While the role of dissociated and complexed forms of organic acids (OAs) on Fenton-like reactions has been widely investigated, the catalytic ability and detailed mechanisms of coprecipitates between iron oxides and OAs were still obscure. Herein, coprecipitates of iron oxides with eco-friendly organic acids including maleic acid (MAA), tetrasodium-N,N-bis(carboxymethyl)-L-glutamate (GLDA), and protocatechuic acid (PCA) possessing different C/Fe molar ratios (OA-FeO