N-heterocyclic carbene functionalized boehmite-supported silver nanoparticles as nanocatalyst for reduction of environmental pollutants

Abstract

The drastic change in the industrial sector and the commercialization has led to the exposure of various hazardous molecules in the atmosphere wherein modern catalytic techniques have played a crucial role in the advancement of technologies to overcome this problem. In this work, we have reported an efficient method for the synthetic fabrication of novel N-heterocyclic carbene functionalized boehmite-supported silver nanoparticles (BML@Ag) as a sustainable nanocatalyst for treating water pollutants like 4-nitrophenol (4-NP) and Congo red (CR) dye. Further, to confirm the successful development of the prepared nanocatalyst we have carried out various spectroscopic and microscopic analyses like FT-IR, p-XRD, FE-SEM, EDS, HR-TEM, BET and TGA. The average crystallite size was found to be 6.69 nm. Further, the BML@Ag nanocatalyst was explored for its catalytic efficacy in the reduction of 4-NP and degradation of the organic diazo dye CR using an aqueous solution of NaBH4 as the reducing agent. The reduction of 4-NP was observed to occur in 2.5 min (99.9%), while CR degraded in 5 min (98.8%), with the rate constants of 36.2×10-3 and 13.6×10-3 s-1 respectively. The recyclability study was demonstrated for both 4-NP and CR dye and recyclability was achieved up to 3 cycles with an excellent conversion efficiency. To explore the convenience of the BML@Ag nanocatalyst, the effects of changing parameters such as catalyst loading, pH, and salt concentration were thoroughly investigated. Furthermore, the ability of the BML@Ag nanocatalyst to reduce/degrade the pollutants was demonstrated with spiked tap and lake water samples. The efficiency of BML@Ag nanocatalyst was found to give the best conversion efficiency for the lake water samples of both 4-NP and CR dye with 99.5% and in the tap water the efficiency was noted to be reduced in both cases. The real-time investigation validated the competence of the BML@Ag nanocatalyst to be extended for commercial use.