Search Results (55)

This study focuses on optimizing the ozonation process in drinking water production from Lake Butoniga to ensure safe water quality while minimizing disinfection by-products (DBPs). Laboratory simulations were conducted using the Box–Behnken design to model the effects of ozone dose and treatment duration on bromate formation, trihalomethanes (THMs), haloacetic acids (HAAs) and specific UV absorption (SUVA). Two ozonation strategies were tested: Strategy 1 aimed to minimize all DBPs, while Strategy 2 focused on controlling bromate levels while keeping THMs, HAAs and SUVA below 80% of maximum contaminant levels. Results showed that Strategy 2 reduced ozone consumption while maintaining water quality within regulatory standards, providing a cost-effective and environmentally sustainable treatment approach. Seasonal and depth-dependent variations in water quality had a significant impact on treatment efficiency and required adjustments to operational settings. The study also addressed discrepancies between laboratory and real plant results and suggested recalibration methods that improved the accuracy of model predictions. These results highlight the potential for integrating predictive modelling and dynamic treatment strategies into large-scale water treatment processes. Full article

Developing an efficient recycling route for spent single-use medical devices is essential for recovering precious metals. The proposed complete hydrometallurgical route goes through the initial pyrolysis and acid digestion steps, expanding upon our previous relevant work in the field, followed by solvent extraction, stripping, and precipitation procedures. In this study, a complete hydrometallurgical process was developed for the recovery of gold, platinum, iridium, and tantalum, separating them from other metals, i.e., from iron, chromium, and nickel, also present in the examined medical devices, i.e., (i) diagnostic electrophysiology catheters, containing gold, (ii) diagnostic guide wires, containing platinum and iridium alloys, and (iii) self-expanding stents, containing tantalum. This study reports the experimental results of selecting an efficient extractant, stripping, and precipitation agent, along with the effects of key factors that influence each consecutive step of the process, i.e., agent concentration, aqueous to organic phase ratio, contact time, and pH, using simulated metal solutions and also applying the obtained optimal conditions to the treatment of real sample solutions. For the selective separation of gold, Aliquat 336 was used to extract it in the organic phase; it was then stripped using a thiourea solution and precipitated by utilizing an iron sulfate (II) solution and proper pH adjustment. The selective separation of platinum was achieved by using Aliquat 336 for the organic phase extraction and a perchlorate acid solution for stripping it back into the aqueous solution and adding a sodium bromate solution to precipitate it. Due to the similar chemical behavior, the selective recovery of iridium followed the same processes as that of platinum, and the separation between them was achieved through selective precipitation, as heating the solution and adjusting the pH value resulted in the selective precipitation of iridium. Lastly, the selective recovery of tantalum consists of extraction by using Alamine 336, then stripping it back to the aqueous phase by using sodium chloride, and precipitation by using potassium salt solution and proper pH adjustment. A total recovery of 88% for Au, 86% for Pt, 84% for Ir, and 80% for Ta was obtained, thus achieving a high uptake of precious metals from the examined real spent/waste samples. Full article

Discharge from Wastewater Treatment Plants (WWTPs) can result in the emission of organic micropollutants (OMPs) and microplastics (MPs) into the aquatic environment. To prevent this harmful release, a pilot plant consisting of an ozonation followed by a granular activated carbon (GAC) filter was operated at a WWTP in Germany, and its side-effects on the concentrations of nitrogen (N) and phosphorous (P) compounds were measured. Over 80% of OMPs and transformation products were removed during the operating time (around 6000 bed volumes) no matter the ozone dose (from around 0.1 to 0.5 mg_O3/mg_DOC), except for Diatrizoic acid, whose breakthrough appeared at 3500 BV. Formation of the oxidation by-product, NDMA, increased with higher ozone doses, but the concentration remained below 100 ng/L. Bromate was formed at a higher ozone dose (>0.4 mg_O3/mg_DOC) but at a low concentration—below 10 µg/L. The MP particles detected in the inflow (PE, SBR, PP, and PS) were effectively eliminated to a high degree, with a removal rate of at least 92%. Carbon parameters (COD, DOC, and SAC₂₅₄) were removed further by the pilot plant, but to different extents. As expected, nitrate was formed during ozonation, while nitrite’s concentration decreased. Further, nitrite decreased and nitrate increased within the GAC filter, while ammonium was eliminated by at least 90%. Total P concentration decreased after the pilot, but the concentration of PO₄-P increased. Full article

Diagenetic spheroids are rounded mineralised structures in sedimentary rocks that span several orders of size dimensions. These objects include rosettes spanning tens of micrometres; millimetre-sized granules; and centimetre- to metre-scale botryoids, nodules, and concretions. Connections between diagenetic spheroids and chemically oscillating reactions (COR) have been established based on chemical and pattern similarities. Nevertheless, it is unknown if there are variations in their occurrences throughout geological time, especially during periods of global environmental change. This is because COR are pattern-forming reactions where carboxylic acids are decarboxylated by strong oxidants like sulphuric acid, bromate, or iodate. The hypothesis is that there should be a greater number of diagenetic spheroids at periods of increased atmospheric and oceanic oxygenation levels. Hence, this work presents the first compilation of occurrences of diagenetic spheroids between 0.541 and 1.8 billion years ago (Ga). The compiled patterned objects are those with concentric laminations and radially aligned crystals, which are patterns akin to equidistant circularly concentric waves that radially diffuse in COR. Another characteristic of diagenetic spheroids, similar to that found in botryoidal minerals, is the destructive interference that forms circular twins; this is identical to the COR pattern formed when circular waves meet. The timeline of Proterozoic diagenetic spheroids produced in this work reveals a significant increase in occurrences across the Ediacaran, which is attributed to an increased environmental oxidation state. During this interval, seawater is known to have become richer in sulphate and iodate, which create ideal conditions for the abiotic and diagenetic oxidation of biomass. Therefore, increased occurrences of diagenetic spheroids in the Neoproterozoic possibly represent sedimentological evidence for abiotic decarboxylation reactions and widespread COR in productive environments. The distribution of diagenetic spheroids observed during the Proterozoic may also be more broadly applicable to other epochs of Earth’s history. Full article

The production and transmission system of the Saudi Water Authority (SWA) faces a number of challenges in maintaining the high quality of potable water. Produced desalinated water is transmitted for long distances and is mixed with ground and surface waters of varying quality. The SWA is also in the process of converting from thermal desalination to seawater reverse osmosis which typically gives higher total dissolved solids, requiring better control of species with possible impacts on system integrity or human health. The results of monitoring across the desalination plants and transmission systems of the SWA in 2020–2022 confirm an overall high quality of water, with levels of disinfection by-products and heavy metals low in comparison to public water supplies in high-income countries dependent on surface and groundwater rather than seawater desalination. The results also indicate that continued operational improvements are required with the transition from thermal desalination technologies to reverse osmosis in order to maintain chloride at a level to avoid corrosion in the distribution system and to maintain boron and bromate within acceptable regulatory limits. Significant improvement in bromate control was observed over the course of the study, and recent innovations in post-treatment suggest that this will improve further. Full article

Bromate, often detected in drinking water, is associated with a significant risk of cancer. Catalytic reduction has been recognized as an effective treatment technique to remove ions by reducing them over metal catalysts in the presence of a reducing agent, usually hydrogen. This work aims to synthesize metallic magnetic nanoparticles of iron oxide (FeO) and mixed iron oxides with manganese (MnFeO), cobalt (CoFeO), and copper (CuFeO) coated with carbon via chemical vapor deposition (C-MNP) to be applied as catalysts to the reduction of bromate in water. The use of magnetic nanoparticles coated with carbon enables catalyst recovery via magnetic separation and takes advantage of the catalytic properties of the carbon materials. The iron particles proved to be the most promising catalysts for the reduction of bromate into bromide, the highest removal being obtained with the CFeO@CVD750 sample, resulting in a 99% conversion after 120 min of reaction under the conditions tested. Due to its magnetic nature, the catalytic material was easily removed after the reaction and applied in four consecutive cycles without losing its catalytic properties. These results highlight the great potential of carbon-coated magnetic nanoparticles for reducing bromate in water. 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

Bromate is a potentially carcinogenic disinfection by-product of potential concern in desalinated waters, where bromide derived from seawater can be converted to bromate by the oxidising species used for disinfection. Historically, it has been difficult to maintain complete adherence to national standards of no more than 10 ppb for bromate at all locations served with desalinated seawater by the Saline Water Conversion Corporation (SWCC) in the Kingdom of Saudi Arabia. In this full-scale study, the addition of 100–200 ppb of ammonia to the produced water of a Multi-Stage Flash Desalination plant effectively controlled the formation of bromate in the transmission system supplying inland centres in the Makkah Province of the Kingdom of Saudi Arabia (Arafa, Taif) on a time scale sufficient for the distribution of water to the consumer, even when the bromide content of the produced water was artificially enhanced (up to 132 ppb) via the addition of seawater. Full article

The passage of cathodic current through the acidized aqueous bromate solution (catholyte) leads to a negative shift of the average oxidation degree of Br atoms. It means a distribution of Br-containing species in various oxidation states between −1 and +5, which are mutually transformed via numerous protonation/deprotonation, chemical, and redox/electrochemical steps. This process is also accompanied by the change in the proton (H⁺) concentration, both due to the participation of H⁺ ions in these steps and due to the H⁺ flux through the cation-exchange membrane separating the cathodic and anodic compartments. Variations of the composition of the catholyte concentrations of all these components has been analyzed for various initial concentrations of sulfuric acid, c_A⁰ (0.015–0.3 M), and two values of the total concentrations of Br atoms inside the system, c_tot (0.1 or 1.0 M of Br atoms), as functions of the average Br-atom oxidation degree, x, under the condition of the thermodynamic equilibrium of the above transformations. It is shown that during the exhaustion of the redox capacity of the catholyte (x pass from 5 to −1), the pH value passes through a maximum. Its height and the corresponding average oxidation state of bromine atoms depend on the initial bromate/acid ratio. The constructed algorithm can be used to select the initial acid content in the bromate catholyte, which is optimal from the point of view of preventing the formation of liquid bromine at the maximum content of electroactive compounds. Full article

Black phosphorene quantum dots (BPQDs) were prepared by ultrasonic-assisted liquid-phase exfoliation and centrifugation with morphologies proved by TEM results. Furthermore, an electrochemical enzyme sensor was prepared by co-modification of BPQDs with horseradish peroxidase (HRP) on the surface of a carbon ionic liquid electrode (CILE) for the first time. The direct electrochemical behavior of HRP was studied with a pair of well-shaped voltammetric peaks that appeared, indicating that the existence of BPQDs was beneficial to accelerate the electron transfer rate between HRP and the electrode surface. This was due to the excellent properties of BPQDs, such as small particle size, high interfacial reaction activity, fast conductivity, and good biocompatibility. The presence of BPQDs on the electrode surface provided a fast channel for direct electron transfer of HRP. Therefore, the constructed electrochemical HRP biosensor was firstly used to investigate the electrocatalytic behavior of trichloroacetic acid (TCA) and potassium bromate (KBrO₃), and the wide linear detection ranges of TCA and KBrO₃ were 4.0–600.0 mmol/L and 2.0–57.0 mmol/L, respectively. The modified electrode was applied to the actual samples detection with satisfactory results. Full article

NaClO₃ and NaBrO₃ are believed to form a complete solid solution from RT to fusion. The unique solid phase can thus be written: NaClO_3(1−x)-NaBrO_3(x) with: 0 ≤ x ≤ 1. This study shows that at high temperatures, this statement might be valid. Nevertheless, up to 50 °C, probably up to 160 °C, and even higher temperatures, this is not true when the system is in thermodynamic equilibrium. A large miscibility gap exists at room temperature (RT). This gap could be reduced up to a complete disappearance by fast crystallization, for instance, spray-drying. The necessary conditions to access equilibrium, including homochirality, are also discussed. Full article

In this study, one type of layered double hydroxide (LDH), the meta-aluminate intercalated mafic-modified hydrotalcite (LDH-2), was engineered through an unprecedentedly facile, affordable one-step procedure. In the interest of meticulous perception regarding our superior strategy, the conventional two-step synthesis method—the fabrication of optimal mafic-modified hydrotalcite through the coprecipitation and roasting process followed by a second aging step (LDH-1)—was also synthesized. After scrutinization of as-derived nanostructures, the adsorption capacity of both structures for bromate remediation was elaborated. When the effect of experimental variation was optimized and the impact of various ions was investigated, the more astounding performance of LDH-2 (0.97 mg/g) was detected when compared with conventional LDH-1 (0.90 mg/g). Therefore, the novel approach for the engineering of meta-aluminate intercalated mafic hydrotalcite not only introduces facile and practical procedures, but also furnishes a much more efficient adsorption system. In the matter of structure durability, the as-synthesized LDH-2 presented exceptional resistance, maintaining activity after five consecutive cycling runs. This investigation sheds light on the facile and affordable synthesis of the LDH construction. Full article

Potassium bromate (PB) is a general food additive, a significant by-product during water disinfection, and a carcinogen (Class II B). The compound emits toxicity depending on the extent of its exposure and dose through consumable items. The current study targeted disclosing the ameliorative efficacy of zinc oxide nanoparticles (ZnO NPs) prepared by green technology in PB-exposed Swiss albino rats. The rats were separated into six treatment groups: control without any treatment (Group I), PB alone (Group II), ZnO alone (Group III), ZnO NP alone (Group IV), PB + ZnO (Group V), and PB + ZnO NPs (Group VI). The blood and kidney samples were retrieved from the animals after following the treatment plan and kept at −20 °C until further analysis. Contrary to the control (Group I), PB-treated rats (Group II) exhibited a prominent trend in alteration in the established kidney function markers and disturbed redox status. Further, the analysis of the tissue and nuclear DNA also reinforced the biochemical results of the same treatment group. Hitherto, Groups III and IV also showed moderate toxic insults. However, Group VI showed a significant improvement from the PB-induced toxic insults compared to Group II. Hence, the present study revealed the significant therapeutic potential of the NPs against PB-induced nephrotoxicity in vivo, pleading for their usage in medicines having nephrotoxicity as a side effect or in enhancing the safety of the industrial use of PB. Full article

An important biomarker of oxidative damage in cellular DNA is the formation of 7,8-dihydro-8-oxo-2′-deoxyguanosine (8-oxodG). Although several methods are available for the biochemical analysis of this molecule, its determination at the single cell level may provide significant advantages when investigating the influence of cell heterogeneity and cell type in the DNA damage response. to. For this purpose, antibodies recognizing 8-oxodG are available; however, detection with the glycoprotein avidin has also been proposed because of a structural similarity between its natural ligand biotin and 8-oxodG. Whether the two procedures are equivalent in terms of reliability and sensitivity is not clear. In this study, we compared the immunofluorescence determination of 8-oxodG in cellular DNA using the monoclonal antibody N45.1 and labeling using avidin conjugated with the fluorochrome Alexa Fluor488 (AF488). Oxidative DNA damage was induced in different cell types by treatment with potassium bromate (KBrO₃), a chemical inducer of reactive oxygen species (ROS). By using increasing concentrations of KBrO₃, as well as different reaction conditions, our results indicate that the monoclonal antibody N45.1 provides a specificity of 8-oxodG labeling greater than that attained with avidin-AF488. These findings suggest that immunofluorescence techniques are best suited to the in situ analysis of 8-oxodG as a biomarker of oxidative DNA damage. Full article

Disinfection by-products (DBPs) are the most common organic contaminants in tap water and are of wide concern because of their highly developmental toxic, cytotoxic, and carcinogenic properties. Typically, to control the proliferation of pathogenic microorganisms, a certain concentration of residual chlorine is retained in the factory water, which reacts with the natural organic matter and the disinfection by-products that have been formed, thus affecting the determination of DBPs. Therefore, to obtain an accurate concentration, residual chlorine in tap water needs to be quenched prior to treatment. Currently, the most commonly used quenching agents are ascorbic acid, sodium thiosulfate, ammonium chloride, sodium sulfite, and sodium arsenite, but these quenching agents can cause varying degrees of DBPs degradation. Therefore, in recent years, researchers have attempted to find emerging chlorine quenchers. However, no studies have been conducted to systematically review the effects of traditional quenchers and new ones on DBPs, as well as their advantages, disadvantages, and scope of application. For inorganic DBPs (bromate, chlorate, and chlorite), sodium sulfite has been proven to be the ideal chlorine quencher. For organic DBPs, although ascorbic acid caused the degradation of some DBPs, it remains the ideal quenching agent for most known DBPs. Among the studied emerging chlorine quenchers, n-acetylcysteine (NAC), glutathione (GSH), and 1,3,5-trimethoxybenzene are promising for their application as the ideal chlorine quencher of organic DBPs. The dehalogenation of trichloronitromethane, trichloroacetonitrile, trichloroacetamide, and bromochlorophenol by sodium sulfite is caused by nucleophilic substitution reaction. This paper takes the understanding of DBPs and traditional and emerging chlorine quenchers as a starting point to comprehensively summarize their effects on different types of DBPs, and to provide assistance in understanding and selecting the most suitable residual chlorine quenchers during DBPs research. Full article