Accelerated Pollutant Degradation by UV/HO at the Air-Water Interface of Microdroplets.

Ultraviolet light-induced homolysis of hydrogen peroxide (UV/HO) can generate powerful hydroxyl radicals (OH) for sustainable water purification. However, the efficiency of the conventional bulk-phase UV/HO system is limited by the low yield and utilization of OH, in turn necessitating high UV energy input and long purification period. In this study, we present an innovative UV/HO microdroplet system for enhanced pollutant degradation.

Quinones stimulate reactive oxygen species production from zero-valent iron over centimeter distances.

Zero-valent iron (ZVI) has demonstrated high potential for in-situ remediation of contaminated groundwater and soils. Upon exposure to oxygen, ZVI generates reactive oxygen species (ROS). In parallel with the electron transfer mediated-reductive path, ROS plays a critical role in the oxidative degradation of organic pollutants during ZVI remediation of groundwater and soil.

Visualizing Electron Transfer through Silver Nanoparticle Formation and Photothermal Imaging: A Case Study of Nanoscale Zerovalent Iron.

Electron release and transfer are pivotal to the efficiency of multiple biogeochemical and pollutant processes. Despite substantial efforts to develop electron-transfer characterization techniques, visualization of electron transfer remains challenging. This study introduces an innovative strategy for mapping electron-transfer distance using nanoscale zerovalent iron (nZVI) as a case study.

Visualizing Hydrogen Peroxide Diffusion in Soils with Precipitation-Based Fluorescent Probe.

Hydrogen peroxide (HO)-based advanced oxidation technology has emerged as a cost-effective and green solution for tackling soil pollution. Given the highly heterogeneous nature of soil, the effectiveness of HO remediation is significantly influenced by its diffusion distance in soils. However, the dynamics of HO diffusion and its effective range remain largely unexplored, primarily due to the lack of analytical methods for mapping HO in soils.

Redox Oscillation-Driven Production of Reactive Oxygen Species from Black Carbon.

Wildfire and stubble burning release substantial amounts of black carbon (BC) into natural environments that experience frequent redox oscillations, such as wetlands and farmlands. Here, we report that redox oscillations can effectively drive ROS production from BC. Following sequential microbial reduction and air exposure, 6.

Accelerated Indirect Photodegradation of Organic Pollutants at the Soil-Water Interface.

Indirect photolysis driven by photochemically produced reactive intermediates (PPRIs) is pivotal for the transformations and fates of pollutants in nature. While well-studied in bulk water, indirect photolysis processes at environmental interfaces remain largely unexplored. This study reveals a significant acceleration of indirect photodegradation of organic pollutants at the soil-water interface of wetlands.

Radial Oxygen Loss Triggers Diel Fluctuation of Cadmium Dissolution in the Rhizosphere of Rice.

Cadmium (Cd) contamination poses a significant global threat to human health, primarily through dietary intake, with rice serving as a major source. While Cd predominantly resides in bound states in soil, the physiological processes by which rice facilitates Cd absorption in the rhizosphere remain largely elusive. This study delves into the mechanisms governing Cd uptake by rice plants in the rhizosphere, emphasizing the impact of daytime and nighttime fluctuations in microenvironmental conditions.

Water Vapor Condensation Triggers Simultaneous Oxidation and Hydrolysis of Organic Pollutants on Iron Mineral Surfaces.

Increasing worldwide contamination with organic chemical compounds is a paramount environmental challenge facing humanity. Once they enter nature, pollutants undergo transformative processes that critically shape their environmental impacts and associated risks. This research unveils previously overlooked yet widespread pathways for the transformations of organic pollutants triggered by water vapor condensation, leading to spontaneous oxidation and hydrolysis of organic pollutants.

Integrative Active Sites of Cathode for Electron-Oxygen-Proton Coupling To Favor HO Production in a Photoelectrochemical System.

The oxygen reduction process generating HO in the photoelectrochemical (PEC) system is milder and environmentally friendly compared with the traditional anthraquinone process but still lacks the efficient electron-oxygen-proton coupling interfaces to improve HO production efficiency. Here, we propose an integrated active site strategy, that is, designing a hydrophobic C-B-N interface to refine the dearth of electron, oxygen, and proton balance. Computational calculation results show a lower energy barrier for HO production due to synergistic and coupling effects of boron sites for O adsorption, nitrogen sites for H binding, and the carbon structure for electron transfer, demonstrating theoretically the feasibility of the strategy.

Natural Disinfection-like Process Unveiled in Soil Microenvironments by Enzyme-Catalyzed Chlorination.

Substantial natural chlorination processes are a growing concern in diverse terrestrial ecosystems, occurring through abiotic redox reactions or biological enzymatic reactions. Among these, exoenzymatically mediated chlorination is suggested to be an important pathway for producing organochlorines and converting chloride ions (Cl) to reactive chlorine species (RCS) in the presence of reactive oxygen species like hydrogen peroxide (HO). However, the role of natural enzymatic chlorination in antibacterial activity occurring in soil microenvironments remains unexplored.

Wavelength-dependent direct and indirect photochemical transformations of organic pollutants.

Sunlight-induced photochemical transformations greatly affect the persistence of organic pollutants in natural environment. Whereas sunlight intensity is well-known to affect pollutant phototransformation rates, the reliance of pollutant phototransformation kinetics on sunlight spectrum remains poorly understood, which may greatly vary under different spatial-temporal, water matrix, and climatic conditions. Here, we systematically assessed the wavelength-dependent direct and indirect phototransformations of 12 organic pollutants.

Field Quantification of Hydroxyl Radicals by Flow-Injection Chemiluminescence Analysis with a Portable Device.

Hydroxyl radical (OH) is a powerful oxidant abundantly found in nature and plays a central role in numerous environmental processes. On-site detection of OH is highly desirable for real-time assessments of OH-centered processes and yet is restrained by a lack of an analysis system suitable for field applications. Here, we report the development of a flow-injection chemiluminescence analysis (FIA-CL) system for the continuous field detection of OH.

Facet-Dependent Productions of Reactive Oxygen Species from Pyrite Oxidation.

Reactive oxygen species (ROS) are widespread in nature and play central roles in numerous biogeochemical processes and pollutant dynamics. Recent studies have revealed ROS productions triggered by electron transfer from naturally abundant reduced iron minerals to oxygen. Here, we report that ROS productions from pyrite oxidation exhibit a high facet dependence.

Accelerated Photolysis of HO at the Air-Water Interface of a Microdroplet.

Photochemical homolysis of hydrogen peroxide (HO) occurs widely in nature and is a key source of hydroxyl radicals (·OH). The kinetics of HO photolysis play a pivotal role in determining the efficiency of ·OH production, which is currently mainly investigated in bulk systems. Here, we report considerably accelerated HO photolysis at the air-water interface of microdroplets, with a rate 1.

Sequential anodic oxidation and cathodic electro-Fenton in the Janus electrified membrane for reagent-free degradation of pollutants.

Electrified membrane technologies have recently demonstrated high potential in tackling water pollution, yet their practical applications are challenged by relying on large precursor doses. Here, we developed a Janus porous membrane (JPEM) with synergic direct oxidation by Magnéli phase TiO anode and electro-Fenton reactions by CuFeO cathode. Organic pollutants were first directly oxidized on the TiO anode, where the extracted electrons from pollutants were transported to the cathode for electro-Fenton production of hydroxyl radical (·OH).

Long-Term Exposure of Graphene Oxide Suspension to Air Leading to Spontaneous Radical-Driven Degradation.

Understanding the environmental transformation and fate of graphene oxide (GO) is critical to estimate its engineering applications and ecological risks. While there have been numerous investigations on the physicochemical stability of GO in prolonged air-exposed solution, the potential generation of reactive radicals and their impact on the structure of GO remain unexplored. In this study, using liquid-PeakForce-mode atomic force microscopy and quadrupole time-of-flight mass spectroscopy, we report that prolonged exposure of GO to the solution leads to the generation of nanopores in the 2D network and may even cause the disintegration of its bulk structure into fragment molecules.

Redox Oscillations Activate Thermodynamically Stable Iron Minerals for Enhanced Reactive Oxygen Species Production.

Reactive oxygen species (ROS) play key roles in driving biogeochemical processes. Recent studies have revealed nonphotochemical electron transfer from redox-active substances (e.g.

Water Vapor Condensation on Iron Minerals Spontaneously Produces Hydroxyl Radical.

The hydroxyl radical (OH) is a potent oxidant and key reactive species in mediating element cycles and pollutant dynamics in the natural environment. The natural source of OH is historically linked to photochemical processes (e.g.

Pyrogenic Carbon Improves Cd Retention during Microbial Transformation of Ferrihydrite under Varying Redox Conditions.

Fe(III) (oxyhydr)oxides are ubiquitous in paddy soils and play a key role in Cd retention. Recent studies report that pyrogenic carbon (PC) may largely affect the microbial transformation processes of Fe(III) (oxyhydr)oxides, yet the impact of PC on the fate of Fe(III) (oxyhydr)oxide-associated Cd during redox fluctuations remains unclear. Here, we investigated the effects of PC on Cd retention during microbial ( MR-1) transformation of Cd(II)-bearing ferrihydrite under varying redox conditions.

Spontaneous Oxidation of Thiols and Thioether at the Air-Water Interface of a Sea Spray Microdroplet.

The transport of dissolved organic sulfur, including thiols and thioethers, from the ocean surface to the atmosphere through sea spray aerosol (SSA) is of great importance for the global sulfur cycle. Thiol/thioether in SSA undergoes rapid oxidation that is historically linked to photochemical processes. Here, we report the discovery of a non-photochemical, spontaneous path of thiol/thioether oxidation in SSA.

Probing Molecular-Level Dynamic Interactions of Dissolved Organic Matter with Iron Oxyhydroxide via a Coupled Microfluidic Reactor and an Online High-Resolution Mass Spectrometry System.

The interactions between dissolved organic matter (DOM) and iron (Fe) oxyhydroxide are crucial in regulating the biogeochemical cycling of nutrients and elements, including the preservation of carbon in soils. The mechanisms of DOM molecular assembly on mineral surfaces have been extensively studied at the mesoscale with equilibrium experiments, yet the molecular-level evolution of the DOM-mineral interface under dynamic interaction conditions is not fully understood. Here, we designed a microfluidic reactor coupled with an online solid phase extraction (SPE)-LC-QTOF MS system to continually monitor the changes in DOM composition during flowing contact with Fe oxyhydroxide at circumneutral pH, which simulates soil minerals interacting with constant DOM input.

Sunlight-Driven Production of Reactive Oxygen Species from Natural Iron Minerals: Quantum Yield and Wavelength Dependence.

Photochemically generated reactive oxygen species (ROS) play numerous key roles in earth's surface biogeochemical processes and pollutant dynamics. ROS production has historically been linked to the photosensitization of natural organic matter. Here, we report the photochemical ROS production from three naturally abundant iron minerals.