Photodegradation of three benzotriazoles induced by four FeIII–carboxylate complexes in water under ultraviolet irradiation

Abstract

Environmental context. Benzotriazoles are chemicals widely used to inhibit corrosion in various industrial processes and in household products. They persist in aquatic environments, even under UV irradiation, and thus there is a need to improve their photolytic degradation to minimise the environmental exposure risks. We investigated the effects of four iron-carboxylate complexes on the UV photodegradation of three benzotriazoles in aqueous solutions and show that they significantly increase the degradation rates of benzotriazoles.Abstract. The effects of Fe III -carboxylate complexes on the photodegradation of three benzotriazoles (BTs), i.e. benzotriazole (BT), 5-methylbenzotriazole (5-TTri) and 5-chlorobenzotriazole (CBT) in aqueous solutions were investigated under exposure to UV irradiation at 254 nm in the presence of Fe III and four carboxylate ions (oxalate, tartrate, succinate and citrate). The results showed that the presence of Fe III -carboxylate complexes significantly enhanced the photodegradation rates of all three selected BTs. The photodegradation of BT, 5-TTri and CBT followed first-order reaction kinetics with half-lives ranging from 0.57 to 3.98 h for BT, 6.08 to 8.25 h for 5-TTri and 2.63 to 5.50 h for CBT in the four systems of the Fe III -carboxylate complexes. In comparison, the half-lives ranged between 3.40 and 4.81 h for BT, 6.42 and 11.55 h for 5-TTri and 4.13 and 6.79 h for CBT in pure aqueous solution and in the presence of Fe III or carboxylate. The degradation rates of these BTs were dependent on the pH values, type of carboxylate and Fe III / carboxylate ratios. Both BT and CBT showed the highest photodegradation rates with the shortest respective half-lives of 0.57 and 2.63 h at the initial Fe III /oxalate ratio of 10/200 mmol L À1 in aqueous solutions at pH 3, whereas 5-TTri had the highest photodegradation rate with the shortest half life of 6.08 h at the initial Fe III /succinate ratio of 10/10 mmol L À1 .

The Effects of Inorganic Ions on Photodegradation of Humic Acids by Fe(III)/Oxalate Systems

“…1) well due to the relatively low substrate concentration compared to the quantum yields. [6] The C 0 and C are the concentration of HA at time 0 min and t, respectively, and k is the first-order rate constant. Half-lives ( t 1/2 ) can be calculated as Eq.…”

“…It has been well proven that variouse contaminants (e.g. orange G, benzotriazoles, and amicarbazone) could be photodegraded by Fe(III)/oxalate system [5][6][7].…”

Synthesis of novel α-Fe2O3-Bi2S3-Gr for efficient photocatalytic degradation of environmental pollutants under visible-LED light irradiation

“…These results could be attributed that iron ions are unstable under basic conditions. On the other hand, the decrease of degradation efficiency under strong alkali solution may also be related to the electrostatic repulsion between α-Fe 2 O 3 -Bi 2 S 3 -Gr (3%) and BTA, which negatively affected the adsorption [59,60]. From a practical application point of view, neutral pH is usually favored and found in wastewater containing pharmaceutical products, BTA degradation at pH = 4.8 without adjustment reduces the cost of water treatment and gives a significantly high degradation efficiency of about 98% within 300 min.…”

Degradation of persistent pesticides via advanced oxidation and reductive processes.

“…Hence, this photoredox cycle of Fe(III) complexes is very important to the environmental self-depuration mechanisms since it also contributes to the photodegradation of especially persistent organic pollutants, such as benzotriazoles (LIU et al, 2013) and pesticides (POZDNYAKOV et al, 2016). However, depending on the natural organic ligand found in water or in the structure of the organic pollutant being considered, stable nonphotoactive iron complexes can be formed and, therefore, the efficiency of the degradation/depuration process can be reduced (MANENTI et al, 2015;SILVA et al, 2010 SERAGHNI et al, 2012;WANG et al, 2006).…”