Upcycling of Fish Scales into a Au-Templated Mechanically Extractable Sturdy and Malleable Supported Catalyst for Cleansing Water

Abstract

Despite a decade of research and exploitation of fish scales for several applications, there is no report on fabricating supported catalysts for catalysis. Herein, simply by exploiting the metal binding and reductive potential of fish scales we autogenically bioengineered golden supported catalysts of ∼1.5 ± 0.4 cm2, sustainably. Providentially, the catalyst acquired mechanical sturdiness (∼65 ± 9 MPa), durability, flexibility, absorbency, and stability against diverse physicochemical barriers. Uniquely, these remarkable characteristics enabled the catalyst for reaction suitable fixative-batch or continuous flow catalysis, a rare compatibility. This was validated by performing large-volume (5 L) degradation of the textile sewage dye 4-nitrophenol (30 mg/L) at a (k) of 0.07 min–1, parallelly generating gram-scale quantities of 4-AP with a turnover frequency of 108 h–1. The continuous flow reactor was operable at a high flow rate of 1.5 mL/min, accommodating a high reduction of 4-NP of over 94%. Most importantly, the wide area of our catalyst made it feasible to hand-retrieve or exchange the catalyst for recycling and monitoring the reaction kinetics without the need for energy intensive processes. Finally, the collagenous biological nature of the support permitted ∼74 ± 5% recovery of gold by etching in Aqua-Regia. Overall, our biowaste-valued, cost-efficient, hand-retrievable, mechanically sturdy, and resilient catalyst with a highly flexible and durable nature can be generalized for reactor specific practical implementation of large scale heterogeneous catalysis.