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This research focuses on the degradation of tetramethylammonium hydroxide (TMAH) using underwater plasma and examines how varying electrical field strengths affect the process.

February 27, 2026Open Access

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

Key Points

This research focuses on the degradation of tetramethylammonium hydroxide (TMAH) using underwater plasma and examines how varying electrical field strengths affect the process.
Used underwater plasma to degrade TMAH under field strengths of 0.8 to 10 kV mm⁻¹.
Performed optical emission spectroscopy to analyze plasma discharge characteristics.
Measured total organic carbon (TOC) removal rates and kinetics of the process.
Applied ion chromatography to detect byproducts like NH4⁺ and NO3⁻.
Identified a range of electron densities from optical emissions indicative of high-field discharge.
Observed a shift from OH-dominated to O-dominated chemistry as field strength increased.
Achieved TOC removal rate constants that increased with field strength up to 4.8 kV mm⁻¹, then plateaued.
Detected accumulation of nitrogen compounds, suggesting competition between carbon and nitrogen conversion processes.

Abstract

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), Hβ, and O I features, with Stark broadening of Hβ indicating electron densities between 5.0 × 1024 and 11.8 × 1024m⁻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 × 10⁻3 to 7.7 × 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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Authors

Ki‐Taik Lee

Hana Lim

Sung Cheol Park

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

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Abstract

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