Improved phenol adsorption from aqueous solution using electrically conducting adsorbents

The electrically conducting and partially porous graphite based adsorbent (called NyexTM 2000) was tested for its adsorption capacity and electrochemical regeneration ability for the removal of phenol from aqueous solution. Nyex™ 2000 was tested in comparison with Nyex™ 1000, which is currently being used for a number of industrial waste water treatment applications. Nyex™ 1000 exhibited small adsorption capacity of 0.1 mg g−1 for phenol because of having small specific surface area of 1 m2 g−1. In contrast, Nyex™ 2000 with specific surface area of 17 m2 g−1 delivered an adsorption capacity of 0.8 mg g−1, which was eight-fold higher than that of Nyex™ 1000. Nyex™ 2000 was successfully electrochemically regenerated by passing a current of 0.5 A, charge passed of 31 C g−1 for a treatment time of 45 minutes. These electrochemical parameters were comparable to Nyex™ 1000 for which a current of 0.5 A, charge passed of 5 C g−1 for a treatment time of 20 minutes were applied for complete oxidation of adsorbed phenol. The comparatively high charge density was found to be required for Nyex™ 2000, which is justified with its higher adsorption capacity. The FTIR results validated the mineralization of adsorbed phenol into CO2 and H2O except the formation of few by-products, which were in traces when compared with the concentration of phenol removed from aqueous solution. The electrical energy as required for electrochemical oxidation of phenol adsorbed onto Nyex™ 1000 & 2000 was found to be 214 and 196 J mg−1, respectively. The comparatively low energy requirement for electrochemical oxidation using Nyex™ 2000 is consistent with its higher bed electrical conductivity, which is twice that of Nyex™ 1000.