Micropollutants pre-concentration using adsorption-desorption cycles: application to chlorinated paraffins and alkyl-phenol derivatives

Abstract

BACKGROUND: Pre-concentration of two different emerging pollutants -an endocrine disruptor and a chlorinated paraffin -was carrxbied out by adsorption/desorption cycles onto carbonaceous materials -activated carbon (GF-40), multiwall carbon nanotubes (MWCNT) and a high surface area graphite (HSAG-500). The breakthrough curves were modeled by Bed Depth Service Time (BDST), Thomas and Yoon-Nelson models.RESULTS: MWCNT presents for both compounds the highest normalized adsorption capacity. Although GF-40 offers 100% elution efficiency, no pre-concentration was obtained with this adsorbent. In contrast, pre-concentration was reached with MWCNT and HSAG-500. The best results were obtained with MWCNT, with a pre-concentration factor of 3.4 for 1,8-dichlorooctane and 2.8 for 2-(4-methylphenoxy)ethanol. BDST and Thomas models can predict the adsorption capacity and Yoon-Nelson the time required to reach the 50% adsorbate breakthrough. CONCLUSIONS: Pre-concentration was reached using MWCNT and HSAG-500 as adsorbent. MWCNT is the best adsorbent, since this material presents the highest normalized adsorption capacity and concentration factor.