The highly efficient photodegradation of 4-bromophenol by TiO2/g-C3N4 nano photocatalyst with LED visible light.

Since traditional photocatalysts have suffered from higher charge carrier recombination and moderate photocatalytic efficiency, developing photocatalysts is crucial for water treatment objectives. Hence, the various ratios of TiO2 on g-C3N4 (CN) to form nano photocatalysts were synthesized by the solvothermal method. The 30%TiO2/CN showed the best performance to degradation and debromination of 4-bromophenol (4-BP) solution completely (kobs = 6.6 × 10-2 min-1) under visible light emitted by LED (420 nm) in 30 min. Remarkably, the photocatalyst showed superior stability and reusability, maintaining its efficiency after four cycles of 4-BP degradation. The dominant ROS participating in 4-BP degradation were ●O-2 and photogenerated holes (h+), as investigated by free radical scavenging tests. The optical properties analysis revealed that the introduction of TiO2 to the bulk CN decreases electron-hole recombination and improve photocatalytic performance by facilitating electrons transfer through the TiO2 nanoparticles in a chain. The findings of this study showed that the TiO2/CN photocatalyst is a promising catalyst for the degradation of 4-BP. It exhibits a higher rate constant and photocatalytic efficiency compared with previous studies conducted under visible light irradiation.

Binary toxicity of engineered silica nanoparticles (nSiO2) and arsenic (III) to zebrafish (Danio rerio): application of response surface methodology.

Increasing production and use of engineered nanoparticles (NPs) leads to their release into the aquatic environments where they can interact with other hazardous contaminants, such as heavy metals, and threaten aquatic organisms. This study considers the ecotoxicity of arsenic (III) and silica nanoparticles (nSiO2), individually and simultaneously, to the zebrafish (Danio rerio) using response surface methodology (RSM) under central composite design (CCD). The results revealed that in the treatments within the concentration range of 1 to 5 mg L-1 arsenic and 1-100 mg L-1 nSiO2, no mortality was observed after 96 h. The optimal conditions for achieving the lowest effect of simultaneous toxicity in the concentration range of nSiO2 and arsenic were 100 and 7 mg L-1, respectively. Accordingly, the desirable function of the predicted model was found to be 0.78. According to these results, arsenic is toxic for zebrafish. Importantly, exposure to nSiO2 alone did not cause acute toxicity in the studied species, while arsenic toxicity decreased by increasing the concentration of nSiO2.