Separation of high-concentration tetramethylammonium hydroxide from photoresist development wastewater using strong acidic cation exchange resin

Wastewater discharged from semiconductor manufacturing industries contains high concentration of tetramethylammonium hydroxide (TMAH), which must be treated due to its corrosive nature and toxicity. In this study, the separation of the high-concentration TMAH by ion exchange with strong acidic cation exchange resins, Diaion SK1-B (gel-type) and PK228L (porous-type), was investigated in the present work. The adsorption process followed pseudo-second-order kinetics, with rate constants of 2.82 g/(mmol·h) for SK1-B and 3.71 g/(mmol·h) for PK228L. Accordingly, PK228L exhibited faster adsorption kinetics than SK1-B, which can be attributed to more efficient intraparticle diffusion of the porous-type resin. Ion exchange was most effective in near neutral pH range at around pH = 7 – 8. The ion exchange behavior conformed to the Langmuir isotherm model, and a higher saturated adsorption amount was observed for PK228L, due to larger specific surface area. Despite its higher adsorption capacity and kinetics, PK228L showed lower elution efficiency, with maximum elution yield of 75.6%, whereas SK1-B achieved elution yield of 89.3% using 3.0 mol/ L NaCl solution in batch system. The ion exchange process was also successfully applied to column operation for the treatment of high-concentration TMAH solutions (approximately 5,000 mg/L) derived from photoresist development wastewater. Complete elution of TMAH from SK1-B was achieved with 2.0 mol/L NaCl in the column system, due to the dynamic mode operation. The separation process of TMAH using the strong acidic cation exchange resin thus shows high potential for the reuse of TMAH used in the semiconductor industry. • Porous type resin showed faster kinetics and higher capacity than gel type resin. • Higher elution yield was obtained on gel type resin. • Adsorption followed pseudo-second-order kinetics and Langmuir isotherm model. • Ion exchange was most efficient near neutral pH conditions. • Column operation confirmed applicability to actual photoresist wastewater.