Date-seed-derived biochar-modified screen-printed electrode for electrochemical determination of Hg(II) in water

Abstract

Mercury (Hg) contamination remains a serious environmental problem because Hg can persist in water and accumulate in living organisms. In this study, we investigated the use of date-seed-derived biochar (DSC-N) as a sustainable modifier for screen-printed carbon electrodes for Hg(II) detection. Date seeds collected in the United Arab Emirates were converted into biochar by a simple one-step carbonization process, without chemical activation or external nitrogen precursors. Biochars prepared at different temperatures were characterized by scanning and transmission electron microscopy, nitrogen adsorption-desorption analysis, X-ray diffraction, Raman spectroscopy, and Fourier-transform infrared spectroscopy. X-ray photoelectron spectroscopy was used to examine the surface chemistry of the DSC-N. Among the tested materials, DSC-N 800 showed the most suitable combination of porosity, carbon structure, defects, and retained oxygen and nitrogen-containing surface groups. The DSC-N800-modified electrode showed the highest Hg(II) stripping signal among the tested DSC-N modified electrodes. The DSC-N 800-modified electrode was then used to determine Hg(II) by differential-pulse anodic stripping voltammetry. Under optimized conditions, the sensor showed a linear response from 0.05 to 40.55 μM, a sensitivity of 0.3576 μA μM −1 , and a detection limit of 21.1 nM. The fabricated sensor electrode showed good repeatability, reproducibility, selectivity, and satisfactory performance in real-water samples containing Hg(II). This study demonstrates a low-chemical-input approach for converting date-seed waste into a functional biochar electrode modifier for monitoring Hg(II) in water.

The authors' abstract, as published at the source. Chemosphere, 2026 · DOI ↗