Photoelectrocatalytic degradation of carbamazepine using Ti/TiO_2 nanostructured electrodes deposited by means of a pulsed laser deposition process

摘要

The objective of the present work is to evaluate the potential of photoelectrocatalytic oxidation (PECO) process using Ti/TiO_2 for the degradation of carbamazepine (CBZ). Ti/TiO_2 prepared by pulsed laser deposition (PLD) has been used as a photo-catalyst in a photoelectrocatalytic cell. The PLD TiO_2 coatings were found to be of anatase structure consisting of nanocrystallites of approximately 15 nm in diameter. Factorial and central and extreme composite design methodologies were successively employed to define the optimal operating conditions for CBZ degradation. Several factors such as current intensity, treatment time, pollutant concentration and cathode material were investigated. Using a 24 factorial matrix, the best performance for CBZ degradation (53.5%) was obtained at a current intensity of 0.1 A during 120 min of treatment time and when the vitreous carbon (VC) was used at the cathode in the presence of 10 mg L~(-1) of CBZ. Treatment time and pollutant concentration were found to be very meaningful for CBZ removal. The PECO process applied under optimal conditions (at current intensity of 0.3 A during 120 min in the presence of 10 mg L~(-1) of CBZ with VC at the cathode) is able to oxidize around 73.5% ±12.8% of CBZ and to ensure 21.2% ± 7.7% of mineralization. During PECO process, CBZ was mainly transformed to acridine and anthranilic acid. Microtox biotests (Vibrio fisberi) showed that the treated - effluent was not toxic. The pseudo-second order kinetic model (k_2 -6 x 10~(-4)L mg~(-1) min~(-1)) described very well the oxidation of CBZ.