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Parasuraman GJ, Vishnuraj R, Kannankuzhiyil S, Govindaraj M, Biji SS, Rangarajan M. Determination of urea, phosphate, and potassium in agricultural runoff waters using electrochemical impedance spectroscopy. Environ Sci Pollut Res Int 2023; 30:98858-98868. [PMID: 35932346 DOI: 10.1007/s11356-022-22369-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 07/29/2022] [Indexed: 06/15/2023]
Abstract
Large-scale use of chemical fertilizers has resulted in the contamination of agricultural runoff waters by soil macronutrients NPK, whose detection is of significant interest. This work reports the determination of macronutrients in the form of urea (N), orthophosphate PO43- (P), and potassium K+ (K) in simulated agricultural runoff waters. Their solutions were prepared by extracting water-soluble constituents of soil. This 'base' solution contains high concentrations of various species, including Cl-, SO42-, NO3-, PO43-, Na+, K+, and NH4+ along with natural organic matter. Predetermined amounts of urea (4 to 22.5 ppm), PO43- (7 to 50 ppm), and potassium K+ (25 to 250 ppm) were added to the base simulated runoff water to prepare standard stock solutions. Using stainless steel working and counter electrodes, a small AC perturbation (±10 mV vs. OCP, vs. Ag/AgCl) was applied and the frequency response of the working electrode-solution interface was measured from 1 Hz to 1 MHz. The interface itself was modeled as a suitable equivalent electrical circuit, and the magnitudes of its components were fitted from experimental data using nonlinear regression. It is observed that PO43- concentration is a linear function of charge transfer resistance arising from redox reaction, K+ concentration is a quadratic function of double-layer capacitance arising from its higher mobility, and urea concentration can be correlated as a linear function of constant phase element arising from its polarization in the presence of an applied electric field. The sensor exhibits good sensitivity, repeatability, and excellent performance against interfering species. These preliminary results show significant potential for development of a real-time or on-site sensing device.
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Affiliation(s)
| | - Ramakrishnan Vishnuraj
- Center of Excellence in Advanced Materials and Green Technologies, Amrita School of Engineering Coimbatore, Amrita Vishwa Vidyapeetham, Coimbatore, India
- Department of Chemical Engineering and Materials Science, Amrita School of Engineering Coimbatore, Amrita Vishwa Vidyapeetham, Coimbatore, India
| | - Surjith Kannankuzhiyil
- Center of Excellence in Advanced Materials and Green Technologies, Amrita School of Engineering Coimbatore, Amrita Vishwa Vidyapeetham, Coimbatore, India
- Department of Chemical Engineering and Materials Science, Amrita School of Engineering Coimbatore, Amrita Vishwa Vidyapeetham, Coimbatore, India
| | - Mohankumar Govindaraj
- Center of Excellence in Advanced Materials and Green Technologies, Amrita School of Engineering Coimbatore, Amrita Vishwa Vidyapeetham, Coimbatore, India
- Department of Chemical Engineering and Materials Science, Amrita School of Engineering Coimbatore, Amrita Vishwa Vidyapeetham, Coimbatore, India
| | | | - Murali Rangarajan
- Center of Excellence in Advanced Materials and Green Technologies, Amrita School of Engineering Coimbatore, Amrita Vishwa Vidyapeetham, Coimbatore, India.
- Department of Chemical Engineering and Materials Science, Amrita School of Engineering Coimbatore, Amrita Vishwa Vidyapeetham, Coimbatore, India.
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