Photodegradation of 4‐chlorophenol using as photocatalyst ZnFe₂O₄ spinels: influence of the complexing agent in the photocatalytic activity

Abstract

BACKGROUND 4‐chlorophenol is one of the most commonly used products in industrial processes. This compound exhibits a high chemical stability that makes its removal from wastewater difficult by conventional methods. Although diverse methods have been applied for its elimination, photocatalysis is one of the only techniques with several advantages, such as nontoxic by‐products and mild reaction conditions. One of the goals in improving this remedial technology is the development of materials with adequate physicochemical properties that enhance the catalytic activity and thus allow the complete degradation of the pollutant or its elimination in shorter periods of time. RESULTS Magnetic ZnFe2O4 catalysts were prepared by the hydrothermal method using as complexing agents oxalic, citric, and tartaric acids. The specific surface areas of the samples were between 23.938 and 48.058 m2/g and the band gap energies were in the range of 1.55–1.90 eV. These materials were evaluated under UV light irradiation (254 nm, 2 W) for the photodegradation of 4‐chlorophenol. All samples showed photodegradation efficiencies around 60% after three hours of reaction at pH 3. CONCLUSION The results confirmed that the complexing agents have an influence on the physicochemical properties of the synthesized catalysts. The catalyst synthesized using citric acid was the only one to exhibit a significant activity at the three pH levels (3, 5, 6). The above can be attributed to the fact that this material presents the lowest bandgap and crystallite size values along with the largest specific surface area of all the synthesized samples. © 2022 Society of Chemical Industry (SCI).

Photocatalytic removal of 2-chlorophenol from water by using waste eggshell-derived calcium ferrite

“…7 are quite similar to those in previous research studies. 36,62 Nonetheless, the characteristic masses ( m / z ) of some intermediates were slightly different from their theoretical molecular weight (±5) probably because the compound has secondary characteristic masses or low concentration, and was converted rapidly to CO 2 within the long reaction time. 37…”

“…The effective separation of electron–hole separation under light irradiation and higher surface area (high density of catalytic active sites) resulted in high chlorophenol photodegradation efficiencies using ferrite-based nanocomposites. 70 On the other hand, ZnFe 2 O 4 36 and CuFe 2 O 4 70 were ineffective in 4-CP degradation, and higher catalyst loading may be required to further improve the 4-CP degradation efficiency.…”

“…The concentration of 2-CP was monitored by measuring the absorbance at λ = 237 nm, 31–33 following the protocol reported previously. 34–36 The % photocatalytic degradation efficiencies were calculated using the formula below.% Photocatalytic degradation efficiency = [( C 0 − C t )/ C 0 ] × 100where C 0 is the initial concentration of the pollutant model (25 ppm) and C t is the concentration of the pollutant model after treatment after specific treatment times. To confirm the 2-CP degradation, the total organic carbon (TOC) values were measured for the treated 2-CP(aq).…”