Methods for inhibiting corrosion, cleaning and/or providing biocidal efficacy in hydrogen rich environments that are in hydrogen systems or hydrogen mediums using saturated alkyl diquaternary compound containing compositions, saturated alkyl quaternary compound containing compositions, aldehyde containing compositions, and/or tetrakis(hydroxymethyl)phosphonium sulfate containing compositions are provided. The methods provide efficacious corrosion inhibition, cleaning and/or biocidal efficacy without loss of stability due to hydrogenation in hydrogen rich environments.

A method of improving corrosion resistance of a metal substrate comprising a zinc surface coated with zirconium oxide conversion coating by, prior to conversion coating, contacting the zinc surface with a composition comprising: a) iron(III) ions, b) a source of hydroxide ion; c) at least one complexing agent selected from organic compounds which have at least one functional group COOX, wherein X represents either a H or an alkali and/or alkaline earth metal; d) 0.0 to about 4 g/l cobalt (II) ions; and optionally e) a source of silicate: wherein the composition has a pH of at least 10.

A method of improving corrosion resistance of a metal substrate comprising a zinc surface coated with zirconium oxide conversion coating by, prior to conversion coating, contacting the zinc surface with a composition comprising: a) iron(III) ions, b) a source of hydroxide ion; c) at least one complexing agent selected from organic compounds which have at least one functional group COOX, wherein X represents either a H or an alkali and/or alkaline earth metal; d) 0.0 to about 4 g/l cobalt (II) ions; and optionally e) a source of silicate: wherein the composition has a pH of at least 10.

Corrosion inhibitors and methods for inhibiting or reducing corrosion of metallic surfaces are provided. A corrosion inhibitor composition may include a water soluble substituted imidazoline or a hydrolysis product thereof. A method of inhibiting corrosion of a metallic surface in an aqueous system includes the step of contacting the surface with an effective amount of a corrosion inhibitor composition. The corrosion inhibitor composition may include other components, such as zinc, and it may also exclude phosphorus.

A nanohybrid chitosan (NHc) composite includes a matrix of a chitosan Schiff base of Formula (I), and a plurality of spherical silver nanoparticles (AgNPs) uniformly distributed throughout the matrix of the chitosan Schiff base. The NHc composite has a porous structure containing a plurality of interconnected pores. A method for inhibiting corrosion of a metal article.

##STR00001##

A nanohybrid chitosan (NHc) composite includes a matrix of a chitosan Schiff base of Formula (I), and a plurality of spherical silver nanoparticles (AgNPs) uniformly distributed throughout the matrix of the chitosan Schiff base. The NHc composite has a porous structure containing a plurality of interconnected pores. A method for inhibiting corrosion of a metal article.

##STR00001##