Enhanced catalytic activity of a zero-valent silver (ZVAg) sensor for reduction of hazardous 4-nitrophenol in aqueous medium

ABSTRACT

4-nitrophenol (4-NP) is considered to be a harmful solid waste because of its toxicity and persistence. It is categorised as a priority contaminant by the United States environmental protection agency. In this work, we present a simple, easy and comprehensive electrochemical investigation of the electrocatalytic reduction of 4-NP in Britton-Robinson buffer solution as the supporting electrolyte at the surface of zero-valent silver electrode (ZVAgE). Different electrochemical methods such as cyclic voltammetry, chronoamperometry, electrochemical impedance spectroscopy, and Tafel plots were used to evaluate heterogeneous kinetics and illustrate the reduction mechanism of 4-NP. The experimentally determined parameters confirm that ZVAgE has a significant electrocatalytic activity towards 4-NP electro-reduction as compared to glassy carbon electrode (GCE). Under optimal conditions, the detection of 4-NP was found to have a low detection limit of 3.03 × 10⁻⁷ mol L⁻¹ in the range from 8.0 × 10⁻⁶ to 1.0 × 10⁻⁴ mol L⁻¹. Additionally, the sensor was successfully applied in the determination of 4-NP even in the presence of other common electroactive interference and real samples analysis (wastewater and river water samples). Therefore, the proposed method is simple, rapid, stable, sensitive, specific, and cost-effective and can be applicable for real sample detection.

KEYWORDS:

• Zerovalent electrode
• heterogeneous electron transfer
• diffusion coefficient
• 4-nitrophenol

Highlights

• Simple and sensitive ZVAgE was used for the electrocatalytic reduction of 4-NP.

• The highest electrocatalytic activity towards 4-NP reduction was shown.

• Heterogeneous electron-transfer constant and diffusion coefficient were evaluated.

• SWV was applied with ZVAgE for the determination of 4-NP in real samples.

Disclosure statement

No potential conflict of interest was reported by the authors.