Efficiency of Expired Drugs Used as Corrosion Inhibitors: A Review

Abstract

Corrosion inhibitors represent one of the most commonly used methods for significantly reducing the corrosion rate of metals and alloys. Adsorption inhibitors have a wide range of applications in cooling water systems, deicing solutions for aircrafts, airports and ways, etching and degreasing solutions, oil pipelines, paints and coatings and metal processing solutions. Adsorption corrosion inhibitors of metals and alloys are generally organic compounds that contain structures with heteroatoms (N, P, S, As, O) in their molecules, having lone pair electrons or π electrons in aromatic rings or multiple bonds. They enable relatively strong interactions between the metal atoms and organic molecules, resulting in a protective layer of organic molecules adsorbed at the metal–corrosive solution interface. Most molecules of active substances from drugs contain similar structures, which is why many drugs have been already tested as corrosion inhibitors. One of the major disadvantages of using drugs for this purpose is their particularly high price. To overcome this impediment, the possibility of using expired drugs as corrosion inhibitors has been investigated since 2009. The present paper is an exhaustive compilation of the scientific published papers devoted to the use of expired drugs as corrosion inhibitors in various aggressive solutions. The inhibitory efficiencies of expired drugs are presented as a function of the studied metal or alloy and the nature of the aggressive solution, as well as the concentration of the inhibitor in such a solution. Research has especially been focused on mild and carbon steel and less on stainless steel, as well as on some metals such as copper, zinc, nickel, tin and aluminum and its alloys. The experimental methods used to assess the inhibitory efficiencies of expired drugs are briefly discussed. Also, the available information on the stability of the active substances in the drugs is presented, although most authors were not concerned with this aspect. Finally, several actions are revealed that must be undertaken by researchers so that the results obtained in the study of the anticorrosive action of expired drugs can be applied at the industrial level and not remain only an academic concern.

Principles and theories of green chemistry for corrosion science and engineering: design and application

“…In this case, expired drugs are preferable as metallic corrosion inhibitors due to their environmental and economic benefits compared to fresh drugs. 472,473…”

“…The effectiveness of fresh and expired pharmaceutical drugs in inhibiting corrosion reactions has been extensively documented in the literature. 471–475 In two distinct reports, investigations were carried out on the inhibition performance of azithromycin for stainless steel 316L in KOH 476 and mild steel in 2 M HCl. 477 These investigations employed electrochemical and surface analytical methods and revealed the ability of azithromycin to significantly reduce the corrosion rate even at minimal doses, functioning as a mixed inhibitor.…”

Efficacy of Expired Antibiotics: A Real Debate in the Context of Repeated Drug Shortages

“…Humidity brings moisture and H 2 O ions, which can destabilize the chemical properties of drugs, such as the beta-lactam core, leading to antibiotic expiration and reduced effectiveness. Moreover, expired drugs, including antibiotics, have been suggested as corrosion inhibitors, potentially decreasing the corrosion rate of metals and alloys, thus highlighting the significance of the biological and chemical properties of drugs [16].…”

Perspective Chapter: Downhole Corrosion in the Oilfield

“…Some examples include inhibitors made from cinnamon, garlic, thyme, rosemary, mint, and turmeric. Other recent research has also investigated reducing the accumulation of waste by utilizing what is considered trash to extract effective corrosion inhibitors for the oilfield [68][69][70][71][72]. Their efficiency, ability to handle hightemperature conditions, compatibility with other additives, and functionality in high concentrations of acid used in the oilfield an important area of research that is ongoing up to this day.…”