A new continuous flow-through structured reactor for the photodegradation of aqueous contaminants

Room temperature sintering of polar ZnO nanosheets: III-Prevention

“…These structures usually have a low polarity, which is probably why no signs of room temperature sintering in these materials have ever been detected. Very high specific surface area (over 100 m 2 g -1 ) polar ZnO structures, such as those described in our previous works [4,5], are less common. Nevertheless, the specific surface area of mesoporous ZnO materials is of prime importance for many physicochemical and electrochemical applications [3,6,7], as well as for the development of new materials [4].…”

“…Dihydrated zinc acetate and urea powder (both from Sigma-Aldrich) were dissolved together in 100 mL of deionized water to obtain solutions of urea and Zn 2+ in molar concentrations of 1.00M and 0.05M, respectively. Next, 85-100 mg of Triton™ X-100 (from ChemLab NV) and 3 cm 3 of 5 ppm aqueous solution of monohydrated methylene blue (from Sigma Aldrich) were added to the synthesized solution [5]. The pH of the solution was then adjusted to 4.88 using a GLP21 pHmeter (Crison) by adding an appropriate amount of acetic acid (from J.T.…”

“…The analysed regions were deconvolved with the aid of Gaussian functions. To determine the point of zero charge (pHpzc) the pH drift method was used [5,16]. Briefly, 50 cm 3 aqueous solutions of NaCl (0.01 M; from Sigma-Aldrich) with pH values in the 4-10 range were prepared by adding either HCl (0.1 M; from J.T.…”

“…Thus, the high surface area polar ZnO catalyst which was the object of our previous studies [1,2] is both an excellent photocatalyst [5] and the precursor of a variety of single and mixed metal oxide nanocatalysts of high specific surface area [4]. As a photocatalyst, the effect of its specific surface area on catalytic activity is not evident, since the activating light only illuminates the outermost surface of the catalyst and the adsorption of the contaminant depends both on the point of zero charge of the material and on the pH of the solution [5]. In its role as sacrificial template [4] the effect of the loss of specific surface area on the properties of the synthesized metal oxide nanoparticles is still unknown.…”

“…Nevertheless, the specific surface area of mesoporous ZnO materials is of prime importance for many physicochemical and electrochemical applications [3,6,7], as well as for the development of new materials [4]. Thus, the high surface area polar ZnO catalyst which was the object of our previous studies [1,2] is both an excellent photocatalyst [5] and the precursor of a variety of single and mixed metal oxide nanocatalysts of high specific surface area [4]. As a photocatalyst, the effect of its specific surface area on catalytic activity is not evident, since the activating light only illuminates the outermost surface of the catalyst and the adsorption of the contaminant depends both on the point of zero charge of the material and on the pH of the solution [5].…”