Mergola Lucia, Carbone Luigi, Stomeo Tiziana, Del Sole Roberta
Department of Engineering for Innovation, University of Salento, Via per Monteroni Km 1, 73100 Lecce, Italy.
National Nanotechnology Laboratory (NNL), Institute of Nanoscience CNR c/o Campus Ecotekne, Via Monteroni, 73100 Lecce, Italy.
Materials (Basel). 2023 Mar 2;16(5):2060. doi: 10.3390/ma16052060.
An environmentally friendly procedure was adopted for the first time to prepare green iridium nanoparticles starting from grape marc extracts. Grape marcs, waste of Negramaro winery production, were subjected to aqueous thermal extraction at different temperatures (45, 65, 80, and 100 °C) and characterized in terms of total phenolic contents, reducing sugars, and antioxidant activity. The results obtained showed an important effect of temperature with higher amounts of polyphenols and reducing sugars and antioxidant activity in the extracts with the increase of temperature. All four extracts were used as starting materials to synthesize different iridium nanoparticles (Ir-NP1, Ir-NP2, Ir-NP3, and Ir-NP4) that were characterized by Uv-Vis spectroscopy, transmission electron microscopy, and dynamic light scattering. TEM analysis revealed the presence of very small particles in all samples with sizes in the range of 3.0-4.5 nm with the presence of a second fraction of larger nanoparticles (7.5-17.0 nm) for Ir-NPs prepared with extracts obtained at higher temperatures (Ir-NP3 and Ir-NP4). Since the wastewater remediation of toxic organic contaminants on catalytic reduction has gained much attention, the application of the prepared Ir-NPs as catalysts towards the reduction of methylene blue (MB), chosen as the organic dye model, was evaluated. The efficient catalytic activity of Ir-NPs in the reduction of MB by NaBH was demonstrated and Ir-NP2 was prepared using the extract obtained at 65 °C, showing the best catalytic performance, with a rate constant of 0.527 ± 0.012 min and MB reduction of 96.1% in just six min, with stability for over 10 months.
首次采用一种环保方法，以葡萄渣提取物为原料制备绿色铱纳米颗粒。葡萄渣是内格罗玛罗酒庄生产过程中的废弃物，在不同温度（45、65、80和100℃）下进行水热提取，并对其总酚含量、还原糖和抗氧化活性进行了表征。结果表明，温度对提取物中多酚、还原糖和抗氧化活性的含量有重要影响，随着温度升高，这些成分的含量增加。所有四种提取物都用作起始原料，合成了不同的铱纳米颗粒（Ir-NP1、Ir-NP2、Ir-NP3和Ir-NP4），通过紫外可见光谱、透射电子显微镜和动态光散射对其进行了表征。透射电子显微镜分析表明，所有样品中都存在非常小的颗粒，尺寸在3.0-4.5纳米范围内，对于用较高温度（Ir-NP3和Ir-NP4）获得的提取物制备的铱纳米颗粒，还存在第二部分较大的纳米颗粒（7.5-17.0纳米）。由于催化还原有毒有机污染物的废水修复受到了广泛关注，因此评估了所制备的铱纳米颗粒作为催化剂对作为有机染料模型的亚甲基蓝（MB）还原的应用。结果表明，铱纳米颗粒在硼氢化钠还原亚甲基蓝的过程中具有高效的催化活性，用65℃获得的提取物制备的Ir-NP2表现出最佳的催化性能，速率常数为0.527±0.012 min，仅在6分钟内亚甲基蓝的还原率就达到96.1%，并且稳定性超过10个月。
