Researchers in Iran tested a simple aqueous extract of walnut leaves as a corrosion inhibitor for carbon steel in a 3.5 percent sodium chloride solution that mimics seawater. Weight loss tests showed up to 98.53 percent inhibition efficiency at a 5 percent extract concentration, while electrochemical measurements confirmed a protective film forming on the steel surface. The study was published in Discover Electrochemistry and is one of the first to examine walnut leaf extract in a neutral salt medium. The extract works best at near-ambient temperatures. At 35 degrees Celsius and above, protection collapses, and at 70 degrees Celsius the extract actually accelerates corrosion. That limits it to applications like cooling water systems or coastal infrastructure that do not run hot. Still, the low-cost preparation from agricultural waste and the absence of toxic solvents make it a promising candidate for replacing petrochemical inhibitors in specific environments.
