Influence of the properties of 7 micro-grain activated carbons on organic micropollutants removal from wastewater effluent

Abstract : Highlights 17 • 7 commercial µGACs were characterized and tested with real wastewater 18 • A percentage of microporous volume higher than 65% reduced OMPs adsorption 19 • DOM reduced the adsorption of negatively-charged OMPs more than positive ones 20 • OMPs charge, hydrophobicity and minimal projection area influenced their adsorption 21 • The µGACs particle size had an impact on UV254 removal in continuous column tests 22 Graphical abstract 23 2 24 Abstract 25 Most studies dedicated to organic micropollutants (OMPs) removal from wastewater effluents by adsorption 26 onto activated carbon (AC) only consider a few conventional AC properties. The link between OMPs removal 27 and these properties is often missing, which limits the understanding of the adsorption process and the 28 interpretation of the results. The chemical, physical and textural properties of seven newly commercialized 29 micro-grain activated carbons (µGACs) were determined to assess their influence on the removal of 28 OMPs. 30 Conventional batch tests with wastewater effluent showed that a high percentage of microporous volume (> 31 65%) was detrimental for the removal of 10 OMPs, probably due to a higher blockage of micropores by 32 dissolved organic matter (DOM). The removal of 5 OMPs was correlated with µGACs surface chemistry 33 properties (i.e. charge) which were potentially modified by DOM adsorption or inorganic species, thus 34 favoring the adsorption of positively-charge compounds. A combination of OMPs properties including their 35 charge, hydrophobicity and minimal projection area could explain their removal. Correlations were found 36 between the removal of several OMPs and UV254 and dissolved organic carbon, suggesting that DOM and 37 OMPs interacted with each other or followed similar adsorption mechanisms. A decrease in µGACs particle 38 size had a positive impact on UV254 removal under continuous-flow conditions in columns representative of a 39 large-scale pilot due to better expansion. 40