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<p>In this study, low-cost electrochemical sensor for natural organic matter (NOM) analysis was fabricated using heterogeneous composites prepared from activated carbon (AC) (prepared with corn husk) and metal oxide nanoparticles (MONPs). The AC, CuO nanoparticles (NPs), ZnO NPs, NiO NPs and their composites (AC/CuO, AC/ZnO and AC/NiO) were characterized using X-ray diffraction (XRD) spectroscopy, Fourier-Transform infrared (FT-IR) spectroscopy, Nitrogen physisorption analysis and scanning electron microscopy (SEM). The Brunauer-Emmett-Teller (BET) specific surface areas of the carbonized biomass and the AC were 47.2122 and 284.1489 m<sup>2</sup>/g, respectively. Electrochemical characterization of glassy carbon electrode (GCE) modified with the AC (AC/GCE), the nanomaterials (CuO/GCE, NiO/GCE and ZnO/GCE) and their composites (AC/CuO/GCE, AC/ZnO/GCE and AC/NiO/GCE) showed that the AC/CuO/GCE and the AC/GCE possessed the best electronic conductivity. The cyclic voltammograms of these modified electrodes revealed that the AC has a characteristic oxidation peak at ~ + 1.1&#xa0;V while the CuO NPs showed characteristic Cu ion redox peaks at ~ + 0.1&#xa0;V. Electroanalysis of humic acid (HA) and alginic acid (AGA) at the bare GCE and the modified GCEs revealed that the intensity of the characteristic AC oxidation peak reduced in the presence of the NOM. The limit of detection (LOD) of HA at AC/CuO/GCE, AC/ZnO/GCE and AC/NiO/GCE were 0.70, 0.59 and 0.29&#xa0;mg/l, respectively. These LODs were recorded over the corresponding linear dynamic range (LDR) of 1.20–7.85, 0.59–6.79 and 0.60–2.35&#xa0;mg/l. The LOD of AGA at AC/CuO/GCE, AC/ZnO/GCE and AC/NiO/GCE were 0.02, 0.03 and 0.01&#xa0;mg/l, respectively, over the corresponding LDR of 0.02–0.11, 0.03–0.08 and 0.02–0.06&#xa0;mg/l. Excess AGA (130&#xa0;mg/l) offered little interference with the characteristic Cu ion oxidation peak at AC/CuO/GCE in the presence of HA (3.5&#xa0;mg/l), while a considerable interference was recorded with excess HA (120&#xa0;mg/l) in the presence of AGA (16.3&#xa0;mg/l). AC/CuO/GCE also showed superior stability in HA than AGA, confirming that the proposed sensor is less susceptible to fouling in HA.</p>

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Electroanalytical Protocol for Humic Acid and Alginic Acid Determination Based on Activated Carbon/Metal Oxide Composite

  • 期刊论文

  • 发表日期：

    2026年2月23日

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  • Saheed E. Elugoke,
  • Abolanle S. Adekunle,
  • Usisipho Feleni,
  • Thabo T.I. Nkambule,
  • Bhekie B. Mamba,
  • Eno E. Ebenso

摘要

In this study, low-cost electrochemical sensor for natural organic matter (NOM) analysis was fabricated using heterogeneous composites prepared from activated carbon (AC) (prepared with corn husk) and metal oxide nanoparticles (MONPs). The AC, CuO nanoparticles (NPs), ZnO NPs, NiO NPs and their composites (AC/CuO, AC/ZnO and AC/NiO) were characterized using X-ray diffraction (XRD) spectroscopy, Fourier-Transform infrared (FT-IR) spectroscopy, Nitrogen physisorption analysis and scanning electron microscopy (SEM). The Brunauer-Emmett-Teller (BET) specific surface areas of the carbonized biomass and the AC were 47.2122 and 284.1489 m2/g, respectively. Electrochemical characterization of glassy carbon electrode (GCE) modified with the AC (AC/GCE), the nanomaterials (CuO/GCE, NiO/GCE and ZnO/GCE) and their composites (AC/CuO/GCE, AC/ZnO/GCE and AC/NiO/GCE) showed that the AC/CuO/GCE and the AC/GCE possessed the best electronic conductivity. The cyclic voltammograms of these modified electrodes revealed that the AC has a characteristic oxidation peak at ~ + 1.1 V while the CuO NPs showed characteristic Cu ion redox peaks at ~ + 0.1 V. Electroanalysis of humic acid (HA) and alginic acid (AGA) at the bare GCE and the modified GCEs revealed that the intensity of the characteristic AC oxidation peak reduced in the presence of the NOM. The limit of detection (LOD) of HA at AC/CuO/GCE, AC/ZnO/GCE and AC/NiO/GCE were 0.70, 0.59 and 0.29 mg/l, respectively. These LODs were recorded over the corresponding linear dynamic range (LDR) of 1.20–7.85, 0.59–6.79 and 0.60–2.35 mg/l. The LOD of AGA at AC/CuO/GCE, AC/ZnO/GCE and AC/NiO/GCE were 0.02, 0.03 and 0.01 mg/l, respectively, over the corresponding LDR of 0.02–0.11, 0.03–0.08 and 0.02–0.06 mg/l. Excess AGA (130 mg/l) offered little interference with the characteristic Cu ion oxidation peak at AC/CuO/GCE in the presence of HA (3.5 mg/l), while a considerable interference was recorded with excess HA (120 mg/l) in the presence of AGA (16.3 mg/l). AC/CuO/GCE also showed superior stability in HA than AGA, confirming that the proposed sensor is less susceptible to fouling in HA.