Zaib Qammer, Jouiad Mustapha, Ahmad Farrukh
Department of Civil, Infrastructure and Environmental Engineering and Materials Science & Engineering, Khalifa University of Science and Technology, Masdar City Campus, P.O. Box 54224, Abu Dhabi, UAE.
Department of Civil and Environmental Engineering, University of Ulsan, 93 Daehakro, Ulsan 680-749, South Korea.
ACS Omega. 2019 Jan 8;4(1):535-545. doi: 10.1021/acsomega.8b02706. eCollection 2019 Jan 31.
In this study, the central composite design of response surface methodology was applied to optimize the ultrasonic synthesis of multiwalled carbon nanotube-titanium dioxide (MWNT-TiO) composites. Twenty composites were prepared by adjusting three parameters (MWNT concentration in water, sonication to disperse/exfoliate MWNTs in water, and sonication to attach TiO onto MWNTs) at five levels. On the basis of the experimental design, semiempirical expressions were developed, analyzed, statistically assessed, and subsequently applied to predict the impact of the studied parameters on composite synthesis. The composite synthesis process was optimized to capture the experimental conditions favoring the highest productivity (i.e., MWNT-TiO formation or percent TiO attachment) utilizing minimal resources. The synthesis process optimization results showed that, to make a MWNT-TiO composite in 10 mL of water, 23.2 mg (∼99% of 23.4 mg) of TiO can be attached to 2.6 mg of MWNTs. This process requires only 727 J sonication energy, of which 592 J is invested to exfoliate MWNTs (Sonication 1) and 135 J to attach TiO (Sonication 2) to MWNTs. Finally, the optimally synthesized composite was extensively characterized using SEM, surface area and porosity analysis, TGA, and ζ-potential analysis/DLS. Also, this composite was tested for stability under variable pH and solvent polarity. The approach developed in this study could be used to optimize the synthesis process of other similar composites.
在本研究中，采用响应面法的中心复合设计来优化多壁碳纳米管 - 二氧化钛（MWNT - TiO）复合材料的超声合成。通过在五个水平上调整三个参数（水中MWNT的浓度、使MWNT在水中分散/剥离的超声处理以及使TiO附着在MWNT上的超声处理）制备了20种复合材料。基于实验设计，开发了半经验表达式，进行了分析、统计评估，随后用于预测所研究参数对复合材料合成的影响。利用最少的资源对复合材料合成过程进行了优化，以获取有利于最高生产率（即MWNT - TiO的形成或TiO附着百分比）的实验条件。合成过程优化结果表明，要在10 mL水中制备MWNT - TiO复合材料，23.2 mg（约占23.4 mg的99%）的TiO可以附着在2.6 mg的MWNTs上。该过程仅需要727 J的超声能量，其中592 J用于剥离MWNTs（超声处理1），135 J用于使TiO附着（超声处理2）到MWNTs上。最后，使用扫描电子显微镜（SEM）、表面积和孔隙率分析、热重分析（TGA）以及ζ电位分析/动态光散射（DLS）对优化合成的复合材料进行了广泛表征。此外，还测试了该复合材料在不同pH值和溶剂极性下的稳定性。本研究中开发的方法可用于优化其他类似复合材料的合成过程。
