Three-field synergy of solar energy for induced the enhancement of the oxidation of acrylonitrile in coordination with the production of hydrogen

摘要

In the review of the successful solar thermal electrochemical process (STEP) of acrylonitrile oxidation for the effective wastewater treatment, the process was actually driven by solar two fields-thermofield and electrofield, essentially activated and motivated for both thermochemistry and electrochemistry. In this paper, the synergistic system of solar three fields, induced by the primary photofield, and sub-thermofield and sub-electrofield, was designed and employed firstly for promoted the efficiency of the solar utilization and pollutant oxidation plus hydrogen production. With the correlative action, the three sub chemical processes were induced by the solar three fields. The action actually conducted a three-field synergy of solar energy with a combination of the thermo-activation, photo catalysis and electrochemistry of the pollutant oxidation. Exemplified by acrylonitrile, the solar oxidation plus hydrogen production was theoretically and experimentally investigated by the single-field, coupled two-fields and coupled three-fields patterns. The results indicated that the coupled three-field pattern achieved high efficiencies in the solar utilization and oxidative reaction plus the hydrogen production, which was superior to ones of the single or two fields. The solar thermofield enables that the activated acrylonitrile was apt to be thermally decomposed, greatly in favor of the subsequent photo- and electrooxidation. The photocatalytic efficiency driven by the single photofield was reached at a rate of 31.01%. The electrolysis efficiency powered by single electrofield gained a rate of 24.56%. For the combination of the solar three-field pattern, the oxidation efficiencies run up to a rates of 32.74%, 38.06%, 55.01% and 76.01% during 60 min at the 25 degrees C, 40 degrees C, 60 degrees C, 75 degrees C, respectively. Especially, a joint of the coupled field realized the 6.38 times of the COD removal rate of acrylonitrile in comparison with the single field pattern. Due to the easy anodic oxidation of acrylonitrile and operation under the high temperature, the cathodic reduction of water was enhanced for the production of hydrogen in the electrolysis of the less potential plus an addition of photocatalysis. The experimental data and mechanistic analysis significantly revealed that the system achieved such a synergetic action. The full mineralization plus the hydrogen production was attributed to a coupling and matching integration of the solar three fields and subchemistries. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.