Simultaneous electrochemical detection of dimethyl bisphenol A and bisphenol A using a novel Pt@SWCNTs-MXene-rGO modified screen-printed sensor.

Since bisphenol A (BPA) and dimethyl bisphenol A (DM-BPA) are human endocrine disruptors (EDCs) with tiny potential differences (44 mV) and widespread applications, there is a lack of published reports on their simultaneous detection. Therefore, this study reports a novel electrochemical detection system capable of simultaneous direct detection of BPA and DM-BPA using screen-printed carbon electrodes (SPCE) as a sensing platform. To improve the electrochemical performance of the SPCE, the SPCE was modified by using a combination of Pt nanoparticles modified with single-walled carbon nanotubes (Pt@SWCNTs), MXene (Ti3C2), and graphene oxide (GO). In addition, the GO in Pt@SWCNTs-MXene-GO was reduced to reduced graphene oxide (rGO) by the action of electric field (-1.2 V), which significantly improved the electrochemical properties of the composites and effectively solved the problem of dispersion of the modified materials on the electrode surface. Under optimal experimental conditions, Pt@SWCNTs-Ti3C2-rGO/SPCE exhibited a suitable detection range (0.006-7.4 µmol L-1) and low detection limits (2.8 and 3 nmol L-1, S/N = 3) for the simultaneous detection of BPA (0.392 V vs. Ag/AgCl) and DM-BPA (0.436 V vs. Ag/AgCl)). Thus, this study provides new insights into detecting compounds with similar structures and slight potential differences. Finally, the developed sensor's reproducibility, stability, interference resistance and accuracy were demonstrated with satisfactory results.

Adsorption of arsenic from aqueous solution using a zero-valent iron material modified by the ionic liquid [Hmim]SbF6.

The environmental and health impacts caused by arsenic (As) in wastewater make it necessary to carefully manage As wastes. In the present work, a composite of the ionic liquid [Hmim]SbF6 and nano-iron (H/Fe) was used as an adsorbent to remove As(v) from aqueous solution. To better understand the removal effect of H/Fe on As(v) in aqueous solution, the reaction parameters of pH, reaction temperature, time and H/Fe dosage were systematically analyzed in detail. The results show that H/Fe has significant removal efficiency toward As(v), and that the adsorption of As(v) by 0.5 g H/Fe reaches its maximum adsorption capacity within 2 h. The adsorption of As(v) on H/Fe is a non-linear, time-varying process. The initial adsorption reaction is fast; however, unlike at the beginning, the later reaction involves sustained slow absorption, resulting in a distinct two-phase adsorption characteristic. Redox reaction may be one of the mechanisms responsible for the slow adsorption of As(v) on H/Fe. At the same time, the As(v) removal effect of H/Fe is greatly restricted by the pH. Electrostatic adsorption, adsorption co-precipitation and redox reactions act together on H/Fe in the As(v) removal process. This study provides a basis for further clarifying the adsorption, adsorption rules and mechanism of As(v) on H/Fe and a feasible method for the improvement of As(v) removal efficiency of zero-valent iron materials.