Efficient electrocatalytic reduction of nitrite species on zeolite modified electrode with Cu-ZSM-5

The electrocatalytic reduction of nitrite has been studied on the surface of zeolite modified electrodeusing exchanged ZSM-5 with copper (ME/Cu-ZSM-5). The process of reduction and kinetics studies were investigated through cyclic voltammetry and chronoamperometry techniques. The i-E characteristics of ME/Cu-ZSM-5 presented the faradic process associated to redox couple Cu ²⁺/Cu⁺with a ΔE = 0.064 V/SCE. On the other hand, voltammetric studies showed that in presence of nitrite, the cathodic peak current of ME/Cu-ZSM-5 increases followed by a decrease in the corresponding anodic current. This indicated thatnitrite species were reduced by a cooperative effect of the acidic properties of zeolite and copper that acts as a redox mediator being immobilized on the electrode surface via an electrocatalytic mechanism. Further experiments showed that electrocatalytic activity increases as Si/Al ratio decreases, the electro-catalytic activity was improved when the material Cu-ZSM-5 was calcined prior to electrode preparation. The values of the rate constant of the catalytic reduction of nitrite and the detection limit obtained were 5.9 × 10² cm³ mol^-1s ^-1 and 1.4 × 10^-5mol L^-1, respectively.