Particle size of nanomaterials has significant impact on their photocatalyst properties. In this paper, TiO₂ nanoparticles with different crystalline sizes were prepared by adjusting the alkali-hydrothermal time (0–48 h). An annealing in N₂ atmosphere after hydrothermal treatment caused TiO₂ reduction and created defects, resulting in the visible light photocatalytic activity. The evolution of physicochemical properties along with the increase of hydrothermal time at a low alkali concentration has been revealed. Compared with other TiO₂ samples, TiO₂-24 showed higher photocatalytic activity toward degrading Rhodamine B and Sulfadiazine under visible light. The radical trapping and ESR experiments revealed that O₂^•- is the main reactive specie in TiO₂-24. Large specific surface areas and rapid transfer of photogenerated electrons are responsible for enhancing photocatalytic activity. The above findings clearly demonstrate that particle size and surface oxygen defects can be regulated by alkali-hydrothermal method. This research will deepen the understanding of particle size on the nanomaterials performance and provide new ideas for designing efficient photocatalysts.

Graphene as a two-dimensional (2D) nanoplatform is beneficial for assembling a 2D heterojunction photocatalytic system to promote electron transfer in semiconductor composites. Here a BiVO₄ nanosheets/reduced graphene oxide (RGO) based 2D-2D heterojunction photocatalytic system as well as 0D-2D BiVO₄ nanoparticles/RGO and 1D-2D BiVO₄ nanotubes/RGO nanocomposites are fabricated by a feasible solvothermal process. During the synthesis; the growth of BiVO₄ and the intimate interfacial contact between BiVO₄ and RGO occur simultaneously. Compared to 0D-2D and 1D-2D heterojunctions, the resulting 2D-2D BiVO₄ nanosheets/RGO composites yield superior chemical coupling; leading to exhibit higher photocatalytic activity toward the degradation of acetaminophen under visible light irradiation. Photoluminescence (PL) and photocurrent experiments revealed that the apparent electron transfer rate in 2D-2D BiVO₄ nanosheets/RGO composites is faster than that in 0D-2D BiVO₄ nanoparticles/RGO composites. The experimental findings presented here clearly demonstrate that the 2D-2D heterojunction interface can highlight the optoelectronic coupling between nanomaterials and promote the electron–hole separation. This study will motivate new developments in dimensionality factors on designing the heterojunction photocatalysts and promote their photodegradation photocatalytic application in environmental issues.

The removal of caffeine (CAF) in aqueous solution by peroxymonosulfate oxidant activated with cobalt ion was investigated under a variety of operating conditions. The effects of various operating parameters, such as oxone and Co2+ concentrations, pH value, and the coexistence of dissolved organic matter and inorganic anions on the removal of CAF have been investigated. The removal efficiency increased with the increase in the concentrations of oxone and Co2+ ion added. The additions of chloride, bicarbonate, and sodium humate have negative effects on the removal of CAF. Near-neutral condition (5.0 < pH < 7.0) is favorable for the removal of CAF. Based on our experiments, 100% degradation of 50 mg/L CAF can be achieved within 4 minutes under the conditions of 1.00 mM oxone and 0.10 mM Co2+ ion at pH 5.0–7.0.

The increasing concentration of residual ciprofloxacin (CIP) can cause potential harm to the environment. Photocatalysis has been regarded as an effective method for the degradation of CIP. Bi/BiVO₄ with excellent photocatalytic performance was synthesized partial reduction with NaBH₄. The structure, morphology, composition, and optical performance of BiVO₄ and Bi/BiVO₄ were characterized by a variety of techniques. The results showed that the Bi/BiVO₄ exhibits high photocatalytic activity in the degradation of CIP. Comparison of BiVO₄ and Bi/BiVO₄ has lower photoluminescence intensity and higher photocurrent responses intensity. The introduction of Bi made Bi/BiVO₄ have a higher charge separation efficiency and generate more active free radicals. In addition, the radical trapping experiments revealed that superoxide free radicals and holes were the main active free radicals during the degradation of CIP. The pathway of CIP degradation was investigated through high performance liquid chromatography-mass spectrometry, and a possible degradation mechanism was proposed.

When Aristolochia plants wilt and decay, aristolochic acids (AAs) are released into the soil, causing soil contamination. It has been demonstrated that aristolochic acid can be accumulated and enriched in crops through plant uptake. However, there is a lack of systematic studies on the migration and accumulation of AAs in a realistic simulated soil environment. In this study, Aristolochia herbal extracts were mixed with soil for growing three typical vegetables: lettuce, celery, and tomato. The contents of AAs in the above-mentioned plants were determined by an established highly sensitive LC-MS/MS method to study the migration and accumulation of AAs. We found that AAs in the soil can be transferred and accumulated in plants. AAs first entered the roots, which were more likely to accumulate AAs, and partially entered the above-ground parts. This further confirms that AAs can enter the food chain through plants and can have serious effects on human health. It was also shown that plants with vigorous growth and a large size absorbed AAs from the soil at a faster rate. The more AAs present in the soil, the more they accumulated in the plant.

A convenient and reliable analytical method was developed for determination of antibacterial triclocarban in aquatic plants based on homogenate extraction, SPE clean-up, and HPLC-ESI-MS/MS determination.