Browsing by Author "Díaz Uribe, Carlos"

Now showing 1 - 3 of 3
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    Cyanobacterial Biomass Pigments as Natural Sensitizer for TiO2 Thin Films
    (2019) Patiño Camelo, Karen; Díaz Uribe, Carlos; Gallego Cartagena, Euler; Vallejo, William; Martínez, Vincent; Quiñones, César; Hurtado, Michel; Schott Verdugo, Eduardo Enrique
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    Improvement of the photocatalytic activity of TiO2 using Colombian Caribbean species (Syzygium cumini) as natural sensitizers : experimental and theoretical studies
    (2018) Díaz Uribe, Carlos; Vallejo, William; Campos, Karina; Solano, Wilfrido; Andrade, Javier; Muñoz Acevedo, Amner; Schott Verdugo, Eduardo Enrique; Zarate, Ximena
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    Study of methylene blue removal and photocatalytic degradation on zirconia thin films modified with Mn-Anderson polyoxometalates
    (2024) Florez, Jiress; Díaz Uribe, Carlos; Vallejo, William; Duran, Freider; Puello, Esneyder; Salazar Canas, Javier Antoni; Zarate, Ximena; Schott Verdugo, Eduardo Enrique
    Recalcitrant pollutants are challenging to degrade during water treatment processes. Methylene blue (MB), a cationic dye, is particularly resistant to degradation and is environmentally persistent. Heterogeneous photocatalysis has emerged as a suitable strategy for removing such pollutants from water. In this work, ZrO2 thin films were modified with Anderson-type Mn-polyoxometalate (MnPOM) ((NH4)3[MnMo6O24H6]), and the efficiency of MB removal from water was studied. ZrO2 was synthesized by a sol-gel method, with thin films deposited using the doctor blade method, and ZrO2 thin films were modified using chemisorption method. The synthesized materials were characterized using SEM, EDX, UV-Vis diffuse reflectance spectroscopy and FTIR. The adsorption kinetics and isotherms for MB were studied for both bare ZrO2 and ZrO2/MnPOM composites. Optical characterization showed a band gap energy of 4.02 eV for bare ZrO2, while the ZrO2/MnPOM composite exhibited a band gap of 3.7 eV. Furthermore, ZrO2 showed lower MB removal capacity (similar to 8%) than ZrO2/MnPOM thin films (similar to 29%). The isothermal adsorption studies indicated that MB adsorption onto both bare ZrO2 and ZrO2/MnPOM followed the Langmuir adsorption model (qm = 20.6 mg g-1 for ZrO2 and qm = 62.9 mg g-1 for ZrO2/MnPOM). Furthermore, the adsorption kinetics of MB were well described by a pseudo-second-order model. Photocatalytic testing under UV irradiation showed an apparent rate constant (kap) of 2 x 10-3 min-1 for bare ZrO2 and a value of kap 5.4 x 10-3 min-1 for ZrO2/MnPOM after 100 minutes. TD-DFT calculations revealed an LMCT interaction between the ZrO2 nanoparticle and the MnPOM, which likely contributes to the enhanced photocatalytic activity of the ZrO2/MnPOM composite.