Reduction Cycle Research Articles

Application of circular economy principles to midstream infrastructural sector: A review of strategies for waste minimization and recycling

Circular economy in midstream operations promotes resource reuse, waste reduction, and sustainable pipeline life cycle management. The transition toward a sustainable oil and gas industry needs to be enabled through the adoption of this concept, especially in the midstream sector, where environmental impact is high. This review focuses on practices in the waste minimization and recycling strategy of midstream infrastructure, including material recycling, reuse of processing debris and the conversion of waste into valuables. It underlines potential lifecycle environmental savings and resource efficiency, besides emphasizing on how innovative approaches are important in mitigating the ecological footprint of midstream activities. It also points out the knowledge gaps on practical integration of the circular economy principles within this very industry and came up with actionable recommendations for industry stakeholders. Through the analysis of the most recent published literatures and case studies of successful implementation, it has been indicated that many companies that use these techniques have succeeded in reducing waste output by over 30%. Conclusively, full scrutiny by this review has helped to attain a holistic approach towards sustainability in the oil and gas industry through wider adoption of recycling and sustainable practices in midstream operations.

The successive reduction of iodate to iodide driven by iron redox cycling

Ferrous iron (Fe(II)) produced by microbial Fe(III) reduction and reactive oxygen species (ROS) generated from aerobic Fe(II) oxidation can mediate iodate (IO3−) reduction and iodide (I−) oxidation, respectively. Nevertheless, how Fe redox cycling under redox fluctuating conditions drives transformation of iodine species remain unclear. In this study, Shewanella oneidensis MR-1 wildtype (WT) and its mutant △dmsEFAB, which lost the ability to enzymatically reduce IO3−, were chosen to conduct ferrihydrite/goethite/nontronite culture experiments under consecutive cycles of anoxic reduction of Fe(III) and re-oxidation of Fe(II) by O2 to reveal the role of Fe redox cycling in the transformation of iodine species. The results showed that both surface-adsorbed and mineral structural Fe(II) chemically reduced IO3−. Chemical IO3− reduction by biogenic Fe(II) was slower than enzymatic IO3− reduction by WT. Compared to △dmsEFAB cultures, WT cultures all showed higher Fe(II) concentrations under anoxic conditions but lower cumulative •OH under oxic conditions, which imply the chemical reaction between I− and ROS. I− oxidation by ROS, however, did not lead to a significant production of IO3− compared with I− formed under anoxic conditions. Consequently, Fe redox cycling successively reduced IO3− to I−, which highlights vital roles of Fe(III)-reducing bacteria in I− formation and mobilization in environments.

Assessment of the Impact of LID Techniques on Water Cycle Recovery in Industrial Complexes

Urbanization and industrialization have significantly disrupted the natural water cycle, leading to increased runoff, flooding, and groundwater depletion. Research on LID (Low Impact Development) techniques is ongoing in order to address these challenges. This study has analyzed the improvement in the water cycle system by applying LID techniques to the Daejeongcheon watershed in Ulsan. Using SWMM, this study has assessed the long-term effects of LID on runoff reduction and water cycle recovery rate improvement. Based on local climate data, topographical information, and regional characteristics, LID elements such as permeable pavements, green roofs, bioretention, and vegetative swales were applied. The results showed that the LID techniques reduced runoff by 8.44% and also improved the water cycle recovery rate by 13.52%. Additionally, the study confirmed that LID techniques effectively contributed to managing runoff from the 25.5 mm rainfall management target. LID techniques are expected to serve as sustainable water management strategies in urbanized and industrialized areas, offering effective restoration and management solutions.

A durable cobalt catalyst supported on Ni foam coated with Al2O3 for hydrogen generation from NaBH4 hydrolysis

A durable cobalt catalyst supported on Ni foam coated with Al2O3 (Co/Al2O3–Ni foam) is developed and analyzed using various analytical methods. In addition, the catalyst is tested to investigate the effects of the Al2O3 coating cycle, Co reduction cycle, and reaction temperature on hydrogen generation from NaBH4 hydrolysis. The Al2O3 coating cycle considerably affects hydrogen generation and the catalyst area required for a hydrogen generation rate of 1 L/min. However, the Co reduction cycle and reaction temperature slightly affect hydrogen generation and the catalyst area required for a hydrogen generation rate of 1 L/min. The catalyst exhibits an apparent activation energy of 64.3 kJ/mol, which is relatively higher than those of the other catalysts. Furthermore, the catalyst exhibits durability comparable to that of other catalysts. Thus, the Co/Al2O3–Ni foam catalyst with high apparent activation energy and comparable catalytic durability is suitable for the NaBH4 hydrogen generation system.

A multifunctional biomass-based solar interface evaporator with feather-like structure for efficient selective transport, antibacterial properties, salt resistance, and oil-fouling prevention

Solar interface evaporation technology has gained prominence as an efficient, low-cost, and CO2-neutral method for water purification. However, the development of interface evaporators with high evaporation efficiency, durability, and environmentally friendly, cost-effective materials remains a significant challenge. In this study, we fabricated a novel solar-powered hydrogel membrane using sodium alginate (SA), reduced graphene oxide (RGO), and vegetable-tanned collagen fibers (CF). Utilizing a dual-structural engineering design strategy, which incorporates surface patterning and microfiber channel construction, the resulting sodium alginate/collagen fibers/reduced graphene oxide (CF/SA/RGO) composite membranes exhibited remarkable selective mass transport efficiency. The inclusion of vegetable-tanned collagen fibers notably enhanced the flow rate of free water within the CF/SA/RGO membranes. Moreover, the reduction in water evaporation enthalpy increased with successive GO reduction cycles, thereby further boosting the evaporation rate. The CF/SA/RGO membranes demonstrated an outstanding evaporation efficiency of 2.88 kg m−2 h−1, ion rejection rates of 98 % for K+, Ca2+, Na+, and Mg2+, and a dye removal efficiency of 99.52 % for RhB, MB, MO, and CR. Additionally, these membranes exhibited excellent underwater oleophobicity, antibacterial properties, and salt resistance. This study offers a novel approach to the design and fabrication of solar interface evaporators, presenting an advancement in achieving high solar energy conversion efficiency and superior operational durability.

Free-standing polyaniline-reduced graphene oxide (PANI-rGO) thermoelectric films via electrochemical synthesis

Abstract Heat-based energy harvesting is gaining attention as an alternative energy source. Thermoelectric materials (TEs) generate voltages in response to a thermal gradient and conductive polymer-carbon composites have properties that make them favorable for these applications. Polyaniline-reduced graphene oxide (PANi-GO) thermoelectric thin films were fabricated by the electropolymerization of PANi with simultaneous co-deposition of graphene onto fluorine-doped tin oxide (FTO). Poly(butyl acrylate) was spin-coated onto these films as backing support to make a stable free-standing film of PANi-rGO. The free-standing film was formed upon GO reduction which resulted in simultaneous delamination from the FTO electrode. Compositional and morphological data were obtained via Raman microspectroscopy and scanning electron microscopy and the TE properties were measured in terms of the Seebeck coefficient and conductivities from Hall effect measurements. The Seebeck coefficients of the films measured between 6.6 μV K−1 to 13.4 μV K−1, whereas Hall effect conductivities ranged from 0.483 to 2.68 S cm−1. The highest film power factor measured was 0.025 μW m−1K−2. Varying the GO content used in the electropolymerized film did not have a significant effect on the overall TE property though varying the reduction cycle number and voltage resulted in significant changes in the film Seebeck coefficients and conductivities.

Waste not want not: the story of surgical trash.

Our escalating reliance on disposable products in the operating room has generated a large amount of waste, cost, and environmental pollution. Heath damages from the pollution caused by the US healthcare industry cause as much harm, as measured by disability-adjusted life years, as total medical errors. Our response to our own environmental impact should be proportional to that harm. Understanding the waste streams we create and the factors that contribute to our large waste generation in the operating room can help us target solutions to our most harmful practices. Recent studies within the field of medical waste in ObGyn have included a systematic review analyzing most effective practices for waste reduction and environmental life cycle analyses of specific medical procedures. Operating room waste includes regulated medical waste, pathologic waste/chemotherapy, sharps, general municipal waste, recycling, linens, and anesthetic gases. The most effective way to reduce the environmental impact from medical waste is to reduce our use of disposable supplies in favor of durable reusable materials. Other important interventions include eliminating 'overage' of unused supplies, optimizing use of anesthetic gas, custom pack scale backs, and proper waste segregation. This review of operative waste is intended to aid healthcare facilities in understanding and addressing their own environmental impact.

Extending the understanding of Shannon’s safe stimulation limit for platinum electrodes: biphasic charge-balanced pulse trains in unbuffered saline at pH = 1 to pH = 12

Objective.In neural electrical stimulation, safe stimulation guidelines are essential to deliver efficient treatment while avoiding neural damage and electrode degradation. The widely used Shannon's limit,k, gives conditions on the stimulation parameters to avoid neural damage, however, underlying damage mechanisms are not fully understood. Moreover, the translation from bench testing toin vivoexperiments still presents some challenges, including the increased polarisation observed, which may influence charge-injection mechanisms. In this work, we studied the influence on damage mechanisms of two electrolyte parameters that are differentin vivocompared to usual bench tests: solution pH and electrolyte gelation.Approach.The potential of a platinum macroelectrode was monitored in a three-electrode setup during current-controlled biphasic charge-balanced cathodic-first pulse trains. Maximum anodic and cathodic potential excursions during pulse trains were projected on cyclic voltammograms to infer possible electrochemical reactions.Main results.In unbuffered saline of pH ranging from 1 to 12, the maximum anodic potential was systematically located in the oxide formation region, while the cathodic potential was located the molecular oxygen and oxide reduction region whenkapproached Shannon's damage limit, independent of solution pH. The results support the hypothesis that Shannon's limit corresponds to the beginning of platinum dissolution following repeated cycles of platinum oxidation and reduction, for which the cathodic excursion is a key tipping point. Despite similar potential excursions between solution and gel electrolytes, we found a joint influence of pH and gelation on the cathodic potential alone, while we observed no effect on the anodic potential. We hypothesise that gelation creates a positive feedback loop exacerbating the effects of pH ; however, the extent of that influence needs to be examined further.Significance.This work supports the hypothesis of charge injection mechanisms associated with stimulation-induced damage at platinum electrodes. The validity of a major hypothesis explaining stimulation-induced damage was tested and supported on a range of electrolytes representing potential electrode environments, calling for further characterisation of platinum dissolution during electrical stimulation in various testing conditions.

Methyl Red degradation by a subseafloor fungus Schizophyllum commune 15R-5-F01: efficiency, pathway, and product toxicity.

Synthetic dyes pose a significant environmental threat due to their complex structures and resistance to microbial degradation. S. commune 15R-5-F01 exhibited over 96% degradation efficiency of Methyl Red in a medium with 100 mg L-1 Methyl Red within 3 h. The fungus demonstrated adaptability to various environmental conditions, including different pH levels, temperatures, oxygen concentrations, salinity, and heavy metals. S. commune 15R-5-F01 is capable of achieving repeated cycles of Methyl Red reduction with sustained degradation duration minimum of 6 cycles. It showed a maximum Methyl Red biodegradation capacity of at least 558 mg g-1 dry mycelia and a bioadsorption capacity of 57 mg g-1. Gas chromatography-mass spectrometry analysis confirmed the azo reduction of Methyl Red into N,N-dimethyl-p-phenylenediamine and 2-aminobenzoic acid. Enzymatic activity assays indicated the involvement of lignin peroxidases, laccases, and manganese peroxidase in the biodegradation process. Phytotoxicity tests on Triticum eastivum, Oryza sativa, and Vigna umbellata seeds revealed reduced toxicity of the degradation products compared to Methyl Red. This study identifies S. commune 15R-5-F01 as a viable candidate for the sustainable degradation of synthetic dyes in industrial wastewater.

Iron-copper bimetallic photo-Fenton system promoted photothermal-hydrogen peroxide production for efficient low-temperature wastewater treatment

Enhancing the velocity of the oxidation–reduction cycle is crucial for improving the catalytic efficiency of Fenton processes. Therefore, the development of an effective strategy for wastewater degradation at low temperatures is essential. In this context, we present the preparation of an NH2-MIL-88B (Fe)/CuInS2 S-scheme heterojunction. Specifically, CuInS2 nanoparticles are introduced onto the Ferro-organic skeleton, resulting in the exposure of a significant number of active surface sites. Furthermore, NH2-MIL-88B (Fe)/CuInS2 demonstrates an extended photoresponse into the long-wavelength region, which contributes to its excellent photothermal properties. Notably, the degradation rate of tetracycline in low-temperature aqueous environments reaches as high as 99.7 %, several times higher than that of the original sample. Additionally, the hydrogen production of NH2-MIL-88B (Fe)/CuInS2 is 2.23 times that of single NH2-MIL-88B (Fe) and 3.46 times that of single CuInS2. Moreover, the system exhibits good H2O2 evolution performance, forming an efficient photo-Fenton system. The charge transfer process in S-scheme heterojunction is confirmed using in-situ X-ray photoelectron spectroscopy and electron paramagnetic resonance. Both transient photoluminescence and photo electrochemical tests further validate the enhanced photoelectrochemical properties of the NH2-MIL-88B (Fe)/CuInS2 S-scheme heterojunction. The exceptional performance of this system can be attributed to the synergistic effects of the S-scheme heterojunction and the bimetallic codoped photo-Fenton system. This research presents a novel approach for the breakdown of low-temperature wastewater using an improved photocatalytic Fenton system.

Unveiling the versatile performance of transition metal sulfides in peroxymonosulfate activation

Advanced oxidation processes (AOPs) are promising treatment options for environmental remediation to reduce chemical oxygen demand (COD) and emerging contaminants. Transition metal sulfides (TMSs) are a class of common catalysts in AOPs, but actually, they also widely exist in the environment in the form of sulfide minerals and seriously contaminated water bodies as black-odorous substances. Therefore, it is crucial to find out their roles during water decontamination using AOPs. This study investigated different mechanisms and performance of four common TMSs (FeS, CuS, CoS and MnS) in peroxymonosulfate (PMS)-based AOPs for the removal of a representative micropollutant tetracycline (TC). The results showed that CoS/PMS was the most efficient with 100 % TC removal within 1 min, followed by FeS/PMS (100 %, 10 min) with the apparent rate constant (kobs) of 0.45 min−1. TC removal by CuS (kobs = 0.10 min−1) and MnS (kobs = 0.02 min−1) took 30 min with 96 % and 82 % removal, respectively. Interestingly, the dominant reactive species were different in these systems, i.e., high-valent iron (Fe(IV)) in FeS/PMS, mainly radicals (•OH, SO4•−, O2•−) and singlet oxygen (1O2) in CuS/PMS, and Co(IV) and 1O2 in CoS/PMS. In comparison, TC was removed in MnS/PMS mainly through cooperative adsorption, reduction and oxidation by MnS. Low valent sulfur species, such as S2− and S22−, may participate in the valence cycles of metals or TC reduction. The above four systems had a wide pH (3.6–11.1) adaptability and a strong anti-interference ability to co-existing Cl−, SO42− and NO3−, but could be hindered by CO32−, PO43− and humic acid. This study provides novel insights into the TMS-based catalysts in AOPs, which will pave the way for advancing AOP technology.

Thermodynamic properties of hercynite (FeAl2O4) for thermochemical water splitting applications: A first-principles approach

FeAl2O4 is considered as a potential material to produce solar thermochemical hydrogen. However, its temperature and pressure dependant thermodynamic properties have not yet been well explored. In this work, first-principles calculations have been applied to investigate the structural, mechanical, electronic and thermodynamic properties of FeAl2O4. The temperature and pressure-dependent thermal expansion coefficient and Grüneisen parameter have been calculated, leading to the calculation of molar heat capacity, cp = 5.50907 + 0.39378 T-202345.44153 T-2-94039T2 at 0 GPa. Change in Gibb's energy can be calculated at a given temperature and pressure during the reduction and oxidation cycle to computationally assess the suitability of FeAl2O4, as a catalyst for thermochemical water splitting. This approach may be further extended using suitable substitution and subsequent compositional variation of Fe and Al atoms, to explore more efficient catalyst.

Redox-Active Carboranyl Diphosphine as an Electron and Proton Transfer Agent.

In this work, we report the first example of the PCET reactivity for a boron cluster compound, the zwitterionic nido-carboranyl diphosphonium derivative 7-P(H)tBu2-10-P(H)iPr2-nido-C2B10H10. This main-group reagent efficiently transfers two electrons and two protons to quinones to yield hydroquinones and regenerate a neutral closo-carboranyl diphosphine, 1-PtBu2-2-PiPr2-closo-C2B10H10. As we have previously reported the conversion of this closo-carboranyl diphosphine into the zwitterionic nido- derivative upon reaction with main group hydrides, the transformation reported herein represents a complete synthetic cycle for the metal-free reduction of quinones, with the redox-active carboranyl diphosphine scaffold acting as a mediator. The proposed mechanism of this reduction, based on pKa determination, electrochemical studies, and kinetic isotope effect determination, involves the electron transfer from the nido- cluster to the quinone coupled with the delivery of protons.

Quantitative Kinetic Insights from Operando-UV/Vis Spectroscopy: An Application to NH3-SCR of NOx on Cu-CHA Catalysts.

We employ UV/Vis Diffuse Reflectance spectroscopy directly coupled with a packed bed flow reactor to extract quantitative kinetic information. We use as a show-case the CuII/CuI redox dynamics during the reduction half cycle of the NH3-Selective Catalytic Reduction (SCR) on Cu-CHA catalysts. Our measurements enable quantification of the fraction of oxidized Cu, reconstructed by Multivariate Curve Resolution (MCR) together with monitoring of the gas-phase evolution during the reaction. These data both on the dynamics of the gas-phase and of the active site oxidation state have been used to assess the reduction half cycle rate equation and estimate the rate constant. Our results in terms of reaction orders and kinetic constant are in line with previous findings in the literature. Overall, our results demonstrate that the combined analysis of the UV spectra and of the gas-phase dynamics provides converging and unparalleled kinetic insight: this approach effectively resolves ambiguities concerning RHC kinetics and mechanism. More in general, this work provides evidence that operando spectroscopy can be used to extract quantitative kinetic information on catalytic cycles.

Computational Design of an Electro-Organocatalyst for Conversion of CO2 into Long Chain Aldehydes.

Density functional theory calculations employing a hybrid implicit/explicit solvation method were used to demonstrate that an electro-organocatalyst designed in our previous work for reducing CO2 to formaldehyde could also be capable of coupling formaldehyde to form long chain aldehydes. The catalytic activity is enabled by an electron-rich vicinal enediamine (>N-C═C-N<) backbone that activates formaldehyde by reversing the polarity on the carbon atom, enabling it to act as a nucleophile in the subsequent aldol addition step. The catalyst then enables reductive dehydroxylation of the aldol addition product by facilitating outer-sphere electron transfer. The optimal pH as well as the limiting potential and formaldehyde concentration are identified and related to the kinetic balance between several rate limiting steps. Finally, the optimal conditions for coupling with the CO2 reduction cycle are discussed, demonstrating that the electro-organocatalyst is capable of efficiently converting CO2 into aldehyde products with a turnover frequency (per carbon atom) on the order of 0.1-1 s-1.

Bimetallic PtZn nanoparticles anchored in high-silica SSZ-13 zeolite for efficient propane dehydrogenation

Direct dehydrogenation of propane to propylene (PDH) is a promising route to meet the ever-growing global propylene demand, but the industrial Pt-based catalysts usually suffer from serious deactivation derived from coke deposition and sintering under harsh reaction conditions. In this work, PtZn bimetallic nanoparticles encapsulated into high-silica SSZ-13 zeolites (PtZn@SSZ-13) were synthesized via a facile ligand-protected interzeolite transformation strategy. In a PDH reaction, the synthesized 0.5Pt3Zn@SSZ-13 catalyst exhibits superior catalytic performance with a propane conversion of 23.7% and a propylene selectivity of 96.8%, which is significantly better than that of PtZn supported on high-silica SSZ-13 (0.5Pt3Zn/SSZ-13). Particularly, the high catalytic activity of this catalyst can be kept during three successive oxidation–reduction cycles. Detailed characterizations including HAADF-STEM, XPS, UV–Vis, H2-TPR reveal that the remarkable improvement of PDH performance is attributed to the PtZn synergistic effect as well as the confinement of SSZ-13 zeolites. The DFT calculations and microkinetic simulations also evidenced that the Pt particles anchored on the Zn-doped SSZ-13 zeolite pore framework possessed obviously higher propane dehydrogenation activity, whereas the anti-coking ability of 0.5Pt3Zn@SSZ-13 was also stronger than Pt (111) surface, demonstrating the superior performance of 0.5Pt3Zn@SSZ-13.

Seasonal coupling of iron (hydr-) oxides and organic carbon across elevations in Phragmites marshes of Yangtze Estuary

As sea levels rise, coastal tidal wetlands are increasingly threatened by flooding and salt stress, highlighting the importance of iron (Fe) (hydr-) oxides in soil for stabilizing organic carbon (OC). This study focuses on Phragmites australis, common in the Yangtze River Estuary, exploring the interplay between OC and Fe (hydr-) oxides in the rhizosphere of P. australis across various seasons and elevations. It also examines microbial community shifts in the Fe oxidation–reduction cycle. Results show that in the non-growing season (January), Fe (hydr-) oxides and total organic carbon (TOC) levels in the rhizosphere soil of high-tide P. australis are significantly higher than during the growing season (August), with a notable increase in Fe oxide-bound OC (Fe-OC). The content of Fe-OC in tidal wetland soil fluctuates with plant growth stages and elevation. Notably, during the growing season, the Fe-OC content in the rhizosphere of low-tide P. australis is markedly higher than in high-tide areas, reversing in the non-growing season. The presence of P. australis roots is found to significantly enhance the accumulation and coupling of Fe (hydr-) oxides and OC, especially in low-tide areas compared to bare flats. This coupling is affected by the organic matter contributed by roots, microbial metabolism, and redox conditions of the soil. The study also highlights how plant and microbial metabolism regulate the response of rhizosphere Fe-OC across different tidal flat elevations. In low-tide environments during the non-growing season, the prevalence of Fe-reducing bacteria results in decreased Fe-OC content, while in high-tide areas, increased organic matter input boosts complexed Fe-OC formation. Overall, this study emphasizes the significance of plant metabolism in understanding the impact of sea level rise on Fe-OC stores in tidal wetlands, a vital factor for comprehending C cycling mechanisms and assessing C sequestration potential under future climate change scenarios.

Phase transition Ni-Co-Ca-O bifunctional catalysts for high and stable hydrogen production from sorption enhanced steam methane reforming

Sorption enhanced steam methane reforming (SESMR) is an effective method to improve the efficiency of hydrogen production from methane reforming while fixing CO2 to reduce carbon emissions. However, the deactivation of adsorbents during high temperature recycling limits the utilization of SESMR. In this paper, by combining the phase transition process of Ca-Co-O species and Ni-Co alloy, we prepared a series of Ni-Co-Ca-O bifunctional catalysts for SESMR hydrogen production. The 1Ni4.5Co4.5CaO catalyst exhibited high catalytic activity in the SESMR reaction with hydrogen concentration exceeding 99.6 % and complete methane conversion. The catalyst also showed high stability in 50 cycle experiments with no significant reduction in hydrogen production and CO2 uptake performance. The Ni-Co-Ca-O bifunctional catalysts consisted of NiO and Co-Ca-O species, by analyzing the fresh and reacted catalysts, the mechanism of the catalyst with high catalytic activity and stability was revealed. Firstly, the catalyst formed Ni-Co alloy and CaO adsorbent by a reduction reaction, and then the SESMR hydrogen production reaction was carried out. After the complete conversion of CaO to CaCO3, the catalyst was re-formed into NiO and Co-Ca-O species by introducing O2 in the regeneration reaction to carry out a new cycle of reduction → hydrogen production. The synergistic interaction between the Ni-Co alloy enhanced the methane reforming and water gas shift reaction, leading to an increase in hydrogen production and methane conversion. The phase transition of Co from Co-Ca-O species to Ni-Co alloy and back to Co-Ca-O species inhibited the sintering of CaO, which significantly enhanced the cyclic stability of the catalyst. The results of this study are expected to provide a new pathway for the design of SESMR bifunctional catalysts.

Oral nitrate-reducing bacteria as potential probiotics for blood pressure homeostasis.

Hypertension is a leading cause of morbidity and mortality worldwide and poses a major risk factor for cardiovascular diseases and chronic kidney disease. Research has shown that nitric oxide (NO) is a vasodilator that regulates vascular tension and the decrease of NO bioactivity is considered one of the potential pathogenesis of essential hypertension. The L-arginine-nitric oxide synthase (NOS) pathway is the main source of endogenous NO production. However, with aging or the onset of diseases, the function of the NOS system becomes impaired, leading to insufficient NO production. The nitrate-nitrite-NO pathway allows for the generation of biologically active NO independent of the NOS system, by utilizing endogenous or dietary inorganic nitrate and nitrite through a series of reduction cycles. The oral cavity serves as an important interface between the body and the environment, and dysbiosis or disruption of the oral microbiota has negative effects on blood pressure regulation. In this review, we explore the role of oral microbiota in maintaining blood pressure homeostasis, particularly the connection between nitrate-reducing bacteria and the bioavailability of NO in the bloodstream and blood pressure changes. This review aims to elucidate the potential mechanisms by which oral nitrate-reducing bacteria contribute to blood pressure homeostasis and to highlight the use of oral nitrate-reducing bacteria as probiotics for oral microbiota intervention to prevent hypertension.

Enhanced visible light driven photodegradation of rifampicin and Cr(VI) reduction activity of ultra-thin ZnO nanosheets/CuCo2S4QDs: A mechanistic insights, degradation pathway and toxicity assessment

In this study, we focused on fabrication of porous ultra-thin ZnO nanosheet (PUNs)/CuCo2S4 quantum dots (CCS QDs) for visible light-driven photodegradation of rifampicin (RIF) and Cr(VI) reduction. The morphology, structural, optical and textural properties of fabricated photocatalyst were critically analyzed with different analytical and spectroscopic techniques. An exceptionally high RIF degradation (99.97%) and maximum hexavalent Cr(VI) reduction (96.17%) under visible light was achieved at 10 wt% CCS QDs loaded ZnO, which is 213% and 517% greater than bare ZnO PUNs. This enhancement attributed to the improved visible light absorption, interfacial synergistic effect, and high surface-rich active sites. Extremely high generation of ●OH attributed to the spin-orbit coupling in ZnO PUNs@CCS QDs and the existence of oxygen vacancies. Besides, the ZnOPUNs@CCS QDs, forming Z-scheme heterojunctions, enhanced the separation of photogenerated charge carriers. We investigated the influencing factors such as pH, inorganic ions, catalyst dosage and drug dosage on the degradation process. More impressively, a stable performance of ZnO PUNs@CCS QDs obtained even after six consecutive degradation (85.9%) and Cr(VI) reduction (67.7%) cycles. Furthermore, the toxicity of intermediates produced during the photodegradation process were assessed using ECOSAR program. This work provides a new strategy for ZnO-based photocatalysis as a promising candidate for the treatment of various contaminants present in water bodies.