Electrochemical Determination of Ascorbic Acid by Mechanically Alloyed Super Duplex Stainless Steel Powders

Abstract

SAF-2507 super duplex stainless steel powders (SDSS) were prepared using a high-energy planetary ball milling process. The X-ray diffraction (XRD) shows peak broadening after 20 h of ball milling and revealed a phase transformation resulting in a two-phase alloy mixture containing nearly equal amounts of ferrite (alpha) and austenite (gamma). After 20 h of ball milling the particle size was reduced to similar to 201 nm. Scanning electron microscope (SEM) micrographs showed small-size irregular grains with an average particle size ranging from 5-7 mu m. The high-resolution transmission microscope (HRTEM) analysis confirmed the presence of nanocrystalline particles with sizes ranging from 10 to 50 nm. The presence of ferrite phase is visible in the corresponding diffraction pattern as well. In this paper, we have discussed the electrochemical sensor application of mechanically alloyed nano-structured duplex stainless steel powders. The fabricated 4 mg duplex stainless steel modified carbon paste electrode (SDSS-MCPE) has shown excellent current sensitivity in comparison with 2, 6, 8, and 10 mg SDSS-MCPEs during the detection of ascorbic acid (AA) in a phosphate buffer solution with a pH of 6.8. The calculated electrode active surface area of SDSS-MCPE was found to be almost two times larger than the surface area of the bare carbon paste electrode (BCPE). The limit of detection (LD) and limit of quantification (LQ) were found to be 0.206 x 10(-8) M and 0.688 x 10(-8) M, respectively, for the fabricated 4 mg SDSS-MCPE.