Naslov
NONTOXIC CORROSION INHIBITORS FOR COPPER IN SULPHURIC ACID

Autori
Stupnišek-Lisac, Ema, Gazivoda, Anita ; Madžarac, Maria

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Meeting Abstracts 2001 ECS and ISE Joint International Meeting / - Pennington (NJ) : ECS, 2001

Skup
2001 ECS and ISE Joint International Meeting

Mjesto i datum
San Francisco (CA), Sjedinjene Američke Države, 02.09.2001. - 07.09.2001

Vrsta sudjelovanja
Poster

Vrsta recenzije
Nije recenziran

Ključne riječi
corrosion inhibitors; sulphuric acid; imidazoles

Sažetak
Because of its excellent thermal conductivity and good mechanical workability, copper is a material commonly used in heating and cooling systems. Scale and corrosion products have a negative effect on heat transfer, and they cause a decrease in heating efficiency of the equipment, which is why periodic descaling and cleaning in sulphuric acid (or hydrochloric acid) pickling solutions are necessary. Corrosion inhibitors effectively eliminate the undesirable destructive effect and prevent metal dissolution. Most of commercial pickling inhibitors are toxic compounds and should be replaced with new environmentally friendly inhibitors. This paper focuses on the efficiency of nontoxic imidazole derivatives as copper corrosion inhibitors in sulphuric acid. Imidazoles are organic compounds with two nitrogen atoms in the heterocyclic ring. One of the nitrogen atoms is of pyrrole type, and the other is a pyridine-like nitrogen atom. The imidazole molecule shows two anchoring sites suitable for surface bonding: the nitrogen atom with its lonely sp2 electron pair and the aromatic ring. Imidazole is known for strong adsorption on gold, copper and silver. The influence of the structure and composition of homologous series of imidazole derivatives on the inhibiting efficiency of copper corrosion in sulphuric acid was studied using electrochemical methods and gravimetric method. Some of the investigated compounds are secondary products in pharmaceutical industry and some of them are specially synthesized for this investigation. The results of the investigation show that all investigated imidazole derivatives have fairly good inhibiting properties for copper corrosion in sulphuric acid. The introduction of functional groups to imidazole ring improved the inhibiting properties. The best protection (93%) was obtained by adding a phenyl ring to the imidazole structure. The values of standard free energies of adsorption, as calculated from the Freundlich isotherm, indicate that in the presence of sulphuric acid as well as in hydrochloric acid imidazole derivatives adsorb on copper by physisorption-based mechanism. This is also supported by the fact that the higher molecular weight imidazole derivatives show better corrosion inhibition. The exception is 1-phenil-4-methylimidazole in sulphuric acid which is (unlike in hydrochloric acid) better inhibitor for copper corrosion than 1-(p-tolyl)-4- methylimidazole.

Izvorni jezik
Engleski

Znanstvena područja
Kemijsko inženjerstvo

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