Constructing Ni4/Fe@Fe3O4-g-C3N4 nanocomposites for highly efficient degradation of carbon tetrachloride from aqueous solution.

Catalytic hydrodechlorination is one of the most potential remediation methods for chlorinated organic pollutants. In this study, Ni4/Fe@Fe3O4-g-C3N4 (NFFOCN) nanocomposites were synthesized for carbon tetrachloride (CT) removal and characterized by SEM, XPS and FTIR. The characterization results demonstrated that the special functional groups of g-C3N4, especially NH groups, effectively alleviated the aggregation of nanoparticles. In addition, the C and N groups of g-C3N4 enhanced the catalytic dechlorination of CT by providing binding sites. The experimental results showed that NFFOCN could effectively remove CT over a wide initial pH range of 3-9, and the CT removal efficiency reached 94.7% after 35 min with only 0.15 g/L of NFFOCN at pH 5.5. The Cl-, SO42-, and HCO3- promoted the removal of CT, while HA and NO3- had the opposite effect. Furthermore, good sequential CT removal by NFFOCN nanocomposites was observed, and the CT removal efficiency reached 77.3% after four cycles. Based on the identification of products, a possible degradation pathway of CT was proposed. Moreover, the main mechanisms regarding CT removal included the direct reduction of nZVI (about 40.51%), adsorption (around 34.79%), and hydrodechlorination of CT by Ni0 using H2 (about 19.40%).

Optofluidic variable optical attenuator controlled by electricity.

An optofluidic variable optical attenuator (VOA) is proposed in this paper, where the microfluidic driving technology adopts the electrically controlled way. The proposed driving technology solves some problems of existing microfluidic driving technologies and introduces a simple structure, a small volume, high precision, and a quick response for the VOA. This VOA has some advantages over other VOAs, such as a wide wavelength band (from visible light to the near infrared), a wide adjustable attenuation range, a low wavelength-dependent loss, and a quick response. The experiment results indicate that the attenuation range of this VOA is more than 80 dB and the wavelength-dependent loss is 0.09 dB at an attenuation of 20 dB in the C-band. Most VOAs have millisecond-scale response times, whereas the response time here is about 155-180 µs. Our work shows a new way to design miniaturized VOAs with good performance and can also promote optofluidics.