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Environmental Science and Pollution... Jul 2024Sulfate radical-based advanced oxidation processes (SR-AOPs) are renowned for their exceptional capacity to degrade refractory organic pollutants due to their wide...
Sulfate radical-based advanced oxidation processes (SR-AOPs) are renowned for their exceptional capacity to degrade refractory organic pollutants due to their wide applicability, cost-effectiveness, and swift mineralization and oxidation rates. The primary sources of radicals in AOPs are persulfate (PS) and peroxymonosulfate (PMS) ions, sparking significant interest in their mechanistic and catalytic aspects. To develop a novel nanocatalyst for SR-AOPs, particularly for PMS activation, we synthesized carbon-coated FeCo nanoparticles (NPs) using solvothermal methods based on the polyol approach. Various synthesis conditions were investigated, and the NPs were thoroughly characterized regarding their structure, morphology, magnetic properties, and catalytic efficiency. The FeCo phase was primarily obtained at [OH] / [Metal] = 26 and [Fe] / [Co] = 2 ratios. Moreover, as the [Fe]/[Co] ratio increased, the degree of xylose carbonization to form a carbon coating (hydrochar) on the NPs also increased. The NPs exhibited a spherical morphology with agglomerates of varying sizes. Vibrating-sample magnetometer analysis (VSM) indicated that a higher proportion of iron resulted in NPs with higher saturation magnetization (up to 167.8 emu g), attributed to a larger proportion of FeCo bcc phase in the nanocomposite. The best catalytic conditions for degrading 100 ppm Rhodamine B (RhB) included 0.05 g L of NPs, 2 mM PMS, pH 7.0, and a 20-min reaction at 25 °C. Notably, singlet oxygen was the predominant specie formed in the experiments in the SR-AOP, followed by sulfate and hydroxyl radicals. The catalyst could be reused for up to five cycles, retaining over 98% RhB degradation, albeit with increased metal leaching. Even in the first use, dissolved Fe and Co concentrations were 0.8 ± 0.3 and 4.0 ± 0.5 mg L, respectively. The FeCo catalyst proved to be effective in dye degradation and offers the potential for further refinement to minimize Co leaching.
PubMed: 38954345
DOI: 10.1007/s11356-024-34145-5 -
Environmental Monitoring and Assessment Jul 2024The activated carbon was produced in the first phase of this investigation by chemically activating hazelnut shell waste with HPO. Composite materials were obtained by...
The activated carbon was produced in the first phase of this investigation by chemically activating hazelnut shell waste with HPO. Composite materials were obtained by coating the activated carbon with zinc oxide, whose BET surface area was calculated as 1278 m g. ZnO-doped ZnO/AC composite was synthesized as an adsorbent for its possible application in the elimination of organic dyestuff MB, and its removal efficiency was investigated. Morphological properties of ZnO/AC were characterized using analytical methods such as XRD, SEM, and BET. The adsorption system and its parameters were investigated and modeled using the response surface method of batch adsorption experiments. The experimental design consisted of three levels of pH (3, 6.5, and 10), initial MB concentration (50, 100, and 150 mg L), dosage (0.1, 0.3, and 0.5 g 100 mL), and contact time (5, 50, and 95 min). The results from the RSM suggested that the MB removal efficiency was 98.7% under the optimum conditions of the experimental factors. The R value, which expresses the significance of the model, was determined as 99.05%. Adsorption studies showed that the equilibrium data fit well with the Langmuir isotherm model compared to Freundlich. The maximum adsorption capacity was calculated as 270.70 mg g.
Topics: Adsorption; Charcoal; Water Pollutants, Chemical; Methylene Blue; Zinc Oxide; Waste Disposal, Fluid; Kinetics; Water Purification; Coloring Agents; Zinc
PubMed: 38954055
DOI: 10.1007/s10661-024-12766-0 -
ACS Applied Materials & Interfaces Jul 2024Modification with conductive organic polymers consisting of a thiophane- or pyrrole-based backbone improved the cathodic photocurrent of a particulate-CuGaS-based...
Enhancing Photocathodic Performances of Particulate-CuGaS-Based Photoelectrodes via Conjugation with Conductive Organic Polymers for Efficient Solar-Driven Hydrogen Production and CO Reduction.
Modification with conductive organic polymers consisting of a thiophane- or pyrrole-based backbone improved the cathodic photocurrent of a particulate-CuGaS-based photoelectrode under simulated solar light. Among these polymers, poly(3,4-ethylenedioxythiophene) (PEDOT) was the most effective in the improvements, providing a photocurrent 670 times as high as that of the bare photocathode. An incident-photon-to-current efficiency (IPCE) for water reduction to form H under monochromatic light irradiation (450 nm at 0 V vs RHE) was ca. 11%. The most important point is that modification of the conductive organic polymers does not involve any vacuum processes. This importance lies in the use of an electrochemically oxidative polymerization, not in a physical process such as vapor deposition of metal conductors. This is expected to be advantageous in the large-scale application of photocathodes consisting of particulate photocatalyst materials toward industrial solar-hydrogen production using photoelectrochemical-cell-based devices. Artificial photosynthesis of water splitting and CO reduction under simulated solar light was demonstrated by combining the PEDOT-modified CuGaS photocathode with a CoO-loaded BiVO photoanode. Furthermore, how the cathodic photocurrent of the particulate-CuGaS-based photocathode was drastically improved by the modification was clarified based on various characterizations and control experiments as follows: (1) selectively filling cavities between the particulate CuGaS photocatalysts and a conductive substrate (FTO; fluorine-doped tin oxide) with the polymers and (2) using a large driving force for carrier transportation governed by the polymers' redox potentials adjusted by functional groups.
PubMed: 38953879
DOI: 10.1021/acsami.4c06083 -
Environmental Science & Technology Jul 2024Investigating the fate of persistent organic pollutants in water distribution systems (WDSs) is of great significance for preventing human health risks. The role of iron...
Investigating the fate of persistent organic pollutants in water distribution systems (WDSs) is of great significance for preventing human health risks. The role of iron corrosion scales in the migration and transformation of organics in such systems remains unclear. Herein, we determined that hydroxyl (OH), chlorine, and chlorine oxide radicals are generated by Fenton-like reactions due to the coexistence of oxygen vacancy-related Fe(II) on goethite (a major constituent of iron corrosion scales) and hypochlorous acid (HClO, the main reactive chlorine species of residual chlorine at pH ∼ 7.0). OH contributed mostly to the decomposition of atrazine (ATZ, model compound) more than other radicals, producing a series of relatively low-toxicity small molecular intermediates. A simplified kinetic model consisting of mass transfer of ATZ and HClO, OH generation, and ATZ oxidation by OH on the goethite surface was developed to simulate iron corrosion scale-triggered residual chlorine oxidation of organic compounds in a WDS. The model was validated by comparing the fitting results to the experimental data. Moreover, the model was comprehensively applicable to cases in which various inorganic ions (Ca, Na, HCO, and SO) and natural organic matter were present. With further optimization, the model may be employed to predict the migration and accumulation of persistent organic pollutants under real environmental conditions in the WDSs.
PubMed: 38953777
DOI: 10.1021/acs.est.4c04022 -
ChemSusChem Jul 2024In the chemical industry, formaldehyde is an important bulk chemical. The traditional synthesis of formaldehyde involves an energy intensive oxidation of methanol over a...
In the chemical industry, formaldehyde is an important bulk chemical. The traditional synthesis of formaldehyde involves an energy intensive oxidation of methanol over a metal oxide catalyst. The selective electrochemical oxidation of methanol is challenging. Herein, we report a catalytic system with an immobilized TEMPO electrode that selectively oxidizes methanol to formaldehyde with high turnover numbers. Upon the addition of various organic and inorganic bases, the activity of the catalyst could be tuned. The highest Faradaic efficiency that was achieved was 97.5 %, the highest turnover number was 17100. Additionally, we found that the rate determining step changed from the step in which the carbonyl specie is created from the methanol-TEMPO adduct to the oxidative regeneration of the TEMPO species. Finally, we showed that the system could be applied to the oxidation of other aliphatic alcohols.
PubMed: 38953395
DOI: 10.1002/cssc.202400582 -
Research (Washington, D.C.) 2024Hyperthermia therapy is considered an effective anticancer strategy. However, high temperature can trigger an excessive inflammatory response, leading to tumor...
Hyperthermia therapy is considered an effective anticancer strategy. However, high temperature can trigger an excessive inflammatory response, leading to tumor self-protection, immunosuppression, metastasis, and recurrence. To address this issue, we reported a multifunctional photothermal nanoplatform to achieve mild hyperthermia photothermal therapy (mild PTT) based on cisplatin (DDP) and a ferrocene metal-organic framework (MOF-Fc) nanocomposite, which can specifically enhance ferroptosis-triggered oxidative stress levels and synchronously amplify mild hyperthermia PTT-mediated anticancer responses. Both in vitro and in vivo antineoplastic results verify the superiority of mild PTT with DDP/MOF-Fc@HA. The combination of DDP and MOF-Fc exhibits Fenton catalytic activity and glutathione depletion capacity, magnifying mild hyperthermia effects via the radical oxygen species (ROS)-adenosine triphosphate (ATP)-HSP silencing pathway, with important implications for clinical hyperthermia therapy.
PubMed: 38952997
DOI: 10.34133/research.0397 -
RSC Advances Jun 2024The photocatalytic field revolves around the utilization of photon energy to initiate various chemical reactions using non-adsorbing substrates, through processes such... (Review)
Review
The photocatalytic field revolves around the utilization of photon energy to initiate various chemical reactions using non-adsorbing substrates, through processes such as single electron transfer, energy transfer, or atom transfer. The efficiency of this field depends on the capacity of a light-absorbing metal complex, organic molecule, or substance (commonly referred to as photocatalysts or PCs) to execute these processes. Photoredox techniques utilize photocatalysts, which possess the essential characteristic of functioning as both an oxidizing and a reducing agent upon activation. In addition, it is commonly observed that photocatalysts exhibit optimal performance when irradiated with low-energy light sources, while still retaining their catalytic activity under ambient temperatures. The implementation of photoredox catalysis has resuscitated an array of synthesis realms, including but not limited to radical chemistry and photochemistry, ultimately affording prospects for the development of the reactions. Also, photoredox catalysis is utilized to resolve numerous challenges encountered in medicinal chemistry, as well as natural product synthesis. Moreover, its applications extend across diverse domains encompassing organic chemistry and catalysis. The significance of photoredox catalysts is rooted in their utilization across various fields, including biomedicine, environmental pollution management, and water purification. Of course, recently, research has evaluated photocatalysts in terms of cost, recyclability, and pollution of some photocatalysts and dyes from an environmental point of view. According to these new studies, there is a need for critical studies and reviews on photocatalysts and photocatalytic processes to provide a solution to reduce these limitations. As a future perspective for research on photocatalysts, it is necessary to put the goals of researchers on studies to overcome the limitations of the application and efficiency of photocatalysts to promote their use on a large scale for the development of industrial activities. Given the significant implications of the subject matter, this review seeks to delve into the fundamental tenets of the photocatalyst domain and its associated practical use cases. This review endeavors to demonstrate the prospective of a powerful tool known as photochemical catalysis and elucidate its underlying tenets. Additionally, another goal of this review is to expound upon the various applications of photocatalysts.
PubMed: 38952944
DOI: 10.1039/d4ra03259d -
Environmental Science & Technology Jul 2024Advanced oxidation processes (AOPs) are the most efficient water cleaning technologies, but their applications face critical challenges in terms of mass/electron...
Advanced oxidation processes (AOPs) are the most efficient water cleaning technologies, but their applications face critical challenges in terms of mass/electron transfer limitations and catalyst loss/deactivation. Bipolar electrochemistry (BPE) is a wireless technique that is promising for energy and environmental applications. However, the synergy between AOPs and BPE has not been explored. In this study, by combining BPE with AOPs, we develop a general approach of using carbon nanotubes (CNTs) as electric-field-induced bipolar electrodes to control electron transfer for efficient water purification. This approach can be used for permanganate and peroxide activation, with superior performances in the degradation of refractory organic pollutants and excellent durability in recycling and scale-up experiments. Theoretical calculations, in situ measurements, and physical experiments showed that an electric field could substantially reduce the energy barrier of electron transfer over CNTs and induce them to produce bipolar electrodes via electrochemical polarization or to form monopolar electrodes through a single particle collision effect with feeding electrodes. This approach can continuously provide activated electrons from one pole of bipolar electrodes and simultaneously achieve "self-cleaning" of catalysts through CNT-mediated direct oxidation from another pole of bipolar electrodes. This study provides a fundamental scientific understanding of BPE, expands its scope in the environmental field, and offers a general methodology for water purification.
Topics: Nanotubes, Carbon; Electrodes; Water Purification; Oxidation-Reduction; Catalysis
PubMed: 38952299
DOI: 10.1021/acs.est.4c03218 -
Chemical Communications (Cambridge,... Jul 2024Mimicking the dissipative assemblies found in living systems fueled by bioenergy, we present a novel chemical fuel-driven transient 2D SOF, formed the redox...
Mimicking the dissipative assemblies found in living systems fueled by bioenergy, we present a novel chemical fuel-driven transient 2D SOF, formed the redox reaction-driven transient self-assembly of tetraphenylene-based structural units and cucurbit[8]uril (CB[8]). The system was initiated by adding sodium dithionite (SDT) as the fuel, leading to the formation of 2D SOFs through 2 : 1 host-guest complexation between the viologen cation radical and CB[8]. These 2D SOFs then spontaneously disassemble over time as the radicals are oxidized by air. The temporal assembly and lifetimes of these transient SOFs can be controlled by adjusting the concentrations of the fuel. Moreover, the resulting transient 2D SOFs exhibited remarkable potential as catalysts for the green synthesis of benzyl sulfones in water.
PubMed: 38952286
DOI: 10.1039/d4cc01535e -
Microbial Cell Factories Jul 2024Advancing the engineering of photosynthesis-based prokaryotic cell factories is important for sustainable chemical production and requires a deep understanding of the...
BACKGROUND
Advancing the engineering of photosynthesis-based prokaryotic cell factories is important for sustainable chemical production and requires a deep understanding of the interplay between bioenergetic and metabolic pathways. Rearrangements in photosynthetic electron flow to increase the efficient use of the light energy for carbon fixation must be balanced with a strong carbon sink to avoid photoinhibition. In the cyanobacterium Synechocystis sp. PCC 6803, the flavodiiron protein Flv3 functions as an alternative electron acceptor of photosystem I and represents an interesting engineering target for reorganizing electron flow in attempts to enhance photosynthetic CO fixation and increase production yield.
RESULTS
We have shown that inactivation of Flv3 in engineered sucrose-excreting Synechocystis (S02:Δflv3) induces a transition from photoautotrophic sucrose production to mixotrophic growth sustained by sucrose re-uptake and the formation of intracellular carbon sinks such as glycogen and polyhydroxybutyrate. The growth of S02:Δflv3 exceeds that of the sucrose-producing strain (S02) and demonstrates unforeseen proteomic and metabolomic changes over the course of the nine-day cultivation. In the absence of Flv3, a down-regulation of proteins related to photosynthetic light reactions and CO assimilation occurred concomitantly with up-regulation of those related to glycolytic pathways, before any differences in sucrose production between S02 and S02:Δflv3 strains were observed. Over time, increased sucrose degradation in S02:Δflv3 led to the upregulation of respiratory pathway components, such as the plastoquinone reductase complexes NDH-1 and NDH-2 and the terminal respiratory oxidases Cyd and Cox, which transfer electrons to O. While glycolytic metabolism is significantly up-regulated in S02:Δflv3 to provide energy for the cell, the accumulation of intracellular storage compounds and the increase in respiration serve as indirect sinks for photosynthetic electrons.
CONCLUSIONS
Our results show that the presence of strong carbon sink in the engineered sucrose-producing Synechocystis S02 strain, operating under high light, high CO and salt stress, cannot compensate for the lack of Flv3 by directly balancing the light transducing source and carbon fixing sink reactions. Instead, the cells immediately sense the imbalance, leading to extensive reprogramming of cellular bioenergetic, metabolic and ion transport pathways that favor mixotrophic growth rather than enhancing photoautotrophic sucrose production.
Topics: Synechocystis; Photosynthesis; Sucrose; Bacterial Proteins; Carbon; Electron Transport; Proteomics; Carbon Dioxide
PubMed: 38951789
DOI: 10.1186/s12934-024-02462-6