Ultrasound-promoted synthesis of high-porosity silica aerogels using embedded recycled PET fibers

Silica aerogel is fabricated through replacement of solvent by the air, so that this stage is of high relevance to achieve appropriate physical properties. Although, evaporation under ambient pressure is considered as simplest drying technique, but leads to irreversible shrinkage and collapse of gel network. Here, we improve the efficiency of ambient pressure drying via increasing the strength of gel network through physically reinforcement of the gel network using recycled polyethylene terephthalate (rPET) fibers. The polymeric phase of rPET was then removed from structure using thermal treatment. Also, the effect of using four different sonication time, from 5 to 35 min, on enhancement of aerogel properties was also investigated. the prepared silica aerogels exhibit a high surface area and porosity and using more sonication time was led to better properties. According to results, surface area and porosity were increased from 593 m2/g and 93% up to 691 m2/g and 96% by enhancing sonication time from 5 min to 35 min, respectively. The reason is thought to be related to create further dispersion among silanol groups and fibers surface. As well, the fabricated silica aerogels showed mesopores structure along with a narrow and uniform pore size. These results indicate the high efficiency of proposed method for synthesize of silica aerogel.