Biocatalyst Electrodes and Their Applications to Sensors and Reactors

Performance, community structure, metabolic pathway, and mechanism in a three-dimensional electrocatalytic biofilter (3DEBF) for the degradation of multiple concentrations of clofibric acid (CA)

A three-dimensional electrocatalytic biofilter (3DEBF) was constructed to remove clofibric acid (CA). This study compared the effectiveness of 3DEBF and biological aerated filter (BAF) in the removal of refractory CA, examined the effects of influent CA concentrations (0.1, 0.3, 0.5, 0.7, and 1.0 mg/L) on microbial community, and proposed a possible 3DEBF degradation mechanism. Results indicated that the average removal efficiency of 3DEBF reached a peak (76.09%) at 0.7 mg/L, which was 14.43% higher than that of BAF. Based on the microbial community analysis, the significant enrichment of Rhodobacter, Mycobacterium, and Sphingopyxis in 3DEBF was associated with the effect of the CA concentration and the electric field. The degradation pathway indicated that xenobiotics biodegradation and metabolism, membrane transport and replication and repair related genes were upregulated in 3DEBAF. Moreover, CA degradation is based on a combination of adsorption, electrochemical oxidation, and biodegradation.

Amperometric glucose biosensor based on assisted ion transfer through gel-supported microinterfaces

A novel amperometric glucose sensor was developed based on the facilitated proton transfer across microinterfaces between two immiscible electrolyte solutions. The combination of a 1,3:2,4-dibenzylidene sorbitol/2-nitrophenyl octyl ether gel membrane and 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine as the ionophore allows the transfer of protons from water to the gellified organic phase; the gel membrane is supported on arrays of microholes drilled on a polyester film. The protons are generated as the result of the dissociation of gluconic acid produced during the enzymatic degradation of glucose by glucose oxidase. The characteristics of the glucose sensor were investigated using several experimental conditions, namely, the concentration of ligand and enzyme. The electrochemical response is typical of an enzymatic electrode and displays a linear behavior in the range 0.2-3 mM glucose. The effect of the experimental parameters of the voltammetric technique was also optimized with the aim of improving sensor sensitivity.