Optimization, kinetics, and electrochemical investigations for green corrosion inhibition of low-carbon steel in 1 M HCl by a blend of onion-garlic leaves wastes

An aqueous extract of onion and garlic leaf extract (OGLE) blend was employed to retard low-carbon steel (LCS) corrosion in 1 M HCl for the first time. The corrosion inhibition ability of OGLE has been tested via weight loss and electrochemical techniques. Firstly, onion and garlic leaf extracts are separately tested at 30 °C using a Doehlert experimental design to find the optimum concentration of each extract. Secondly, a full-factorial design is used to evaluate the corrosion rate at different blend concentrations and temperatures. Experimental results revealed that the OGLE blend can be considered a good green inhibitor. At 300 ppm OGLE and 60 °C, the maximum blend corrosion inhibition efficacy was 96.65 %. The Langmuir adsorption isotherm demonstrates that OGLE adsorbed with negative heat of adsorption, suggesting a stable monolayer developed spontaneously on LCS. According to electrochemical experiments, when OGLE is present, corrosion current densities are greatly reduced.