Electrochemical sensor for rapid detection of orthophosphate in hydroponic water

Orthophosphate (Ortho-P), an inorganic form of phosphorus (P), plays a crucial role in cellular metabolism and is a limiting factor in plant growth in agricultural systems. Although Ortho-P is widely used as a fertilizer, excessive application can lead to environmental issues such as eutrophication and harmful algal blooms (HABs) due to runoff. This study presents a nanohybrid sensor for phosphate detection, utilizing laser-inscribed graphene electrodes (LIG) coated with chitosan (CHI) nanobrushes. The chitosan coating was applied using Frequency Modulated Electropolymerization (FMEP) at pH 5. The resulting chitosan nanoparticles, averaging 1728 nm in diameter, exhibited good stability with a positive zeta potential of +41 mV. X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDS) confirmed the successful polymerization, with four characteristic peaks demonstrating the crystallinity of chitosan and the in-plane structure of LIG. EDS also revealed 1.8% phosphate absorption at the surface of LIG+CHI after exposure to a 1000 ppm phosphate solution for one minute. Scanning electron microscopy (SEM) confirmed the successful growth of CHI nanobrushes on the LIG electrode surface, with the FMEP method effectively functionalizing the surface for ortho-P detection. Surface zeta potential analysis showed a shift in the isoelectric point from 6.1 for bare LIG to 9.5 for LIG+CHI, indicating enhanced positive surface charge and improved phosphate binding. These findings suggest that the FMEP technique and microwave-assisted chitosan nanoparticle synthesis offer a promising approach for developing phosphate sensors with strong potential for nutrient monitoring and environmental protection applications.

Presentation Preference: Poster

Primary Presenter: Maria Torres, Clemson University (mtorre3@g.clemson.edu)

Authors:

Maria Torres, Clemson University  (mtorre3@g.clemson.edu)

Brian. Rodenhausen, Anton Paar, USA  (brian.rodenhausen@anton-paar.com)

Tyler Erikson, Anton Paar, USA  (tyler.erickson@anton-paar.com)

Eric McLamore, Clemson University  (emclamo@clemson.edu)