| Summary: | 博士 === 國立臺灣科技大學 === 化學工程系 === 101 === Due to the rise in thin-film transistor liquid crystal display and semiconductor manufacturing, amount of chemicals extensively used in production process have increased as well. Tetramethylammonium hydroxide (TMAH) is one the chemicals, widely used as a major ingredient of photoresist developer in light emitting diode (LED) production, as well as an alkaline etchant and cleaning solution in semiconductor manufacturing. TMAH is a strong base and highly toxic, thus TMAH-containing wastewater has to be properly treated before it is discharged to the environment.
In this study, ion exchange process using commercial ion exchange resin was selected. Two cation exchange resins, namely strong acid (SAC) and weak acid (WAC) cation exchange resin were used to remove TMAH from aqueous solution. Both resins showed high TMA+ ion removal. Ion exchange process was completed within 20 minutes when using SAC and 40 minutes when using WAC. Pseudo second order kinetics model was chosen to represent experimental data, which showed that SAC has faster exchange rate compared to WAC. Investigation on the effect of solution pH revealed WAC was more predominantly affected, and equilibrium pH above 6.5 needs to be maintained. Freundlich and Langmuir adsorption isotherm showed that adsorption was favorable; with Langmuir parameters implied that WAC has stronger interaction with TMA+ compared to SAC. Desorption study using HCl suggested that ion exchange resins used in this study can performed well after 5 cycles. Calculated selectivity coefficient for TMA+ uptake using SAC and WAC was 5.16 and 46.28, respectively.
The presence of interfering ions, both simple and more complex ones, affected TMA+ uptake. When amines were present in solution, the extent of TMA+ uptake decrease was as high as 37%, due to strong interaction between resin matrix with amine molecule
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