Photocatalytic visible-light-driven removal of the herbicide imazapyer using nanocomposites based on mesoporous TiO 2 mo
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ORIGINAL ARTICLE
Photocatalytic visible‑light‑driven removal of the herbicide imazapyer using nanocomposites based on mesoporous TiO2 modified with Gd2O3 I. A. Mkhalid1 · J. L. G. Fierro2 · R. M. Mohamed1,3 · A. A. Alshahri1 Received: 25 April 2020 / Accepted: 4 June 2020 © King Abdulaziz City for Science and Technology 2020
Abstract In this work, mesoporous G d2O3-TiO2 nanocomposites synthetized by a sol–gel with vary G d2O3 concentration were investigated for photo-destruction of imazapyr herbicide waste. Textural, structural and surface properties of the synthetized nanocomposites are verified by N2 physisorption, X-ray diffractometry, HRTEM and various spectroscopic techniques (FTIR, DRS UV–Vis, Raman, PL and XPS). HRTEM micrographs of the calcined G d2O3-TiO2 revealed the existence of a mesoporous matrix consisting of homogeneously distributed T iO2 nanoparticles (NPs, 12 nm) which are decorated with Ga2O3 nanoparticles. It was found a reverse correlation between the amount of Gd2O3 concentration and the TiO2 nanoparticle size: the formation of smaller TiO2 nanoparticles was favored by the use of high Gd2O3 concentration. The photocatalytic efficiency of the synthetized G d2O3-TiO2 nanocomposites was appraised in the photo-destruction of imazapyr herbicide below visible-light irradiation. The best herbicide destruction was achieved using 3%Gd2O3-TiO2 photocatalyst and degraded the imazapyr herbicide 20.5 and 8.2 times faster than a commercial P25 and non-promoted TiO2, respectively, indicating that modification of TiO2 with Gd2O3 led to a significant improvement of photocatalyst efficiency. This was explained as due to a lessening of the apparent optical bandgap and the formation of a large amount of surface defect states favoring the separation between electrons and holes. Besides its high efficiency, the 3%Gd2O3-TiO2 photocatalyst demonstrated to be recyclable and stable in the visible-light-driven photocatalytic destruction of imazapyr herbicide. Keywords Imazapyr herbicide · Photodegradation · Mesoporous Gd2O3-TiO2 · Nanocomposite
Introduction Currently, diverse photodegradation procedures presents the most effectual means for destructing organic toxins in waste waters (Fujishima and Honda 1972; Shawky et al. 2019a; Mohamed et al. 2019; Park et al. 1999). In this sense, the anatase-type T iO2 materials demonstrated to be powerful nanophotocatalysts according to the high * I. A. Mkhalid [email protected] 1
Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Kingdom of Saudi Arabia
2
Sustainable Energy and Chemistry Group, Instituto de Catálisis y Petroleoquímica, CSIC, Marie Curie 2, Cantoblanco, 28049 Madrid, Spain
3
Advanced Materials Department, Central Metallurgical R&D Institute, CMRDI, P.O. Box 87, Helwan 11421, Cairo, Egypt
chemical solidity, nontoxicity and excessive activity. However, the large band gap of TiO2 (~ 3.25 eV) restricts its efficiency for the absorption of the visible range photons. An effic
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