Regeneración de carbones activados mediante tratamientos térmico / gasificación y oxidación húmedaaplicación en ciclos de adsorción

Abstract

The aim of the present Doctoral Thesis is the study of the regeneration of activated carbons which have been used for the adsorption of paranitrophenol. Before their saturation, the study of the corresponding equilibrium adsorption and kinetics was studied (in batch and column continuous mode). Regarding the adsorbent regeneration processes, the experimentation was divided into two main sections: a) thermal regeneration, by means of thermogravimetry under inert atmosphere (analyzing the different thermal events and relating them to the nature of the type of adsorption process involved), and by means of heating in one or two reactors (with or without the addition of an activant agent, and with or without subsequent cracking of the gases released), and b) wet oxygen oxidation. In both cases, the influence of characteristical experimental conditions were studied (temperature, pressure, use of oxidant agent, and heating rate, among others). The search of optimal conditions was based on the carbon porosity regain, costs and degradation of toxic desorbed species. The results obtained indicated the good behaviour of thermal regeneration in conjunction with carbon dioxide or steam activation; especially in the latter case the use of the carbon in adsorption/desorption cycles, even achieving porosity characteristics which were better than those of the original carbon. Wet oxidation processes were also very interesting, especially when high temperatures and pressures were used. The results also showed an slight decrease on the porosity development of the carbons as the number of cycles was increased.