Photocatalytic removal of nitrate from water using activated carbon-loaded with bimetallic Pd -Ag nanoparticles under natural solar radiation

• Nitrate reduction in water is efficiently achieved by photocatalysis. • The photocatalyst was prepared from activated carbon decorated with single metal (Ag, Cu and Pd), and bimetal (Pd-Cu and Pd-Ag). • Significant photocatalytic activity was observed for activated carbon when modified with Pd–Ag. • Formic acid was the most effective among all of the tested scavengers. • The catalyst exhibited high activity in the removal of nitrate ions from river water (100%) and ground water (94%). The increase of nitrate contamination of surface and groundwater has raised a concern, because of its impact on both environment and human health. In this study, photocatalysis for nitrate treatment in water was conducted using activated carbon prepared from date palm stone decorated with single and bimetals nanoparticles using solar radiation. The prepared catalyst was characterized by XPS, SEM, EDX, TGA, and surface area analyzer instruments. The photocatalytic effect of the prepared catalyst was studied using nitrate solution and acid scavengers with different concentrations. Significant photocatalytic activity was observed for activated carbon when modified with Pd–Ag. The obtained results showed that the conversion of nitrate takes place mainly through nitrogen gas (N 2 ) rather than nitrite (NO 2 - ) or ammonium (NH 4 + ). Formic acid as a hole scavenger with 0.05 M shows the maximum conversion for nitrate. The prepared photocatalyst shows stability for five cycles of nitrate ion reduction. Moreover, the results showed that the prepared catalyst could be applied for the removal of nitrate from groundwater and river water samples.