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Sulfur Dioxide Degradation by Composite Photocatalysts Prepared by Recycled Fine Aggregates and Nanoscale Titanium Dioxide

by Xue-Fei Chen 1,2 and Shi-Cong Kou 1,2,*
1
School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
2
College of Civil and Transportation Engineering, Shenzhen University, Shenzhen 518000, China
*
Author to whom correspondence should be addressed.
Nanomaterials 2019, 9(11), 1533; https://doi.org/10.3390/nano9111533
Received: 21 October 2019 / Revised: 26 October 2019 / Accepted: 28 October 2019 / Published: 29 October 2019
To alleviate the heavy burden on landfilling, construction and demolition wastes (C&DWs) are recycled and reused as aggregates in cementitious materials. However, the inherent characteristics of recycled fine aggregates (RFA), such as the high crushing index and high-water absorption, magnify the reusing difficulty. Nevertheless, attributing to the high porosity and high level of calcium hydroxides existing in the old mortar, RFA is featured with a high specific surface area and a high alkalinity. These features are useful to augment the total photo-degradation of SO2 by nano-TiO2 (NT) intermixed mortar, leading RFA to be an excellent potential carrier to load nano-TiO2 and prepare the composite photocatalyst. Hence, this study proposed to load NT onto the surface of RFAs and river sands (RSs) (the control) by the soaking method, preparing composite photocatalysts denoted as [email protected] and [email protected], respectively. The prepared composite photocatalysts were then utilized as sands in photocatalytic mortar to evaluate for SO2 degradation. Experiments identified a 50% higher amount of NT was loaded onto the surface of FRA relative to the control. This higher loading amount plus higher alkalinity ultimately translated into a higher photocatalytic activity. In addition, the mortar containing [email protected] exhibited 46.3% higher physiochemical absorption and 23.9% higher photocatalytic activity than that containing [email protected] In addition, the durability, embodied by the reuse and anti-abrasive properties, of [email protected] exceeded that of [email protected] The overall findings reveal that the [email protected] not only garners beneficial effect from the high porosity but also generates positive effect from the high alkalinity. Though a number of studies deal with building materials with NT, this study is the first to load NT onto RFA and prepare composite photocatalysts which were then used as fine aggregates in building materials. Consequently, this study proves the potential high-added-value reusability of RFA in green construction materials and provides a low-cost, high-efficiency approach to degrade atmospheric SO2. View Full-Text
Keywords: construction waste; nano-TiO2; recycled fine aggregate; SO2 degradation; composite photocatalyst; photocatalytic mortar construction waste; nano-TiO2; recycled fine aggregate; SO2 degradation; composite photocatalyst; photocatalytic mortar
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MDPI and ACS Style

Chen, X.-F.; Kou, S.-C. Sulfur Dioxide Degradation by Composite Photocatalysts Prepared by Recycled Fine Aggregates and Nanoscale Titanium Dioxide. Nanomaterials 2019, 9, 1533.

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