  Emerging contaminants (ECs) have come out as the latest class of
environmental contaminants, which are highly recalcitrant and toxic in nature.
Currently, no suitable rectification methods are available against the ECs,
resulting in a continuous increase in their concentration. Non-thermal plasma,
as an advanced oxidation process, has been emerging as a promising technology
against the ECs treatment. In the present work, a detailed experimental study
is carried out to evaluate the efficacy of a non-thermal plasma jet with two
dyes, Rhodamine B and Methylene Blue, as model contaminants. The plasma jet
provided a complete dye decoloration in 30 min with an applied voltage of 6.5
kV. .OH, having the highest oxidation potential, acts as the main reactive
species, which with direct action on contaminants also acts indirectly by
getting converted into H2O2 and O3. Further, the effect of critical operational
parameters viz., sample pH, applied voltage (4.5-6.5 kV), conductivity (5-20
mScm-1), and sample distance on plasma treatment efficacy was also examined.
Out of all the assessed parameters, the applied voltage and sample conductivity
was found to be the most significant operating parameter. A high voltage and
low conductivity were found to favor the dye decoloration, while the pH effect
was not that significant. To understand the influence of plasma discharge gas
on treatment efficacy, all the experiments are conducted with Argon and Helium
gases under the fixed geometrical configuration. Both the gases provided a
similar dye decoloration efficiency. The DBD plasma system with complete dye
removal also rendered maximum mineralization of 73 % for Rd. B, and 60 % for
Met. Blue. Finally, the system's efficiency against the actual ECs (four
pharmaceutical compounds, viz., metformin, atenolol, acetaminophen, and
ranitidine) and microbial contaminant (Escherichia coli) was also tested.
