Interaction of sodium titanate nanotubes with organic acids and base: chemical, structural and morphological stabilities

Abstract

Este trabalho relata a interação de nanotubos de titanato de sódio (Na-TiNT) com soluções aquosas de ácido benzóico, ácido fenilfosfônico e anilina. Os Na-TiNT foram obtidos através do tratamento hidrotérmico de TiO 2 em solução aquosa de NaOH. Os resultados obtidos através de FTIR, XRD, TEM e análise elementar mostraram que a estabilidade química, estrutural e morfológica dos nanotubos está relacionada à natureza química do meio (básico ou ácido) e às condições de tratamento (temperatura e tempo de contato). A fase α-fenilfosfonato de titânio(IV) foi formada a partir da interação dos Na-TiNT com ácido fenilfosfônico; a quantidade da nova fase foi dependente do tempo de contato e sua cristalinidade da temperatura. Porém, TiO 2 ou nanotubo de titanato contendo H + foram obtidos, em função das condições de tratamento, a partir da interação dos Na-TiNT com ácido benzóico. Quando os Na-TiNT interagiram com a anilina nenhuma mudança estrutural, morfológica ou composicional foi observada.This work reports the interaction of sodium titanate nanotubes (Na-TiNT) with aqueous solutions of benzoic and phenylphosphonic acids and of aniline. The Na-TiNT were obtained from hydrothermal treatment of TiO 2 in aqueous NaOH solution. The results obtained from FTIR, XRD, TEM and elemental analyses showed that the chemical, structural and morphological stability of the nanotubes is related to the medium (acidic or basic) and to the treatment conditions (temperature and contact time). A titanium(IV) α-phenylphosphonate phase was obtained from interaction between Na-TiNT and phenylphosphonic acid. The amount and crystallinity of the new phase were dependent of the contact time and temperature, respectively. On the other hand, TiO 2 or protonrich titanate nanotubes were formed, depending on treatment conditions, from interaction between Na-TiNT and benzoic acid. When Na-TiNT interacted with aniline, no chemical, morphological or compositional change was observed.Keywords: titanium oxide, titanium oxide nanotubes, phase transformation, adsorption, carboxylic acid IntroductionIntensive investigation on physical and chemical properties of inorganic one-dimensional (1D) nanostructures such as nanotubes, nanofibers and nanorods has been reported. 1 In particular, titanate nanotubes have attracted great attention from the scientific community due to their potential applications in biosensors, electronic, optical, magnetic, electrochromic and solar cell devices, as well as in heterogeneous photocatalysis. [2][3][4][5][6][7][8][9] Additionally, 1D titanate nanostructures have also been used as support for the immobilization of myoglobin, 10 and as host for platinum oxide and lithium intercalation. 11,12 Titanate nanotubes can be prepared by hydrothermal treatment of TiO 2 powders (anatase or rutile) in aqueous NaOH solutions. 13,14 Although the preparation method is very simple, there is still a great debate in the literature related to the atomic structure and chemical composition of the nanotubes produced by this method. The exact determina...

Expeditious isomerization of glucose to fructose in aqueous media over sodium titanate nanotubes

“…Overall, the analyses result authenticated the expected structural property of the as-synthesized Na-TNT and found to be consistent with the literature reports. 25,30,31 Performance of Na-TNT on glucose to fructose isomerization Typical base catalyzed GI reaction follows the classical Lobry de Bruyn-Alberda van Ekenstein (LdB-AvE) rearrangement mechanism. 32 Accordingly, the postulated reaction mechanism scheme of the GI reaction in the presence of Na-TNT is depicted in Fig.…”

Gas Transport Properties of Polybenzimidazole and Poly(Phenylene Oxide) Mixed Matrix Membranes Incorporated with PDA-Functionalised Titanate Nanotubes

“…These nanotubes possess similar morphology as CNTs, but the synthesis is carried out at far lower temperatures and at low cost [26, 27]. Moreover, variations of TiNT compositions and structures may be practically unlimited and the possibility of functionalisation is a useful way of treatment that may improve adhesion to polymer matrices.…”

“…Moreover, variations of TiNT compositions and structures may be practically unlimited and the possibility of functionalisation is a useful way of treatment that may improve adhesion to polymer matrices. To date, most research about TiNTs has been directed towards the efficient synthesis and functionalisation of this filler as well on investigation of its unique morphology and physico-chemical properties [27–29]. However, almost all underlying studies about nanotubes for use in MMMs are connected to CNTs.…”

Superhydrophobic adhesive surface on titanate nanotube brushes through surface modification by capric acid

“…Layered metal hydroxide materials are generally unstable toward organic acids and bases because of their lower lattice enthalpy than that of the equivalent oxides [41]. Indeed, layered titanate structures collapse after reacting with phosphonic acid, short-chain carboxylic acids, and aniline [9,42]. When short-chain carboxylic acids are used for the surface modification of TNTs, they penetrate into the interlayers of the titanate structure, leading to the collapse of the TNTs and the formation of anatase nanoparticles [9].…”