What is it about?
In this work, zinc-aluminum layered double hydroxides were synthesized with and without the presence of polyvinyl alcohol by co-formation and co-precipitation methods, respectively. The photocatalytic activity of the obtained nanocomposites was studied and a comparative analysis was performed. The mechanism of photocatalytic decomposition of Ponceau 4R (P4R) on the nanocomposites has been explained in detail by relating it to the compositional and structural properties of the nanocomposite. The structural and optical properties of nanocomposites are characterized by XRD, UV–vis, PL, and SEM in a pure state, dye loaded and after photodegradation. The bandgap of nanocomposites (Eg = 3,23 eV) was reduced after sorption (Eg = 3,1 eV) and photocatalytic degradation (Eg = 2,87 eV) of P4R. This result is in good agreement with basal spacing determined by XRD. To study the sunlight degradation of P4R at different initial concentrations (8, 12, 16, 20, 30, 40, 50 mg L-1), firstly sorption was developed with Langmuir and other isothermal models. The Langmuir constant value (KL = 0,102) of ZnAl-LDH/PVA is close to the Langmuir–Hinshelwood constant (KL-H = 0,094) obtained from the kinetics of the photodegradation in sunlight. The photocatalytic degradation of P4R onto the obtained nanocomposites follows the Langmuir-Hinshelwood kinetic model.
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Why is it important?
• Zinc-aluminum layered double hydroxides were synthesized with and without the presence of polyvinyl alcohol • A reduction in the optical bandgap energy of the ZnAl-LDH was achieved during the photodegradation of Ponceau 4R dye. • The photocatalytic degradation of P4R onto the obtained nanocomposites follows the theLangmuir-Hinshelwood kinetic model.
Perspectives
In this study, a reduction in the optical bandgap energy of the ZnAl- LDH/PVA nanocomposite was achieved during the photodegradation of dyes. On the other hand, by achieving intercalation in LDH, it was possible to control the kinetics of photodegradation, reduce electron-hole recombination, and complete mineralization. The electrons transferred to the conduction band are responsible for the reduction reactions due to the potential lying between +0,5 and -1,0 V. This band can mediate the reduction of inorganic ions, but can also generate importantly oxidant species, such as the superoxide anion (.O2-) and hydrogen peroxide.
Ofeliya Balayeva
Baku State University
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This page is a summary of: Photocatalytic degradation of Ponceau
4R
by
ZnAl
‐layered double hydroxide nanostructures obtained with and without polyvinyl alcohol, Journal of the Chinese Chemical Society, July 2022, Wiley,
DOI: 10.1002/jccs.202200121.
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