School of Chemical Sciences, Universiti Sains Malaysia, Gelugor, Penang 11800, Malaysia.
School of Materials & Mineral Resources Engineering, Universiti Sains Malaysia, Nibong Tebal, Penang 14300, Malaysia.
Molecules. 2021 Apr 25;26(9):2509. doi: 10.3390/molecules26092509.
In this work, mesoporous TiO-modified ZnO quantum dots (QDs) were immobilised on a linear low-density polyethylene (LLDPE) polymer using a solution casting method for the photodegradation of tetracycline (TC) antibiotics under fluorescent light irradiation. Various spectroscopic and microscopic techniques were used to investigate the physicochemical properties of the floating hybrid polymer film catalyst (8%-ZT@LLDPE). The highest removal (89.5%) of TC (40 mg/L) was achieved within 90 min at pH 9 due to enhanced water uptake by the LDDPE film and the surface roughness of the hybrid film. The formation of heterojunctions increased the separation of photogenerated electron-hole pairs. The QDs size-dependent quantum confinement effect leads to the displacement of the conduction band potential of ZnO QDs to more negative energy values than TiO. The displacement generates more reactive species with higher oxidation ability. The highly stable film photocatalyst can be separated easily and can be repeatedly used up to 8 cycles without significant loss in the photocatalytic ability. The scavenging test indicates that the main species responsible for the photodegradation was O. The proposed photodegradation mechanism of TC was demonstrated in further detail based on the intermediates detected by LC-time-of-flight/mass spectrometry (LC/TOF-MS).
在这项工作中，采用溶液浇铸法将介孔 TiO 修饰的 ZnO 量子点（QD）固定在线性低密度聚乙烯（LLDPE）聚合物上，用于在荧光光照射下光降解四环素（TC）抗生素。使用各种光谱和显微镜技术研究了悬浮混合聚合物膜催化剂（8%-ZT@LLDPE）的物理化学性质。在 pH 9 下，在 90 分钟内，由于 LLDPE 薄膜的吸水性增强和混合薄膜的表面粗糙度，TC（40mg/L）的去除率最高达到 89.5%。异质结的形成增加了光生电子-空穴对的分离。QD 尺寸相关的量子限制效应导致 ZnO QD 的导带势向比 TiO 更负的能量值位移。这种位移产生了具有更高氧化能力的更多活性物质。高稳定性的薄膜光催化剂可以很容易地分离，并可重复使用 8 次以上，而光催化能力没有明显损失。清除试验表明，O 是光降解的主要物质。根据 LC-飞行时间/质谱（LC/TOF-MS）检测到的中间产物，进一步详细说明了 TC 的光降解机理。
