Further applications of photocatalysis were limited by the high recombination probability of photo-induced electron–hole pairs in traditional titanium dioxide nanoparticles (TiO2 NPs). Herein, we modified them with rare earth metal via a facile sol–gel method, using tetrabutyl titanate as a precursor and terbium (III) nitrate hexahydrate as terbium (Tb) source. The resulting samples with different Tb doping amounts (from 0 to 2%) have been characterized by X-ray diffraction, UV–visible diffuse reflectance spectroscopy, X-ray photo-electron spectroscopy and a scanning electron microscope. The photocatalytic performance of Tb-doped TiO2 was evaluated by the degradation of methylene blue. The effects of Tb doping amount and initial pH value of solution were investigated in detail. The composite with Tb doping amount of 1.0 wt% showed the highest photocatalytic performance. It exhibited approximately three times enhancement in photocatalytic activity with a reaction rate constant of 0.2314 h−1 when compared with that of commercial P25 (0.0827 h−1). In addition, it presented low toxicity on zebrafishes with 96 h-LC50 of 23.2 mg l−1, and has been proved to be reusable for at least four cycles without significant loss of photocatalytic activity. A probable photocatalytic mechanism of Tb-doped TiO2 was proposed according to the active species trapping experiments. The high photocatalytic performance, excellent reusability and low toxicity of Tb-doped TiO2 indicated that it is a promising candidate material in the future treatment of dye wastewater.

No abstract

In this study, a naphthalene Schiff-base P which serves as a dual-analyte probe for the quantitative detection of Al3+ and Mg2+ has been designed.

Meishe River is the longest urban river in Haikou. The level of microplastics pollution in this river may affect the ecological balance, and can have an adverse effect on human health. Thus, it is essential to gain a comprehensive understanding of the microplastics pollution in the river to ensure safety of the human living environment. Microscopic examination and Micro-Fourier Transform Infrared Spectroscopy (μ-FTIR) were used to investigate the distribution and characteristics of microplastic pollution in surface water and sediments of the Meishe River. The results revealed that microplastics extracted from Meishe River mainly consisted of polyethylene (PE) and poly octadecyl acrylate (POA), and the abundance of microplastics in the surface water and sediments lay in the range of 3–10 items/L and 61–205 items/100 g dry weight, respectively. With respect to shapes and colors of microplastics, among the micro plastics found in the surface water, 74% were fiber and 57% were white colored, while among those in the sediments, 88% were fiber and 55% were of white colored. In terms of particle size, microplastics with the particle size of 0.1–0.5 mm were the most abundant (49% approximately) in surface water, while the microplastics with particle size 1.0–5.0 mm were dominant (74%) in the sediments. The results clearly showed that the Meishe River was polluted by microplastics, which may eventually flow into the nearby sea and adversely affect the sea environment. Consequently, some organisms in the urban river may be adversely affected.