Electrochemical advanced oxidation of glucosinolates derived from rapeseed meal: Parameter optimization, degradation mechanism and toxicity assessment

Abstract

Glucosinolates (GLS) are a group of antinutritional compounds present in rapeseed meal that limit its use as feed ingredients. Considering their potentially hazardous effects on both the aquatic environment and animal health, it is necessary to develop green and efficient degradation options for GLS. In the current work, the electrochemical advanced oxidation technology with a boron-doped diamond (BDD) electrode was initially employed for the degradation of GLS. To facilitate parameter optimization, a sequential strategy comprising a definitive screening design and a central composite rotatable design was implemented. Particular attention was paid to the differing roles of five electrolyte salts (NaCl, NaNO3, Na2SO4, NaHCO3 and Na3PO4) during the electrolytic oxidations. The optimal conditions for GLS degradation were found to be a flow rate of 400 mL min−1, a applied current density of 7.75 mA cm−2 and a 2.0 mM NaNO3 medium, yielding mineralization of 82.2 % at 120 min of electrolysis. By combining the results of computational simulation and LC/MS analysis, four possible degradation pathways of allyl GLS at the BDD anode were proposed. And the ecotoxicity of each detected degradation product was determined using the ECOSAR program. Further biological toxicity assay revealed that crude GLS electrolysis reduced the toxicity on model organism Caenorhabditis elegans, reducing its death percentage by 26.80 % and its lipofuscin level by 37.59 % at 48 h. The results showed great promise of BDD technology in engineering applications as a powerful option for the treatment of GLS derived from rapeseed meal.