Centre of Nanotechnology, King Abdulaziz University, Jeddah, Saudi Arabia.
SABIC Plastic Application Development Center, Riyadh 11551, Saudi Arabia.
Methods. 2022 Mar;199:37-53. doi: 10.1016/j.ymeth.2021.09.004. Epub 2021 Sep 17.
Oil fly ash (OFA) is a byproduct generated by the burning of heavy crude oil in factories and power plants. Millions of tons of OFA is produced annually worldwide and is mostly treated as solid waste. Extensive efforts have been made to utilize OFA and reduce its environmental effects. Recently, OFA has been found to be a suitable catalyst and co-precursor for carbon nanotube (CNTs) production. However, the treatment methods used are expensive and time consuming. Here, we describe a new method for OFA treatment and provide optimized growth conditions for CNTs production. Pre-sintering of OFA at elevated temperatures (400-450 °C) in air or vacuum using a chemical vapor deposition (CVD) tube furnace (80-100 min) is a very effective treatment method for CNTs growth under optimum growth conditions. The optimum parameters for CNTs growth were growth temperature, gas pressure, gas flow rate, and growth time. Well-defined, thin nanotubes with diameters of 20-40 nm were produced. Bamboo-like nanotubes with zigzag curved walls were also observed in the produced CNTs. The weight percentage of the produced CNTs was approximately twice that of the treated OFA. Consequently, the pre-sintering method exhibited suitability for the mass production of CNTs. Thus, large quantities of the nanomaterial can be supplied for use in various applications, e.g., polymer composites, the rubber industry, construction materials, and lubricant additives.
油飞灰（OFA）是工厂和发电厂燃烧重油产生的副产品。全球每年产生数百万吨的 OFA，大部分被视为固体废物。人们已经做出了大量努力来利用 OFA 并减少其对环境的影响。最近，OFA 已被发现是生产碳纳米管（CNTs）的合适催化剂和共前体。然而，所使用的处理方法既昂贵又耗时。在这里，我们描述了一种 OFA 处理的新方法，并提供了 CNTs 生产的优化生长条件。在空气或真空中使用化学气相沉积（CVD）管式炉在升高的温度（400-450°C）下对 OFA 进行预烧结（80-100 分钟）是在最佳生长条件下生长 CNTs 的非常有效的处理方法。CNTs 生长的最佳参数是生长温度、气压、气体流速和生长时间。生成的 CNTs 具有 20-40nm 的直径，且具有良好定义的薄壁。还观察到在生成的 CNTs 中存在具有锯齿形弯曲壁的竹状纳米管。生成的 CNTs 的重量百分比约为处理过的 OFA 的两倍。因此，预烧结方法适用于 CNTs 的大规模生产。因此，可以供应大量的纳米材料用于各种应用，例如聚合物复合材料、橡胶工业、建筑材料和润滑剂添加剂。
