Chemical removal of thiourea from hydrochloric acid
AssigneeDowell Schlumberger Incorporated
InventorStanley B. McConnell
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Abstract
A chemical method of removing thiourea from spent hydrochloric acid cleaning solutions comprising the steps of: adjusting the pH to not less than 12 by addition of base to remove metal hydroxides; oxidizing thiourea to urea by the addition of at least a stoichimetric amount of oxidant per mole of thiourea; and further oxidizing urea to nonregulated/nonhazardous compounds by the addition of at least 3 moles of a hypochlorite per mole of urea. UV analysis confirms a greater than 98% removal of thiourea from solutions containing 0.4 to 2.7 wt. % thiourea after as little as 3 hours with an exotherm, .DELTA.t, of less than 105.degree. F.
Claims16
A method of removing thiourea from a thiourea containing acid solution comprising the stage of:
- (a) adding an effective amount thereof to a Group Ia hydroxide, Group IIa hydroxide or a mixture thereof to adjust the pH to not less than about 12, thus precipitating any alkaline insoluble metal hydroxides present in said acid solution producing an alkaline thiourea containing solution and separating said metal hydroxides from said alkaline thiourea containing solution;
- (b) adding an effective amount of ozone to the alkaline thiourea containing solution produced in step (a), thus oxidizing the thiourea to urea;
- and
- (c) adding an effective amount of a hypohalite, salt MOX where M is a Group Ia or Group IIa element and X is a halogen, to the alkaline urea containing solution produced in step (b) according to the reaction, ##STR7##
A method of removing thiourea from a thiourea containing hydrochloric acid solution comprising the steps of:
- (a) adding an effective amount of a Group Ia hydroxide, Group IIa hydroxide or mixture thereof to adjust the pH to not less than about 12, thus precipitating any alkaline insoluble metal hydroxides present in said acid solution and producing an alkaline thiourea containing solution and separating said metal hydroxides from said alkaline thiourea containing solution;
- (b) adding an effective amount of ozone to the alkaline thiourea containing solution produced in step (a), thus oxidizing the thiourea to urea;
- and
- (c) adding an effective amount of a hypochlorite salt MOCl wherein M is a Group Ia or Group IIa element, to the alkaline urea containing solution produced in step (b) according to the reaction, ##STR8##
Dependencies are inferred from the claim text.