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Herein, we report a solution-processable memristive device based on bismuth vanadate (BiVO

Carbon dioxide is considered an inert gas that rarely participates in atmospheric chemical reactions. Nonetheless, we show here that CO2 is involved in some important photo-oxidation reactions in the atmosphere through the formation of carbonate radicals (CO3⚫-). This potentially active intermediate CO3⚫- is routinely overlooked in atmospheric chemistry concerning its effect on sulfate formation. The present work demonstrates that the SO2 uptake coefficient is enhanced by 17 times on mineral dust particles driven by CO3⚫-. Importantly, upon irradiation, mineral dust particles are speculated to produce gas-phase carbonate radical ions when the atmospherically relevant concentration of CO2 presents, thereby potentially promoting external sulfate aerosol formation and oxidative potential in the atmosphere. Employing a suite of laboratory investigations of sulfate formation in the presence of carbonate radicals on the model and authentic dust particles, ground-based field measurements of sulfate and (bi)carbonate ions within ambient PM, together with density functional theory (DFT) calculations for single electron transfer processes in terms of CO3⚫--initiated S(IV) oxidation, a novel role of carbonate radical in atmospheric chemistry is elucidated.

Lead (Pb) and cadmium (Cd) are considered as a typical heavy metals in aqueous solution, which may pose adverse health effects on human beings. For the removal of these two pollutants, magnesium oxide (MgO) was successfully immobilized onto eucalyptus biochar (BC) matrix via simple and cost-effective pyrolysis process of MgCl2-pretreated eucalyptus biomass under high temperature (500 °C). Synthesized MgO nanoparticles-biochar composites (MBC) exhibited superior removal performance for target pollutants, and achieve 99.9% removal efficiency for Pb(II) and Cd(II) at optimum conditions (0.02 g, pH in range of 4–7, and reaction time 120, 240 min). Furthermore, the maximum theoretical adsorbing amount of MBC was 829.11 mg/g for Pb(II) and 515.17 mg/g for Cd(II). Pseudo-second-order model and Langmuir models were well-determined for isotherm and adsorption kinetics. FTIR, XRD, and XPS analysis revealed that precipitation and ion exchange was of great importance for the removal of contaminants. Besides, cation-π interaction and complexation from the carbon-containing functional groups should not be neglected. Considering the advantage of low-cost, facile preparation, and brilliant adsorption capacity, it is anticipated that MBC has a promising prospect for the broad application in Pb(II)/Cd(II)-containing wastewater treatment.

Carbon dioxide is considered an inert gas that rarely participates in atmospheric chemical reactions. However, we show here that CO2 is involved in some important photo-oxidation reactions in the atmosphere through the formation of carbonate radicals (CO3∙-). This potentially active intermediate CO3∙- is routinely overlooked in atmospheric chemistry regarding its effect on sulfate formation. Present work demonstrates that SO2 uptake coefficient is enhanced by 17 times on mineral dust particles driven by CO3∙-. It can be produced through two routes over mineral dust surfaces: i) hydroxyl radical + CO32-; ii) holes (h+) + CO32-. Employing a suite of laboratory investigations of sulfate formation in the presence of carbonate radical on the model and authentic dust particles, field measurements of sulfate and (bi)carbonate ions within ambient PM, together with density functional theory (DFT) calculations for single electron transfer processes in terms of CO3∙--initiated S(IV) oxidation, a new role of carbonate radical in atmospheric chemistry is elucidated.

Visible-light-driven photoelectrochemical (PEC) catalysis has been widely studied as a promising technique for the degradation of organic pollutants in wastewater. Herein, we report a sulfite-enhanced PEC degradation process for the degradation of organic pollutant. The degradation rate was significantly enhanced by ～30 times with the addition of 16 mM sulfite. The Electron Spin Resonance (ESR), Transient Absorption (TA) and hole scavenger studies showed that sulfite radicals ( S O 3 ⦁ - ) were the main reactive species in the reactions. The pollutant degradation pathway was studied by in-situ techniques and mass spectrometer, showing that the sulfite addition can promote the cleavage of aromatic ring C C bond and C N bond.

Summary Recently, the environmental impacts of microplastics have received extensive attention owing to their accumulation in the environment. However, developing efficient technology for the control and purification of microplastics is still a big challenge. Herein, we investigated the photocatalytic degradation of typical microplastics such as polystyrene (PS) microspheres and polyethylene (PE) over TiO2 nanoparticle films under UV light irradiation. TiO2 nanoparticle film made with Triton X-100 showed complete mineralization (98.40%) of 400-nm PS in 12 h, while degradation for varying sizes of PS was also studied. PE degradation experiment presented a high photodegradation rate after 36 h. CO2 was found as the main end product. The degradation mechanism and intermediates were studied by in situ DRIFTS and HPPI-TOFMS, showing the generation of hydroxyl, carbonyl, and carbon-hydrogen groups during the photodegradation of PS. This study provides a green and cost-efficient strategy for the control of microplastics contamination in the environment., Graphical Abstract, Highlights • Efficient degradation of microplastics under UV light by TiO2 film • Triton-based TiO2 film showed higher photocatalytic performance • The role of radical species during microplastics degradation was elucidated • Degradation mechanism and reaction intermediates were explored, Catalysis; Environmental Chemistry; Nanomaterials

Despite the increased awareness of heterogeneous reaction on mineral dust, the knowledge of how the intensity of solar irradiation influences the photochemistry activity remains a crucially important part in atmospheric research. Relevant studies have not seriously discussed the photochemistry under weak sunlight during haze, and thus ignored some underlying pollution and toxicity. Here, we investigated the heterogeneous formation of nitrate and nitrite under various illumination conditions by laboratory experiments and field observations. Observed by in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), water-solvated nitrate was the main surface product, followed by other species varying with illumination condition. The growth of nitrate formation rate tends to be slow after the initial fast with increasing light intensity. For example, the geometric uptake coefficient (γgeo) under 30.5 mW/cm2 (5.72 × 10−6) has exceeded the 50 % of that under 160 mW/cm2 (1.13 × 10−5). This case can be explained by the excess NO2 adsorption under weak illumination while the excess photoinduced active species under strong irradiation. Being negatively associated with nitrate (R2 = 0.748, P

As a green adsorbent, biochar has attained progressive attention due to its advantages such as high carbon content, high surface area, stable structure, and heavy metals removal through cation exchange capacity. Biochar can be synthesized from the feedstock, agricultural, and organic waste. In this study, the activated biochar (AC) and ammonia modified biochar (NAC) were prepared from Eucalyptus waste by acid activation. The adsorption properties of pure AC and NAC were compared for aqueous Cr(VI) removal. Advanced characterization techniques such as scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR) were used to examine the morphology, elemental composition, and functional groups. Several influencing factors on adsorption processes such as solution pH, adsorption dosage, contact time, and initial concentration were investigated. The ammonia modified biochar (NAC) could remove 85.67% of Cr (VI), whereas 76.73% removal rate was observed for the activated biochar (AC) at an initial concentration of 300 mg/L at pH 2.0 and 25 °C with a dosage of 0.025 g/25 mL. The pseudo-second-order kinetic and Freundlich isotherm adsorption models showed close-fitting for the activated biochar (AC) and the ammonia modified biochar (NAC) adsorption in Cr(VI) equilibrium state. Cr (VI) oxidizes nitrogen and oxygen functional groups on NAC following the conversion into Cr (III). The removal and adsorption mechanism was the coexistence of physical adsorption and chemical reduction examined by FTIR and XPS illustrating Cr(VI) removal.

Biochar, due to its ability to remediate heavy metals and organic contaminants from polluted water is considered as an economic adsorption material. This work involved pyrolysis driven eucalyptus carbon (EC) to produce eucalyptus activated carbon (AC) through a novel mechanism of using phosphoric acid (H3PO4) and its subsequent testing for efficient adsorption of Cr (VI) from aqueous environments. Advanced characterization techniques like XRD, SEM, BET, FTIR, and XPS were employed to characterize the structure and composition of EC and AC. The AC could remove 99.76% of Cr(VI), which was higher than EC removal rate of 25.24%. The surface area of AC increased by almost 5 times 1265.56 m2/g compared to EC (253.25 m2/g). The removal rate of Cr(VI) was highly influenced by adsorption capacity, pH, adsorption time, temperature, kinetics, and isotherm. Reaction rate kinetics, isothermal, and thermodynamic analysis revealed that the adsorption curve of AC fits well with the quasi-second-order kinetic model. AC adsorption process was a spontaneous endothermic reaction limited by intraparticle diffusion and a combination of chemical and physical adsorption.

Bisphenol A (BPA) is known as an endocrine-disrupting chemical, generally present in the environment. It has a harmful effect on aquatic lives and human health, therefore it is needful to exploit highly efficient innovative treatment methods for its removal. Herein, we report a Co-BiVO4 photoanode to activate peroxymonosulfate (PMS) for the complete removal of BPA via a photoelectrochemical (PEC) process. The Co-BiVO4 could degrade 99.16% of BPA in the presence of 2 mM PMS within 60 min, whereas the degradation rate constant is 0.08034 min−1, which was 20.86 times higher than the electrocatalytic (EC) and 5.35 times higher than the photocatalytic (PC) process. Notably, Co-BiVO4 showed significant activity toward PMS activation and BPA degradation as compared to other synthesized photocatalysts. Their photoelectrocatalytic performance followed the sequence Co-BiVO4 > Fe-BiVO4 > Ni-BiVO4 > pure-BiVO4 > without catalysts. Several influencing factors on the decomposition process, such as the effect of PMS concentration, applied potential, illumination time, initial pH, BPA concentration, Co loading, and co-existing anions were studied in detail. Radical scavenging experiment and transient absorption result showed that sulfate radicals (SO4•─) were the dominant reactive species. Moreover, a significant synergistic effect was noticed in Co-BiVO4/PEC/PMS system for BPA degradation. Degradation mechanism and reaction intermediates were studied by in-situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) and liquid chromatography-mass spectroscopy (LC-MS) presenting the enhanced bond cleavage in PEC activated PMS system. The BPA showed 92.47% and 87.27% removal in tap and river water samples after 60 min of reaction using Co-BiVO4/PMS PEC system. Our finding proposed an efficient method for wastewater treatment in an eco-friendly way.