Activated carbon selection for the adsorption of marine DOC and analysis of DOC fractionation

AbstractAdsorption on granular activated carbon (GAC) and fractionation of marine dissolved organic carbon (DOC) was investigated with the objective of mitigating RO membrane biofouling in the context of a reverse osmosis process for seawater pretreated by ultrafiltration. The behaviours of six commercial GAC compounds were compared. Batch kinetics experiments showed that 80% of DOC in seawater was adsorbed within four hours. Adsorption kinetics fitted the Ho and McKay model well, and isotherms followed the Freundlich model. GAC A and GAC F had the best adsorption capacities. For GAC A, the adsorption mechanism was mainly related to high occupation of the porous volume, whereas for GAC F, the adsorption was mainly related to electrostatic interactions. GAC A was selected for a fixed bed column experiment continuously fed with seawater as GAC F released acidic groups into the feed water. This filtration set-up enabled more than 70% of DOC to be removed from seawater. Moreover, LC-OCD analysis showed that G...