Nanoarchitectured  Biomass-Waste Derived Activated Charcoal Nanozymes and its Application in Visual Analysis of Nitrite in Pickled Food

Abstract

The development of the emerging field of nanozymes has brought unprecedented opportunities and challenges to activated charcoal materials derived from biomass waste. By introducing specific nanostructures or elements, it is expected to break through the bottlenecks of insufficient catalytic active sites and poor electron transfer efficiency of traditional activated charcoal, further explore its potential application value. In this study, we successfully synthesized a trace Fe-doped activated charcoal (Fe-AC) with graphene-like structure from biomass-waste. The Fe atom was dispersed on the activated charcoal support with a high surface area. This can not only effectively increase more catalytic active sites, but also improve the efficiency of electron transfer, as well as the mobility and collision probability of the substrate. Compared to pristine activated charcoal, the prepared Fe-AC manifested multiple enzyme-like activities (oxidase-like, peroxidase-like, and catalase-like activity). By combining their peroxidase-like enzyme activity with nitrite specific diazotization reactions, we developed a portable smartphone-assisted on-site ratiometric colorimetric hydrogel for nitrite determination. Based on the smartphone-assisted digital image, the developed portable sensor enabled quantitative analysis of nitrite at concentrations ranging from 1~200 µmol/L with a low detection limit of 1 µmol/L. The approximate range of dangerous concentrations of nitrite can be easily identified with the naked eye and the proposed strategy can also be applicable in real sample. This sensor makes full use of waste resources, effectively reducing its production cost. It has higher economic feasibility and environmental friendliness, and is expected to be promoted and applied in a wider range of fields.

Keywords: Nitrite, Nanozyme, Activated Charcoal, Ratiometric, Colorimetric, Hydrogel