A
pigment grade
corrosion inhibitor and a method of forming the inhibitor is disclosed. The inhibitor is comprised of a host species comprised of an
inorganic compound having a
layered structure and a guest species comprised an anionic species of a weak acid. The host species is preferably a double
hydroxide having a structure of: [M(II)1-xM(III)x(OH−)2] [An−x / n.y H2O], where M(II) is a
divalent metal cationic species, M(III) is a trivalent
metal cationic species, and An− is an anionic species, preferably with the species present in a range of: 0.2≦M(III) / (M(II)+M(III))≦0.4. The guest species include: ortho-phosphoric, pyrophosphoric, tripoly-phosphoric, polyphosphoric acid; mono- and di-
alkyl or
aryl-esters of ortho-phosphoric and
pyrophosphoric acid; metaphosphoric, trimeta-phosphoric, poly-
metaphosphoric acid; phosphorous (phosphonic) acid; derivatives of phosphonic acid;
alkyl and
aryl esters of
thio-phosphoric and dithio-
phosphoric acid; molybdic, phospho-molybdic, silico-
molybdic acid;
boric acid; cyanamidic acid;
nitrous acid; derivatives of
thio- and dithiocarbonic acid, including o-
alkyl esters; derivatives of dithiocarbamic acid, including N-alkyl dithiocarbamates; pyrrolidinecarbodithioic acid;
thio-organic compounds functionalized with at least one —SH group of acidic character, including: 2,5-dimercapto-1,3,4-thiadiazole (DMTD), 2,4-dimercapto-s-triazolo-[4,3-b]-1,3-4 thiadiazole,
trithiocyanuric acid (TMT), and dithiocyanuric acid, various N—,S— and N,N—, S,S— and N,S-substituted derivatives of the above DMTD and TMT compounds; various S-substituted derivatives of
trithiocyanuric acid;
dimer and
polymer derivatives of the above DMTD and TMT compounds, including 5,5′ dithio-bis (1,3,4 thiadiazole-2(3H)-thione or (DMTD)2, and (DMTD)n, polymers of DMTD and (TMT)2, dimers and polymers of TMT; various combinations of all the above; soluble salts of DMTD and TMT; poly-
ammonium salt of DMTD or (DMTD)n and TMT formed with polyamines; mercapto-
benzothiazole, mercapto-
benzoxazole, mercapto-
benzimidazole, and combinations, thereof; di- and poly-
mercapto compounds, including: di-mercapto derivatives of
thiophene,
pyrrole, furane, diazoles, and
thiadiazoles; di- and tri-mercapto derivatives of
pyridine, diazines, triazines,
benzimidazole, and
benzothiazole, including dimercaptopyridine, 2, 4-dithiohydantoine, and 2,4,-dimercapto-6-amino-5-
triazine; and carboxylic and di-carboxylic acids, including ascorbic,
salicylic acid,
phthalic acid, nitro-
phthalic acid,
succinic acid, and derivatives of
succinic acid, including 1-(benzothiazol-2-ylthio)
succinic acid.