Photocatalysis of environmental organic pollutants and antioxidant activity of flavonoid conjugated gold nanoparticles

[Display omitted] •Isolation of hesperidin from orange peel and characterization by UV–visible spectroscopy, FTIR and NMR.•Synthesis and characterization of Hesperidin gold nanoparticles by UV–visible spectroscopy, FTIR, TEM and SAED.•Photocatalytic degradation study of environmental organic pollutants.•Antioxidant activity assessment by scavenging of DPPH, ABTS and hydroxyl free radical of hydrogen peroxide. The unique properties of nanomaterials have the potential application in different fields of biomedical application along with the management of environmental pollutants. This research work involved the isolation of hesperidin from the orange peel and the preparation of hesperidin gold nanoparticles by the chemical reduction method. The high substrate specificity and lower band gap enable the excitation of gold nanoparticles in visible light. Hence gold nanoparticles are chosen nowadays for the management and removal of organic pollutants. The efficacy of hesperidin gold nanoparticles was evaluated by the photocatalytic activity on organic dyes and pollutants like methyl orange, methylene blue, bromocresol green, and 4 – nitro phenol with sodium borohydride as reducing agent and the antioxidant study by scavenging of free radicals of DPPH, ABTS, and hydroxyl free radicals of hydrogen peroxide. The kinetics of photocatalytic degradation of organic dyes and 4 – nitro phenol was found to follow the first order with rate constants of 10 × 10−3, 37 × 10−3, 23 × 10−3 and 49 × 10−3 min−1 for methyl orange, methylene blue, bromocresol green and 4 – nitro phenol respectively. The hesperidin gold nanoparticles showed significant antioxidant activity as compared to ascorbic acid as standard. The flavonoid conjugated gold nanoparticles can be an efficient antioxidant and photocatalyst for the management of different diseases and wastewater treatment respectively.