INHIBITION OF CORROSION AND HYDROGEN EMBRITTLEMENT OF A HSLA STEEL IN0.5 M H2SO4 BY NITRILE COMPOUNDS

The inhibitive action of valeronitrile, benzonitrile and derivatives o f benzonitrile on the corrosion and hydrogen embrittlement behaviour o f HSLA steel in 0.5 M H2SO4 was investigated. All these inhibitors red uced the corrosion rate of the steel with naphthonitrile showing the h ighest inhibitive efficiency and valeronitrile the lowest. All the inh ibitors adsorbed on the steel as per the Temkin adsorption isotherm. T he steel become less active on the addition of benzonitrile, 3-chlorob enzonitrile, 4-chlorobenzonitrile, 4-methylbenzonitrile and naphthonit rile to the acid while valeronitrile and 2-chlorobenzonitrile made the steel more active. Naphthonitrile reduced the rate of the hydrogen ev olution reaction most efficiently. Derivatives of benzonitrile inhibit ed hydrogen absorption most effectively.