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[Display omitted] • State of the art in electrosorption of organic compounds (EOC) critically reviewed. • EOC shows promise against poorly adsorbable, highly polar, and ionized pollutants. • Enhanced adsorption and active control of ad-/desorption by electric potential. • Insightful performance parameters proposed to unify rapidly growing EOC research. • EOC application for on-site regenerable adsorbers and in treatment trains discussed. The widespread contamination of water resources with emerging organic contaminants necessitates the development of sustainable and cost-effective water treatment technologies. Adsorption, as a widely used water remediation process, is hampered by severe performance limitations against ionic and hydrophilic organic contaminants. In addition, no facile on-site regeneration techniques are available. Electrosorption of organic compounds (EOC) is a promising alternative to not only improve adsorption performance, but also to facilitate adsorbent regeneration by green electricity. The number of studies on EOC has grown exponentially over the past decades. There are numerous examples showing that applied electric potentials can significantly enhance the adsorption affinity, capacity, and kinetics of conductive carbon adsorbents. However, whether these effects are specific to certain compound classes or more generally applicable remains unclear as well as the optimal criteria for designing EOC processes. Therefore, we critically evaluated the current state of the art of EOC in terms of active control of adsorption and desorption processes and the achievable effects for ionic and neutral organic compounds. Through a detailed consideration of compound speciation and surface chemistry of electrode materials, we derive mechanistic insights into the EOC process and discuss differences between electrosorption of inorganic and organic compounds. We provide definitions and propose insightful performance parameters to unify the rapidly growing EOC research. Potential application scenarios and future research directions are discussed. Overall, EOC is less likely to be a one-fits-all solution for removing contaminants, but adds a valuable tool especially for the hydrophilic and ionic organic contaminants that challenge conventional adsorption processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Geosmin and MIB removal by O 2 NBs was investigated under freshwater conditions. • Volatilization and oxidation were the two main removal mechanisms by O 2 NBs. • Nanobubbles/microbubbles mixing enhanced the formation of •OH radicals. • Organic matter, alkalinity and chloride inhibited the oxidative removal pathway. Nanobubbles (NBs) have emerged for water/wastewater treatment, removal of pollutants from sediments and soils, and other environmental and biomedical applications. In this study, the application of NB technology was investigated to control extracellular geosmin and 2-methylisoborneol (MIB) which are naturally occurring terpenoid alcohols produced by cyanobacteria (blue-green algae) and actinomycetes (bacteria) found in surface waters. In addition, their removal mechanisms by oxygen NBs were systematically examined. Volatilization was the dominant mechanism for the removal of geosmin (∼40%) and MIB (∼20%) from distilled and deionized water, while oxidation by reactive oxygen species (ROS) brought additional removals up to ∼ 15%. The formation of hydroxyl (•OH) radicals was promoted when NBs were mixed with microbubbles (MBs), while there was no evidence of geosmin/MIB oxidation by either oxygen NBs or MBs alone. Alkalinity decreased the removal rates of both geosmin and MIB by scavenging •OH radicals, while elevated temperature increased the removal of geosmin and MIB due to enhanced volatilization and oxidation. Natural organic matter (NOM) and chloride ion slightly decreased the removal of geosmin and MIB. The effect of pH in the range of 3–10 was found insignificant. When oxygen NBs were applied to selected natural waters with a wide range of water characteristics, the oxidative pathway was significantly suppressed by ambient alkalinity, NOM, and chloride by which •OH radicals can be quenched. These findings will guide the applications of the oxygen NBs technology in the water treatment, and the further investigations for the improvement of its oxidation potential. [ABSTRACT FROM AUTHOR]

[Display omitted] • Charging activated carbon (AC) tunes adsorption of ionic but not nonionic compounds. • Defunctionalized AC allows better electro-assisted trap&release performance. • Combine surface modification and electric polarization for promoted removal. • Long-term (20 d) stable electro-assisted trap&release with high enrichment effects. • Electro-assisted trap&release promising for on-site AC regeneration. Highly water-soluble, persistent, and mobile organic compounds (PMOCs) are more and more often detected in surface and groundwater, evoking potential threats to the environment and human health. Traditional water treatment strategies, including adsorption by activated carbon materials, fail to efficiently remove PMOCs due to their hydrophilic nature. Electro-assisted sorption processes offer a clean, facile, and promising solution to remove PMOCs on activated carbon-based electrodes and potentially allow an easy on-site sorbent regeneration (trap&release). In this work, the electrosorption of five selected PMOCs, that is, tetrapropylammonium (TPA+), benzyltrimethylammonium (BTMA+), p -tosylate (p -TsO-), p -toluenesulfonamide (p -TSA), and methyl- tert -butyl ether (MTBE), were investigated on two comprehensively characterized activated carbon felt (ACF) types carrying different surface functionalities. Significant enrichment factors in ranges of 102 to 103 for charged PMOCs were expected by our first estimation for electro-assisted trap&release on ACFs in flow systems applying potentials in the range of −0.1 V/+0.6 V vs. SHE for ad-/desorption, respectively. Defunctionalized ACF carrying larger density in surface π-systems and lower O-content promises a higher capability in electrosorption processes than the pristine material in terms of better material stability (tested for 5 cycles over 500 h) and better removal efficiency of ionic PMOCs. To improve ACFs adsorption performance for cationic and anionic PMOCs, permanent chemical surface modification and reversible electric polarization as alternative strategies are compared. Our findings explore future electrode and process design of electrosorption for applications to treat water contaminated by emerging PMOCs. [ABSTRACT FROM AUTHOR]