Influência da geometria e liga catódica sobre o desprendimento de hidrogênio a partir da eletrólise da salmoura.

Abstract

The influence of geometry and cathodic alloy on the detachment of hydrogen from the electrolysis from brine electrolysis was study using a bench scale electrochemical cell for the production of soda- chlorine by the diaphragm process. The general objective was to investigate the influence of the cathodic alloy/geometry (perforated plates and meshes) called commercially for: SAE 1020 and SAF 2205 on the detachment of hydrogen from brine electrolysis. The following parameters had been investigated:: average cathodic potencial distribution , potential cell , energy consumption, current and energy efficiency, chloride and chlorates concentration, with the aim to correlate the obtained data with the geometric morphology of the studied electrodes and in function of this, to identify to advantages and disadvantages (amongst the studied materials) to chose the best geometry and alloys for the process of electrolytic production of soda -chlorine. The operational conditions had been: diaphragm of asbestos and polymer, continuous feeding of an acid pickling brine (pH between 4,0 and 4,5) from 320g/L concentration, current density varying from 0,75 to 3,28 KA/m2 (cathode perforated plate) and from 0,75 to 1,74 KA/m2 (cathode mesh), time of polarization of approximately 3,5 hours (cathode perforated plate) and of approximately 2,15 hours (cathode mesh) with a total time of operation of the electrolytic cell in the current intensity of 13,1A of approximately 28 hours, until reaching the concentration of 12% of NaOH (in accordance with the industrial parameters). For the iinvestigation of the cathodic potential distribution, 17 reference electrodes located of in strategical points had been used, taking as reference the height (H = 80 mm) and width (L = 70 mm) of the cathodic window. For representation of the results, the values measured in each one of the reference electrodes had been dimensionless through the ratio Xi/L and Yi/H (I = 1,2... 17). The experimental measures of potential had been taken in relation to a reference electrode of Hg/HgO/NaOH, (1,0 M).