Facile Synthesis of Marshmallow‐like Macroporous Gels Usable under Harsh Conditions for the Separation of Oil and Water

Abstract

The separation of oil and water is an important pursuit for saving endangered environments. In 2010, the Gulf of Mexico oil spill widely and seriously damaged the ocean and coast near the oilfield. The number of similar accidents is increasing with the development of industry, and materials that can reduce environmental pollution are in high demanded. At the same time, in the area of analytical chemistry, the efficient separation of molecules is a key technique, which determines the efficiency and accuracy of chemical analysis and detection. For these purposes, hydrophobic porous materials are in common use, because hydrophobic surfaces effectively adsorb/absorb oily target compounds that are mixed with an aqueous phase. Therefore, many researchers have been studying hydrophobic porous materials and their application as oil/water separation media. [1] Various chemical compositions have been investigated, such as carbon-based materials, [2] metal oxide nanowires (such as manganese [3,4] ), biomass nanofibers (such as cellulose [5,6] ), organic polymers (such as polyester, [7] polydivinylbenzene, and polythiophene [8] ) and hydrophobic macroporous aerogels. [9,10] Other materials based on polydimethylsiloxane (PDMS) or fluorocarboncoated materials, [3,7,10, 11] and the design of a biomimetic rough surface, through the use of etching techniques, to enhance hydrophobicity [6,12] are also widely reported. However, these methods have problems such as complicated and lengthy processes and high costs for reagents and devices, which prevents the use of these materials in practical and commercial applications.We have investigated hydrophobic porous polymethylsilsesquioxane (PMSQ, CH 3 SiO 1.5 ) materials, derived from methyltrimethoxysilane (MTMS), consisting of transparent aerogels and xerogels with mesoporous to macroporous monoliths that are created by controlling phase separation in the sol-gel process. [13] Polymethylsilsesquioxane gels have a superhydrophobic surface owing to methyl groups that are directly bonded to silicon atoms; this flexible network structure allows the material to spring back after compression. This mechanical feature allows the preparation of aerogel-like xerogels by ambient-pressure drying. Last year, we first reported bendable, marshmallow-like porous gels derived from a co-precursor system of MTMS and dimethyldimethoxysilane (DMDMS) in almost the same way as PMSQ gels. [14] Marshmallow-like gels not only show compression/ reexpansion properties similar to that of PMSQ gels, but also very soft and bendable mechanical features. A high sound absorption property has also been previously reported, owing to the soft networks. The flexiblity and intrinsic hydrophobicity indicate that these materials can be used like a sponge as an adsorption/absorption media for the quick removal of unwanted organic liquids. Herein, we report the outstanding capability of these materials for absorbing organic liquids over a wide temperature range, and discuss the possibility for their application as separation me...

Coating sponge with a hydrophobic porous coordination polymer containing a low-energy CF3-decorated surface for continuous pumping recovery of an oil spill from water

“…3,4 Thus far, various porous sorbents, such as resins, gels, carbon-based sponges/ solids and diverse polymeric materials, have been explored. [5][6][7][8] Previous studies have excessively focused on the oil sorption capacity, and the spilled oil has been recovered mainly via distillation and squeezing, [9][10][11][12] which are time-consuming, tedious and energydemanding and are thus seriously restricted in their practical application.…”

Flexible organofunctional aerogels

“…20 Nevertheless, there have been few reports of silsesquioxane aerogels that combine flexibility or bendability with active functional groups on their surface after sol-gel processing. [21][22][23] So far and to the best of our knowledge, there is no study published on the variability and accessibility of these functionalities. Herein, we describe the first systematic investigation of the co-condensation approach of MTMS and further organofunctional alkoxysilanes RSi(OMe) 3 with reactive functional groups, e.g.…”

Fabrics coated with hot-iron-treated graphene oxide for a self-cleaning and mechanically robust water–oil separation material

“…As we know, hydrophobic materials repel water and permit oil and low polarity organic solvents to ow through them. 21,22 Therefore, if the hydrophilic fabrics' surfaces were converted into hydrophobic materials by reduced GO through thermal treatment, they would be endowed with a hydrophobic feature. GO could be reduced with reducing agents such as sodium borohydride, hydrazine, and vitamin C. 20,[23][24][25] To simplify the preparation process, to further reduce the cost, and to avoid containment by other reducing agents, thermal reduction was chosen in our investigation as the method to achieve rGO.…”