Electrochemical regeneration of granular activated carbons loaded with phenol and natural organic matter

Abstract

The main objective of this study was to assess the performance of electrochemical regeneration of granular activated carbon via a set of bench-scale experiments using different operating conditions in the regeneration of several different activated carbons loaded with phenol or natural organic matter. The regeneration efficiency can be increased by increasing the charge applied, whether this was achieved by an increase in current or regeneration time. The degree of phenol-adsorption saturation did not significantly affect the regeneration efficiencies. The regeneration efficiencies of the various types of phenol-loaded activated carbon were quite similar despite the differences in their conductivity. The activated carbon exhibiting fully reversible adsorption of phenol had slightly higher regeneration efficiencies than those involving partially irreversible adsorption. Electrochemical regeneration of activated carbon is feasible at a laboratory scale as regeneration efficiencies up to 80% were achieved during electrochemical regeneration of phenol-loaded or natural organic matter-loaded activated carbons.

Novel decentralized greywater treatment system based on combined adsorption and electrochemical oxidation

“…Zhou and Lei (2006) reported values of regeneration efficiencies close to 90% for AC saturated with p-nitrophenol in 1.5 hours, and this value remained constant after five regeneration cycles (Zhou and Lei 2006b). Electrochemical regeneration of AC exhausted with phenol or NOM was achieved by Cen (1994) andKarimi-Jashni (2008), at values close to 100% and 80% respectively Cen 1994, Narbaitz andKarimi-Jashni 2008). Phenol loaded AC has been reported to be electrochemically regenerated achieving 85.2% and 80% by Zhang (2002) and Zhang et al (2002) respectively (Zhang 2002.…”

“…Promising efficiency of electrochemical regeneration of AC, by oxidation of the adorbed pollutants, has been demonstrated in the recent years (Narbaitz and Cen 1994, Narbaitz and Karimi-Jashni 2008, Wang and Zhao 2010, Zhang et al 2013). This process presents several advantages (Narbaitz and Cen 1994, Narbaitz and KarimiJashni 2008, Zhang 2002:…”

“…Regeneration efficiencies of this process are above 90%, however, it is a high energy consuming process, it implies high investment capital and operational costs, and it is characterized by a 5-10% of material losses (Brown et al 2004a, Brown et al 2004b, Narbaitz and Karimi-Jashni 2008, Streat and Horner 2000, Zhang et al 2013, Zhang 2002. Furthermore, the saturated material need to be transported long distances to the regeneration plant, which will result in an increase in the process costs (Zhang 2002), thus this process is economically feasible when AC average usage rate is over 620 kg d -1 (Narbaitz and Karimi-Jashni 2008).…”

“…Some studies have opted for the addition of NaCl or chlorine species as an electrolyte (Brown et al 2004b, Narbaitz and Cen 1994, Narbaitz and Karimi-Jashni 2008, Zhang 2002, Zhang and Vecitis 2014, Zhou and Lei 2006b) to achieve higher conductivities in the system in order to improve the electrochemical process. However, when chlorine species are present in electrochemical processes, special attention has to be paid on the formation of halogenated by-products with high health risk (i.e., organohalogens, ClO 2 , ClO 3 -, and ClO 4 -) (Bergmann and Rollin 2007, Butkovskyi et al 2013, Fang et al 2006.…”

“…AC is usually chosen due to its good adsorption properties, low cost, and possibility of electrochemical regeneration (Brown et al 2004b, García-Otón et al 2005, Narbaitz and Cen 1994, Narbaitz and Karimi-Jashni 2008, Zhang et al 2013, Zhang 2002, Zhou and Lei 2006b). …”