Synthesis of novel MTF aerogels with adsorption performance

• Published in: Journal of sol-gel science and technology Vol. 94; no. 3; pp. 582 - 595
• Main Authors: Zhen-Tao, Q. I., Fang, H. E.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.06.2020; Springer Nature B.V
• Subjects: Adsorption; Aerogels; Ceramics; Chemistry and Materials Science; Composites; Copper; environment and building applications; Formaldehyde; Fourier transforms; Gelation; Glass; Infrared analysis; Inorganic Chemistry; Material properties; Materials Science; Melamine; Metal ions; Nanotechnology; Natural Materials; Noble metals; Optical and Electronic Materials; Original Paper: Sol-gel and hybrid materials for energy; Particle size distribution; Pore size distribution; Porosity; Porous materials; Resins; Selective adsorption; Silver; Specific surface; Surface area; Surface chemistry; Thioureas; Reaction mechanism; Gelation time; MTF aerogel; Sol–gel; Adsorption and selective adsorption capacity
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-019-05185-y

The designability of aerogels and the grafting capability of groups were used in this study. A novel type of aerogel based on melamine–formaldehyde (MF) aerogels was synthesized by introducing thiourea groups, and the changes in sol particle diameter, formation mechanism of wet gel, and gel time during the formation of wet gel were studied in detail. Laser particle size, Brunauer–Emmett–Teller, and Fourier transform infrared analyses were combined with scanning electron microscopy and other characterization methods. Results showed that the thiourea group was successfully introduced into the MF aerogels. The specific surface area of the melamine–thiourea–formaldehyde (MTF) aerogel was 439.3 m 2 /g, and the average pore diameter was as high as 1.8 nm without losing the typical 3D spatial network structure and porous material properties of aerogels. The change in particle diameter in the gelation process was systematically revealed for the first time, and the gelation time of wet gel was shortened to 218 min. The properties of aerogel porous materials and the complexing capability of amino and thiourea groups with regard to noble metal ions were used to test the performance of MTF aerogels in the adsorption and selective adsorption of noble metal ions. The findings indicated that the adsorption capacity of MTF aerogel was 88 mg·g −1 and the adsorption capacity of the MTF resin was 63 mg·g −1 , and the adsorption value of aerogel increased by 39% compared with MTF resin. In the selective adsorption experiment, the uptake values of MTF aerogel were found as 57.5 mg Ag + ·g −1 , 6.1 mg Cu 2+ ·g −1 , and 3.6 mg Zn 2+ ·g −1 . And the selective adsorption values of MTF resin were 16.3 mg Ag + ·g −1 , 0.1 mg Cu 2+ ·g −1 , and 0.05 mg Zn 2+ ·g −1 . The results show that the adsorption and selective adsorption capacity of MTF aerogel to silver (I) ions was higher than MTF resin. It was seen that the MTF aerogel prepared in this study has a large specific surface area, uniform pore size distribution, and strong adsorption and selective adsorption capacity for noble metals. It provides a new method for the selective adsorption of noble metal ions. The preparation of the aerogel is also simple and quick and entails a short gelation time and low cost. The formation mechanism of MTF aerogels was revealed, meanwhile, comparing before and after the adsorption and selective adsorption of precious metal ions by MTF aerogel, it can be confirmed that the MTF aerogel was successfully synthesized and possessed better adsorption and selective adsorption for precious metal ions. Highlights The melamine-thiourea-formaldehyde (MTF) aerogel containing thiourea group was fabricated. The gelation time of wet gel was shortened to 218 min. The MTF aerogels possess high specific surface area (439.3 m 2 /g) and total pire volume (2.3 cm 3 /g). The adsorption and selective adsorption values of MTF aerogels on silver (I) ions were 88 mg·g −1 and 57.5 mg·g −1 , respectively, which were higher than that of resins.