Biochar from Brewers’ Spent Grain: A Green and Low-Cost Smart Material to Modify Screen-Printed Electrodes

Abstract

In the present study, biochar from brewers’ spent grain was used, for the first time, to develop screen-printed electrodes. After having investigated the dispersion behaviour of biochar in different organic solvents, a biochar-based screen-printed electrode was prepared with the drop-casting technique. In order to understand the electrochemical potentiality and performances of the biochar/sensor tool, different electroactive species, i.e., ferricyanide, benzoquinone, epinephrine, ascorbic, and uric acids, were used. The results were compared with those of the same electrodes that were modified with commercial graphene, confirming that the proposed electrode showed improved electrochemical behaviour in terms of resolution, peak-to-peak separation, current intensity, and resistance to charge transfer. Furthermore, a tyrosinase biosensor was developed by direct immobilisation of this enzyme on the biochar/screen printed electrode, as an example of the potential of biochar for disposable biosensor development. The efficiently occurred immobilisation of the biochar on the screen printed electrode’s (SPE’s) surface was demonstrated by the observation of the working electrode with a scanning electron microscope. The detection was performed by measuring the current due to the reduction of the corresponding quinone at low potential, equal to −0.310 V for epinephrine. The experimental conditions for the tyrosinase immobilization and the analytical parameters, such as applied potential and pH of buffer, were studied and optimized. Under these conditions, the electrochemical biosensors were characterized. A linear working range of epinephrine was obtained from 0.05 up to 0.5 mM. The detection limit was 2 × 10−4 mM for the biosensor.

Brewer’s Spent Grains—Valuable Beer Industry By-Product

“…Trials showed that tested additions were effective and allowed for the production of a biodegradable counterpart for expanded polystyrene trays [ 115 ]. Moreover, BSG has been mentioned as a sustainable material that could be used for the manufacturing of electrodes [ 116 ].…”

The role of microorganisms on biotransformation of brewers’ spent grain

“…In particular, the antioxidant, anti-atherogenic, anti-inflammatory, and anti-carcinogenic activities of chemical compounds in BSG have been considered (Ikram et al 2017 ; Lynch et al 2016 ; McCarthy et al 2013 ). Finally, methods for exploitation of BSG in terms of food and energy production, and in the chemical and agronomic sectors have been reviewed (Cancelliere et al 2019 ; Mussatto 2014 ; Xiros and Christakopoulos 2012 ; Aliyu and Bala 2011 ; Mussatto et al 2006 ). In this context, the aim of this mini-review is to present the current literature on BSG from a microbiological point of view.…”

HTC of Wet Residues of the Brewing Process: Comprehensive Characterization of Produced Beer, Spent Grain and Valorized Residues

“…Biological activity of these residues makes long term storage difficult. The literature reports ongoing work on various new ways of using BSG, including extraction of polyphenols [10,11], other anti-oxidants [12,13], functional cardioprotective lipids for pharmaceutic use [14], proteins [15], fodder for edible insects [16], material for disposable trays [17], natural rubber modifier [18], as well as feedstock for production of pigments [19] and biochar, for subsequent use as soil amendment [20] or sustainable material for electrodes [21].The potential use of this residue as a fuel has been suggested by several authors so far [7][8][9]22,23]. The relatively high initial moisture content of spent grain makes hydrothermal valorization techniques the most sensible choice [8,9].…”