A solvent extraction approach to recover acetic acid from mixed waste acids produced during semiconductor wafer process |
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Authors: | Shin Chang-Hoon Kim Ju-Yup Kim Jun-Young Kim Hyun-Sang Lee Hyang-Sook Mohapatra Debasish Ahn Jae-Woo Ahn Jong-Gwan Bae Wookeun |
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Affiliation: | R&D Center, Daeil Development Co., Ltd., Ansan 425-836, Republic of Korea. shinch777@chol.com |
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Abstract: | Recovery of acetic acid (HAc) from the waste etching solution discharged from silicon wafer manufacturing process has been attempted by using solvent extraction process. For this purpose 2-ethylhexyl alcohol (EHA) was used as organic solvent. In the pre-treatment stage >99% silicon and hydrofluoric acid was removed from the solution by precipitation. The synthesized product, Na(2)SiF(6) having 98.2% purity was considered of commercial grade having good market value. The waste solution containing 279 g/L acetic acid, 513 g/L nitric acid, 0.9 g/L hydrofluoric acid and 0.030 g/L silicon was used for solvent extraction study. From the batch test results equilibrium conditions for HAc recovery were optimized and found to be 4 stages of extraction at an organic:aqueous (O:A) ratio of 3, 4 stages of scrubbing and 4 stages of stripping at an O:A ratio of 1. Deionized water (DW) was used as stripping agent to elute HAc from organic phase. In the whole batch process 96.3% acetic acid recovery was achieved. Continuous operations were successfully conducted for 100 h using a mixer-settler to examine the feasibility of the extraction system for its possible commercial application. Finally, a complete process flowsheet with material balance for the separation and recovery of HAc has been proposed. |
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