Delamination of CuMgAl layered double hydroxides by non-thermal plasma treatment for photocatalytic degradation of Congo Red dye

<p dir="ltr">Effectively removing pollutants from wastewater remains a significant challenge to achieving a sustainable future. Dyes are a class of pollutants that exhibit chemical stability, are not biodegradable, and have the potential to convert into dangerous substances. Layered double hydroxides (LDHs) have emerged as a promising adsorbent for addressing this problem due to their ion-exchange properties and high surface area. Recent studies indicate that the effectiveness of the LDHs can be further improved by delamination into nano sheets.</p><p dir="ltr">In this manuscript we explore the use of argon dielectric barrier discharge (DBD) plasma, a type of non-thermal plasma, as an innovative, greener and milder method to delaminate CuMgAl-LDH turning it into nanosheets. Congo Red (CR) dye was selected as the model pollutant in this study. The resulting plasma treated CuMgAl-LDH (P-CuMgAl-LDH) exhibits a better CR dye adsorption rate. The photodegradation of CR at a concentration of 500 mg L⁻¹ was achieved using 1.0 mg mL⁻¹ of P-CuMgAl-LDH and irradiating with a 370 nm LED. It was found that P-CuMgAl-LDH has significantly higher performance, showing a full discoloration of CR within 1 h and up to 80 % of mineralisation within 1.5 h of irradiation compared to only 16.1 % for CuMgAl-LDH. The photodegradation mechanism studies reveals highly efficient formation of superoxide radical anions (O₂^-•) that further confirm the presence of oxygen vacancies on the P-CuMgAl-LDH. Thus, we conclude that Argon DBD plasma is a valuable tool to efficiently delaminate CuMgAl-LDH under mild conditions and improve its adsorption and photocatalytic properties without the addition of other chemicals.</p>