Study of parameters affecting the degradation of rhodamine-B and methyl orange dyes by Annona muricata leaf extract synthesized nanoparticles as well as their recyclability

Abstract

In this work, a facile and green approach has been employed for the degradation of toxic dyes like rhodamine-B (rh-B) and methyl orange (MO) individually as well as in combination (rh-B+MO) in presence of sodium borohydride (NaBH4). The silver-silver chloride nanoparticles (Ag-AgCl NPs) fabricated using aqueous Annona muricata leaf extract were used as nano-catalysts. Effect of reaction parameters such as nano-catalyst dosage, NaBH4 dosage, temperature and pH were investigated to achieve maximum catalytic efficiency. The maximum degradation was obtained at 100 μg of Ag-AgCl NPs (mass of nano-catalyst), 25 mg of NaBH4 (mass of reducing agent) and 60 °C (temperature). pH 8, 6 and 6 showed maximum degradation for rh-B, MO and rh-B+MO dyes respectively. The experimental data obtained was following the pseudo-first order reaction kinetics. About 96.79 ± 2.61% (0.7485 min−1), 97.51 ± 2.14% (1.0542 min−1) and 97.08 ± 2.63% (0.3474 min−1) degradation was observed for rh-B (under 5 min), MO (under 4 min) and rh-B+MO (under 10 min) dyes respectively. Recyclability studies showed that Ag-AgCl NPs can be recycled and reused up to Cycle 5 (51.11 ± 3.34%) for rh-B, Cycle 6 (47.35 ± 3.19%) for MO and Cycle 3 (45.53 ± 2.32%) for rh-B+MO combination.