Organic Phosphorus Compounds as Inhibitors of Corrosion of Carbon Steel in Circulating Cooling Water: Weight Loss Method and Thermodynamic and Quantum Chemical Studies

Abstract

Circulating cooling water plays an important role in industrial water use. In this study, the corrosion inhibition effects of PBTCA, HEDP, and ATMP organic phosphorus inhibitors were investigated using the weight loss method by varying the dosage of inhibitors, ClO2 concentrations, and pH values on carbon steel in recirculating cooling water with a low concentration of ClO2 solution. The results showed that the three corrosion inhibitors had a satisfactory corrosion inhibition effect and that corrosion inhibition efficiency is positively correlated with the concentration of organic phosphorus inhibitors and pH. The average corrosion inhibition efficiency of the three inhibitors was about 80% at the concentration of inhibitors = 35 mg/L, pH = 9.0, and the concentration of ClO2 = 7.0 mg/L, of which the single-phosphorus molecular corrosion inhibitor proved to be the best inhibitor. When the ClO2 concentration was 7 mg/L, the corrosion inhibition efficiencies of the three corrosion inhibitors were relatively stable. Using the density functional theory (DFT) algorithm in the Gaussian 09 program, the optimization calculation was completed by the B3LYP/6-31G (d, p) method at the microlevel. The molecular structures of the three organic phosphorus inhibitors and the number of phosphorus-containing atoms were compared to the sustained-release properties. Organic phosphorus inhibitors, as an electronic buffer, not only provided electrons but also received electrons. They formed a complex with iron and zinc ions in water in order to attach to the surface of the carbon steel and to alleviate corrosion. In addition, the adsorption with a metal surface followed the Langmuir adsorption isotherm.

Airport Deicers: An Unrecognized Source of Phosphorus Loading in Receiving Waters

“…The role of phosphorus-containing compounds in these products is not directly disclosed by manufacturers; however, numerous formulations list nonspecific corrosion inhibitors as a constituent, and compounds such as phosphonic acids, orthophosphates, and other phosphorus-based chemicals are used in many industrial applications for this purpose. − The compounds containing phosphorus in ADAF and PDM formulations were not identified for the current research, but additional chemical analysis for this purpose would be valuable to advance the knowledge in future research for the evaluation of potential effects of phosphorus-based compounds on the aquatic ecosystem.…”

Thin Protective Coatings on Metals Formed by Organic Corrosion Inhibitors in Neutral Media

“…Despite all the advantages of phosphonate CIs, their use can be limited due to the tightening of environmental regulations for the phosphorus content in water. The disadvantages of these CIs also include the possibility of local corrosion, a decrease in efficiency in stagnant zones and in the presence of even small quantities of hydrogen sulfide, and degradation in the presence of oxidizing biocides [135,138,170]. A targeted change in the chemical structure of PAs and phosphonates to give them a high protective ability is one of the main directions in the development of new environmentally friendly and efficient CIs of phosphonate type [146].…”

Flame Retardancy and Thermal Behavior of Wool Fabric Treated with a Phosphorus-Containing Polycarboxylic Acid

“…As presented, this compound is composed of the phosphorus element, which was regarded as having flame-retarding property, and multi-carboxyl groups, which has been found to be able to crosslink with hydroxyl (-OH) groups in cellulose [ 30 , 31 ] and -OH and/or amino (-NH 2 ) groups in keratin chains in the wool [ 19 , 28 ]. Initially, PBTCA has been widely explored as an effective scale inhibitor, dispersant, and corrosion inhibitor due to its excellent chelating property [ 29 , 32 , 33 ]. Moreover, PBTCA has been examined as an anti-wrinkle agent for cotton fabrics as it possesses the structural character of polycarboxylic acids, forming ester crosslinking with -OH groups in the cellulose [ 34 , 35 ].…”