Molecules, Vol. 23, Pages 1502: One-Dimension Diffusion Preparation of Concentration-Gradient Fe2O3/SiO2 Aerogel

Molecules, Vol. 23, Pages 1502: One-Dimension Diffusion Preparation of Concentration-Gradient Fe2O3/SiO2 Aerogel
Molecules doi: 10.3390/molecules23071502
Authors:
Ting Zhang
Haoran Wang
Bin Zhou
Xiujie Ji
Hongqiang Wang
Ai Du

Concentration-gradient Fe2O3/SiO2 aerogels were prepared by placing an MTMS (methyltrimethoxysilane)-derived SiO2 aerogel on an iron gauze with an HCl atmosphere via one-dimensional diffusion, ammonia-atmosphere fixing, supercritical fluid drying and thermal treatment. The energy dispersive spectra show that the Fe/Si molar ratios change gradually from 2.14% to 18.48% with a height of 40 mm. Pore-size distribution results show that the average pore size of the sample decreases from 15.8 nm to 3.1 nm after diffusion. This corresponds well with TEM results, indicating a pore-filling effect of the Fe compound. In order to precisely control the gradient, diffusion kinetics are further studied by analyzing the influence of time and position on the concentration of the wet gel. At last, it is found that the diffusion process could be fitted well with the one-dimensional model of Fick’s second law, demonstrating the feasibility of the precise design and control of the concentration gradient.

Source: Molecules - June 21, 2018 Category: Chemistry Authors: Ting Zhang Haoran Wang Bin Zhou Xiujie Ji Hongqiang Wang Ai Du Tags: Article Source Type: research