Vol.:(0123456789) 1 3 Journal of the Iranian Chemical Society https://doi.org/10.1007/s13738-018-01574-2 ORIGINAL PAPER Modeling and optimization of characterization of nanostructure anodized aluminium oxide membranes Hamed Azami 1  · Mohammad Reza Omidkhah 2 Received: 21 July 2018 / Accepted: 15 December 2018 © Iranian Chemical Society 2019 Abstract This study indicates the importance of statistical analysis and modeling to investigate the synthesis and optimization of anodized aluminium oxide (AAO) properties for template-assisted synthesis of nanostructure particles. The response surface methodology was used to optimize pore size and porosity of AAO. The impacts of four main parameters including type of acidic electrolyte, concentration of acid, bath temperature and electrical potential of anodization on characterization of AAO were investigated. Statistical analysis showed that the linear and quadratic terms of these variables had signifcant efects. Based on the statistical analysis, a possible mechanism of the anodization was proposed. The proposed mechanism helped us to develop an analytical model. The analytical model could predict the experimental results with an appropriate accuracy. Results indicated the rate-limiting reaction in anodization process is water dissociation which was conducted at the pore bot- tom of the AAO. In addition, concentrated electrical feld at pore base induced water splitting so that the activation energy of water dissociation decreased ten times and reached to 9898.5 J mol . Keywords Anodized aluminium oxide · Nanoporous materials · Electrochemical synthesis · Pore perforation · Statistical analysis Introduction Nowadays, nanostructured materials attract a great scien- tifc attention since they have unique characterization. These properties open the new insight to develop a variety of mod- ern technologies such as chemical processes, pharmaceutical science and electronic devices [1–3]. In this regard, exten- sive studies have been conducted to develop new, simple and non-expensive procedures to synthesize nanomaterials. Among them, template-assisted methods are the simple tech- niques which usually are applied to fabricate various nano- structure materials such as nanowires, nanotubes, nanodots and nonporous membrane [4–7]. Porous anodic aluminium oxide (AAO) membranes synthesized through anodization of aluminium in acidic electrolytes have become one of the most appropriate templates for nanofabrication [8–10]. A simple, two-step anodization of aluminium does not involve any sophisticated and expensive procedures [11, 12]. The porous aluminium oxide layer consists of honeycomb hex- agonal cells which contain vertically aligned nanopores. Research studies have revealed that there is a relation between various parameters including concentration of acidic electrolyte, electric potential of anodization and temperature of the process on the AAO membrane proper- ties and their separation efciency [13–15]. Therefore, it is essential to have a good understanding and control on inter- action of these parameters to obtain an AAO membrane with desirable characteristics. Montero-Moreno et al. studied the impact of the alumin- ium surface pretreatment and anodizing voltage on struc- ture of AAO membranes, produced by two-step anodiza- tion of aluminium foil in oxalic acid at 20 °C. The authors proposed three steps in the pretreatment of the aluminium surface consisting of degreasing by ethanol and acetone Electronic supplementary material The online version of this article (https://doi.org/10.1007/s13738-018-01574-2) contains supplementary material, which is available to authorized users. * Hamed Azami h.azami@ub.ac.ir 1 Department of Chemical Engineering, Faculty of Engineering, University of Bojnord, Bojnord, Iran 2 Department of Chemical Engineering, Tarbiat Modares University, Tehran 14155-4838, Iran