Effect of organic agents on the oxidation process of chalcopyrite in a sulfuric acid solution

•Adsorption of organic agents conditions the oxidation of chalcopyrite by H2O2.•Ethylene glycol delays the formation of the passive layer on chalcopyrite.•Tween 80 delays and limits build-up of the passive layer on chalcopyrite.•Passive layer modification by organic agents improves the dissolution of chalcopyrite. The improved dissolution effect of ethylene glycol and polysorbates on the leaching of chalcopyrite (CuFeS2) was studied using electrochemical techniques, such as linear voltammetry (LV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). Although the mixed potential of a chalcopyrite electrode in solutions with either ethylene glycol or polysorbates in conjunction with hydrogen peroxide lies within the potential region of passive layer formation (which is typically associated with slow kinetics), it was confirmed that the oxidation rate for these organics is enhanced. The electrochemical results show that the passive layer is present, although apparently with differences in its structure (thickness and/or porosity), which is modified as the leaching process progresses. It was found that the formation of this passive layer was delayed and/or conditioned by adsorption of organic agents on the chalcopyrite surface. However, the process of surface structure modification was different for each organic employed.