Department of Chemistry, Universität Hamburg, Bundesstraße 45, 20146 Hamburg, Germany.
Metall-Chemie Technologies GmbH, Kaiser-Wilhelm-Straße 93, 20355 Hamburg, Germany.
Molecules. 2022 Mar 8;27(6):1778. doi: 10.3390/molecules27061778.
Organic acids, typically derived from an oil-based value chain, are frequently used as corrosion inhibitors in industrial metal working fluids. The criteria for selection of these corrosion inhibitors have changed in the last decades, and are today not only performance-driven, but influenced by ecological considerations, toxicity and regulatory standards. We present scalable semisynthetic approaches to organic corrosion inhibitors based on phosphonic acids from renewable resources. They have been evaluated by chip filter assay, potentiodynamic polarization measurements, electrochemical impedance measurements and gravimetry for corrosion protection of iron and steel in an aqueous environment at slightly alkaline pH. The efficacy of several phosphonic acids tested was found to be strongly dependent on structural features influencing molecular self-assembly of protective layers, and the solubility of salts formed with di- and trivalent cations from the media or formed during corrosion. A carboxyphosphonic acid (derived from castor oil) was found to have remarkable anticorrosive effects in all media tested. We attribute the anticorrosion properties of this carboxyphosphonic acid to the formation of particularly stable protective layers on the metal surface. It might thus serve as a commercially attractive substitute for current acidic corrosion inhibitors, derived from renewable resources.
有机酸通常来源于基于油的价值链，常被用作工业金属加工液中的腐蚀抑制剂。在过去几十年中，这些腐蚀抑制剂的选择标准发生了变化，不仅受性能驱动，还受到生态考虑、毒性和监管标准的影响。我们提出了基于可再生资源的膦酸的可规模化半合成有机腐蚀抑制剂方法。它们已经通过芯片过滤试验、动电位极化测量、电化学阻抗测量和重量法进行了评估，用于在微碱性 pH 值的水介质中保护钢铁免受腐蚀。测试的几种膦酸的功效被发现强烈依赖于影响保护层分子自组装的结构特征，以及与介质中的二价和三价阳离子形成的盐的溶解度或在腐蚀过程中形成的盐的溶解度。一种从蓖麻油衍生的羧基膦酸被发现对所有测试的介质都具有显著的防腐效果。我们将这种羧基膦酸的防腐性能归因于其在金属表面形成特别稳定的保护层。因此，它可以作为当前从可再生资源衍生的酸性腐蚀抑制剂的商业上有吸引力的替代品。
