Ciba-geigy Corporation

Alan Marshall

Barry Cook

John G Dingwall

Michael A Finan

Norman Richardson

David R Clark

A method of inhibiting the deposition of calcium phosphate scale from an aqueous system treated with a corrosion inhibitor formulation containing a phosphono-carboxylic acid and a polyphosphate comprises adding to the aqueous system a minor amount of hydrolyzed polymaleic anhydride having a molecular weight in the range of from 300 to 5000 as determined by calculation following osmometric measurement on the polymaleic anhydride before hydrolysis, or a water-soluble salt or a hydrolyzed copolymer of polymaleic anhydride.

Method for scale control

A compound or mixture of compounds of the general formula: ##STR1## in which m and n may be 0 or 1 but both cannot be 1, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are independently H or CH.sub.3, X.sup.1, X.sup.2, Z.sup.1 and Z.sup.2 are independently hydrogen or straight or branched chain C.sub.1 -C.sub.4 alkyl; and the water-soluble inorganic or organic salts thereof, with the proviso that at least one of R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 must be CH.sub.3, and when m and n are both 0, R.sup.2 and R.sup.3 are each methyl and R.sup.4 and R.sup.5 have their previous significance, when added to an aqueous system imparts one or more of the following beneficial effects to be treated system:

Method of treating aqueous systems with phosphonoadipic acids

A process for the removal of hydrogen sulphide from gases or liquid hydrocarbons, comprising contacting the gas or liquid hydrocarbon with an aqueous alkaline solution, preferably having a pH value of 8 to 10, comprising

Purification process

Compositions useful for inhibiting the corrosion of ferrous metals in contact with aqueous systems comprise (a) a telomeric compound of formula: ##STR1## or salts thereof, wherein R.sup.11 is hydrogen or a methyl or ethyl residue; R is hydrogen, a straight- or branched alkyl residue having from 1-18 carbon atoms, a cycloalkyl residue having from 5-12 carbon atoms, an aryl residue, an aralkyl residue, a residue of formula: ##STR2## wherein R.sup.11 has its previous significance; and the sum of n+m is an integer of at most 100; or a residue --OX wherein X is hydrogen or a straight- or branched alkyl residue having 1-4 carbon atoms and R.sup.1 is a residue --OX, wherein X has its previous significance.

Telomeric phosphorus corrosion inhibiting compositions

A compound or mixture of compounds of the general formula: ##STR1## in which m and n may be 0 or 1 but both cannot be 1, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are independently H or CH.sub.3, X.sup.1, X.sup.2, Z.sup.1 and Z.sup.2 are independently hydrogen or straight or branched chain C.sub.1 -C.sub.4 alkyl; and the water-soluble inorganic or organic salts thereof, with the proviso that at least one of R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 must be CH.sub.3, and when m and n are both 0, R.sup.2 and R.sup.3 are each methyl and R.sup.4 and R.sup.5 have their previous significance, when added to an aqueous system imparts one or more of the following beneficial effects to be treated system: (a) the corrosion of ferrous metals in contact with the system is inhibited; (b) the precipitation of scale-forming salts of calcium, magnesium, barium and strontium from the treated aqueous system is inhibited; and (c) inorganic materials present in the treated aqueous system are dispersed.

Phosphonoadipic acid additives to aqueous systems

Aqueous compositions containing compounds having the formula: ##STR1## wherein R is a straight- or branched alkyl residue containing 11 to 17 carbon atoms and X and Y are the same or different and each is an alkali metal, an alkaline earth metal, ammonium, an amine radical or hydrogen for selectively flocculating iron ions.

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Macclesfield, United Kingdom

Alan Marshall