Photoelectrocatalytic degradation of humic acid in aqueous solution using a Ti/TiO2 mesh photoelectrode

Abstract

Humic acid (HA) is one of natural organics existing in water supply as a precursor of trihalomethanes formation in chlorination. The photo-degradation of HA in aqueous solution by photoelectrocatalytic (PEC) oxidation using a Ti/TiO 2 mesh electrode was investigated in terms of UV absorbance at 254 nm, colour and TOC concentration. The key factors affecting the PEC oxidation efficiency were studied, including the concentration of electrolyte, electrical bias applied, pH value of HA solution, the intensity of incident light and the area of Ti/TiO 2 mesh photoelectrodes. The first order kinetic model was applied to describe the PEC oxidation, in which the kinetic constant k was verified by the experimental data as a function of the concentration of electrolyte, light intensity, the area of Ti/TiO 2 mesh electrode and the voltage of electrical bias applied. It was found that there was an optimal bias voltage of 1.63V and low pH value was favourable for TOC removal in HA solution. Our investigation showed that PEC oxidation was a convenient way to mineralise the organic matters with high efficiency. KEYWORDS

Concentration and UV reactivity of total organic carbon in the upper layer in the oligotrophic subtropical western North Pacific

“…These results indicate that most of the biomolecules are susceptible to the specific UV irradiation applied in the present study. Humic substances exhibited an especially high susceptibility from 77 to 82%, in agreement with recent studies showing that such substances are easily decomposed when exposed to UV irradiation even at the natural level [Wang et al, 2001;Li et al, 2002].…”

Characteristic transformation of humic acid during photoelectrocatalysis process and its subsequent disinfection byproduct formation potential

“…It was clear that significant synergetic effects occurred during PEC process. When a potential greater than the flat-band potential of the TiO 2 /Ti electrode was applied, the charge recombination process will be inhibited (Li et al, 2002;Pinhedo et al, 2005;Huseyin, 2010). Thus, the HA was efficiently degraded during PEC process.…”

“…The process, which is also referred to as photoelectrocatalysis (PEC), has successfully demonstrated the degradation of HA (Kim and Anderson, 1994;Li et al, 2002;Pinhedo et al, 2005;Huseyin and Miray, 2008;Huseyin, 2010). Previous studies on the PEC oxidation of HA focused on the effect of treatment parameters, such as pH, external potential, and HA dose on the removal efficiency (Pinhedo et al, 2005).…”

“…Previous studies on the PEC oxidation of HA focused on the effect of treatment parameters, such as pH, external potential, and HA dose on the removal efficiency (Pinhedo et al, 2005). In addition, these studies used bulk parameters, such as DOC analysis and UV spectrophotometry to assess treatment performance (Kim and Anderson, 1994;Li et al, 2002;Huseyin and Miray, 2008;Huseyin, 2010). However, these parameters may not be adequate to fully elucidate the chemical process.…”

Synthesis and Characterization of CNT / TiO₂Photoelectrocatalytic Electrodes for Methlene Blue Degradation

“…Therefore, the higher PC activity of the CNTs/TiO 2 composites prepared might be attributed to chemical degradation. At the same time, the conductive of CNTs network can facilitate the electron transfer between the adsorbed MB molecules and the catalyst substrate [31][32][33][34] ; it was beneficial for the PEC reaction because the PEC reaction is carried out on the surface of the CNT/TiO 2 composites catalysts and the CNTs network. So the CNT/TiO 2 composites would show an excellent PEC activity.…”