Compared with traditional hydrothermal synthesis, microwave-assisted synthesis has the advantages of being faster and more energy efficient. In this work, the MoS₂/BiVO₄ heterojunction photocatalyst was synthesized by the microwave-assisted hydrothermal method within 30 min. The morphology, structure and chemical composition were characterized by X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and high-resolution transmission electron microscopy (HRTEM). The results of characterizations demonstrated that the synthesized MoS₂/BiVO₄ heterojunction was a spherical structure with dimensions in the nanorange. In addition, the photocatalytic activity of the samples was investigated by degrading tetracycline hydrochloride (TC) under visible light irradiation. Results indicated that the MoS₂/BiVO₄ heterojunction significantly improved the photocatalytic performance compared with BiVO₄ and MoS₂, in which the degradation rate of TC (5 mg L⁻¹) by compound where the mass ratio of MoS₂/BiVO₄ was 5 wt% (MB5) was 93.7% in 90 min, which was 2.36 times of BiVO₄. The active species capture experiments indicated that •OH, •O₂⁻ and h⁺ active species play a major role in the degradation of TC. The degradation mechanism and pathway of the photocatalysts were proposed through the analysis of the band structure and element valence state. Therefore, microwave technology provided a quick and efficient way to prepare MoS₂/BiVO₄ heterojunction photocatalytic efficiently.

Magnetic solid phase extraction based on a 3D reduced graphene oxide composite coupled with spectrofluorometry was proposed to determine the presence of trace rhodamine B in chili powder and tap water. The characterization results showed that Fe₃O₄ covered the surface of the 3D reduced graphene oxide (3D-RGO) composite. The adsorption behaviour and adsorption capacity of the 3D-RGO composite were investigated. Several significant factors that affect the adsorption and desorption performance were optimized. The proposed method gave a wide linear range, from 0.025 to 150 μg L⁻¹ with R² = 0.9991, and low limits of detection (3S_b) and quantification (10S_b) of 0.0074 μg L⁻¹ and 0.025 μg L⁻¹ (n = 3), respectively. Furthermore, this method was successfully applied to determine the amount of rhodamine B in real samples, and the recoveries at three different spiked levels (0.03, 10, and 20 μg L⁻¹) were in the range of 95.66–99.98%, with a relative standard deviation of less than 2.01% (n = 3).