The impact of ozone (O3) pollution events on the plant drought response needs special attention because spring O3 episodes are often followed by summer drought. By causing stomatal sluggishness, O3 could affect the stomatal dynamic during a subsequent drought event. In this context, we studied the impact of O3 exposure and water deficit (in the presence or in the absence of O3 episode) on the stomatal closure/opening mechanisms relative to irradiance or vapour pressure deficit (VPD) variation. Two genotypes of Populus nigra x deltoides were exposed to various treatments for 21 days. Saplings were exposed to 80 ppb/day O3 for 13 days, and then to moderate drought for 7 days. The curves of the stomatal response to irradiance and VPD changes were determined after 13 days of O3 exposure, and after 21 days in the case of subsequent water deficit, and then fitted using a sigmoidal model. The main responses under O3 exposure were stomatal closure and sluggishness, but the two genotypes showed contrasting responses. During stomatal closure induced by a change in irradiance, closure was slower for both genotypes. Nonetheless, the genotypes differed in stomatal opening under light. Carpaccio stomata opened more slowly than control stomata, whereas Robusta stomata tended to open faster. These effects could be of particular interest, as stomatal impairment was still present after O3 exposure and could result from imperfect recovery. Under water deficit alone, we observed slower stomatal closure in response to VPD and irradiance, but faster stomatal opening in response to irradiance, more marked in Carpaccio. Under the combined treatment, most of the parameters showed antagonistic responses. Our results highlight that it is important to take genotype-specific responses and interactive stress cross-talk into account to improve the prediction of stomatal conductance in response to various environmental modifications.

Removal of toxic formaldehyde from environmental waters is crucial to maintain ecosystem sustainability and human health. In this work, MIL-100(Fe) as a heterogeneous Fenton-like photocatalyst was used for the treatment of formaldehyde-contaminated water. The MIL-100(Fe) was synthesized via a facile solvothermal method and fully characterized using different spectroscopic and microscopic techniques. Based on the results, the formation of highly porous, crystalline, and stable visible light-responsive MIL-100(Fe) was confirmed. The Fenton-like photocatalytic efficiency of the MIL-100(Fe) toward the degradation of formaldehyde was then studied under visible light irradiation. For this purpose, the effect of initial concentration of formaldehyde, photocatalyst dose, H₂O₂ concentration, solution pH, and contact time on the removal efficiency of the MIL-100(Fe) was investigated using central composite design. The obtained results showed that the removal efficiency of the MIL-100(Fe) is significantly affected by the initial concentration of formaldehyde. A second-order model with R² = 0.93 was developed for the system that was able to adequately predict the percentage removal of formaldehyde by the MIL-100(Fe) under different experimental conditions. According to the numerical optimization results, by using 1.13 g L⁻¹ photocatalyst and 0.055 mol L⁻¹ H₂O₂, 93% of formaldehyde can be removed after 119 min from an aqueous solution containing 700 mg L⁻¹ of formaldehyde at pH 6.54.

The impact of ozone (O3) pollution events on the plant drought response needs special attention because spring O3 episodes are often followed by summer drought. By causing stomatal sluggishness, O3 could affect the stomatal dynamic during a subsequent drought event. In this context, we studied the impact of O3 exposure and water deficit (in the presence or in the absence of O3 episode) on the stomatal closure/opening mechanisms relative to irradiance or vapour pressure deficit (VPD) variation. Two genotypes of Populus nigra x deltoides were exposed to various treatments for 21 days. Saplings were exposed to 80 ppb/day O3 for 13 days, and then to moderate drought for 7 days. The curves of the stomatal response to irradiance and VPD changes were determined after 13 days of O3 exposure, and after 21 days in the case of subsequent water deficit, and then fitted using a sigmoidal model. The main responses under O3 exposure were stomatal closure and sluggishness, but the two genotypes showed contrasting responses. During stomatal closure induced by a change in irradiance, closure was slower for both genotypes. Nonetheless, the genotypes differed in stomatal opening under light. Carpaccio stomata opened more slowly than control stomata, whereas Robusta stomata tended to open faster. These effects could be of particular interest, as stomatal impairment was still present after O3 exposure and could result from imperfect recovery. Under water deficit alone, we observed slower stomatal closure in response to VPD and irradiance, but faster stomatal opening in response to irradiance, more marked in Carpaccio. Under the combined treatment, most of the parameters showed antagonistic responses. Our results highlight that it is important to take genotype-specific responses and interactive stress cross-talk into account to improve the prediction of stomatal conductance in response to various environmental modifications.

The development of powdery photocatalyst has long been studied, yet the low recovery in water is still its bottleneck. In this work, magnetic recyclable lanthanum-doped TiO₂/copper ferrite/diatomite (La-TCD) ternary composite was synthesized via sol-gel method. The physicochemical properties of various hybrid catalysts were characterized and studied, and their photocatalytic properties were evaluated via the decomposition of antibiotic oxytetracycline and disinfection of bacteria Escherichia coli under visible light. The formation of heterojunction between La-doped TiO₂ and copper ferrite hindered the recombination of photo-induced charge carriers and improved the photocatalytic activity. The photodecomposition rate of OTC was accelerated by the high adsorption ability of diatomite, due to the adsorption and decomposition synergistic effect between catalysts and substrate diatomite. The optimal La dopant amount as well as optimal catalyst dosage was determined. The composite could simply be recovered from waterbody via an external magnet, and the repetition tests indicated no obvious decrease of photoactivity. This nanocomposite presented good potential to be applied in environmental remediation process, due to its high photocatalytic efficiency under visible light, as well as its good reusability and stability.

A novel non-toxic hybrid BiVO₄-GO-TiO₂-polyaniline (PANI) (BVGT-PANI) composite with superior photocatalysis was successfully prepared via a one-pot hydrothermal reaction. The structural and morphological characterizations of the synthesized compounds were analyzed by a series of techniques. We found excellent photocatalytic efficiencies for methylene blue (MB) and phenol degradation under visible light irradiation after adhering the PANI to the photocatalyst. The degradation rates of MB and phenol reach up to approximately 85% and 80%, respectively, after 3 h of irradiation. For photodegradation MB, BVGTA exhibit the highest kₐₚₚ rate constant of about 1.06 × 10⁻² min⁻¹, which is about 1.63-fold faster than BVG and 2.94-fold faster than BVGT. For photodegradation of phenol, BVGTA exhibits the highest kₐₚₚ rate constant, of about 8.86 × 10⁻³min⁻¹, which is about 1.2-fold faster than BVG and 1.96-fold faster than BVGT. Furthermore, vitro toxicity test against Bacillus subtilis and Staphylococcus aureus demonstrated that the nanophotocatalyst is non-toxic.

Atrazine, one of the most widespread herbicides in the world, is considered as an environmental estrogen and has potential carcinogenicity. In this study, atrazine was degraded on boron-fluorine co-doped TiO₂ nanotube arrays (B, F-TiO₂ NTAs), which had similar morphology with the pristine TiO₂ NTAs. The structure and morphology of TiO₂ nanotube samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV-visible diffuse reflectance spectroscopy (DRS). It showed that the decoration of fluorine and boron made both the absorption in the visible region enhanced and the band edge absorption shifted. The efficiency of atrazine degradation by B, F-TiO₂ NTAs through photoelectrocatalysis was investigated by current, solution pH, and electrolyte concentration, respectively. The atrazine removal rate reached 76% through photoelectrocatalytic reaction by B, F-TiO₂ NTAs, which was 46% higher than that under the photocatalysis process. Moreover, the maximum degradation rate was achieved at pH of 6 in 0.01 M of Na₂SO₄ electrolyte solution under a current of 0.02 A and visible light for 2 h in the presence of B, F-TiO₂ NTAs. These results showed that B, F-TiO₂ NTAs exhibit remarkable photoelectrocatalytic activity in degradation of atrazine.

Large amount of volatile organic compounds (VOCs) are emitted from industrial, mobile, and domestic sources, causing adverse effects on human health and environment. Among VOCs, toluene and isopropanol (IPA) are commonly used as solvent, soldering flux, and spray paint and their emissions need to be reduced. Several VOCs abatement technologies are available to reduce VOC emission and photocatalytic oxidation of VOC is regarded as a viable technique due to its advantage of utilizing solar energy. TiO₂ has been investigated for its oxidation capability toward VOCs because of its good photocatalytic activity. However the utilization is limited to UV due to its wider bandgap; furthermore, its fast recombination rate of electron-hole pair reduces the oxidation rate of VOCs. Black-TiO₂ and perovskite-type photocatalyst such as LaFeO₃ can be applied to enhance photocatalytic activity due to narrower bandgap and longer electron-hole pair lifetime. In this study, black-TiO₂ and LaFeO₃ are prepared and investigated for their photocatalytic oxidation rates toward toluene and IPA. Results show that toluene removals achieved with black-TiO₂ and LaFeO₃ are 89% and 98% while IPA removals are 90% and 94%, respectively. Both photocatalysts show better photocatalytic activity than TiO₂ and good absorption capability toward visible light. Graphical abstract

Biosynthesized nanocomposites are attracting growing interests because they are environmentally friendly. Ag₂S nanoparticles (Ag₂S NPs) are deposited in situ on the surfaces of TiO₂ nanotubes (TNTs) via Shewanella oneidensis MR-1 to form Ag₂S/TNT nanocomposites. The prepared Ag₂S/TNTs nanocomposites are characterized using high-resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and energy-dispersive X-ray spectroscopy. The results show that Ag₂S NPs smaller than 8 nm are successfully synthesized and fabricated on the TNT surfaces with relatively uniform distribution. The catalytic performance of the Ag₂S/TNT nanocomposites is evaluated for catalytic reduction in the presence of NaBH₄ and the photocatalytic degradation of 4-nitrophenol (4-NP) under visible light. The Ag₂S/TNT nanocomposites show excellent catalytic activity and good stability in the 4-NP reduction process. The 4-NP degradation ratio reaches 98.3% in 50 min, and 87% conversion was achieved after eight cycles. The Ag₂S/TNT nanocomposites also exhibit excellent photocatalytic activity for 4-NP at a rate of 0.69 h⁻¹, and the complete degradation of 4-NP was observed within 5 h. Therefore, this study offers an environmentally friendly approach to synthesize nanocomposites for practical applications.