Electro-reductive deiodination of iohexol catalyzed by vitamin B12 and biodegradability investigation

•Electroreduction of iohexol led to its total deiodination.•Vitamin B12 catalyzes the electroreduction reaction.•Vitamin B12 leads to a faster reaction and improved current efficiency.•Total dehalogenation of iohexol was not sufficient to improve its biodegradability.•Stable oxidized by-products were formed during the biological treatment of iohexol.