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Chitosan is a kind of biodegradable natural polysaccharide, and it is a very promising adsorber material for removing metal ions from aqueous solutions. In this study, chitosan-based magnetic adsorbent CMC@Fe3O4 was synthesized by a one-step method using carboxymethyl chitosan (CMC) and ferric salts under relatively mild conditions. The Fe3O4 microspheres were formed and the core–shell structure of CMC@Fe3O4 was synthesized in the meantime, which was well characterized via SEM/TEM, XRD, VSM, FT-IR, thermo gravimetric analysis (TGA), XPS, size distribution, and zeta potential. The effects of initial arsenic concentration, pH, temperature, contact time, and ionic strength on adsorption quantity of inorganic arsenic was studied through batch adsorption experiments. The magnetic adsorbent CMC@Fe3O4 displayed satisfactory adsorption performance for arsenic in water samples, up to 20.1 mg/g. The optimal conditions of the adsorption process were pH 3.0, 30−50 °C, and a reaction time of 15 min. The adsorption process can be well described by pseudo-second-order kinetic model, suggesting that chemisorption was main rate-controlling step. The Langmuir adsorption model provided much higher correlation coefficient than that of Freundlich adsorption model, indicating that the adsorption behavior is monolayer adsorption on the surface of the magnetic adsorbents. The above results have demonstrated that chitosan-based magnetic adsorbent CMC@Fe3O4 is suitable for the removal of inorganic arsenic in water.

As a new type of organic pollutant, benzotriazole seriously threatens the ecological environment and human health. In recent years, semiconductor photocatalytic technology has been widely used in the field of photocatalytic degradation of organic pollutants, but there are still few studies on the degradation of benzotriazole, and the degradation efficiency needs to be improved. In this paper, PtCl2 was applied in the field of photocatalysis for the first time, and it was loaded on Ta2O5 nanosheets to prepared a novel heterojunction photocatalyst Ta2O5/PtCl2 nanosheets by chemical vapor deposition method. The study found that Ta2O5/PtCl2 nanosheets has excellent visible light absorption capacity due to its local surface plasma resonance (LSPR) effect. Ta2O5/PtCl2 nanosheets achieves the best degradation effect when the mass ratio of Ta2O5 and PtCl2 is 1:1, it can remove about 99% of rhodamine B (5 mg/L) in 30 min and 94% of benzotriazole (10 mg/L) in 120 min, and corresponding apparent first-order kinetic constants are 1.06 * 10−1 (min−1) and 2.11 * 10−2 (min−1), respectively. Moreover, the photocatalytic degradation results are also supported by the photoelectric performance test. Finally, the electrons transfer process and mechanism of photocatalytic degradation of organic pollutants are also speculated. These studies provide new design ideas for the preparation of new heterojunction photocatalysts, which have broad research and development prospects.

Tantalum oxide is a semiconductor material with excellent physical properties, but its wide band gap limits its application in the field of photocatalysis. In this article, we synthesized novel hexagonal Ta2O5 nanosheets with oxygen defects in one step by chemical vapor deposition. The results suggest that Ta2O5 nanosheets prepared at 500 °C (3.49 eV) have excellent photocatalytic degradation ability, and the photodegradation efficiency for RhB is 4.3 times than commercial Ta2O5 (3.7 eV). The X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) results confirmed the existence of oxygen-defects in Ta2O5 nanosheets, and photoluminescence (PL) and photoelectric tests proved that oxygen- defects can form defect energy levels, thereby effectively promoting the separation efficiency of photogenerated carriers in Ta2O5 nanosheets. In addition, the contribution of reactive oxygen species (ROS) in photodegradation was obtained in the following order: 1O2, > h+ ≈ OH– ≈ O2–. The results indicated that singlet oxygen is used as the main active species in the photocatalytic degradation process of Ta2O5 nanosheets, and it can achieve high-efficiency degradation of RhB under the combined action of several other active species. This study synthesized a tantalum oxide material with a new structure through a simple method, and greatly enhanced the light absorption capacity of tantalum oxide, which provided a promising prospect for the application of tantalum oxide in the field of photocatalysis.

Morphology and porous structure of the pitch-based carbon aerogels (CAs) were characterized by scanning electron microscopy (SEM) and N2 adsorption–desorption measurement. Their electrochemical performances as electric double-layer capacitor (EDLC) electrodes were studied by cyclic voltammetry and galvanostatic charge–discharge measurements. It was found that the particle size of the CAs decreased with the increase of the volume ratio of toluene to acetic acid (T/A ratio). The BET surface areas of the obtained CAs were in the range of 290–450 m2 g−1. CA electrodes had good electrochemical performance and appropriate specific capacitance. Moreover, the electrochemical performance of the CAs was enhanced by the existence of extensive mesoporous networks of the CAs. CA with 2.23 of T/A ratio had the highest specific capacitance, i.e., 131.9 F g−1 for cyclic voltammetry. Thus, it was thought that the pitch-based CAs were suitable electrode materials for EDLCs.

The porous structure of pitch-based carbon aerogels (P-CAs) can be modified by KOH activation. It is found that decreasing the carbonization temperature of precursor CAs and increasing the mass ratio of KOH to CAs help to the formation of 0.7 nm-sized micropores and 2.7 nm-sized mesopores, respectively. The origin and the pore size of micropores play an important role in controlling electrochemical properties. The carbonization-forming micropores have stronger energy storage efficiency than activation-forming micropores, and only those with diameter below 1 nm (Microp −1 at 5 mA cm −2 , 1.8 times as large as that of their precursor CAs. Furthermore, this capacitance is still up to 173.3 F g −1 when increasing the current density to 50 mA cm −2 , indicating that the activated samples have a high-rate charge–discharge performance.

In this work, bentonite magnetic nanoparticles synthesized by a typical coprecipitation method were used as the adsorbent for the magnetic solid-phase extraction of six quinolones (ciprofloxacin, difloxacin, enrofloxacin, norfloxacin, sarafloxacin, and lomefloxacin) from milk samples followed by high-performance liquid chromatography with fluorimetric detection. Under the optimized conditions, the linear quantitation range for the six quinolones was 0.3-200 ng/mL, and the correlation coefficients of the calibration curves ranged from 0.9994 to 0.9999. The detection limit of the method was 0.1 ng/mL. Recoveries of quinolones from pure and low-fat spiked milk samples varied from 80.4 to 92.7% and from 81.3 to 93.5%, respectively. These results demonstrated that the proposed method for the determination of six quinolones in milk samples was rapid, reliable, and efficient.