Pine needle extract as inhibitor in heat exchanger pickling process to improve the performance of multi-stage flash desalination

Abstract

Pine needle extract (PNE) was obtained through decoction method, utilizing distilled water as the solvent. This method not only ensures the efficient extraction of active ingredients from pine needles, but also achieves process optimization that is green, environmentally friendly, low-cost, and free of organic solvent residues. The PNE showed excellent performance for Cu90Ni10 in H₂SO₄ environment. The results from the electrochemical experiments reveal that a concentration of 600 mg/L of pine needle extract exhibits corrosion inhibition performance exceeding 97 %. Between 298 K and 318 K, the pine needle extract consistently demonstrates anti-corrosion efficiency exceeding 95 %. The polarization curve indicates that the PNE has the ability to suppress both cathodic oxygen reduction and anodic metal dissolution processes in Cu90Ni10. The scanning electron microscopy (SEM) observations indicate that the addition of PNE significantly reduces surface pitting and oxidation on the Cu90Ni10 alloy immersed in H₂SO₄ medium. XPS analysis reveals that the ingredients in PNE can form CuN bonds and can form effective chemical adsorption to form molecular films. Theoretical calculations demonstrate that bio-active constituents within PNE possess exceptional corrosion-inhibiting capabilities. Adsorption modeling confirms that the interaction between PNE and copper-nickel alloy involves a combination of physical adsorption and chemical bonding mechanisms.