Removal and Oxidation\nof Low Concentration <i>tert</i>-Butanol from Potable Water\nusing Nonthermal Plasma\nCoupled with Metal Oxide Adsorption

Taste and odor are crucial factors in evaluating the\nquality of\ndrinking water for consumers. Geosmin is an example of a pollutant\ncommonly found in potable water responsible for earthy and musty taste,\nand odor even at low concentrations. We have investigated the use\nof a hybrid two-step adsorption-mineralization process for low-level\nvolatile organic compounds removal from potable water using dielectric\nbarrier discharge over common metal oxides (MO). The system proposed\nis a proof of principle with <i>tert</i>-butanol (TBA) used\nas a model compound for geosmin removal/degradation during wastewater\ntreatment when combined with an appropriate metal oxide adsorbent.\nInitial assessments of the adsorption properties of titania by density\nfunctional theory (DFT) calculations and experimental tests indicated\nthat the adsorption of geosmin and TBA with water present results\nin only weak interactions between the sorbate and the metal oxide.\nIn contrast, the DFT results show that alumina could be a suitable\nadsorbent for these tertiary alcohols and were reinforced by experimental\nstudies. We find that while there is a competitive effect between\nthe water and TBA adsorption from gaseous/liquid feed, the VOC can\nbe removed, and the alumina will be regenerated by the reactive oxygen\nspecies (ROS) produced by a dielectric barrier discharge (DBD). The\nuse of alumina in conjunction with NTP leads to efficient degradation\nof the adsorbate and the formation of oxygenated intermediates (formates,\ncarbonates, and carboxylate-type species), which could then be mineralized\nfor the regeneration of the adsorbent. A reaction mechanism has been\nproposed based on the <i>in-situ</i> infrared measurements\nand DFT calculations, while the removal of TBA with conventional heating\nis indicative of a gradual desorption process as a function of temperature\nrather than the destruction of the adsorbate. Furthermore, steady\nperformance was observed after several adsorption–regeneration\ncycles, indicating no alteration of the adsorption properties of alumina\nduring the NTP treatment and demonstrating the potential of the approach\nto be applied in the treatment of high throughput of water, without\nthe challenges faced by the biocatalysts or formation of toxic byproducts.