초록 ▼

A method for treating a spent caustic solution having a pH greater than about 10.5 includes the steps of (a) lowering the pH of the caustic solution into the range of between about 10 to 10.5 to produce a pH-modified caustic solution; (b) oxidizing the pH-modified caustic solution until the solution

A method for treating a spent caustic solution having a pH greater than about 10.5 includes the steps of (a) lowering the pH of the caustic solution into the range of between about 10 to 10.5 to produce a pH-modified caustic solution; (b) oxidizing the pH-modified caustic solution until the solution to produce a non-sulfide reactive oxidized solution; and (c) lowering the pH of the oxidized solution to a pH less than 9.

대표청구항 ▼

We claim: 1. A method for treating a spent caustic solution having a pH greater than about 10.5, the method comprising: (a) lowering the pH of the caustic solution into the range of between about 10 to 10.5 to produce a pH-modified caustic solution; (b) oxidizing the pH-modified caustic solution t

We claim: 1. A method for treating a spent caustic solution having a pH greater than about 10.5, the method comprising: (a) lowering the pH of the caustic solution into the range of between about 10 to 10.5 to produce a pH-modified caustic solution; (b) oxidizing the pH-modified caustic solution to produce a non-sulfide reactive oxidized solution; and (c) lowering the pH of the oxidized solution to a pH less than 9, wherein steps (a), (b) and (c) are performed at ambient temperature. 2. The method of claim 1 further comprising the step of removing a non-aqueous phase from a solution produced in either pH-lowering step. 3. The method of claim 1 wherein either pH-lowering step comprises the step of exposing the caustic solution or the oxidized solution to an acidic gas selected from the group consisting of CO 2, SO2 and HCl. 4. The method of claim 1 wherein the step of lowering the pH of the oxidized solution comprises the step of exposing the oxidized solution to a mineral acid selected from the group consisting of H 2SO4, HCl, H3PO4, and HNO3. 5. The method of claim 1 wherein the step of oxidizing the pH-modified caustic solution comprises the step of exposing the pH-modified caustic solution to an oxidizing agent selected from the group consisting of oxygen, ozone, air, and air enriched with oxygen. 6. The method of claim 1 wherein the oxidation step and the second pH-lowering step are performed simultaneously. 7. The method of claim 1 wherein the second pH-lowering step liberates carbon dioxide, the method further comprising the step of treating additional spent caustic solution with the liberated carbon dioxide. 8. A method for treating a spent caustic solution having a pH greater than about 10.5, the method comprising: (a) lowering the pH of the caustic solution into the range of between about 10 to 10.5 to produce a pH-modified caustic solution; (b) oxidizing the pH-modified caustic solution to produce a non-sulfide reactive oxidized solution; and (c) lowering the pH of the oxidized solution to a pH less than 9, wherein the second pH-lowering step liberates carbon dioxide, the method further comprising the step of treating additional spent caustic solution with the liberated carbon dioxide.