Detection Limits and Decomposition Mechanisms for Organic Contaminants in Water Using Optical Emission Spectroscopy

Abstract

In addition to drinking water resources, the need for clean water in many industrial processes is critical. Among potential contaminants, those associated with fuel oxygenate additives (e.g. MTBE) are of concern as they partition into aqueous phases. Development of methods for detection and decontamination, including plasma pollution control, have been the objective of many studies. Here, inductively‐coupled rf plasmas were used for detection of organic contaminants (CH3OH, MTBE) in water. Parent molecule decomposition was followed using actinometric OES. Emission from CO* yielded a detection limit of 0.01 ppm for each compound. Complementary mass spectrometry data were also collected to explore decomposition mechanisms.

Using Fundamental Spectroscopy to Elucidate Kinetic and Energetic Mechanisms within Environmentally Relevant Inductively Coupled Plasma Systems

“…In some cases, no specific formation and destruction of species were detected on the time scale of our system, further discussed below. Limitations of OES for reliable species density has been described in detail previously. ,, These include the observations that the actinometer and species of interest must undergo known electron impact excitation processes; be primarily excited from the ground state; optical emission branching ratios of lines of interest and other de-excitation pathways should be constant; and both species must have similar thresholds for the electron impact cross sections …”

Isoelectric points of plasma‐modified and aged silicon oxynitride surfaces measured using contact angle titrations

“…All substrate treatments were performed in a tubular, glass inductively coupled rf (13.56 MHz) reactor, the general design of which has been described in detail previously 25–27. The reactor used for all experiments described here was 38 cm in length and 5 cm in diameter.…”

“…Optical emission spectroscopy (OES) data were acquired in the reactor described above fitted with a replaceable fused quartz window at the downstream end, allowing for the coaxial collection of plasma emission for maximum signal intensities 27. Plasma emission was imaged onto the 10 µm entrance slit of an Avantes multichannel spectrometer fitted with four optical fibers fused into one cable.…”

Comparing Isoelectric Point and Surface Composition of Plasma Modified Native and Deposited SiO2 Films Using Contact Angle Titrations and X‐ray Photoelectron Spectroscopy

“…All plasma treatments and film depositions were performed in a tubular, glass inductively coupled, low density rf (13.56 MHz) reactor, the general design of which has been described in detail previously 13–15. The reactor used for all experiments described here was 38.1 cm in length and 5 cm in diameter.…”