Abstract
Nanoparticle (NP) catalysts are widely used for removal of dyes for single use, but there is an acute need for developing catalysts with high efficiency and reusability for mixed dyes. Here we first optimized the process (reactant proportion, temperature, time, and pH) for biosynthesis of monometallic Ag, Au and bimetallic Au–Ag alloy NP catalysts using Polyalthia longifolia leaf extract. The biosynthesized NP catalysts were characterized by UV-vis, DLS, Zeta potential, TEM and EDX study while the probable biomolecules responsible for biosynthesis were identified by FTIR and GC-MS/MS analysis. The NPs are found to be mostly spherical in shape (size 5–20 nm) with prolonged stability. We evaluated their chemo-catalytic performance through degradation of dyes (methyl orange, methyl violet, methylene blue) in individual and ternary mixture in presence of NaBH4. The degradation percentage (80.06–96.59% within 5 min), degradation kinetics (k = 0.361–1.518 min–1), half-life (T50 = 0.457–1.920 min) and 80% degradation (T80 = 1.060–4.458 min) of dyes indicated highest catalytic activity of alloy in ternary mixture. Here we report a unique vacuum filtration system using alloy coated beads with excellent catalytic activity which could be reused thrice for removal of hazardous ternary mixed dyes with great promise for environmental remediation.
Highlights
Over a decade, catalysis plays a prominent role for more than 90% of the chemicals manufacturing process in institutional research and industrial applications such as chemical, energy, pharmaceutical, polymers and in the protection of our environment[1,2,3]
surface plasmon resonance (SPR) band intensity depends on the type of NPs, morphology, composition, and surrounding medium[23]
UV–vis spectroscopy is one of the major characterization methods to investigate the nature of synthesized bimetallic Au–Ag NPs
Summary
Catalysis plays a prominent role for more than 90% of the chemicals manufacturing process in institutional research and industrial applications such as chemical, energy, pharmaceutical, polymers and in the protection of our environment[1,2,3]. The exciting improvement on nanoparticle (NP) catalysts and their potential applications for the removal of dyes from different types of wastewater has gained remarkable scientific attention in the field of catalysis research[3,4,5]. Biosynthesis of NPs using plants is certainly a better option than other biological method because of less or no chances of contamination, cost-effective and requirement of very simple laboratory setup for NPs production. Polyalthia longifolia is a lofty, straight columnar and evergreen plant with horizontal short branches It is a multipurpose tree whose extracts and isolated compounds have been studied for various biological activities[20,21,22]. Various physico–chemical parameters of NPs were systematically studied by chromatographic, spectroscopic and microscopic method Their chemo-catalytic activity and reusability of NPs for degradation of dyes in aqueous solution has been investigated
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