Aerogel as an advanced nanostructure is being used as a suitable adsorbent for organic and petroleum pollutant removal from water due to its unique properties such as high porosity and specific surface area, low density, good biocompatibility, reusability, and the possibility of oil recovery and its potential of modification by functional groups. The other works on petroleum pollution removal by aerogel are limited to the use of hydrophobic silica aerogel granules and chemical interactions between the adsorbent and oil. While the oil physical absorption mechanism affected by the pore structure of aerogel has been investigated, restrictively. On the other hand, the use of fibrous materials containing aerogel (aerogel blanket) as an oil absorbent has been limitedly reported. Therefore, the investigation of the petroleum and oil absorption by the hydrophobic silica aerogels with different pore structures and aerogel blankets prepared from polypropylene nonwoven fabric was aimed in this work. Silica aerogel particles with different pore structures, physical properties, and hydrophobicity were synthesized via a two-step sol-gel process, modification by trimethylchlorosilane (TMCS), and ambient pressure drying. The aerogel blanket samples were prepared by the in situ synthesis of aerogel particles on the nonwoven fabric. The aerogel granules and blankets were characterized by using the FE-SEM, nitrogen absorption and desorption analysis, FTIR, and contact angle tests, and then their petroleum and oil absorption capacity was eva‎luated. The results revealed that the oil absorption by the hydrophobic aerogel sample with an average pore size of 29 nm and a pore volume of 4.02 cm3/g improved 5-fold compared to the hydrophilic aerogel sample with an average pore size of 6 nm and a pore volume of 1.64 cm3/g. Also, an increase of 3-fold in the engine oil absorption performance of the hydrophobic aerogel sample was achieved by increasing the average pore size and the total pore volume. Aerogel blanket samples with different aerogel synthesis conditions, types of nonwoven layers, and coating methods were synthesized and the effect of different factors on their petroleum and oil absorption was eva‎luated. In most of the previous works, aerogel blanket has been prepared via the immersing textile layer in the silica sol which required a large sol volume leading to the obstruction of macro pores of the textile in the in situ synthesis method. This makes it difficult to mass transfer the petroleum and oil into the blanket structure which decreases the oil and petroleum adsorption capacity of the aerogel blanket as an absorbent. In the present work to prepare the aerogel blanket by in situ synthesis method, the low volume of silica sol sprayed on the fabric surface while preserving the macro pore of the fabric layer leads to the better mass transfer of petroleum or oil into the aerogel blanket structure. The results showed that the engine oil absorption of the obtained blanket improved by more than 60% compared to the blanket sample prepared by the conventional immersion method. In optimal conditions, the crude petroleum absorption performance of the aerogel blanket increased by 106% and 45% respectively, compared to the aerogel particles and the control fabric layer. Also, an increase of 25% and 80% in the crude petroleum absorption into the aerogel blanket and the control nonwoven layer respectively, was achieved by designing a three-layer fibrous structure including two PP nonwoven layers and an aerogel blanket.

زهرا طالبي مزرعه‌شاهي، پرهام سلطاني

مصطفي يوسفي، حسين فشندي