Underwater Plasma-Driven Decomposition of Tetramethylammonium Hydroxide (TMAH) Under Different Applied Field Strengths

초록

Tetramethylammonium hydroxide (TMAH), a toxic and persistent compound widely used in semiconductor manufacturing, was degraded using underwater plasma at applied fields ranging from 0.8 to 10 kV mm(-)1. Optical emission spectroscopy revealed OH(A-X), H beta, and O I features, with Stark broadening of H beta indicating electron densities between 5.0 x 1024 and 11.8 x 1024 m(-)3, characteristic of high-field discharge. Spectral analysis showed a field-dependent shift from OH-dominated to O-dominated chemistry. Total organic carbon (TOC) removal followed pseudo-first-order kinetics, with rate constants increasing from 3.6 x 10(-)3 to 7.7 x 10(-)3 min(-)1 but plateauing above 4.8 kV mm(-)1. Ion chromatography detected NH4 + and NO3(-) accumulation, suggesting that oxidative flux was partially diverted toward nitrogen conversion, thereby competing with carbon mineralization.

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