A solvent extraction approach to recover acetic acid from mixed waste acids produced during semiconductor wafer process.
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.
Shin
Chang-Hoon
CH
R&D Center, Daeil Development Co., Ltd., Ansan 425-836, Republic of Korea. shinch777@chol.com
Kim
Ju-Yup
JY
Kim
Jun-Young
JY
Kim
Hyun-Sang
HS
Lee
Hyang-Sook
HS
Mohapatra
Debasish
D
Ahn
Jae-Woo
JW
Ahn
Jong-Gwan
JG
Bae
Wookeun
W
D019342:Acetic Acid / Q000302:isolation & purification*; D000143:Acids / Q000737:chemistry*; D012666:Semiconductors; D012997:Solvents / Q000737:chemistry*; D014961:X-Ray Diffraction
D000143:Acids; D012997:Solvents; D019342:Acetic Acid