pH Values Research Articles

Pipeline Corrosion Prediction and Uncertainty Analysis with an Ensemble Bayesian Neural Network Approach

This study developed an ensemble Bayesian Neural Network (BNN) model for pipeline corrosion prediction incorporating uncertainty analysis. The performance of the proposed BNN model was compared with different empirical and data-driven models. Shapley Additive Explanation (SHAP) values were used to quantify the importance of input factors. Results indicate that the ensemble BNN model demonstrates superior prediction accuracy, achieving the highest R2 value of 0.949, with the lowest Mean Absolute Error (MAE) of 0.33mm and Root Mean Square Error (RMSE) of 0.449mm on corrosion depth. It outperforms other models in predicting maximum corrosion depth and uniquely captures uncertainty information, which deterministic models cannot provide. Key factors influencing corrosion include chloride content, pH, pipe-to-soil potential, and pipeline age. Specifically, conditions such as a pipe-to-soil potential exceeding -0.85V, a pipeline age over 20 years, and pH values below 7 are found to significantly accelerate corrosion. The model also illustrates the effects of different influencing factors on corrosion growth uncertainty. Higher chloride content, lower pH values, and higher pipe-to-soil potentials may expand the uncertainty bounds. The proposed model presents the dynamic changes in prediction uncertainty over time, which is usually ignored in previous models. It can improve the precision and reliability of long-term predictions concerning pipeline corrosion depth. This knowledge of corrosion uncertainty is crucial for making informed decisions about pipeline inspection and maintenance strategies.

In Ukrainian

An important environmental problem is the removal of contaminants and the purification of domestic and industrial water from pollutants of various nature. There is a separate issue of cleaning the effluents of pharmaceutical enterprises. Various chemical and physical methods are used to solve these problems, such as settling, coagulation, filtration, and sorption techniques. Adsorption with using efficient and reusable adsorbents is the most effective and cheap. In recent years special attention has been paid to the use of sorption materials based on hydrolysis lignin, which has a high sorption activity in relation to ions of some heavy metals, dyes, organic compounds and pharmaceuticals. The use of lignin as an adsorbent simultaneously solves two problems: the disposal of paper production waste and the purification of sewage from various types of pollutants. The aim of this work was to study the sorption properties of hydroylysis lignin in aqueous solution in relation to some medical substances of different chemical nature, existing in solution in cationic, anionic or neutral forms. The point of zero charge of hydrolysis lignin was determined, which is equal to рНPZC = 4.95. The adsorption of rivanol, proflavin, doxorubicin, levofloxacin, furacilin, and salicylic acid by hydrolysis lignin was studied as dependence on the pH of the solutions and the concentration of adsorbates. It was found that adsorption largely depends on the structure of the pharmaceuticals and the pH values of the solutions. It is shown that the studied medical compounds, which exist in the solution in the form of cations, are adsorbed the best (rivanol, proflavin, doxorubicin). Adsorption of these substances occurs mainly due to electrostatic interaction with negatively charged surface groups. Adsorption of anionic form (salicylic acid) is the smallest and is observed only at quite low pH values. Levofloxacin is adsorbed mainly in the form of zwitter ions, and furacilin is in neutral form. The adsorption of these both compounds occupies an intermediate value of adsorption amount. The obtained adsorption isotherms are well lined up in Langmuir coordinates. Quantitative parameters of adsorption values - of maximum adsorption and equilibrium constants were calculated. Quite high values of these parameters indicate that hydrolysis lignin can be used as an adsorbent for the removal of these pharmaceuticals.

Metal Complexes in Biology and Medicine: The System Cadmium (II)/ Iron (II)/ Zinc (II)- α- Aminobutyric Acid

Metal ions play an important role in biological systems. The importance of metal ions to essential functions of living systems and for wellbeing of living organisms is well known. Complexation reactions of α– aminobutyric acid with cadmium (II), iron (II) and zinc (II) have been studied in solution phase using paper ionophoretic technique. The present method is based upon the migration of a spot of metal ion on a paper strip at different pH values of background electrolyte containing 0.01M α -aminobutyric acid. A graph of pH against mobility was used to obtained information in the binary complexes and to calculate its stability constants. The logarithm stability constants of ML and ML2 complexes of α -aminobutyric acid were found to be (4.01 ± 0.02; 2.72 ± 0.01), (3.73 ± 0.03; 2.65 ± 0.09), (4.45 ± 0.02; 2.80 ± 0.03) for cadmium (II), iron (II) and zinc (II) complexes, respectively at ionic strength 0.1 molL-1 and a temperature of 35º C. Metal based drugs bioactivity can be increase by metal chelation, which in turn increase their absorbance and stability. Metal complexes can offer their action such as anti-inflammatory, anti-diabetic, antimicrobial, anticancer and ant thyroid compounds.

In Ukrainian

The paper discusses the results of saponite research from the Tashkiv deposit of Ukraine. X-ray structural analysis proved the necessity of preliminary cleaning of saponites from mineral impurities. The study of the morphology, nanoprofile and topography of the surface of saponite by the methods of SEM-microscopy and Atomic Force Microscopy revealed that the mineral is represented by aggregates of nano- and microparticles of a pyramidal shape. Its characteristic feature is the heterogeneity of isomorphic substitutions of ions in the tetrahedral and octahedral sheets of the structural elementary package. According to X-ray fluorescence analysis, saponite contains a significant amount of Fe3+, which isomorphically replaces magnesium Mg2+ and, accordingly, is located mastly in the octahedral sheet of the structural package with a charge from +0.37 to +0.35. The number and mechanism of isomorphic substitutions determine the presence of a total negative charge of the crystal lattice (from –0.38 to –0.3), the value of which ensures intensive interaction with water molecules of the interpacket space with the formation of surface OH groups. Accordingly, both acidic and alkaline Lewis and Brønsted centers are present on the surface with a predominance of acidic ones, so the acidity function is 5.82, and the point of zero proton charge is pH = 5.5. During dispersion in water, a part of the alkaline centers of the side surface are transformed into Brønsted acid centers as a result of their protonation, which causes an increase in the pH of the dispersion medium to pH = 8–8.6. Accordingly, the isoionic state is reached at pH = 7.5. The difference in pH values characterizing the isoionic state of the surface and the point of zero net proton charge (PZNPC) indicates the presence of weak acid-alkaline centers on the surface. The study of the adsorption of acid-alkaline dyes showed the adsorption of alkaline (pK = 1¸3) and acid (pK = 7¸14) dyes on saponites. The latter is significantly reduced due to the preliminary hydration of the solid surface - mainly the lateral edges of the particles. Acidic dyes are not adsorbed from a dispersion medium with pH < 5.5 (PZNPC), and basic dyes are adsorbed at pH > 5,5( PZNPC).

Natural Polyelectrolyte Hydrogels with Two Types of Cross-Links with Different Energy

For the first time, gels of a polymer cross-linked by two types of ionic cross-links of different energies, namely trivalent chromium (III) ions and divalent iron (II) ions, were prepared. The negatively charged polysaccharide xanthan, a polyelectrolyte of natural origin, was used as a polymer. A study of xanthan gels cross-linked with each cross-linker separately was carried out to identify the optimal concentrations of each cross-linker for the production of a double cross-linked gel. The mechanical properties of hydrogels under oscillatory shear deformations were then studied. It was demonstrated that the simultaneous use of two cross-linkers resulted in a synergistic increase in the elastic modulus (plateau storage modulus) compared to gels cross-linked with each cross-linker separately. For a gel with two types of cross-links, the elastic modulus was 16 Pa. In contrast, for gels cross-linked with either chromium (III) cations or iron (II) cations, the elastic modulus was approximately 0.6 and 0.5 Pa, respectively. The strong effect can be attributed to the different nature of cross-linking between xanthan macromolecules and chromium (III) and iron (II) cations, as well as the different strength of the cross-links formed. The optimal range of pH values was determined in which a synergistic increase in the elastic modulus of gels with two types of cross-links was observed compared to the corresponding gels cross-linked with each cross-linker separately. Consequently, the concurrent utilisation of two cross-linking agents that generate cross-links with disparate energy levels represents an efficacious strategy to improve the tensile strength of polymer hydrogels.

Performance of sugarcane molasses in concrete under hot weather

AbstractThe present research studies the effect of adding sugar factory waste sugarcane molasses as an alternative to chemical inhibitory additives manufactured on concrete cast during hot weather in the summer of Iraq. The current study includes a study of the setting time for cement paste and workability for fresh concrete and some mechanical properties of hardened concrete with sugarcane molasses using percentage 0–0.3% of cement weight. The study also included studying the value of pH of concrete to investigate the effect of sugarcane molasses on reinforced concrete. The results showed that the sugarcane molasses can be used by about 0.1% of cement weight for medium projects and between 0.1 and 0.2% for large projects. It was also found that the compression strength increased by about 11.5% and the indirect tensile strength increased by about 7.5 and 7.4% for splitting and flexural test, respectively for concrete mixtures containing 0.2% of sugarcane molasses.

Using Gold‐nanoparticles‐based Nanozyme to Accelerate the Self‐assembly of Silk Fibroin

AbstractThe design and development of nanomaterials with intrinsic enzyme‐like activities (nanozymes) have attracted huge interest during the past several decades. Herein, by incorporating the concept of nanozyme‐involved biomimetic catalysis into the molecular assembly, we introduce an exciting example of utilizing the gold nanozyme system to expedite the sol‐gel transition of silk fibroin. In this system, silica‐encapsulated gold nanoparticles (MSN‐AuNPs) possess an intrinsic glucose oxidase‐like activity, and the activity of AuNPs has been studied by using first‐principles calculations. The catalytic oxidization of glucose into gluconic acid by MSN‐AuNPs leads to a significant decrease in the pH value of silk fibroin solution, rapidly accelerating the self‐assembly of silk fibroin solution into physical hydrogel. Since nanozymes can be further remotely controlled via different stimuli, this simple, rational control and accelerated method is a significant breakthrough, will lead to a large pool of opportunities for further exploration of nanozymes in the field of molecular assembly.

Efficient recovery of phosphorus and iron from the lithium extraction slag by the leaching precipitation method

ABSTRACT The key to recovering waste LiFePO4(LFP) is the recovery of lithium; however, the effective and synchronous recovery of phosphorus and iron resources still needs to be achieved. In this paper, a new process was proposed for recovering phosphorus and iron from the lithium extraction slag (LES) of waste LFP by the leaching and precipitation method. Based on the thermodynamic analysis of Fe3+ and PO4 3− and XRD results, the experimental conditions were discussed in detail. There were three stable regions when the solution pH value was from 0 to 5, no precipitation at pH = 0–0.664, stable existence of FePO4(s) at pH = 0.664–1.203, coexistence of FePO4(s), and AlPO4(s) when pH > 1.203, respectively. The leaching solution of LES by hydrochloric acid could prepare FePO4·2H2O under the following optimal conditions: 95°C, pH 1.5, feeding speed 1.5 mL min−1. The synthesised iron phosphate was pure and distributed in flakes. Additionally, the discharge capacity of the LiFePO4/C prepared by the regenerative FePO4·2H2O was 147 mAh g−1 at 0.1 C and showed good cycle stability at 1 C. The method not only recovers FePO4 from the LES but also shows simple operation and high efficiency.

A study of chloride binding capacity of concrete containing supplementary cementitious materials

Chloride-induced steel corrosion is known to be a very common kind of deterioration of reinforced concrete. It is beneficial to bind free chloride ions to reduce the corrosion probability of the reinforcement embedded in the concrete. The binding capacity of the concrete varies according to its cementitious system. This paper investigates the chloride binding capacity of different kinds of supplementary cementitious materials (SCMs): Ground granulated blast furnace slag (GGBFS), Fly ash, and Metakaolin as a partial replacement of Ordinary Portland Cement (OPC). Different properties of concrete after chloride binding are assessed by carrying out the following tests: half-cell potential, accelerated corrosion test, compressive strength, rapid chloride penetration test, sorptivity test, measuring pH value of concrete, and XRD. The results showed that utilizing the SCMs in concrete can enhance the chloride binding capacity, especially those materials that have high quantities of aluminate and calcium in their chemical composition like GGBFS. Based on testing results, it’s recommended that the limit of the chloride content in the different codes should be revised regarding the binding capacity according to the type and quantity of the cementitious materials used.

Photocatalytic, antimicrobial and antibiofilm activities of MgFe2O4 magnetic nanoparticles

This study reports the antibacterial and antibiofilm activities of Magnesium ferrite nanoparticles (MgFe2O4) against gram-positive and gram-negative bacteria. The photocatalytic degradation of Carbol Fuchsin (CF) dye (a class of dyestuffs that are resistant to biodegradation) under the influence of UV-light irradiation is also studied. The crystalline magnesium ferrite (MgFe2O4) nanoparticles were synthesized using the co-precipitation method. The morphology of the resulting nanocomposite was examined using scanning electron microscopy (SEM), while transmission electron microscopy (TEM) was employed for further characterization of particle morphology and size. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) were utilized to analyze the crystalline structure, chemical composition, and surface area, respectively. Optical properties were evaluated using UV–Vis spectroscopy. The UV-assisted photocatalytic performance of MgFe2O4 nanoparticles was assessed by studying the decolorization of Carbol fuchsin (CF) azo dye. The crystallite size of the MgFe2O4 nanoparticles at the (311) plane, the most prominent peak, was determined to be 28.5 nm. The photocatalytic degradation of 10 ppm CF using 15 mg of MgFe2O4 nanoparticles resulted in a significant 96% reduction after 135 min at ambient temperature (25 °C) and a pH value of 9. Additionally, MgFe2O4 nanoparticles exhibited potent antibacterial activity against E. coli and S. aureus in a dose dependent manner with maximum utilized concentration of 30 µg/ml. Specifically, MgFe2O4 nanoparticles demonstrated substantial antibacterial activity via disk diffusion and microbroth dilution tests with zones of inhibition and minimum inhibitory concentrations (MIC) for E. coli (26.0 mm, 1.25 µg/ml) and S. aureus (23.0 mm, 2.5 µg/ml), respectively. Moreover, 10.0 µg/ml of MgFe2O4 nanoparticles elicited marked percent reduction in biofilm formation by E. coli (89%) followed by S. aureus (78.5%) after treatment. In conclusion, MgFe2O4 nanoparticles demonstrated efficient dye removal capabilities along with significant antimicrobial and antibiofilm activity against gram-positive and gram-negative bacterial strains suggesting their potential as promising antimicrobial and detoxifying agents.

Comparative Study of the Tribocorrosion Performance of NiTiNOL60 in Acidic, Alkaline, and Saline Environments

AbstractIn order to enhance the durability of tribological interfaces, an investigation into the synergistic effects of sliding wear, corrosion, and their interactions is crucial. This study focuses on understanding the deformation mechanisms of NiTiNOL60, a nickel-rich nickel-titanium alloy, during sliding against Al2O3 in different corrosive environments, including acidic, alkaline, and saline mediums. The pH of the environments is found to play a significant role in the tribocorrosion process, leading to electromechanically induced transformations and various wear patterns. Plastic deformations are observed on the wear track surfaces, particularly in the severe and mild wear regimes. In an alkaline environment, depassivation of the oxide layer triggers oxidational wear, with the depassivation rate dependent on factors like contact pressure, sliding velocity, and passive film properties. The wear volume is highest in saline environments, with contributions from mechanical wear, corrosion, and third-body abrasion. Grain deformations occur in the alkaline environment due to shear forces, while in the acidic medium, corrosion accelerates mild wear involving abrasion and delamination. The findings provide insights into wear mechanisms and localized corrosion, highlighting the influence of H+ and OH− groups (pH values) on corrosive wear and crack propagation.

Biodegradation of Two Textile Dyes by Bacillus Subtilis

This study revealed the efficiency of Bacillus subtilis in degrading two textile dyes (disperse red and disperse yellow), the rates of red dye removal when measured after 24, 48, 72 and 96 hours for the concentrations of 50 ppm were 51.67, 67.56, 84.67 and 95.33%, for the concentration 150 ppm were 41.67, 62.67, 80.67 and 89.67%, while for the concentration 300 ppm were 25.67, 42.67, 71.67 and 84.33%. The results of yellow dye removal showed that the concentration of 50 ppm were 49.67, 65.33, 83.33 and 92.67%, for the concentration of 150 ppm were 38.33, 60.33, 77.33 and 87.33%, and for the concentration, 300 ppm were 24, 36.67, 68.33 and 81.67%, when measured after 24, 48, 72 and 96 hours. Results recorded a slight decrease in pH values for all concentrations for each dye during 96 hours. Results also revealed a high reduction of EC and TDS values for both dye concentrations after 96 hours.

Speleomycological and chemical assessment of sediments in Demänovská Slobody Cave (Slovakia)

Our study unveils the complex interplay between fungal diversity and geochemical environments within the Demänovská Slobody Cave, marking the first comprehensive speleomycological and chemical investigation of its kind. Through meticulous analysis using both microscopic techniques and ITS region gene barcoding, we recorded 17 fungal species, including four previously unrecorded in subterranean settings (Cladosporium ramotenellum, Porostereum spadiceum, Rhexocercosporidium carotae, and Trichocladium nigrospermum), with Porostereum spadiceum as the most prevalent. These findings illuminate the crucial role of fungi in subterranean biogeochemical cycles, demonstrating how nutrient levels and pH significantly influence fungal populations. Namely, the levels of mineral nutrients (N, P, K, Mg, Ca) and organic matter in sediments within the cave were lower than in soil those outside it. Conversely, the pH values of the tested samples inside the cave were higher compared to those outside. Positive correlations were observed between the average number of fungi and the content of N, P, K, CO, and organic matter (p < 0.05). Conversely, the concentration of fungi decreased with increasing levels of Mg, Ca, and pH (p < 0.05). This research not only expands our understanding of cave ecosystems but also sets a new precedent for exploring the ecological impact of fungi in extreme environments.

Antioxidant and antimicrobial characteristics of mangosteen peel extract and synergistic capacity in beef burger preservation

SummaryThis study aimed to investigate the efficiency of mangosteen peel extract (MPE) in preservation of beef burgers. MPE was first evaluated for its total phenolic content (TPC), total flavonoid content (TFC) and antioxidant and antimicrobial activities. Subsequently, beef burgers were prepared with different MPE amounts (0–1%) and stored for 1 day, 3 days and 5 days. The synthetic antioxidant 2,6‐di‐tert‐butyl‐4‐methyl phenol (BHT) and synthetic antimicrobial sodium benzoate (SB) were used for comparison. The changes of burgers in physicochemical parameters (moisture, cooking loss, storage loss and pH), lipid and protein oxidation (peroxide value, PV; thiobarbituric acid reactive substances, TBARS and carbonyl content), microbiological (total viable count, TVC) and sensory characteristics were assessed. The results revealed that MPE contained a high TPC of 128.93 mg gallic acid equivalent g−1 dry extract and TFC of 62.98 mg rutin equivalent g−1 dry extract. These bioactive compounds rendered MPE with its antioxidant activity approximately equivalent to ascorbic acid and antimicrobial activities against Escherichia coli and Staphylococcus aureus comparable with SB. MPE‐combined burger samples had higher moisture and cooking loss (P &lt; 0.05) but almost equal storage loss and pH value compared with the control samples (P &gt; 0.05). However, the incorporation of MPE into beef burgers did not affect the sensory attributes and preferences of consumers (P &gt; 0.05). The burger with 1% MPE had lower values of PV, TBARS and carbonyl content than all other samples (P &lt; 0.05), including the one added with BHT, indicating the strong potential of MPE as natural antioxidant alternative to prevent the oxidation of lipids and proteins. Through the TVC test, 1% MPE was demonstrated to result in the safe preservation of burgers up to 5 days of storage, equivalent to SB (P &gt; 0.05). Therefore, MPE could become a natural synergistic alternative to both synthetic antioxidant and antimicrobial in the preservation of meat and meat products.

Oncom from Surplus Bread Enriched in Vitamin B12 via In Situ Production by Propionibacterium freudenreichii

Bread is a frequently wasted food product. Surplus or stale bread can be successfully processed by solid-state fermentation and used as the only fermentation substrate. Oncom, which originated in Indonesia, is made with moulds of the Neurospora genus. This experiment aimed to obtain oncome from stale bread enriched in vitamin B12. Co-fermentation with N. sitophila and Propionibacterium freudenreichii was carried out on two types of bread differing in chemical composition and initial pH value. Oncom obtained after 5 days of fermentation, depending on the substrate used and the fermentation variant (fungal, fungal-bacterial), contained from 35 to 40% dry mass, from 17.5 to about 23% protein, about 2 to max 5% fat, and from 65 to 74% carbohydrates by weight in dry mass. Vitamin B12 content depended largely on the bacterial strain, the colony-forming unit dose in the inoculum, and also the initial pH of the substrate. The oncom product obtained after co-fermentation with P. freudenreichii DSM 20271 contained a maximum of 1.3 µg/100 g, which corresponds to the vitamin B12 level in a chicken egg.

Scanning electron microscopy (SEM)-assisted mechanistic study: pH-driven compressive strength and setting time behavior in geopolymer concrete

This research study investigates the influence of pH on the setting time, compressive strength (CS), and surface roughness of different waste materials, namely fly ash, rice husk ash (RHA), red mud, and ground granulated blast furnace slag (GGBS). The average pH values for these waste materials were found to be 8.77, 9.3, 8.3, and 11, respectively. The initial setting time (IST) and final setting time (FST) varied among the materials, with red mud having maximum IST and FST with a value of 180 min and 24 h. CS (MPa) measurements revealed that GGBS exhibited the highest value of 36 MPa, followed by RHA (28 MPa), red mud (22 MPa), and fly ash (24 MPa). Surface roughness analysis showed that red mud had the highest roughness value of 69.71, followed by fly ash (62.81), RHA (53.14), and GGBS (49.08). The findings indicate a positive correlation between pH levels and CS of 97%, and setting time surface roughness has a negative correlation with CS when analyzed with a heatmap. Higher pH values were associated with increased CS, particularly after 28 days of curing which is shown by the heatmap and sub-plots. Additionally, microscopic analysis provided insights into particle size, orientation, and clustering, aiding in understanding the bonding and reactivity patterns contributing to the observed variations in CS.

Chitosan/Polyvinyl Alcohol-Based Biofilms Using Ternary Deep Eutectic Solvents towards Innovative Color-Stabilizing Systems for Anthocyanins.

Anthocyanins are amazing plant-derived colorants with highly valuable properties; however, their chemical and color instability issues limit their wide application in different food industry-related products such as active and intelligent packaging. In a previous study, it was demonstrated that anthocyanins could be stabilized into green plasticizers namely deep eutectic solvents (DESs). In this work, the fabrication of edible films by integrating anthocyanins along with DESs into biocompatible chitosan (CHT)-based formulations enriched with polyvinyl alcohol (PVA) and PVA nanoparticles was investigated. CHT/PVA-DES films' physical properties were characterized by scanning electron microscopy, water vapor permeability, swelling index, moisture sorption isotherm, and thermogravimetry analysis. Innovative red-to-blue formulation films were achieved for CHT/PVA nanoparticles (for 5 min of sonication) at a molar ratio 1:1, and with 10% of ternary DES (TDES)-containing malvidin-3-glucoside (0.1%) where the physical properties of films were enhanced. After immersion in solutions at different pH values, films submitted to pHs 5-8 were revealed to be more color stable and resistant with time than at acidic pH values.

Research on the Asymmetric Phenomenon of Voltage Polarity Based on Dielectric Wetting.

The present research investigated the voltage polarity asymmetry phenomenon based on dielectric wetting. In an ITO-hydrophobic layer-droplet setup, three reagents with different pH values (3.96, 7.0, and 10.18), two types of hydrophobic materials (AF1601 and 6%T6), and two different thicknesses (340 nm and 2.5 μm) of each material were systematically investigated. The results show that the thickness of the hydrophobic dielectric layer and the pH of the droplets had a significant impact on the droplet contact angle variation with the voltage. The contact angle on the thick hydrophobic dielectric layer followed the Lippmann-Young equation as the voltage changed. The angle of the thin hydrophobic dielectric layer was affected by its own properties and the type of droplet, which led to the occurrence of voltage polarity asymmetry of the electrowetting phenomenon. After further investigation of this phenomenon, it was found that it mainly accounted for the decrease in electric field strength at both ends of the droplet, which was caused by electrochemical reactions and changes in circuit resistance. The leakage current is an important indicator, and this phenomenon can be prevented by increasing the thickness of the hydrophobic dielectric layer.

Adsorption Behavior of Co2+, Ni2+, Sr2+, Cs+, and I- by Corrosion Products α-FeOOH from Typical Metal Tanks.

Throughout the nuclear power production process, the disposal of radioactive waste has consistently raised concerns about environmental safety. When the metal tanks used for waste disposal are corroded, radionuclides seep into the groundwater environment and eventually into the biosphere, causing significant damage to the environment. Hence, investigating the adsorption behavior of radionuclides on the corrosion products of metal tanks used for waste disposal is an essential component of safety and evaluation protocols at disposal sites. In order to understand the adsorption behavior of important radionuclides 60Co, 59Ni, 90Sr, 135Cs and 129I on α-FeOOH, the influences of different pH values, contact time, temperature and ion concentration on the adsorption rate were studied. The adsorption mechanism was also discussed. It was revealed that the adsorption of key nuclides onto α-FeOOH is significantly influenced by both pH and temperature. This change in surface charge corresponds to alterations in the morphology of nuclide ions within the system, subsequently impacting the adsorption efficiency. Sodium ions (Na+) and chlorate ions (ClO3-) compete for coordination with nuclide ions, thereby exerting an additional influence on the adsorption process. The XPS analysis results demonstrate the formation of an internal coordination bond (Ni-O bond) between Ni2+ and iron oxide, which is adsorbed onto α-FeOOH.

Efficient Nimesulide degradation via chlorination and sun-simulated radiation: Kinetic insights, reactive species formation, and application to real wastewater

Hypochlorite mediated oxidation had been established as an efficient process for degrading organic pollutants in water. In this research work, it was evaluated the synergistic potential of solar light irradiation combined with hypochlorite on a emerging contaminant model such as Nimesulide (NIM), a nonsteroidal anti-inflammatory drug. These experiments shown that at pH 3.0, where only hypochlorous acid (HOCl) prevails, the degradation constant of NIM exhibited an increase from 2.50 × 10−4 s−1 (under dark conditions) to 1.53 × 10−3 s−1 (sun-simulated radiation), signifying an approximately six-fold acceleration in degradation. Moreover, under approximately neutral pH value (7.5) wherein both HOCl and hypochlorite ion (ClO−) coexist, the enhancement observed was approximately twofold, in particular a mineralization up to 32 % was observed. This investigation also included quenching experiments conducted at varying pH levels, shedding light on the role of specific reactive species and their contributions to the degradation mechanism. The impact of synergistic effect between solar-simulated irradiation and hypochlorite systems on NIM degradation showcases a remarkable kinetic enhancement, particularly evident at lower pH values. The degradation byproducts have been identified via high resolution HPLC-MS and the main ion formed during the reaction have been monitored by IC-MS. Experiments in real sewage treatment plant waters using sun radiation revealed the promising potential and efficiency of this alternative method, despite a comparatively lower degradation rates when compared with UV lamp application. This approach offers a sustainable and economically advantageous solution for wastewater treatment.