PPy-Fe3O4/Kaolin was prepared with polypyrrole functionalized magnetic Kaolin by a simple, green, and low cost method to improve the agglomeration and low adsorption capacity of Kaolin. PPy-Fe3O4/Kaolin was employed to remove Hg2+ and the results were characterized by various methods. Relevant factors, including solution pH, dosage of adsorbent, concentration (C0), and temperature (T), were optimized by Response Surface Methodology (RSM) and Central Composite Designs (CCD). The optimal results show that the importance for adsorption factors is pH > T > C0 > dosage, and the optimal adsorption conditions of PPy-Fe3O4/Kaolin are pH = 7.2, T = 315 K, C0 = 50 mg/L, dosage of 0.05 g/L, and the capacity is 317.1 mg/g. The adsorption process conforms to the pseudo-second-order and Langmuir models. Dubinin–Radushkevich model shows that adsorption process is spontaneous and endothermic. Moreover, the adsorption of mercury by PPy-Fe3O4/Kaolin was achieved mainly through electrostatic attraction, pore diffusion, and chelation between amino functional groups and Hg2+. PPy-Fe3O4/Kaolin has excellent reproducibility, dispersity, and chemical stability, and it is easy to be separated from solution through an external magnetic field. The experiments show that PPy-Fe3O4/Kaolin is an efficient and economical adsorbent towards mercury.

The study of oil sorbents with high oil sorption capacity is of great significance for oil-water separation, especially for oil spillage on seawater. In this work, we report polysulfone, poly(lactic acid), and polysulfone/poly(lactic acid) nanoporous fibrous mats prepared by one-step electrospinning process used as oil sorbents for oil-water separation. The morphology, porous structure, oleophilicity and hydrophobicity, oil sorption capacity, and oil retention of these nanoporous fibrous mats are investigated in detail. It is noticeable that the motor oil and linseed oil sorption capacity of polysulfone and polysulfone/poly(lactic acid) fibrous mats have little difference, but the motor oil sorption capacity (147.8 g g À1 ) of polysulfone is approximately 2.95 times as much as that (50.1 g g À1 ) of poly(lactic acid). The linseed oil sorption capacity (131.3 g g À1 ) is approximately 3.74 times than that (34.6 g g À1 ) of poly(lactic acid). Besides, they all exhibit quick oil sorption speed and high buoyancy. It is suggested that polysulfone and polysulfone/poly(lactic acid) nanoporous fibrous mats have a better oil sorption capacity than poly(lactic acid)

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Hexagonal boron nitride (BN), an effective diffusion material for mass transport, was functionalized with molybdenum disulfide (MoS2) and Au nanoparticles (Au NPs). Then, the working electrodes with developed nanomaterials were applied to construct an electrochemical paraquat sensor. BN was prepared using a solid-state synthesis method combined with solvent-cutting. The electrochemical properties of the BN/MoS2/Au NP-based glassy carbon electrode (GCE) were investigated using differential pulse voltammetry and cyclic voltammetry. An excellent response signal to paraquat was found from 0.1 to 100 μM with a limit of detection of 0.074 μM, and it had acceptable reproducibility (relative standard deviation = 2.99%, n = 5) and good anti-interference ability. The modified GCE showed superior performance owing to the synergistic effects among all three given nanomaterials. With the proposed method, paraquat in grass samples from an orchard was then investigated. The results of the electrochemical analysis agreed with those of experiments and obtained a 96.28% confidence level via high-performance liquid chromatography, exhibiting relatively high stability. Therefore, the fabricated sensor can be a candidate for the determination of paraquat.