Layer-by-Layer Assembly and Photocatalytic Activity of Titania Nanosheets on Coal Fly Ash Microspheres

Abstract

In order to address the problem with titania distribution and recovery, series of Ti 0.91 O 2 /CFA photocatalysts (Ti 0.91 O 2 /CFA-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mrow><mml:mi>n</mml:mi></mml:mrow></mml:math>,<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mi>n</mml:mi><mml:mo>=</mml:mo><mml:mn>2,4</mml:mn><mml:mo>,</mml:mo><mml:mn>6,</mml:mn></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M3"><mml:mrow><mml:mn>8</mml:mn></mml:mrow></mml:math>) were fabricated by assembling Ti 0.91 O 2 nanosheets on coal fly ash (CFA) microspheres via the layer-by-layer assembly (LBLA) process and characterized by scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), N 2 -sorption, and ultraviolet-visible absorption (UV-vis) techniques. The SEM images and UV-vis spectra illustrated that Ti 0.91 O 2 nanosheets were immobilized successfully on the CFA by the LBLA approach and changed the characteristics of CFA noticeably. The photocatalytic activity of Ti 0.91 O 2 /CFA was evaluated by the photodegradation of methylene blue (MB) under UV irradiation. The results demonstrated that Ti 0.91 O 2 /CFA-6 showed the best photocatalytic activity among the series of Ti 0.91 O 2 /CFA irradiated for 60 min, with a decoloration rate above 43%. After photocatalysis, the Ti 0.91 O 2 /CFA could be easily separated and recycled from aqueous solution and Ti 0.91 O 2 nanosheets were still anchored on the CFA.