Production of highly oxidized starch in a flow cell using a nickel anode

Abstract

This study emphasizes the potential of using sustainable and low-cost methods to process biopolymers, contributing to eco-friendly biorefinery technologies. In this context, the transformation of potato starch, a readily available biopolymer, into carboxylic acid starch (CAS) with high yield using an electrochemical process was achieved. As a result of the green transformation, the potato starch was oxidized into CAS, achieving 31 % oxidation of the available glycosyl groups. The transformation was conducted using a NiOOH anode in a FM01-LC flow cell, consuming 19 kWh/kg of energy per kilogram of modified starch. Different analytical techniques such as FTIR and NMR spectroscopies, iodine test, elemental analysis, Scanning Electron Microscopy (SEM) and acid base titration were used to characterize the electrolyzed samples. The results of these analyses revealed CC bond cleavage, opening of the glycosyl rings without significant degradation of the polymer structure. Data from the oxidation of model compounds, maltose and maltotriose at a nickel anode in the same medium supports that CC bond cleavage occurs at the ring carbons under these specific conditions. The use of a lab-scale flow cell with a higher electrode area and lower electrolyte volume improved energy efficiency, making this method affordable and easily scalable.