Electro-Absorbers: A Comparison on Their Performance with Jet-Absorbers and Absorption Columns

Monserrat Castañeda-Juárez,Pablo Cañizares,Ivonne Linares-Hernández,Martín Muñoz-Morales,Fernanda Lourdes Souza,Cristina Sáez,Perla Tatiana Almazán-Sánchez,Manuel Andrés Rodrigo

doi:10.3390/catal10060653

Abstract

This work focuses on the removal of perchloroethylene (PCE) from gaseous streams using absorbers connected with electrolyzers. Two types of absorption devices (jet absorber and absorption column) were compared. In addition, it has been evaluated the different by-products generated when a simultaneous electrolysis with diamond anodes is carried out. PCE was not mineralized, but it was transformed into phosgene that mainly derivates into carbon tetrachloride. Trichloroacetic acid was also formed, but in much lower amounts. Results showed a more efficient absorption of PCE in the packed column, which it is associated to the higher gas–liquid contact surface. Jet absorber seems to favor the production of carbon tetrachloride in gaseous phase, whereas the packed column promotes a higher concentration of trichloroacetic acid in liquid. It was also evaluated the scale up of the electrolytic stage of these electro-absorption devices by using a stack with five perforated electrode packages instead of a single cell. Clarification of the effect of the applied current density on the speciation attained after the electrolysis of the absorbent has been attempted. Experiments reveal similar results in terms of PCE removal and a reduced generation of gaseous intermediates at lower current densities.

Highlights

In recent years, many studies have been carried out to evaluate the removal of persistent pollution from water and wastewater, but a reduced attention has been paid to the vapors emitted during these treatments [1,2]
Gaseous emissions associated to these streams in food waste treatments plants have been studied over last decades, developing technologies capable to remove compounds, such as methyl mercaptan [5], hydrogen sulfide, and trimethylamine [6,7], typically associated with odor
To determine the absorption capacity of the two absorbers evaluated in this work, a single and gaseousprocess phaseswas werecarried measured in the bothproposed liquid waste desorption (LWD)

Summary

Introduction

Many studies have been carried out to evaluate the removal of persistent pollution from water and wastewater, but a reduced attention has been paid to the vapors emitted during these treatments [1,2]. It is important to highlight technologies such as thermal oxidation, selective catalyst reduction, chemical scrubbing, bioscrubbing, and biofiltration [8,9] These technologies have shown several disadvantages, such as catalyst deactivation and high operating costs [10]. For this reason, other technologies such as scrubbing are gaining relevance, it is important to take in mind that this absorption process does not attain a complete removal but it only promotes the transference of the gaseous pollutants into a liquid stream that needs for further treatment [11]. The mass transfer is a key aspect and efficiency is controlled by residence times and gas–liquid contact surfaces, so that a design with good hydrodynamic behavior is required using high and wide contactors [6,12,13,14]

Methods

Results

Conclusion