up to 640 °C. Ex situ spectroscopic characterizations reveal that the short-chain sulfur provides high capacity through reversible formation of K2S. Moreover, its special hollow structure not only provides ample space for highly active short-chain sulfur reactants but also effectively mitigates volume expansion during the sulfur conversion process. This work offers new perspectives on enhanced K+ storage performance from an interesting anode design and the space-limited domain principle.

Non-enzymatic electrochemical impedance sensor for selective detection of electro-inactive organophosphate pesticides using Zr-MOF/ZrO2/MWCNT ternary composite

The existence of multiple pesticide residues in fruits and vegetables constitutes a direct peril to living organisms. Therefore, it is crucial to develop a low-cost screening method for determining organophosphate pesticides (OPPs) in food samples. This study describes the solvothermal synthesis of a ternary composite comprising multi-walled carbon nanotubes (MWCNT), zirconium oxide, and a zirconium-metal-organic framework (Zr-MOF). The ternary composite was characterised using XRD, FESEM, FTIR, and BET. The ternary composite provides a large surface area (1158 m2/g) compared with the pristine Zr-MOF (868 m2/g). The composite-modified glassy carbon electrode was used to determine nine pesticides, including organophosphate (malathion, dimethoate, chlorpyrifos, monocrotophos, and glyphosate) and non-organophosphate (thiophanate methyl, carbendazim, atrazine, and 2,4, D). In particular, various chemical combinations of OPPs were selected, such as S–P=S, P=S, P=O, and non-OPPs such as C=S (with sulphur), and without sulphur. The sensor results show that the sensor selectivity is high for OPPs containing both phosphorus and sulphur molecules. The low detection limit of the sensor was 2.02, 2.8, 2.5, 1.11, and 2.01 nM for malathion, chlorpyrifos, dimethoate, monocrotophos, and glyphosate, respectively. The electrode exhibited significant chemical stability (93%) after 100 cycles, good repeatability, and a long shelf life. The sensor is reliable for qualitative real-time applications.

Laser induction of hierarchically micro/nanostructured CoNi-LDH/C composite for high-performance lithium-sulfur batteries

Li-S batteries suffer from limited electronic conductivity and shuttle effect of soluble LiPSs, which can hinder redox kinetics and reduce overall electrochemical performance. To solve these issues, we propose a strategy to synthesize a CoNi-layered double hydroxide/carbon composite (L-CoNi-LDH/C) through laser treatment and hydrothermal reaction. The resulting L-CoNi-LDH/C composite possesses a high specific surface area, enabling effectively anchor sulfur molecules and adsorb LiPSs. Moreover, the 2D layered structure of LDH and porous carbon framework can facilitate electron and ion transport. The Co and Ni species in the LDH structure act as catalysts, promoting the conversion of LiPSs into Li2S/Li2S2 and enhancing redox kinetics. A Li-S battery using CoNi-LDH/C as S host (S@CoNi-LDH/C) shows an initial capacity of 1574 mAh g−1 and maintains a reversible capacity of 1097 mAh g−1 after 100 cycles.

Experimental, isotherm, kinetic, and thermodynamic studies of the novel modified zeolite ZSM-5 adsorbent for use in clean fuel processing

Reducing the amount of sulfur in fuels is the simplest way to reduce the emission of sulfur oxide gases into the air. Among various desulfurization methods, adsorptive desulfurization stands out for its mild conditions and affordability. This research used ZSM-5 zeolite as a desulfurization adsorbent. However, adsorption capacity and selectivity are two major challenges that adsorptive desulfurization is facing. Introducing mesoporosity into zeolite is a potential solution. The study focused on mesoporous formation via desilication and dealumination. Desilication involved treating zeolite with 0.2 M and 0.5 M NaOH, while dealumination used 1 M HCl at 80 °C. Adsorbent properties were analyzed using XRD, BET, FT-IR, and FE-SEM. Initial findings indicated dealumination removed only extra-framework aluminum. Conversely, desilication removed silicon, producing a hierarchical structure even at reduced concentrations. Des-0.5M also exhibited the highest adsorption capacity for thiophene compared to the Parent sample, increasing from 4.5 to 11 mgS/g. Moreover, the adsorption capacity for larger sulfur molecules such as dibenzothiophene increased from 2.5 to approximately 6 mgS/g, indicating the significance of the hierarchical structure developed in the adsorbents. In summary, this study highlights the potential of mesoporous formation through desilication to enhance the adsorption capacity of ZSM-5 zeolite for the adsorptive desulfurization of fuels.

Germination Study of Some Protein-Based Gels Obtained from By-Products from the Leather Industry on Tomato and Pepper Seeds.

This study aimed to evaluate the biostimulant effects of three protein-based gels, GHC 1-B (20% gelatin (GPU-B) obtained by thermal hydrolysis from residual untanned leather and 80% collagen hydrolysates (HCE-B) obtained by alkaline-enzymatic hydrolysis from residual bovine-tanned leather), GHC 2-B (40% keratin hydrolysate (HKU-B) obtained by alkaline-enzymatic hydrolysis from sheep wool + 40% HCE-B + 20% GPU-B), and GHC 3-B (20% GPU-B + 80% hydrolyzed collagen (HPU-B) obtained by thermal and enzymatic hydrolysis from residual untanned leather). A germination study was carried out on pepper and tomato seeds at concentrations of 1%, 3%, and 10%. As a result of the study, it was found that all three protein-based gels showed a stimulatory effect on the tomato seeds at a 1% concentration, where the Gi (germination index) was ˂100%. The GHC 2-B variant had the highest stimulatory effect (Gi-190.23%). Pepper seeds have proven to be more sensitive to the gel's composition. The concentration at which it proved to be non-inhibitory (Gi-88.29%) was 1% in the case of GHC 2-B. It was found that the presence of hydrolyzed keratin in the composition can be a plus compared to the other two protein gels tested due to its composition, which is richer in phytonutrient compounds (e.g., sulfur molecules).

Unravelling the kinetics, isotherms, thermodynamics, and mass transfer behaviours of Zeolite Socony Mobil - 5 in removing hydrogen sulphide resulting from a dark fermentative biohydrogen production process.

Research into the speciation of sulfur and hydrogen molecules produced through the complex process of thermophilic dark fermentation has been conducted. Detailed surface studies of solid-gas systems using real biogas (biohydrogen) streams have unveiled the mechanisms and specific interactions between these gases and the physicochemical properties of a zeolite as an adsorbent. These findings highlight the potential of zeolites to effectively capture and interact with these molecules. In this study, the hydrogen sulphide removal analysis was conducted using 0.8 g of the adsorbent and at various reaction temperatures (25-125 °C), a flow rate of 100 mL min-1, and an initial concentration of approximately 5000 ppm hydrogen sulphide. The reaction temperature has been observed to be an essential parameter of Zeolite Socony Mobil - 5 adsorption capacity. The optimum adsorption capacity attains a maximum value of 0.00890 mg g-1 at an optimal temperature of 25 °C. The formation of sulphur species resulting from the hydrogen sulphide adsorption on the zeolite determines the kinetics, thermodynamics, and mass transfer behaviours of Zeolite Socony Mobil - 5 in hydrogen sulphide removal and Zeolite Socony Mobil - 5 is found to improve the quality of biohydrogen produced in thermophilic environments. Biohydrogen (raw gas) yield was enhanced from 2.48 mol H2 mol-1 hexose consumed before adsorption to 2.59 mol H2 mol-1 hexose consumed after adsorption at a temperature of 25 °C. The Avrami kinetic model was fitted for hydrogen sulphide removal on Zeolite Socony Mobil - 5. The process is explained well and fitted using the Temkin isotherm model and the investigation into thermodynamics reveals that the adsorption behaviour is exothermic and non-spontaneous. Furthermore, the gas molecule's freedom of movement becomes random. The adsorption phase is restricted by intra-particle diffusion followed by film diffusion during the transfer of hydrogen sulphide into the pores of Zeolite Socony Mobil - 5 prior to adsorption on its active sites. The utilisation of Zeolite Socony Mobil - 5 for hydrogen sulphide removal offers the benefit of reducing environmental contamination and exhibiting significant applications in industrial operations.

Pervaporative Desulfurization: A Comprehensive Review of Principles, Advances, and Applications

Pervaporative desulfurization is a potential method for removing sulfur compounds from liquid hydrocarbon streams, having many advantages over existing methods. This overview covers the fundamentals, recent breakthroughs, and different applications of pervaporative desulfurization. The paper begins by explaining pervaporative desulfurization's core concepts, focusing on how polymeric membranes selectively separate sulfur molecules from liquid hydrocarbons. It explores membrane properties, operating conditions, and feed composition in pervaporative separation. It highlights how pervaporative desulfurization may reduce sulfur content to ultra-low levels and meet strict environmental and fuel quality standards. Finally, this comprehensive review paper concludes with a discussion on the future prospects and research directions in the field of pervaporative desulfurization. It highlights the need for continued innovation in membrane materials, module design, and process optimization, as well as the importance of addressing challenges related to scale-up and industrial implementation. Overall, this review paper provides valuable insights into the advancements, challenges, and potential applications of pervaporative desulfurization, offering a comprehensive understanding of this technology for researchers, engineers, and all parties involved in the development and implementation of sustainable sulfur removal processes.

The sulfur species in hot rocky exoplanet atmospheres

AbstractThe first JWST observations of hot Jupiters showed an unexpected detection of SO in their hydrogen‐rich atmospheres. We investigate how much sulfur can be expected in the atmospheres of rocky exoplanets and which sulfur molecules can be expected to be most abundant and detectable by transmission spectroscopy. We run thermochemical equilibrium models at the crust–atmosphere interface, considering surface temperatures 500–5000 K, surface pressures 1–100 bar, and various sets of element abundances based on common rock compositions. Between 1000 and 2000 K, we find gaseous sulfur concentrations of up to 25% above the rock in our models. SO, SO, HS, and S are by far the most abundant sulfur molecules. SO shows potentially detectable features in transmission spectra at about 4 m, between 7 and 8 m, and beyond 15 m. In contrast, the sometimes abundant HS molecule is difficult to detect in these spectra, which are mostly dominated by HO and CO. Although the molecule PS only occurs with concentrations ppm, it can cause a strong absorption feature between 0.3 and 0.65 m in some of our models for high surface pressures. The detection of sulfur molecules would enable a better characterization of the planetary surface.

Evolution of Chemistry in the envelope of HOt corinoS (ECHOS)

Context. Within the project Evolution of Chemistry in the envelope of HOt corinoS (ECHOS), we present a study of sulphur chemistry in the envelope of the Class 0 source B 335 through observations in the spectral range λ = 7, 3, and 2 mm. Aims. Our goal is to characterise the sulphur chemistry in this isolated protostellar source and compare it with other Class 0 objects to determine the environmental and evolutionary effects on the sulphur chemistry in these young sources. Methods. We have modelled observations and computed column densities assuming local thermodynamic equilibrium and large velocity gradient approximation. We have also used the code Nautilus to study the time evolution of sulphur species, as well as of several sulphur molecular ratios. Results. We have detected 20 sulphur species in B 335 with a total gas-phase S abundance similar to that found in the envelopes of other Class 0 objects, but with significant differences in the abundances between sulphur carbon chains and sulphur molecules containing oxygen and nitrogen. Our results highlight the nature of B 335 as a source especially rich in sulphur carbon chains unlike other Class 0 sources. The low presence or absence of some molecules, such as SO and SO+, suggests a chemistry not particularly influenced by shocks. We, however, detect a large presence of HCS+ that, together with the low rotational temperatures obtained for all the S species (<15 K), reveals the moderate or low density of the envelope of B 335. Model results also show the large influence of the cosmic ray ionisation rate and density variations on the abundances of some S species (e.g. SO, SO2, CCS, and CCCS) with differences of up to ~4 orders of magnitude. We also find that observations are better reproduced by models with a sulphur depletion factor of 10 with respect to the sulphur cosmic elemental abundance. Conclusions. The comparison between our model and observational results for B 335 reveals an age of 104 < t < 105 yr, which high-lights the particularly early evolutionary stage of this source. B 335 presents a different chemistry compared to other young protostars that have formed in dense molecular clouds, which could be the result of accretion of surrounding material from the diffuse cloud onto the protostellar envelope of B 335. In addition, the theoretical analysis and comparison with observations of the SO2/C2S, SO/CS, and HCS+/CS ratios within a sample of prestellar cores and Class 0 objects show that they could be used as good chemical evolutionary indicators of the prestellar to protostellar transition.

Searching for bacteria able to metabolize polycyclic aromatic sulfur compounds in 12-years periodically fed bioreactor.

Biodesulfurization is a promising alternative for removing sulfur molecules from the polycyclic aromatic sulfur compounds (PASC) found in petroleum. PASC consists of recalcitrant molecules that can degrade fuel quality and cause a range of health and environmental problems. Therefore, identifying bacteria capable of degrading PASC is essential for handling these recalcitrant molecules. Microorganisms in environments exposed to petroleum derivatives have evolved specific enzymatic machinery, such as the 4S pathway associated with the dszABC genes, which are directly linked to sulfur removal and utilization as nutrient sources in the biodesulfurization process. In this study, bacteria were isolated from a bioreactor containing landfarm soil that had been periodically fed with petroleum for 12years, using a medium containing dibenzothiophene (DBT), 4.6-dimethylbenzothiophene, 4-methylbenzothiophene, or benzothiophene. This study aimed to identify microorganisms capable of degrading PASC in such environments. Among the 20 colonies isolated from an inoculum containing DBT as the sole sulfur source, only four isolates exhibited amplification of the dszA gene in the dszABC operon. The production of 2-hydroxybiphenyl (HPB) and a decrease in DBT were detected during the growth curve and resting cell assays. The isolates were identified using 16S rRNA sequencing belonging to the genera Stutzerimonas and Pseudomonas. These isolates demonstrated significant potential for biodesulfurization and/or degradation of PASC. All isolates possessed the potential to be utilized in the biotechnological processes of biodesulfurization and degradation of recalcitrant PASC molecules.

Chemical evolution of primordial salts and organic sulfur molecules in the asteroid 162173 Ryugu

Samples from the carbonaceous asteroid (162173) Ryugu provide information on the chemical evolution of organic molecules in the early solar system. Here we show the element partitioning of the major component ions by sequential extractions of salts, carbonates, and phyllosilicate-bearing fractions to reveal primordial brine composition of the primitive asteroid. Sodium is the dominant electrolyte of the salt fraction extract. Anions and NH4+ are more abundant in the salt fraction than in the carbonate and phyllosilicate fractions, with molar concentrations in the order SO42− > Cl− > S2O32− > NO3− > NH4+. The salt fraction extracts contain anionic soluble sulfur-bearing species such as Sn-polythionic acids (n < 6), Cn-alkylsulfonates, alkylthiosulfonates, hydroxyalkylsulfonates, and hydroxyalkylthiosulfonates (n < 7). The sulfur-bearing soluble compounds may have driven the molecular evolution of prebiotic organic material transforming simple organic molecules into hydrophilic, amphiphilic, and refractory S allotropes.

Cystathionine β-Synthase Suppresses NLRP3 Inflammasome Activation via Redox Regulation in Microglia.

Aims: Cystathionine β-synthase (CBS) is essential for homocysteine (Hcy) transsulfuration, yielding cysteine as a common precursor of hydrogen sulfide (H2S), glutathione (GSH), and other sulfur molecules, which produce neuroprotective effects in neurological conditions. We previously reported a disruption of microglial CBS/H2S signaling in a Parkinson's disease (PD) mouse model. Yet, it remains unclear whether CBS affects nucleotide-binding oligomerization domain, leucine-rich repeat and pyrin domain-containing 3 (NLRP3) inflammasome activity and other pathologies in PD. Results: Microglial CBS expression decreased after lipopolysaccharide (LPS) stimulation. Elevated GSSG (the oxidized GSH) content and decreased H2S generation were found in the brains of microglial cbs conditional-knockout (cbscKO) mice, whereas serum and brain Hcy levels remained unaltered. Moreover, microglial cbscKO mice were susceptible to NLRP3 inflammasome activation and dopaminergic neuron losses caused by LPS injection into the substantia nigra, whereas cbs overexpression or activation produced opposite effects. In vitro studies showed that cbs overexpression or activation suppressed microglial NLRP3 inflammasome activation and interleukin (IL)-1β secretion by reducing mitochondrial reactive oxygen species (mitoROS) level. Conversely, ablation of cbs enhanced NLRP3 expression and mitoROS generation and augmented microglial NLRP3 inflammasome activity in response to adenosine triphosphate challenge, which was blocked by the mitoROS scavenger. Innovation and Conclusion: The study demonstrated an elevated GSSG level and reduced H2S generation, which correlated with a susceptible status of microglia in the brain of cbscKO mice. Our findings reveal a critical role of CBS in restraining the microglial NLRP3 inflammasome by controlling redox homeostasis and highlight that activation or upregulation of CBS may become a potential strategy for PD treatment.

Stability of sulfur molecules and insights into sulfur allotropy

Stability of sulfur molecules and insights into sulfur allotropy

Tailoring short-chain sulfur molecules to drive redox dynamics for sulfur-based aqueous battery

Solid-solid reactions stand out in rechargeable sulfur-based batteries due to the robust redox couples and high sulfur utilization in theory. However, conventional solid-solid reactions in sulfur cathode always present slow reaction kinetics and huge redox polarization due to the low electronic conductivity of sulfur and the generation of various electrochemical inert intermediates. In view of this, it is crucial to improve the electrochemical activity of sulfur cathode and tailor the redox direction. Guided by thermodynamics analysis, short-chain sulfur molecules (S2-4) are successfully synthesized by space-limited domain principle. Unlike conventional cyclic S8 molecules with complex routes in solid-solid reaction, short-chain sulfur molecules not only shorten the length of the redox chain but also inhibit the formation of irreversible intermediates, which brings excellent redox dynamics and reversibility. As a result, the Cu-S battery built by short-chain sulfur molecules can deliver a high reversible capacity of 3,133 mAh g-1. To put this into practice, quasi-solid-state aqueous flexible battery based on short-chain sulfur molecules is also designed and evaluated, showing superior mechanical flexibility and electrochemical property. It indicates that the introduction of short-chain sulfur molecules in rechargeable battery can promote the development and application of high-performance sulfur-based aqueous energy storage systems.

One‐pot Synthesis of Bulk NiMoS Catalysts: Influence of pH and Addition of Pluronic®P123. Hydrodesulfurization of Model Sulfur Molecules Representative of FCC Gasoline

AbstractThe worldwide continual reinforcement of regulations for the production of cleaner fuels along with the larger demand for energy urge us to develop hydrotreatment sulfide catalysts exhibiting higher activity in hydrodesulfurization reactions and explore innovative synthesis strategies. In this work, a novel one‐pot synthesis method of unsupported NiMoS catalysts in water at ambient pressure and moderate temperature is described. The reaction conditions including pH variations and addition of a copolymer structuring agent were thoroughly investigated. Catalytic performances of the prepared bulk NiMoS catalysts were measured for the hydrodesulfurization of two model sulfur molecules, representative of FCC gasoline. Catalysts prepared at pH 7 without or with polymer exhibited roughly similar activity, resulting however from different characteristics favorable for catalyst efficiency probably compensating one another, i. e. a very high promotion rate for the first one and smaller particles along with larger specific surface area for the second.

Fabrication of Ag nanostar and PEI-based SERS substrate for sensitive and rapid detection of SO2: Application for detection of sulfite residues in beer

Because of sulfite's potential toxicity, there is a growing concern about detecting and controlling its concentration in foods, alcoholic beverages, pharmaceuticals, and environmental samples to ensure public health. A branched polyethyleneimine-coated silver nano-star (AgNS@PEI) surface-enhanced Raman scattering (SERS) substrate was synthesized in this study for use as a sensitive, simple, rapid, stable, and reproducible non-destructible sulfite detection analytical technique. The seed morphology of the nano-star was created by using hydroxylamine (NH2OH) solution as a primary reducing agent, followed by a slow secondary reduction by trisodium citrate dihydrate (HOC(COONa)(CH2COONa)2 2H2O), resulting in the complete growth of the silver nano-star. For extra stability and selective absorption of sulfur dioxide from the headspace extraction of SO2 from sulfites, the nano-stars were thin coated with branched polyethyleneimine (b-PEI). The results showed that the thin-coated plasmonic substrates selectively absorb sulfur dioxide molecules, allowing sulfites in beer samples to be detected with a detection limit of 0.48 mg/L. Furthermore, the PEI-coated silver nano-star demonstrated increased stability and reproducibility, allowing for longer use of the substrate. Recovery experiments with recovery rates ranging from 95 to 112% and relative standard deviations ranging from 1.55 to 8.1% demonstrated that headspace extraction, selective SO2 absorption by the synthesized substrate, and subsequent SERS detections were reliable and valid for practical applications. Finally, this study developed an SO2-sensitive, selective, and robust Si@AgNS@PEI substrate for effective SERS detection and monitoring of sulfite levels in real-world environmental samples.