Electrochemical conversion of phenolic wastewater on carbon electrodes in the presence of NaCl

Abstract

The electrochemical conversion of highly concentrated synthetic phenolic wastewater was studied on carbon electrodes in a batch electrochemical reactor. The effects of reaction temperature, electrolyte concentration, current density and initial phenol concentration on phenol conversion were elucidated. The wastewater was synthetically prepared and used in reactions carried out generally at 25°C with an initial phenol concentration of 3500 mg dm À3. Although current density increased, phenol conversion% and initial phenol conversion rate did not increase correspondingly above 35°C and an electrolyte concentration of 90 g dm À3 .As the voltage values applied were increased, the increasing current density resulted in fast phenol conversion. Kinetic investigations denoted that overall phenol destruction kinetics was of zero order with an activation energy of 10.9 kJ mol À1 . Under appropriate conditions, phenol was completely converted within 15 min for an initial phenol concentration of 98 mg dm À3 while 8 h was required to gain 95% conversion using 4698 mg dm À3. Solid polymeric materials were produced at initial phenol concentrations above 500 mg dm À3 using the appropriate current density. In the reaction medium, only mono-, di-and tri-substituted chlorophenols were formed and 100% of all species were either oxidised or contributed to the formation of a polymeric structure. Almost all of the phenol loaded to the reactor was converted into non-passivating polymeric products, denoting a safe and easy method for the separation of phenol.

Removal of tannins and polyhydroxy phenols by electro‐chemical techniques

“…Such polymeric derivatives were observed while subjecting phenolic wastewater to electro-chemical oxidation. 33 Anodic oxidation of phenol in the presence of NaCl has led to organochlorinated compounds, which were further oxidized to volatile CHCl 3 . Although chlorophenols are formed in the initial stages they were eventually converted to polymeric compounds free from chlorine.…”

Electrochemical oxidation of phenol in a parallel plate reactor using ruthenium mixed metal oxide electrode

“…Electrochemical oxidation of phenol has been studied by various workers at platinum [7][8][9], doped SnO 2 [8,9], PbO 2 [8,[12][13][14], Bi 2 O 5 -PbO 5 [14], IrO 2 [10], carbon [15] and borondoped diamond anodes [16]. Among these electrode materials, besides the diamond electrode, metal oxide electrodes, which are cheaper, are also preferred.…”

Electrochemical performance and electroreduction of maleic acid on Ce-doped nano-TiO2 film electrode

“…The catholyte was a solution of 0.1 M MA in 1.0 M H 2 SO 4 . The current density was 58 mA cm −2 (the cell voltage range was 3.80-4.10 V) and the teperature of the water bath was 60 • C, the same temperature as that used in several published works [36,37]. As shown in Table 1, the SA yield and the current efficiency using the Ti/Ce nano-TiO 2 electrode (Ce/Ti molar ratio = 0.003), 98% and 91% respectively, were higher than those obtained with the Ti/nano-TiO 2 electrode, 81% and 80%.…”