Comparative study of diethyl phthalate degradation by UV/H2O2 and UV/TiO2: kinetics, mechanism, and effects of operational parameters

Abstract

The photodegradation of diethyl phthalate (DEP) by UV/H2O2 and UV/TiO2 is studied. The DEP degradation kinetics and multiple crucial factors effecting the clearance of DEP are investigated, including initial DEP concentration ([DEP]0), initial pH values (pH0), UV light intensity, anions (Cl(-), NO(3-), SO4 (2-), HCO3 (-), and CO3 (2-)), cations (Mg(2+), Ca(2+), Mn(2+), and Fe(3+)), and humic acid (HA). Total organic carbon (TOC) removal is tested by two treatments. And, cytotoxicity evolution of DEP degradation intermediates is detected. The relationship between molar ratio ([H2O2]/[DEP] or [TiO2]/[DEP]) and degradation kinetic constant (K) is also studied. And, the cytotoxicity tests of DEP and its degradation intermediates in UV/H2O2 and UV/TiO2 treatments are researched. The DEP removal efficiency of UV/H2O2 treatment is higher than UV/TiO2 treatment. The DEP degradation fitted a pseudo-first-order kinetic pattern under experimental conditions. The K linearly related with molar ratio in UV/H2O2 treatment while nature exponential relationship is observed in the case of UV/TiO2. However, K fitted corresponding trends better in H2O2 treatment than in TiO2 treatment. The Cl(-) is in favor of the DEP degradation in UV/H2O2 treatment; in contrast, it is disadvantageous to the DEP degradation in UV/TiO2 treatment. Other anions are all disadvantageous to the DEP degradation in two treatments. Fe(3+) promotes the degradation rates significantly. And, all other cations in question inhibit the degradation of DEP. HA hinders DEP degradation in two treatments. The intermediates of DEP degradation in UV/TiO2 treatment are less toxic to biological cell than that in UV/H2O2 treatment.

Enhanced ozonation of antibiotics using magnetic Mg(OH)2 nanoparticles made through magnesium recovery from discarded bischofite

“…5d and e). The decrease in the reaction rate of MNZ might be caused by the capture of $OH by the coexistent chloride ions since Ca 2þ and Mg 2þ belong to alkali metal with stable valences without participating the degradation reaction (Song et al, 2016).…”

Catalytic Ozonation of Sulfonamide, Fluoroquinolone, and Tetracycline Antibiotics Using Nano-Magnesium Hydroxide from Natural Bischofite

“…Reaction conditions: antibiotics concentration 50 mg L −1 , catalyst dosage 0.15 g L −1 , ozone concentration 0.5 g h −1 , ozone flow rate 0.1 L min −1 20.9% and 31.7%, respectively, when the concentration of Mg 2+ increased from 0 to 0.5 mol L −1 . The Ca 2+ and Mg 2+ are stable and do not participate in the reaction (Song et al 2016). The adsorption of these cations on the catalyst might also lead to catalyst contamination and reduction in numbers of reaction sites on catalyst surface, which subsequently jeopardized the degradation of antibiotics.…”

Catalytic ozonation of nitroimidazole antibiotics using nano-magnesium hydroxide as heavy-metals free catalyst

“…The removal rate constant of MNZ, TNZ, and DMZ decreased by 63.4%, 57.6%, and 70.3%, respectively, when the initial concentration of Ca 2+ increased from 0 to 0.5 mol L -1 while that of MNZ, TNZ, and DMZ decreased by 52.4%, 55.9%, and 68.7%, respectively, when the initial concentration of Mg 2+ increased from 0 to 0.5 mol L -1 . One reasonable explanation was that Ca 2+ and Mg 2+ belonged to alkali metal and their valences were stable so as not to take part in the degradation reaction [52]. On the other hand, when the concentrations of Ca 2+ and Mg 2+ were further increased, the content of Clin the system increased exponentially so that the capture of radical increased.…”