Chen Xue-Fei, Kou Shi-Cong
School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
College of Civil and Transportation Engineering, Shenzhen University, Shenzhen 518000, China.
Nanomaterials (Basel). 2019 Oct 29;9(11):1533. doi: 10.3390/nano9111533.
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 SO by nano-TiO (NT) intermixed mortar, leading RFA to be an excellent potential carrier to load nano-TiO 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 NT@RFA and NT@RS, respectively. The prepared composite photocatalysts were then utilized as sands in photocatalytic mortar to evaluate for SO 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 NT@RFA exhibited 46.3% higher physiochemical absorption and 23.9% higher photocatalytic activity than that containing NT@RS. In addition, the durability, embodied by the reuse and anti-abrasive properties, of NT@RFA exceeded that of NT@RS. The overall findings reveal that the NT@RFA 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 SO.
为减轻填埋负担，建筑与拆除废物（C&DWs）被回收并作为胶凝材料中的骨料再利用。然而，再生细骨料（RFA）的固有特性，如高破碎指数和高吸水率，加大了再利用难度。尽管如此，由于旧砂浆中存在高孔隙率和高氢氧化钙含量，RFA具有高比表面积和高碱度的特点。这些特性有助于增强纳米TiO₂（NT）掺杂砂浆对SO₂的总光降解效果，使RFA成为负载纳米TiO₂并制备复合光催化剂的优异潜在载体。因此，本研究提出通过浸泡法将NT负载到RFA和河砂（RSs，作为对照）表面，分别制备复合光催化剂NT@RFA和NT@RS。然后将制备的复合光催化剂用作光催化砂浆中的砂来评估对SO₂的降解情况。实验表明，相对于对照，RFA表面负载的NT量高50%。这种更高的负载量加上更高的碱度最终转化为更高的光催化活性。此外，含NT@RFA的砂浆比含NT@RS的砂浆表现出高46.3%的物理化学吸附和高23.9%的光催化活性。此外，NT@RFA在再利用和抗磨性能方面体现出的耐久性超过了NT@RS。总体研究结果表明，NT@RFA不仅从高孔隙率中获得有益效果，还从高碱度中产生积极影响。尽管有许多研究涉及含NT的建筑材料，但本研究首次将NT负载到RFA上并制备复合光催化剂，然后将其用作建筑材料中的细骨料。因此，本研究证明了RFA在绿色建筑材料中潜在的高附加值再利用性，并提供了一种低成本、高效率降解大气中SO₂的方法。
