Phytosynthesis of Prosopis farcta fruit-gold nanoparticles using infrared and thermal devices and their catalytic efficacy

[Display omitted] •IR light has been used with Prosopis farcta fruits to phyto-synthesize Au NPs for the first time.•The Prosopis farcta-AuNPs size decreased with IR treatments compared with the heat strategy.•AuNPs synthesized by IR have an exceptional catalytic efficacy to remove MB from water.•FTIR analysis indicates that phenolic compounds of P. farcta extract are protected in the AuNPs synthesized by IR irradiation. This study is a new attempt to synthesize gold nanoparticles (AuNPs) using the extract of fresh mature fruits of the Iraqi Prosopis farcta plant (Fabaceae). The synthesis has been performed under infrared (IR) irradiation treatment and compared with the heating procedure at 90 °C. P. farcta-AuNPs has been investigated as a nanocatalyst to remove Methylene blue (MB) dye from aqueous solutions. TEM, FE-SEM, EDX, XRD, size Distribution Report by Intensity, Zeta Potential, UV–Vis, GC-Mass and FTIR have been used to characterize the synthesized AuNPs. The color transformation of colloidal AuNPs under both IR radiation and heat confirmed the efficient reduction of Au+ to Au0 and its stabilization using P. farcta extract. AuNPs synthesized using IR were mainly spherical with an average diameter hydrodynamic size of 25.43 nm, and Zeta Potential of −26.5 mV. While AuNPs prepared using the heating treatment showed a quasi-spherical shape with an average size of 53.12 nm and Zeta Potential of −24.4 mV. FTIR analysis indicates that phenolic compounds of P. farcta extract are protected in the AuNPs synthesized by IR irradiation, but they are lost in another sample. Thus, the AuNPs bio-synthesized using IR radiation have higher colloidal stability, smaller size, more spherical and more preserved core–shell structure than Au NPs prepared using the heat treatment. Bionano-reduction of MB using synthesized AuNPs using IR irradiation best than synthesized using the heating procedure. This work encourages using IR irradiation as a new method to produce and improve AuNPs for catalytic handling.