Visible-Light-Mediated Photodynamic Water Disinfection @ Bimetallic-Doped Hybrid Clay Nanocomposites

Author(s):Show less -

Ugwuja, Chidinma G. ^{[1, 2]} ; Adelowo, Olawale O. ^[3] ; Ogunlaja, Aemere ^{[1, 4]} ; Omorogie, Martins O. ^{[1, 2]} ; Olukanni, Olumide D. ^{[1, 2]} ; Ikhimiukor, Odion O. ^[3] ; Iermak, Ievgeniia ^[5] ; Kolawole, Gabriel A. ^{[1, 2, 6]} ; Guenter, Christina ^[7] ; Taubert, Andreas ^[8] ; Bodede, Olusola ^[9] ; Moodley, Roshila ^[9] ; Inada, Natalia M. ^[5] ; de Camargo, Andrea S. S. ^[5] ; Unuabonah, Emmanuel I. ^{[1, 2, 5]}

Affiliation

^[1] Redeemers Univ, African Ctr Excellence Water & Environm Res ACEWA, PMB 230, Ede 220005, Osun State - Nigeria

^[2] Redeemers Univ, Dept Chem Sci, PMB 230, Ede 220005, Osun State - Nigeria

^[3] Univ Ibadan, Dept Microbiol, PMB 5116, Ibadan 200284, Oyo State - Nigeria

^[4] Redeemers Univ, Dept Biol Sci, PMB 230, Ede 220005, Osun State - Nigeria

^[5] Univ Sao Paulo, Sao Carlos Inst Phys, Ave Trabalhador Saocarlense 400, BR-13566590 Sao Carlos, SP - Brazil

^[6] Univ Zululand, Dept Chem, ZA-3886 Kwa Dlangezwa - South Africa

^[7] Univ Potsdam, Inst Geosci, D-14476 Golm - Germany

^[8] Univ Potsdam, Inst Chem, D-14476 Golm - Germany

^[9] Univ KwaZulu Natal, Sch Chem & Phys, Westville Campus, ZA-3630 Durban - South Africa

• Document type: Journal article
• Source: ACS APPLIED MATERIALS & INTERFACES; v. 11, n. 28, p. 25483-25494, JUL 17 2019.
• Web of Science Citations: 1

Abstract

This study reports a new class of photocatalytic hybrid clay nanocomposites prepared from low-cost sources (kaolinite clay and Carica papaya seeds) doped with Zn and Cu salts via a solvothermal process. X-ray diffraction analysis suggests that Cu-doping and Cu/Zn-doping introduce new phases into the crystalline structure of Kaolinite clay, which is linked to the reduced band gap of kaolinite from typically between 4.9 and 8.2 eV to 2.69 eV for Cu-doped and 1.5 eV for Cu/Zn hybrid clay nanocomposites (Nisar, J.; Arhammar, C.; Jamstorp, E.; Ahuja, R. Phys. Rev. B 2011, 84, 075120). In the presence of solar light irradiation, Cu- and Cu/Zn-doped nanocomposites facilitate the electron hole pair separation. This promotes the generation of singlet oxygen which in turn improves the water disinfection efficiencies of these novel nanocomposite materials. The nanocomposite materials were further characterized using high-resolution scanning electron microscopy, fluorimetry, therrnogravimetric analysis, and Raman spectroscopy. The breakthrough times of the nanocomposites for a fixed bed mode of disinfection of water contaminated with 2.32 x 10(7) cfu/mL E. coli ATCC 25922 under solar light irradiation are 25 h for Zn-doped, 30 h for Cu-doped, and 35 h for Cu/Zn-doped nanocomposites. In the presence of multidrug and multimetal resistant strains of E. coli, the breakthrough time decreases significantly. Zn-only doped nanocomposites are not photocatalytically active. In the absence of light, the nanocomposites are still effective in decontaminating water, although less efficient than under solar light irradiation. Electrostatic interaction, metal toxicity, and release of singlet oxygen (only in the Cu-doped and Cu/Zn-doped nanocomposites) are the three disinfection mechanisms by which these nanocomposites disinfect water. A regrowth study indicates the absence of any living E. coli cells in treated water even after 4 days. These data and the long hydraulic times (under gravity) exhibited by these nanocomposites during photodisinfection of water indicate an unusually high potential of these nanocomposites as efficient, affordable, and sustainable point-of-use systems for the disinfection of water in developing countries. (AU)

• FAPESP's process: 17/26803-3 - Reconstruction of lignocellulosic materials in ionic liquids for the preparation of new functionalized porous hybrid materials (PHMs) for disinfection of water
• Grantee: Andrea Simone Stucchi de Camargo Alvarez Bernardez
• Support Opportunities: Research Grants - Visiting Researcher Grant - International
• FAPESP's process: 13/07793-6 - CEPIV - Center for Teaching, Research and Innovation in Glass
• Grantee: Edgar Dutra Zanotto
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC