Simultaneous photocatalytic removal of Cr (VI) and 4 Nitrophenol using CuNiFe LDH/Carbon nitride nanosheets under Visible Light

Abstract

Photocatalysis has made significant progress in the treatment of wastewater. Photocatalytic systems are constantly improving to incorporate the complexity of real environmental matrices, so that the results can be implemented for practical use. As the host of pollutants (organics and heavy metals) coexist in wastewater, it is important to understand how their presence influences remediation interventions. This study investigates simultaneous degradation of different organics and reduction of heavy metals in a concurrent photocatalytic reaction. A new CuNiFe LDH/C3N4 composite catalyst was synthesized to examine the photoredox behavior of different organics (4-nitophenol, 2-chlorophenol and levofloxacin) in presence of Cr(VI). The system was thoroughly characterized using a variety of structural, morphological, and optical techniques (such as XRD, SEM, FTIR, UV-Vis, and PL). CuNiFe LDH/C3N4 photocatalyst demonstrates enhanced charged transfer due to highly dispersed MO6 in brucite-like sheets, and transition metals electron transfer. First, a 62.5% of Cr(VI) reduction was achieved in 180 minutes which increases to 72% and 78% in the presence of 4 NP and LEV, respectively. However, reduction decreases to 41% with 2-CP. Additionally, 4 NP, 2-CP, and LEV show a photocatalytic degradation of 59.15%, 57.9%, and 63.1%, respectively, when treated alone. Intriguingly, in the presence of Cr(VI), the degradation of 4 NP decreases to 19%, while the degradation of 2-CP (88.4%) and LEV (68%) remain significantly higher. Furthermore, radical scavenging experiments were performed to assess the species involved in the removal of the targeted pollutants. Based on these results, a generalized mechanism for this photoredox process was proposed. The work is a step forward in implementing photocatalytic systems for the remediation of complex environmental matrices.