Efficient photodecomposition of herbicide imazapyr over mesoporous Ga2O3-TiO2 nanocomposites

Adel A Ismail; Ibrahim Abdelfattah; M Faisal; Ahmed Helal

doi:10.1016/j.jhazmat.2017.08.046

Efficient photodecomposition of herbicide imazapyr over mesoporous Ga₂O₃-TiO₂ nanocomposites

J Hazard Mater. 2018 Jan 15:342:519-526. doi: 10.1016/j.jhazmat.2017.08.046. Epub 2017 Aug 23.

Authors

Adel A Ismail¹, Ibrahim Abdelfattah², M Faisal³, Ahmed Helal⁴

Affiliations

¹ Wastewater Treatment and Reclamation Technologies (WTRT), Water Research Center, Kuwait Institute for Scientific Research, P.O. Box 24885, Safat 13109, Kuwait; Advanced Materials Department, Central Metallurgical R&D Institute, CMRDI, P.O. Box 87, Helwan 11421, Cairo, Egypt. Electronic address: adelali141@yahoo.com.
² Water Pollution Research Dept., National Research Centre, 33 EL Bohouth St.(Former EL Tahrir St.), P.O. 12622, Dokki, Giza, Egypt.
³ Advanced Materials and Nano-Research Centre, Najran University, P.O. Box: 1988, Najran 11001, Saudi Arabia.
⁴ Advanced Materials Department, Central Metallurgical R&D Institute, CMRDI, P.O. Box 87, Helwan 11421, Cairo, Egypt.

PMID: 28886564
DOI: 10.1016/j.jhazmat.2017.08.046

Abstract

The unabated release of herbicide imazapyr into the soil and groundwater led to crop destruction and several pollution-related concerns. In this contribution, heterogeneous photocatalytic technique was employed utilizing mesoporous Ga₂O₃-TiO₂ nanocomposites for degrading imazapyr herbicide as a model pollutant molecule. Mesoporous Ga₂O₃-TiO₂ nanocomposites with varied Ga₂O₃ contents (0-5wt%) were synthesized through sol-gel process. XRD and Raman spectra exhibited extremely crystalline anatase TiO₂ phase at low Ga₂O₃ content which gradually reduced with the increase of Ga₂O₃ content. TEM images display uniform TiO₂ particles (10±2nm) with mesoporous structure. The mesoporous TiO₂ exhibits large surface areas of 167m²g^-1, diminished to 108m²g^-1 upon 5% Ga₂O₃ incorporation, with tunable mesopore diameter in the range of 3-9nm. The photocatalytic efficiency of synthesized Ga₂O₃-TiO₂ nanocomposites was assessed by degrading imazapyr herbicide and comparing with commercial photocatalyst UV-100 and mesoporous Ga₂O₃ under UV illumination. 0.1% Ga₂O₃-TiO₂ nanocomposite is considered the optimum photocatalyst, which degrades 98% of imazapyr herbicide within 180min. Also, the photodegradation rate of imazapyr using 0.1% Ga₂O₃-TiO₂ nanocomposite is nearly 10 and 3-fold higher than that of mesoporous Ga₂O₃ and UV-100, respectively. The high photonic efficiency and long-term stability of the mesoporous Ga₂O₃-TiO₂ nanocomposites are ascribed to its stronger oxidative capability in comparison with either mesoporous TiO₂, Ga₂O₃ or commercial UV-100.

Keywords: Ga(2)O(3)-TiO(2); Imazapyr herbicide; Mesoporous; Nanocomposites; Photodegradation.