Dart Industries Inc.

Silvester P Valayil

Moenes L Elias

Improved metal dissolution rates are obtained when using a solution containing sulfuric acid, hydrogen peroxide and a catalytic amount of a heterocyclic nitrogen compound containing at least one free mercapto group substitution.

Dissolution of metals utilizing an aqueous H.sub.2 SO.sub.Y --H.sub.2

Improved metal dissolution rates are obtained when using a solution containing sulfuric acid, hydrogen peroxide and a catalytic amount of a thioamide having the general formula ##STR1## wherein R is an aryl or a heterocyclic group.

Dissolution of metals utilizing an aqueous H.sub.2 O.sub.2 -H.sub.2

Improved metal dissolution rates are obtained when using a solution containing sulfuric acid, hydrogen peroxide and a catalytic amount of 3-sulfopropyldithiocarbamate sodium salt having the general formula ##STR1## wherein R can be a C.sub.1 -C.sub.4 alkyl group, phenyl, a C.sub.7 -C.sub.10 alkaryl group or a C.sub.7 -C.sub.10 aralkyl group.

Dissolution of metals utilizing an aqueous H.sub.2 SO.sub.4 -H.sub.2

Improved metal dissolution rates are obtained when using a solution containing sulfuric acid, hydrogen peroxide and a catalytic amount of a polysulfide compound having the general formula ##STR1## wherein R is a hydroxyl group, a carboxyl group, a sulfonic acid group or a sulfonic acid salt group, each X independently from each other can be hydrogen, hydroxyl or C.sub.1 -C.sub.4 alkyl, each Y independently from each other can be hydrogen, hydroxyl or C.sub.1 -C.sub.4 alkyl, m is an integer from 1 to 18, and n is an integer from 2 to 5.

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Youngstown, OH, United States of America

Silvester P Valayil