Degradation Rate Constants Research Articles

Synthesis of a novel Bi19Cl3S27/Bi2MoO6 Z-type heterojunction for efficient photocatalytic removal of tetracycline antibiotic and Cr(VI): Intermediate toxicity and mechanism insight

Novel Bi19Cl3S27/Bi2MoO6 (BCS/BMO) Z-type heterojunctions were synthesized using a straightforward hydrothermal method. Benefiting from the large specific surface area (62.41 m2/g) and the effective separation of photogenerated carriers facilitated by the Z-scheme heterojunction, the BCS/BMO exhibited remarkable improved photocatalytic tetracycline degradation and Cr(VI) reduction efficiency in comparison to BCS, BMO, and their physical mixture. Specifically, the photocatalytic degradation rate constants for TC and Cr(VI) are 0.0209 and 0.0218 min-1, respectively, which are 16.08 and 15.57 times those of BCS, 1.74 and 1.31 times those of BMO, and 2.4 and 1.73 times those of the physical mixture. Additionally, based on density functional theory (DFT) calculations and empirical data, three potential photocatalytic pathways of tetracycline were presented. This study presents a novel approach for designing and synthesizing high-efficiency Z-scheme photocatalysts for the degradation of TC and the reduction of Cr(VI) in wastewater.

SnO2-x/CD-MOF S-Scheme heterostructure photocatalysts synergized by oxygen vacancies and highly porous for rhodamine B and tetracycline degradation: Process, and mechanism analysis

To enhance the performance of environmentally friendly cyclodextrin metal-organic framework (CD-MOF) materials for more effective removal of organic pollutants and wastewater treatment, also the composites underwent optimization, and the adsorption-enhanced photocatalytic mechanism was thoroughly investigated. This study presents the synthesis of novel SnO2-x/CD-MOF (SCM) photocatalysts were prepared by a simple solvothermal method, which were characterized by oxygen vacancies (OVs), high specific surface area and heterojunction. SCM exhibited outstanding photodegradation performance for rhodamine B (RhB) and tetracycline (TC) when exposed to visible light. Specifically, the RhB removal efficiency was an impressive 93.5 %, achieved with a degradation rate constant of 0.0484 min−1, while the removal efficiency of TC was 83.1 %, with a degradation rate constant of 0.0246 min−1. The photodegradation activity of SCM was predominantly influenced by ·O2-, h+, and ·OH. The mechanism of action involves three phases: adsorption, photocatalysis, and desorption-diffusion. The exceptional performance of SCM in terms of photocatalysis can be gave the credit to the synergistic effect of the high specific surface area of γ-CD-MOF and the oxygen vacancy-induced enhancement of SnO2-x catalytic activity. TC degradation intermediates and possible degradation pathways were analyzed and the toxicity of the intermediates was assessed. This study introduces a novel approach to designing CD-MOF-based photocatalysts.

Construction of a novel Z-scheme FeTiO3/MOF-derived In2S3 catalyst for visible-light-driven photo-Fenton degradation of pollutants

The rapid recombination rate of photoexcited carriers for iron titanate (FeTiO3) is still limited the process performance of photo-Fenton. This article reports the successful synthesis of the highly efficient Z-scheme FeTiO3/MOF-derived In2S3 photocatalyst using the hydrothermal method, compensating for the susceptibility of FeTiO3 photo-generated carriers to complexation to a certain extent. A series of characterization have been carried out to explore the structure, morphology and composition of FeTiO3/MOF-derived In2S3 heterostructure. The 0.5 FeTiO3/MOF-derived In2S3 exhibits the excellent photo-Fenton performance for TCH, Cr6+ and OTC, the degradation rate constants (k2) are up to 0.6297 L·mg−1·min−1, 1.332 L·mg−1·min−1, and 0.427 L·mg−1·min−1, respectively. Active species capture experiments and electron paramagnetic resonance (EPR) spectra show that photo-generated holes (h+) and superoxide radicals (·O2-) are present in the photo-Fenton system. The superior photo-Fenton performance is mainly manifested in the following: the MOF-derived In2S3 micro-floral carrier extends the reaction interface of 0.5 FM-I; FeTiO3 effectively enhances the photo-absorption ability of 0.5 FM-I in visible range; the construction of Z-scheme FeTiO3/MOF-derived In2S3, forming the new carriers transport channels and enhancing the generation of ·O2- and ·OH. This experimental exploration provided a reasonable experimental basis for the preparation of efficient photocatalysts.

From aromatic rings to aliphatic compounds - degradation of duloxetine with the use of visible light driven Z-scheme photocatalyst

The growing consumption of antidepressants, associated with their high chemical stability and low biodegradability, become a serious problem for aquatic environment. Many of their components are resistant to conventional water treatment technologies. The photocatalytic processes with the use of semiconductors becoming attractive methods of drugs degradation because the highly reactive species: electrons, holes, hydroxyl radicals (⦁OH) and superoxide anion radicals (O2⦁−) generated under illumination may be involved directly or indirectly in decomposition of complicated organic molecules.In this work we have shown for the first time that Z-scheme photocatalyst, consisted of bismuth vanadate (BiVO4), graphitic-like carbon nitride (g-C3N4) and Au nanoparticles (Au NPs) as a charge transfer mediator, is very efficient in degradation of duloxetine (DLX). We performed the comprehensive evaluation focused not only on degradation rate, mechanism of photocatalytic process, but also identification of decomposition products and the pathways of DLX degradation. Due to application of the elaborated Z-scheme photocatalyst, the degradation rate constant was more than 2-3 times higher than that obtained for photolysis, but more important, the final compounds were mainly aliphatic products, formed by opening of aromatic rings. The chemical structure of the degradation products were determined with the use of HPLC and LC-MS. The toxicity of photoproducts with respect to water organisms was tested by means of Spirotox and Microtox assays. The Microtox test indicated that toxicity of the products after 6h of the solution irradiation in the presence of Z-scheme photocatalyst is about 4 times lower than that after photolysis.

VUV Activated Fe(VI) by Promoting the Generation of Intermediate Valent Iron and Hydroxyl Radicals.

In this study, vacuum ultraviolet (VUV) was first proposed to activate ferrate (Fe(VI)) for degrading micropollutants (e.g., carbamazepine (CBZ)). Results indicated that VUV/Fe(VI) could significantly facilitate the CBZ degradation, and the removal efficiencies of VUV/Fe(VI) were 30.9-83.4% higher than those of Fe(VI) at pH = 7.0-9.0. Correspondingly, the degradation rate constants of VUV/Fe(VI) were 2.3-36.0-fold faster than those of Fe(VI). Free radical quenching and probe experiments revealed that the dominant active species of VUV/Fe(VI) were •OH and Fe(V)/Fe(IV), whose contribution ratios were 43.3 to 48.6% and 48.2 to 46.6%, respectively, at pH = 7.0-9.0. VUV combined with Fe(VI) not only effectively mitigated the weak oxidizing ability of Fe(VI) under alkaline conditions (especially pH = 9.0) but also attenuated the deteriorating effect of background constituents on Fe(VI). In different real waters (tap water, river water, WWTPs effluent), VUV/Fe(VI) retained a remarkably enhanced effect on CBZ degradation compared to Fe(VI). Moreover, VUV/Fe(VI) exhibited outstanding performance in the debasement of CBZ and sulfamethoxazole (SMX), as well as six other micropollutants, displaying broad-spectrum capability in degrading micropollutants. Overall, this study developed a novel oxidation process that was efficient and energy-saving for the rapid removal of micropollutants.

Elevated efficiency in tartrazine removal from wastewater through boron-doped biochar: enhanced adsorption and persulfate activation

Boron-doped biochar (B-BC) was synthesized by pyrolysis using solid waste of sorghum straw as raw material. The specific surface area of B-BC increased significantly by 2.38 times compared to that of pure BC. This enhancement allowed B-BC (0.3 g L−1) to achieve complete adsorption of 10 mg L−1 tartrazine (TTZ) within 40 min. Moreover, acidic conditions were more favorable for TTZ adsorption, achieving complete removal of TTZ in only 15 min at a pH of 3.0. Interestingly, the adsorption rate of TTZ by B-BC in the presence of 0.05 M Cl− was approximately 2.12 times higher than that in the absence of Cl−. When other background electrolytes were present, excluding PO43−, complete adsorption of TTZ could also be achieved within 60 min. Thermodynamic analysis and DFT calculations described the parameters of B-BC for TTZ adsorption, including ΔGΘ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Delta {\ ext{G}}^{\\Theta }$$\\end{document} (< 0 kJ mol−1), ΔHΘ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Delta {\ ext{H}}^{\\Theta }$$\\end{document} (− 2.199 kJ mol−1), ΔSΘ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Delta {\ ext{S}}^{\\Theta }$$\\end{document} (− 6.068 J mol−1 K−1), and the adsorption energy (Eads = − 0.6919 eV), indicating a tendency towards a spontaneous adsorption process. Moreover, the strong electron transfer ability of B-BC and the oxygen-containing groups promoted the activation of PDS and generation of active substances such as 1O2, O2•−, and SO4•−, thereby degrading TTZ into products with lower biological toxicity. When the added PDS was only 0.1 mM, the degradation rate constant of TTZ could reach 0.1481 min−1. Furthermore, boron doping enhanced the stability of biochar, enabling the complete removal of 10 mg L−1 TTZ even after recycling and regeneration. In summary, this study offers a practical solution for the resource utilization of solid waste sorghum straw and the treatment of TTZ-polluted wastewater.Graphical

Mechanistic insights into ultrafast degradation of electron-rich emerging pollutants by waste cyanobacteria resource utilization

Biochar has the issues with inadequate stability and low catalytic activity. In this study, two-step ball milling method was applied to synthesis carbon nitride co-modified cyanobacteria biochar (CN-BC). The optimized CN-BC can effectively activate peroxymonosulfate (PMS) to degrade emerging pollutants. The degradation rate constant of enrofloxacin in the CN-BC/PMS system reached 0.506 min−1, and 95 % of enrofloxacin could be effectively degraded within 10 min. Free radical quenching experiments and electrochemical experiments confirmed that the electron transfer and 1O2 were the main pathways in the CN-BC/PMS system. The CN-BC/PMS system has selective degradation of electron-rich pollutants, and the pollutants containing electron-donating groups are more easily degraded than those containing electron-withdrawing group. The selective degradation pathway of pollutants by CN-BC was further analyzed using density functional theory (DFT). Continuous flow CN-BC/PMS membrane system showed long-term abatement of emerging pollutants. This study improves the understanding of the mechanism of PMS activation by cyanobacterial biochar catalysts and provides a new pathway for membrane-based domain-limited catalysis.

Synthesis and mechanism of Bi/SnO2 for enhanced photocatalytic activity in the degradation of humic acid under visible light

Humic acid (HA) is a typical refractory organic matter, widely existing in natural water and many types of wastewaters. In this study, Bi/SnO2 composites were synthesized by a simple one-step hydrothermal method for photocatalytic degradation of HA. Due to the surface plasmon resonance (SPR) effect of Bi, the light absorption of Bi/SnO2 composites expands from UV to visible light compared to pure SnO2. Under visible light irradiation for 120 min, the UV254 removal reached 93.58 %, color number (CN) removal reached 94.41 %. The degradation rate constant of Bi/SnO2 (0.0178 min−1) is 14.83 times higher than that of SnO2 (0.0012 min−1), indicating the superior photocatalytic degradation efficiency of Bi/SnO2 composites. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was found that photocatalysis mainly degraded most CHO-containing organic matter and reduced the amount of organic matter (from 7240 to 3886). The molecular number of organic compounds with m/z of 400–500 and 500–600 exhibited a significant decrease, specifically by 1052 and 770, respectively. This observation suggests that the photocatalytic process effectively eliminates low and moderate molecular weight organics. The molecular number, aromaticity and molecular weight of dissolved organic matter (DOM) were reduced mainly by carboxylic acid reaction, dealkylation reaction and oxygen addition reaction.

Adjustable double cation vacancies MnSex/FeSex p-n heterojunction catalysts on improving multifunctional photocatalytic and photoelectrochemical performance

MnSex is a type of p-type semiconductor that combines with n-type FeSex in a one-step hydrothermal method to form a MnSex/FeSex p-n type heterojunction. The heterostructures showed good photocatalytic performance. The photocatalytic degradation rate constant of MFS3 was 0.01114 min−1, while that of MnSex was 0.00213 min−1. The photocatalytic degradation activity of MFS3 was 423 % higher than that of MnSex. Afterwards, the MnSex/FeSex catalyst was further soaked in ethylenediaminetetraacetic acid (EDTA) to form metal vacancies through metal complexation. A large number of pores can be seen in the SEM image of MFS3v catalyst, and Mn and Fe bimetallic vacancies can be seen in the TEM results. The signal of the electron paramagnetic spectrum is significantly enhanced, with a significant shift in its g value. The above results confirm the formation of Mn and Fe bimetallic vacancies in the catalyst. The two-hole heterojunction catalyst significantly improves its photochemical activity, and the photocurrent density of MFS3v at 0 V vs. RHE is −2.438 mA/cm2, 18.2 and 2.5 times that of the original MnSex and MnSex/FeSex heterojunction, respectively. Tests have confirmed that this double vacancy can increase the active sites and enhance the photoelectrochemical hydrogen production ability. This study proposes a method that combines heterojunctions and vacancies to achieve multifunctional catalysts.

Highly efficient defluorination of perfluorooctanoic acid by a BiOCl-ND photocatalyst: Enhanced charge transfer and synergistic mechanism

Considerable attention has been given to the control of perfluorooctanoic acid (PFOA) environmental pollution due to its degradation resistance and potential risks. In this study, Bismuth oxychloride based nanodiamond (BiOCl-ND) composite materials were successfully synthesized by using hydrothermal method. The complete decomposition of PFOA and a high defluorination ratio of 74.6% by BiOCl-ND 10:1 was obtained under UV light irradiation within 60 min, and the composite's degradation rate constant was nearly 3.8 times than that of pure BiOCl. It was demonstrated that critical roles played in PFOA degradation were photogenerated holes (h+) and superoxide radicals (·O2−). A synergistic effect between BiOCl and ND and the heterostructure was revealed, the differences of the energy band structure between BiOCl and ND reduced the recombination of photogenerated e−-h+ and enhanced the charge transfer. In this process, a large number of h+ with oxidizing properties and·O2− generated from both BiOCl and ND played a critical role, and oxygen vacancies (OVs) also participated in the reaction as active species and contributed to electron transfer. Additionally, the photocatalytic decomposition intermediates of PFOA and the release of fluorine ions were analyzed to verify the effective defluorination of PFOA, and the results confirmed a gradual decrease in the toxicity of the reaction matrix during PFOA degradation. Hence, these results might provide insights for the development of photocatalysts to improve the photodegradation effect of PFOA in water.

Characteristics of pomegranate (Punica granatum L.) peel polyphenols encapsulated with whey protein isolate and β-cyclodextrin by spray-drying

Pomegranate peel polyphenols (PPPs) are recognized as promising food additives due to their diverse bioactivities; however, their application is limited by poor stability. To address this critical issue, three types of PPPs microcapsules were prepared using β-cyclodextrin (CD), whey protein isolate (WPI), and a composite material of CD-WPI through ultrasound treatment (US). Results revealed that ultrasound treatment can enhance the PPPs-wall material interaction, as evidenced by MD simulations. The encapsulation efficiency of CD-WPI-PPPs was 93.73 %, which was significantly higher than that of CD-PPPs and WPI-PPPs (p < 0.05). The degradation rate constant of CD-WPI-PPPs was reduced by 95.83 %, and its t1/2 was extended by 23-fold compared to that of unencapsulated PPPs. Furthermore, CD-WPI-PPPs exhibited greater DPPH scavenging activity and inhibited polyphenol release during oral and gastric digestion while promoting release during intestinal digestion. These outcomes were attributed to enhanced integrity and interactions between PPPs and composite materials in the microcapsules formed through ultrasound treatment, as supported by SEM images and FT-IR spectra. Consequently, the application of US in the preparation of PPPs microcapsules presents a promising strategy for developing natural nutrient additives for food applications, thereby enhancing the functional properties of food products.

Bi2SiO5 nanosheets as piezo-photocatalyst for efficient degradation of 2,4-Dichlorophenol

Piezo-photocatalysis is an effective solution for degrading organic pollutants. In this study, Bi2SiO5 nanosheets are successfully synthesized via a one-step hydrothermal method. The piezo-photocatalytic degrading mechanisms of 2,4-Dichlorophenol (2,4-DCP) on Bi2SiO5 nanosheets are thoroughly investigated through the integration of experimental study and density functional theory (DFT) calculations. Experimental results revealed outstanding piezoelectric properties for Bi2SiO5 nanosheets with a piezoelectric coefficient of 250 pC/N, outperforming previously reported piezo-photocatalysts. The degradation rate constant of 2,4-DCP on Bi2SiO5 nanosheets reached 0.0891 min−1 by piezo-photocatalysis, which is 17 and 1.8 times higher than that by solitary photo- and piezo-catalysis, respectively. Furthermore, DFT calculations for Bi2SiO5 explain the crucial role of piezoelectric effects in bending its band structure, regulating photogenerated carrier behaviors, and promoting reactive oxygen species (ROS) generation. Finally, the degradation pathways of 2,4-DCP on Bi2SiO5 nanosheets were revealed with details. The results of this study offer valuable insights for water treatment with piezo-photocatalysis.

A new perspective on contaminants as "activators": Aromatic amine groups promoted degradation of tetracycline by ferrate(VI)

Occasionally, our group found that the degradation of tetracycline by ferrate(VI) could be promoted by four co-exist contaminants, containing aromatic amines (ofloxacin, diatrizoic acid, sulfadiazine and alachlor). This study investigated the promotion of aromatic amine groups on tetracycline degradation by ferrate(VI) by using aniline as a model compound. The results implied that the presence of aniline increased the degradation rate of tetracycline by 2.76 times, and the enhancement was weakened gradually with the decrease of pH from 10 to 7.5. The generation of Fe(IV) and·OH by the reaction between ferrate(VI) and aniline was proposed to enhance the degradation of tetracycline, supported by quenching experiments, electron paramagnetic resonance (EPR) and theoretical calculations. A positive correlation was found between the rate constant of tetracycline degradation and the electron-donating ability of the substituted amines (quantified by the Hammett substituent constants). In addition, the degradation of tetracycline was remarkably inhibited by HA and some inorganic ions such as NO3-, SO42-, Cl-, Ca2+, and Mg2+, and the inhibition also happened in the Songhua River water and the secondary effluent. The present study provided an insight into the complex oxidation process for the degradation of micropollutants containing aromatic amine by ferrate in water treatment.

Effective sonophotocatalytic degradation of tetracycline in water: Optimization, kinetic modeling, and degradation pathways

Hybrid advanced oxidation processes (AOPs) are gaining interest in degradation of variety of recalcitrant compounds for water and wastewater treatment, due to possible synergistic effects. The present study systematically evaluated the degradation of tetracycline (TC) with a sonophotocatalytic process combining acoustic cavitation (sonocavitation) and photocatalysis based on N-doped TiO2 catalyst. The TC degradation rate constant was 2.4 × 10−2 min−1, i.e., much higher than individual sonocatalytic (0.5 × 10−2 min−1) and photocatalysis (0.6 × 10−2 min−1) processes at the optimized conditions. The synergy index was 2.14, which reveals a significant improvement in the process performance. Maximum TC degradations of 55.5 ± 1.8 % for photocatalysis, 66.4 ± 1.8 % for sonocatalysis, and 79.5 ± 0.3 % for sonophotocatalysis were observed for 10 mg L−1 initial TC concentration after 90 min of treatment. The photocatalytic experiments were extended further to 210 min to achieve a maximum degradation of 78.9 ± 0.2 % at the optimized condition. Scavenging experiments confirmed that hydroxyl radicals (•OH), electron holes (h+), and superoxide radical anions (O2−•) played a significant role in the degradation of TC. Further, the degradation intermediates for each process were identified and degradation pathways were proposed. Empirical kinetic models based on operational parameters were also developed and validated.

Dispersion of ZnO or TiO2 nanoparticles onto P. australis stem-derived biochar for highly efficient photocatalytic removal of doxycycline antibiotic under visible light irradiation

Abstract Biochar (BC) derived from reed stems was prepared by high-temperature pyrolysis, and two types of ZnO/biochar (ZBC) and TiO2/biochar (TBC) composite materials were synthesized via a simple hydrolysis method. These composites, compared to pure ZnO and TiO2, exhibit not only improved but significantly enhanced crystalline structures and larger specific surface areas. This enhancement in the physical and chemical properties of ZBC and TBC composites is a crucial aspect of our research, as it leads to a distinct red-shifted absorption edge and excellent visible-light absorption characteristics. The photocatalytic degradation efficiency of ZBC and TBC composite materials, a key finding of our study, was evaluated using doxycycline antibiotic as a simulated pollutant under visible-light irradiation. The results demonstrate a 6.0-fold and 7.3-fold increase in photocatalytic degradation efficiency of ZBC and TBC composites compared to pure ZnO and TiO2, respectively, further underscoring the significance of these enhanced properties. Furthermore, active species trapping experiments reveal that ·OH radicals are the dominant reactive species in the photocatalytic degradation process of doxycycline. A Langmuir–Hinshelwood kinetic model accurately represents this degradation process. Kinetic data indicate that the degradation rate constants (k) of ZBC and TBC catalysts are 4.314 × 10−2 min−1 and 3.416 × 10−2 min−1, respectively. The photocatalysts exhibit no significant decrease in degradation efficiency for ZBC and TBC even after the fourth cycle, indicating their relatively high reusability. These results suggest that ZBC and TBC materials can be used as stable, efficient, cost-effective, and sustainable photocatalytic composite materials for antibiotic-contaminated wastewater treatment.

Synthesis of multifunctional rGO/g-C3N4/FeTiO3 ternary nanocomposites for photocatalyst, antibacterial, and ecotoxicity assessment of zebrafish embryo model

The wastewater from the dye and pharmaceutical industries antibiotics has caused serious environmental and health problems for humans and other species. For the development of superior photocatalysts, effective separation of photogenerated electron-hole pairs is essential in addition to optimizing solar absorption throughout a wide wavelength range. In order to produce bare, rGO/g-C3N4, rGO/FeTiO3, and rGO/g-C3N4/FeTiO3 (GCNFeT NCs) nanocomposites, this study describes the fabrication of perovskite-type titanate (FeTiO3) and its incorporation onto graphitic carbon nitride (g-C3N4) and reduced graphene oxide (rGO) using a hydrothermal synthesis technique. The generated nanocomposites structural, morphological, and optical properties were evaluated. After being exposed to solar light for 90 min, the resultant GCNFeT NCs efficiently broke down 80 % of Tetracycline (TC) and 90 % of Malachite Green (MG) dye. The photocatalytic efficacy is significantly improved by these results when compared to the pure and binary composites. Substantial catalytic efficiency to GCNFeT NCs was shown by the degradation rate constant (k) for MG and TC elimination by GCNFeT NCs, which was almost 20 times greater than that of pure and binary composites. Additionally, the antibacterial activity of GCNFeT nanocomposites was studied, and the results showed that it was significantly more efficient against Gram-negative bacteria than Gram-positive bacteria, including Escherichia coli and Staphylococcus aureus. Furthermore, the freshwater zebrafish embryo development proved effective in assessing the non-toxicity of GCNFeT NCs. Our research findings indicate that high doses, GCNFeT NCs induce less toxicity in zebrafish embryo (6.25–100 µg/L). These results demonstrated the enhanced mechanism of GCNFeT NCs, indicating their great potential for use in antibacterial and water remediation applications.

The solar/chlorine system degradation of iopamidol: Roles of reactive species, degradation pathway, and toxicity

The study systematically examined the changing trends of the percentage contributions of reactive species to the degradation of Iopamidol (IPM) under various conditions in the solar/chlorine system. Results showed that compared with chlorine alone and solar radiation system, the solar/chlorine system had an obvious effect on the degradation of IPM under control experiment conditions. HO• and reactive chlorine species played major roles in the apparent pseudo-first-order rate constants of IPM degradation (kobs). The increase of oxidant dosage significantly promoted the steady-state concentration of RCS and the contributions of those to kobs. The concentrations of various radicals at pH 9 were lower than those of at pH 5, while only the percentage contribution of ClO• on kobs was increased. The presence of Cl- could increase the steady-state concentration of Cl•, which further promoted the kobs. NOM would significantly reduce the steady-state concentration of ClO• and Cl•, which leads to a significant increase in the percentage contribution of Cl2−• to kobs, indicating the important role of Cl2−• on organic removal in real water. HCO3-/CO32- had almost no effect on kobs. The degradation products of IPM were identified through HPLC-MS, and the Fukui function was employed to ascertain the sites of degradation, which were formulated by deiodination reactions and the production of organic radicals. According to structure Activity Relationships Program v.2.2 and acute toxicological tests, byproducts did not exhibit significant toxicity. The findings illustrate that the solar/chlorine system is effective in decomposing IPM into non-toxic and non-hazardous small molecules, with potential applications.

Modified sono-Fenton process for oxidative degradation of chloramphenicol.

Oxidative degradation of chloramphenicol (CAP) using a hybrid approach (US/HA+/n-Fe2O3/SPC) involving sodium percarbonate (SPC; "solid H2O2" carrier), Fe2O3 nanoparticles (n-Fe2O3; H2O2 decomposition catalyst), hydroxylamine in its protonated form (HA+; Fe (III) to Fe (II) reducer), and ultrasonic cavitation (to increase the generation of hydroxyl radicals) has been studied for the first time. The average size of n-Fe2O3 synthesized by the sonochemical method, as calculated according to the Debye-Scherrer equation, was ~ 18nm. The maximum degradation degree of CAP (83.1%) and first-order oxidative degradation rate constant of CAP as 1.253 × 10-3s-1 were achieved using the modified sono-Fenton process under the optimized conditions as the initial concentration of CAP - 50mg/L, the molar ratio of CAP:HA+:n-Fe2O3:SPC of 1:100:100:100, pH as 3, the temperature as 318K, the specific ultrasonic power as 53.3 W/L, and the treatment duration of 7200s. In general, the efficiency and intensity of CAP degradation increased with a decrease in the pH value, an increase in the molar ratio of CAP:HA+:n-Fe2O3:SPC, a decrease in the initial concentration of CAP, an increase in temperature, and showed a minor change with the specific power of US. The synergistic coefficient for the combination of the US and the heterogeneous Fenton process was 17.9. The active participation of hydroxyl radicals in the oxidative degradation of CAP using the modified sono-Fenton process was confirmed by scavenging experiments performedusing tert-butyl alcohol. The proposed process can be a promising direction in the remediation of pharmaceutical effluents with significant potential for commercial exploitation.

Synergistic enhancement of singlet oxygen generation in Au and oxygen vacancy co-modified Bi2MoO6 ultrathin nanosheets for efficient ciprofloxacin degradation

Solar-driven molecular oxygen activation (MOA) is crucial for generating reactive oxygen species (ROS) for pollutant degradation, while the low activation efficiency greatly weakens the degradation efficiency. Herein, oxygen vacancies (OVs) and Au nanoparticles are co-introduced into Bi2MoO6 (ABMOH) to enhance the photocatalytic activity of Bi2MoO6 (BMO), thereby promoting MOA efficiency. Density functional theory demonstrates that the introduction of OVs not only improves the molecular oxygen adsorption on BMO, and but also strengthens the O-O bond dissociation of molecular oxygen, which is beneficial to MOA. Meanwhile, the unique localized surface plasmon resonance effect of Au nanoparticles immensely increases the photo-absorption capacity. Crucially, both OVs and Au nanoparticles work as “electron traps” to capture photogenerated electrons, thereby accelerating charge transfer. Based on the advantage of OVs and Au nanoparticles, ABMOH displays excellent MOA efficiency, and the degradation rate constant of ciprofloxacin (CIPF) by ABMOH-4 is 3.62-fold higher than BMO. Free radical trapping experiment and electron spin resonance suggest that singlet oxygen (1O2) can be selectively formed in the ABMOH system for CIPF degradation, and superoxide radical (•O2–) conversion and energy transfer are two pathways for 1O2 formation. This investigation serves as a beacon for the strategic design of high-performance and stable photocatalysts for MOA activation, paving the way for advancements in environmental remediation.

Enrichment of White Chocolate with Microencapsulated β-Carotene: Impact on Quality Characteristics and β-Carotene Stability during Storage.

This study developed functional white chocolate enriched with free (WC-F) and encapsulated β-carotene using whey protein isolate (WPI) and pullulan (PUL) blends through spray drying (WC-SP), freeze drying (WC-LP), and coaxial electrospinning (WC-EL). The thermal properties, rheological properties, hardness, and color of the chocolates were evaluated, and the stability of β-carotene was monitored over 4 months at 25 °C. No significant differences were found in melting profile temperatures among samples; however, WC-LP and WC-EL exhibited higher melting energies (30.88 J/g and 16.00 J/g) compared to the control (12.42 J/g). WC-F and WC-SP showed rheological behaviors similar to those of the control, while WC-LP and WC-EL displayed altered flow characteristics. Hardness was unaffected in WC-F and WC-SP (7.77 N/mm2 and 9.36 N/mm2), increased slightly in WC-LP (10.28 N/mm2), and decreased significantly in WC-EL (5.89 N/mm2). Over storage, melting point, rheological parameters, and hardness increased slightly, while color parameters decreased. β-carotene degradation followed a first-order reaction model, with degradation rate constants (k) of 0.0066 day-1 for WC-SP, 0.0094 day-1 for WC-LP, and 0.0080 day-1 for WC-EL, compared to 0.0164 day-1 for WC-F. WC-SP provided the best β-carotene retention, extending the half-life period by 2 times compared to WC-F (126.04 days vs. 61.95 days). Practical implications: The findings suggest that WC-SP, with its superior β-carotene stability, is particularly suitable for the development of functional confectionery products with extended shelf life, offering potential benefits in industrial applications where product stability is crucial. Future research directions: Further studies could explore the incorporation of additional bioactive compounds in white chocolate using similar encapsulation methods, as well as consumer acceptance and sensory evaluation of these enriched products.