Search Results (23)

The discharge of medical and domestic wastewater has resulted in increasing levels of pharmaceutical pollutants in water bodies. We combined dielectric barrier discharge (DBD) technology with an Fe³⁺/sodium sulfite oxidation system to address the limitations associated with traditional water treatment technologies in removing carbamazepine, exploring the application efficacy and mechanisms of this approach in carbamazepine degradation. Under optimized experimental conditions, our system achieved a 97% degradation efficiency for carbamazepine within 4 min, significantly outperforming both DBD and sodium sulfite standalone systems. Using response surface methodology to optimize experimental parameters, the effects of sodium sulfite concentration, pH, and Fe³⁺ concentration on degradation efficiency were assessed. Under optimal conditions, the system’s degradation efficiency was 2.5 times higher than that of individual systems. Hydroxyl and sulfate radicals contributed 65% and 85%, respectively, to carbamazepine degradation, while superoxide radicals contributed only 30%. The study demonstrated that this system effectively breaks down the molecular structure of carbamazepine. Eight primary intermediate degradation products were identified, and, as degradation progressed, the concentrations of these intermediates gradually decreased, ultimately achieving a mineralization rate exceeding 85%. This study not only provides an effective technical solution for rapidly treating recalcitrant organic pollutants in water but also offers new insights for environmental protection and the sustainable use of water resources while providing theoretical and experimental data for future related research. Full article

Deltamethrin’s global use as a potent insecticide against pests is well-established. However, the compound’s diverse levels of toxicity are increasingly under scrutiny, drawing significant attention to treatments of deltamethrin. Transition metal activation of sulfite is a promising technology for micropollutant degradation. In this study, iron-activated sulfite was used for the degradation of deltamethrin. The degradation effects and influencing factors and the underlying mechanism of deltamethrin degradation in the system were investigated. The degradation of deltamethrin was effectively achieved by the Fe (III)/sulfite system. The optimal reaction conditions at laboratory scale were determined to be an initial pH of 4, a Fe (III) concentration of 100 μM, and a ${\mathrm{HSO}}_3^{-}$ concentration of 1 mM, where the degradation rate was approximately 69.5%. Dissolved oxygen was identified as an essential factor in the reaction process, with the degradation rate of deltamethrin decreasing by up to 22% under anaerobic conditions. The presence of light facilitated the degradation of deltamethrin within the reaction system, while bicarbonate and natural organic compounds were found to inhibit its degradation. Quenching experiments verified the presence of hydroxyl radicals (HO^•) and sulfate radicals (${\mathrm{SO}}_4^{•-}$) in the reaction system, with HO^• being the predominant species. This was further confirmed by EPR experiments. Additionally, density functional theory calculations indicated the propensity for bond breaking between C16 and O21 in deltamethrin molecules, and the degradation pathway was validated through GC-MS analysis of the products formed. Moreover, the Fe (III)/sulfite system demonstrated good degradation performance for deltamethrin in secondary effluent, achieving degradation rates of 46.3%. In particular, the Fe (III)/sulfite system showed minimal bromate formation, attributed to the capacity of sulfite to reduce active bromine intermediates into bromine ions. Full article

Squid ink melanin can be efficiently extracted from the byproduct ink sac generated during squid processing. As a natural food colorant, it possesses inherent antioxidant properties and the capability to adsorb heavy metals. This study aims to investigate the solubility of water-soluble squid ink melanin (WSSM) obtained from the ink sac, as well as its stability under various conditions including temperature, pH, salt, sugar, potassium sorbate, metal ions, sodium benzoate, sodium sulfite (reducing agent), and hydrogen peroxide (oxidizing agent). Moreover, it explores the scavenging effects of WSSM on free radicals and cadmium ions. The findings suggest that WSSM’s stability is insignificantly affected by high temperature, sucrose, and salt. However, acidity, sodium benzoate, potassium sorbate, sodium sulfite (Na₂SO₃), and hydrogen peroxide (H₂O₂) significantly influence its stability. Most metal ions do not impact the stability of WSSM, except for Fe²⁺, Fe³⁺, Al³⁺, and Cu²⁺, which result in the precipitation of WSSM. Additionally, WSSM exhibits remarkable antioxidant activity with IC₅₀ values of 0.91, 0.56, and 0.52 mg/mL for scavenging superoxide anion radicals (O²⁻·), hydroxyl radicals (·OH), and DPPH radicals, respectively. It also demonstrates the ability to adsorb the heavy metal Cd²⁺, with the adsorption rate gradually increasing with a higher temperature and larger amounts of WSSM added. Infrared spectroscopy analysis reveals the weakening of characteristic peaks (-COOH and -OH) during the process of Cd²⁺ adsorption by WSSM, while SEM confirms surface roughening and structural damage after Cd²⁺ adsorption. This study provides valuable insights for the utilization of squid melanin products as natural antioxidants and heavy metal adsorbents in the food industry. Full article

N-nitrosodimethylamine (NDMA), as an emerging nitrogenous disinfection byproduct, is strictly controlled by multiple countries due to its high toxicity in drinking water. Advanced reduction processes (ARPs) are a new type of water treatment technology that can generate highly reactive reducing radicals and make environmental contaminants degrade rapidly and innocuously. In this study, a systematic investigation on the kinetics of the NDMA degradation via the chosen UV/sulfite ARP and the impacts of some key parameters of reaction system was conducted. The results indicated that the UV/sulfite ARP was an efficient and energy saving method for the reductive degradation of NDMA. A total of 94.40% of NDMA was removed using the UV/sulfite ARP, while only 45.48% of NDMA was removed via direct UV photolysis under the same reaction conditions. The degradation of NDMA via the UV/sulfite ARP followed pseudo-first-order kinetics. Increasing both the UV light intensity and sulfite dosage led to a proportional increase in the NDMA removal efficiency. The alkaline condition favored the degradation of NDMA, with the removal efficiency increasing from 21.57% to 66.79% within the initial 5 min of the reaction when the pH increased from 3 to 11. The presence of dissolved oxygen substantially decreased the removal efficiency of NDMA due to the formation of oxidizing superoxide radicals, which competed with NDMA by capturing the reducing active radicals during the reaction. An analysis of the degradation products indicated that several refractory intermediates such as dimethylamine, methylamine and nitrite were completely decomposed via the UV/sulfite ARP, and the final degradation products were formate, ammonia and nitrogen. Full article

Ultrafiltration (UF) has been proven effective in removing algae during seasonal algal blooms, but the algal cells and the metabolites can induce severe membrane fouling, which undermines the performance and stability of the UF. Ultraviolet-activated sulfite with iron (UV/Fe(II)/S(IV)) could enable an oxidation-reduction coupling circulation and exert synergistic effects of moderate oxidation and coagulation, which would be highly preferred in fouling control. For the first time, the UV/Fe(II)/S(IV) was systematically investigated as a pretreatment of UF for treating Microcystis aeruginosa–laden water. The results showed that the UV/Fe(II)/S(IV) pretreatment significantly improved the removal of organic matter and alleviated membrane fouling. Specifically, the organic matter removal increased by 32.1% and 66.6% with UV/Fe(II)/S(IV) pretreatment for UF of extracellular organic matter (EOM) solution and algae-laden water, respectively, while the final normalized flux increased by 12.0–29.0%, and reversible fouling was mitigated by 35.3–72.5%. The oxysulfur radicals generated in the UV/S(IV) degraded the organic matter and ruptured the algal cells, and the low-molecular-weight organic matter generated in the oxidation penetrated the UF and deteriorated the effluent. The over-oxidation did not happen in the UV/Fe(II)/S(IV) pretreatment, which may be attributed to the cyclic redox Fe(II)/Fe(III) coagulation triggered by the Fe(II). The UV-activated sulfate radicals in the UV/Fe(II)/S(IV) enabled satisfactory organic removal and fouling control without over-oxidation and effluent deterioration. The UV/Fe(II)/S(IV) promoted the aggregation of algal foulants and postponed the shift of the fouling mechanisms from standard pore blocking to cake filtration. The UV/Fe(II)/S(IV) pretreatment proved effective in enhancing the UF for algae-laden water treatment. Full article

This review sums up in detail the sulfite-based chemiluminescence (CL) systems and the impact of various enhancers such as metal ions and their complexes, solvents, nanomaterials (NMs), and carbon dots (CDs) on the CL system. Recent developments and strategies employed to enhance the sulfite-based CL systems are under lengthy discussion, especially in view of the emitting species and the reaction mechanism. The production of free radicals in the systems is thought to be critical for the improvement of the sulfite CL system due to their potential to degrade organic pollutants via advanced oxidation processes (AOPs). However, different chemicals can either favor or disfavor the formation of free radicals, ultimately having a positive or negative impact on CL response. Interestingly, these reagents can be easily differentiated by observing fluctuations in CL response with changes in concentration. We anticipate that an in-depth understanding of the mechanism of action of the sulfite CL system and the role of various enhancers on the efficiency of the system will be helpful in designing a highly selective and sensitive CL system for the detection of specific reagents. The development of improved sulfite CL systems, which use reagents that give a linear CL response with concentration, and their use in chemical, food and agricultural, forensic, pharmaceutical, clinical, agricultural, and environmental analysis is judiciously highlighted. Full article

A glycal radical enzyme called isethionate sulfite-lyase (Isla) breaks the C–S bond in isethionate to produce acetaldehyde and sulfite. This enzyme was found in the Gram-negative, colonial Bilophila wadsworthia bacteria. Sulfur dioxide, acetate, and ammonia are produced by the anaerobic respiration route from (sulfonate isethionate). Strong genotoxic H₂S damages the colon’s mucous lining, which aids in the development of colorectal cancer. H₂S production also contributes to inflammatory bowel diseases such as colitis. Here, we describe the structure-based drug designing for the Isla using an in-house database of naturally isolated compounds and synthetic derivatives. In structure-based drug discovery, a combination of methods was used, including molecular docking, pharmacokinetics properties evaluation, binding free energy calculations by the molecular mechanics/generalized born surface area (MM/GBSA) method, and protein structure dynamics exploration via molecular dynamic simulations, to retrieve novel and putative inhibitors for the Isla protein. Based on the docking score, six compounds show significant binding interaction with the Isla active site crucial residues and exhibit drug-like features, good absorption, distribution, metabolism, and excretion profile with no toxicity. The binding free energy reveals that these compounds have a strong affinity with the Isla. In addition, the molecular dynamics simulations reveal that these compounds substantially affect the protein structure dynamics. As per our knowledge, this study is the first attempt to discover Isla potential inhibitors. The compounds proposed in the study using a multi-fold computational technique may be verified in vitro as possible inhibitors of Isla and possess the potential for the future development of new medications that target Isla. Full article

To break the bottlenecks of slow hydrolysis and low acid production efficiency of waste-activated sludge (WAS) in the traditional anaerobic fermentation process, this study investigated the employment of ferrous-iron (Fe(II))-activated sulfite to produce hydroxyl, sulfate, and other highly oxidizing radicals on WAS floc cracking and short-chain fatty acid (SCFAs) production during anaerobic fermentation. The effect of the dosage ratio of Fe(II)/S(IV) was also studied. Results showed that the combined pretreatment of Fe(II)-activated sulfite significantly promoted the exfoliation of extracellular polymers and the subsequent SCFAs production. The highest concentration of SCFAs reached 7326.5 mg COD/L under the optimal dosage of 1:2 for Fe(II)/S(IV), which was 1.1~2.1 times higher than that of other research groups. Meanwhile, the analysis by 3D fluorescence spectroscopy and EPR (electron paramagnetic resonance) showed that Fe(II)-activated sulfite had a synergistic effect on the rupture of sludge cells and the stripping of extracellular polymers, with SO₄⁻ and OH as the key radicals generated and being much stronger in the 1:1 and 1:2 groups. High-throughput sequencing showed that the Fe(II)-activated sulfite system significantly changed the functional microbial diversity. The anaerobic fermentation bacteria and sulfate-reducing bacteria were significantly enriched. The underlying mechanism of Fe(II)-activated sulfite oxidation and molecular ecological network of key microbiomes were unveiled. Full article

The isomorphism of S-bearing feldspathoids belonging to the cancrinite, sodalite, tugtupite, vladimirivanovite, bystrite, marinellite and scapolite structure types has been investigated using a multimethodical approach based on infrared, Raman and electron spin resonance (ESR), as well as ultraviolet, visible and near infrared (UV–Vis–near IR) absorption spectroscopy methods and involving chemical and X-ray diffraction data. Sapozhnikovite Na₈(Al₆Si₆O₂₄)(HS)₂ and sulfite and thiosulfate analogues of cancrinite are synthesized hydrothermally and characterized by means of electron microprobe analyses, powder X-ray diffraction and Raman spectroscopy. The possibility of the incorporation of significant amounts of SO₄²⁻, S₄ and SO₃²⁻ in the crystal structures of cancrisilite, sulfhydrylbystrite and marinellite, respectively, has been established for the first time. Thermal conversions of S-bearing groups in the synthetic sulfite cancrinite and sapozhnikovite analogues as well as natural vladinirivanovite and S₄-bearing haüyne under oxidizing and reducing conditions have been studied using the multimethodical approach. The SO₄²⁻ and S²⁻ anions and the S₃^•– radical anion are the most stable S-bearing species under high-temperature conditions (in the range of 700–800 °C); their ratio in the heated samples is determined by the redox conditions and charge-balance requirement. The HS⁻ and S₅²⁻ anions are stable only under highly reducing conditions. Full article

1,4-Napththoquinones (NQs) are clinically relevant therapeutics that affect cell function through production of reactive oxygen species (ROS) and formation of adducts with regulatory protein thiols. Reactive sulfur species (RSS) are chemically and biologically similar to ROS and here we examine RSS production by NQ oxidation of hydrogen sulfide (H₂S) using RSS-specific fluorophores, liquid chromatography-mass spectrometry, UV-Vis absorption spectrometry, oxygen-sensitive optodes, thiosulfate-specific nanoparticles, HPLC-monobromobimane derivatization, and ion chromatographic assays. We show that NQs, catalytically oxidize H₂S to per- and polysulfides (H₂S_n, n = 2–6), thiosulfate, sulfite and sulfate in reactions that consume oxygen and are accelerated by superoxide dismutase (SOD) and inhibited by catalase. The approximate efficacy of NQs (in decreasing order) is, 1,4-NQ ≈ juglone ≈ plumbagin > 2-methoxy-1,4-NQ ≈ menadione >> phylloquinone ≈ anthraquinone ≈ menaquinone ≈ lawsone. We propose that the most probable reactions are an initial two-electron oxidation of H₂S to S⁰ and reduction of NQ to NQH₂. S⁰ may react with H₂S or elongate H₂S_n in variety of reactions. Reoxidation of NQH₂ likely involves a semiquinone radical (NQ^·−) intermediate via several mechanisms involving oxygen and comproportionation to produce NQ and superoxide. Dismutation of the latter forms hydrogen peroxide which then further oxidizes RSS to sulfoxides. These findings provide the chemical background for novel sulfur-based approaches to naphthoquinone-directed therapies. Full article

The Fe(III)-S(IV) system used for advanced oxidation processes (AOPs) at acidic pH has just been proposed and demonstrated valid for very few contaminants in the last several years. In this work, we investigated the effect of ultraviolet A (UVA) radiation on the degradation efficiency of the Fe(III)/S(IV) system at near-neutral pH. Paracetamol (PARA) was selected as a model contaminant. The influencing factors, such as initial pH and Fe(III)/S(IV) molar ratio on chemical kinetics, and the mechanism of PARA degradation are investigated, with an emphasis on the determination of dominant oxidant species. Our results show that irradiation enhances the PARA degradation by accelerating the decrease of pH to acidic levels, and the optimal pH for the degradation of PARA in the Fe(III)/S(IV)/O₂ system was around 4.0. At near-neutral pH, more than 60% of PARA was decomposed within 40 min under irradiation, whereas no significant degradation of PARA was observed using Fe(III)/S(IV) at pH 7.0 without irradiation. Mechanism investigation revealed that sulfate radical (SO₄^•‒) is the main oxidant species generated and responsible for the PARA degradation under these conditions. This finding may have promising implications in developing a new degradation process for dealing with wastewater at near-neutral pH by the Fe(III)/S(IV)/O₂ system under UVA irradiation. Full article

Food spoilage makes foods undesirable and unacceptable for human use. The preservation of food is essential for human survival, and different techniques were initially used to limit the growth of spoiling microbes, e.g., drying, heating, salting, or fermentation. Water activity, temperature, redox potential, preservatives, and competitive microorganisms are the most important approaches used in the preservation of food products. Preservative agents are generally classified into antimicrobial, antioxidant, and anti-browning agents. On the other hand, artificial preservatives (sorbate, sulfite, or nitrite) may cause serious health hazards such as hypersensitivity, asthma, neurological damage, hyperactivity, and cancer. Thus, consumers prefer natural food preservatives to synthetic ones, as they are considered safer. Polyphenols have potential uses as biopreservatives in the food industry, because their antimicrobial and antioxidant activities can increase the storage life of food products. The antioxidant capacity of polyphenols is mainly due to the inhibition of free radical formation. Moreover, the antimicrobial activity of plants and herbs is mainly attributed to the presence of phenolic compounds. Thus, incorporation of botanical extracts rich in polyphenols in perishable foods can be considered since no pure polyphenolic compounds are authorized as food preservatives. However, individual polyphenols can be screened in this regard. In conclusion, this review highlights the use of phenolic compounds or botanical extracts rich in polyphenols as preservative agents with special reference to meat and dairy products. Full article

The main focus of the current study was to sustain the releasing behavior of theophylline by fabricated polymeric microgels. The free radical polymerization technique was used for the development of aspartic acid-co-poly(2-acrylamido-2-methylpropanesulfonic acid) microgels while using various combinations of aspartic acid, 2-acrylamido-2-methylpropanesulfonic acid, and N′,N′-methylene bisacrylamide as a polymer, monomer, and cross-linker, respectively. Ammonium peroxodisulfate and sodium hydrogen sulfite were used as initiators. Characterizations such as DSC, TGA, SEM, FTIR, and PXRD were performed for the fabricated microgels to assess their thermal stability with unreacted polymer and monomer, their surface morphology, the formation of a new polymeric system of microgels by evaluating the cross-linking of functional groups of the microgels’ contents, and to analyze the reduction in crystallinity of the theophylline by fabricated microgels. Various studies such as dynamic swelling, drug loading, sol–gel analysis, in vitro drug release studies, and kinetic modeling were carried out for the developed microgels. Both dynamic swelling and percent drug release were found higher at pH 7.4 as compared to pH 1.2 due to the deprotonation of functional groups of aspartic acid and AMPS. Similarly, sol–gel analysis was performed and an increase in gel fraction was observed with the increasing concentration of microgel contents, while sol fraction was decreased. Conclusively, the prepared carrier system has the potential to sustain the release of the theophylline for an extended period of time. Full article

Iopromide (IOP), an iodinated X-ray contrast medium (ICM), is identified as a precursor to iodide disinfection byproducts that have high genotoxicity and cytotoxicity to mammals. ICM remains persistent through typical wastewater treatment processes and even through some hydroxyl radical-based advanced oxidation processes. The development of new technologies to remove ICMs is needed. In this work, mackinawite (FeS)-activated sulfite autoxidation was employed for the degradation of IOP-containing water. The experiment was performed in a 500 mL self-made temperature-controlled reactor with online monitoring pH and dissolved oxygen in the laboratory. The effects of various parameters, such as initial pH values, sulfite dosages, FeS dosages, dissolved oxygen, and inorganic anions on the performance of the treatment process have been investigated. Eighty percent of IOP could be degraded in 15 min with 1 g L⁻¹ FeS, 400 μmol L⁻¹ sulfite at pH 8, and high efficiency on the removal of total organic carbon (TOC) was achieved, which is 71.8% via a reaction for 1 h. The generated hydroxyl and oxysulfur radicals, which contributed to the oxidation process, were identified through radical quenching experiments. The dissolved oxygen was essential for the degradation of IOP. The presence of Cl⁻ could facilitate IOP degradation, while NO₃⁻ and CO₃²⁻ could inhibit the degradation process. The reaction pathway involving H-abstraction and oxidative decarboxylation was proposed, based on product identification. The current system shows good applicability for the degradation of IOP and may help in developing a new approach for the treatment of ICM-containing water. Full article

Oenotannins are nowadays widely used as co-adjuvant in the winemaking process. The increasing cultivation and consumption of pomegranate (Punica granatum L.) leads to high amounts of by-products, mainly peels. Aim of this study was to propose a dried tannin-rich extract from pomegranate by-products as a new oenotannin. A decoction was prepared from mesocarp of the Wonderful pomegranate variety only using hot water as extracting solvent. The dried decoction was physical-chemically characterized and compared to 7 existing commercial oenotannins from different botanical origin (grape seed, oak, gallnut), according to UV-Vis Spectroscopy, Colorimetric analysis (CIELab), gelatin index, reactivity to proteins, HPLC-DAD, DPPH, and Total Polyphenols content by both Folin-Ciocalteu and the International Organization of Vine and Wine (OIV) methods. Data showed the lowest antiradical (AR) and total polyphenolic content (TPC) for the pomegranate tannin but also the highest AR/TPC ratio suggesting a good radical scavenging potential of this new tannin. Pomegranate tannin showed high reactivity with proteins, a unique chromatographic profile, and a low color impact. The new pomegranate tannin showed an interesting potential for oenological applications in particular for reducing the use of sulfites during vinification and for the white wine stabilization. Full article