Non-passivating polymeric structures in electrochemical conversion of phenol in the presence of NaCl.

The formation of non-passivating polymeric structures was investigated during electrochemical conversion of phenol using carbon electrodes and NaCl as electrolyte. The influence of initial phenol concentration, current density and reaction temperature on phenol conversion and polymer morphology was studied by FTIR and STM, while the fate of intermediate compounds was analyzed by GC/MS. Unlike previous work, non-passivating solid polymer was produced at high voltage and current density values in the presence of NaCl. The most orderly polymer formed at 912 mg l(-1) initial phenol concentration, current density 32.9 mA cm(-2), NaCl concentration 120 g l(-1) and temperature 25 degrees C. Higher operational parameters yielded disorderly formed aggregates of the polymer in decreasing surface density on STM images. Along with the polymer, only toxic mono-, di- and tri-chlorophenols were formed as intermediate compounds during the electrochemical conversion, which eventually were polymerized and/or oxidized to final products. FTIR analysis and enlarged STM image implied the repeating phenol units in the polymer structure. The results may lead to appropriate techniques for the removal of phenol from wastewater in the form of a solid polymer.