Electrochemical Sensor Based on Porous Biochar-Loaded MnO2 Nanocomposite for Sensitive Detection of Cd(II)

Overview

This paper reports the synthesis of a manganese dioxide (MnO2) nanoparticle-loaded porous biochar composite (MnO2/KLSC), derived from longan shells, as the electrode material for an electrochemical Cd2+ sensor. The sensor achieves a LOD of 9.8 nmol/L with a linear range of 0.01–80 µmol/L using square-wave anodic stripping voltammetry (SWASV). The sensor is validated against spiked rice and seawater samples. In the rice sample, Cd was at or below the detection limit before spiking; only recovery rates from spiked additions are reported. No measured Cd occurrence data from actual rice are provided.

Key numbers

• Sensor LOD: 9.8 nmol/L (≈1.1 µg/L); linear range: 0.01–80 µmol/L
• Real sample results (Table 2, standard addition method):
  • Rice: Cd detected = 0.00 µmol/L (below LOD); spiked recoveries 97.80%–104.60% (RSD < 4.92%)
  • Seawater: Cd detected = 0.00 µmol/L (below LOD); spiked recoveries 95.40%–104.90%
• Published in Foods 2025, 14, 4252 (MDPI)

Methods (brief)

Longan shell biomass pyrolyzed to porous biochar (KLSC), then loaded with MnO2 via KMnO4 reduction. SWASV. Rice acid-digested with HNO3/HClO4 (4:1 v/v, 150°C/6h); seawater filtered and centrifuged. No ICP-MS cross-validation reported.

Implications

Certification: No occurrence data for Cd in rice extractable from this source. The undetected baseline in the purchased rice sample is consistent with clean-market rice but the sample size (n=1, from a local farmers’ market) has no statistical meaning. Courses: Useful example of biomass-derived electrode materials and on-site food safety monitoring technology. App: No contamination profile data extractable.

Wiki pages updated on ingest

• Cadmium
• Rice

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