Magnetic Fe3O4 Nanoparticles Decorated Phosphorus-Doped Biochar-Attapulgite/bismuth Film Electrode for Smartphone-Operated Wireless Portable Sensing of Ultra-Trace Multiple Heavy Metal Ions.

Pollution caused by both forestry wastes and heavy metals has increasingly drawn attention owing to environmental safety concerns. After essential oil is extracted from Cinnamomum camphoras (L.), the branches are used as forestry wastes to prepare a phosphorus-doped biochar–attapulgite/bismuth film electrode decorated with magnetic Fe3O4 nanoparticles (MBA-BiFE). The smartphone-operated wireless portable sensor is employed for the simultaneous ultratrace voltammetric detection of multiple heavy metal ions (Cd2+, Pb2+, and Hg2+). Cd2+, Pb2+, and Hg2+ exhibit excellent electrochemical responses in linear ranges of 0.1 nM–5 μM, 0.01 nM–7 μM, and 0.1 nM–3 μM with limits of detection equal to 0.036, 0.003, and 0.011 nM, respectively. The recoveries of MBA–BiFE for Cd2+, Pb2+, and Hg2+ are 93.6–109.9