Using Si/SiC solid waste to design urchin‐like mullite whiskers for oil‐water separation

Abstract

Using recyclable industrial waste Si/SiC and Al2(SO4)3 as starting materials, urchin‐like mullite whiskers were successfully synthesized via the molten salt method. The characterizations were focused on the phase transformations and morphology evolution of mullite whiskers. The circular oxidation‐dissolution‐precipitation mechanism was proposed for the growth of urchin‐like mullite whiskers. Then, the pressing‐sintering process was used for fabricating porous whisker‐structured mullite ceramics for oil‐water separation applications. Physical properties of porous ceramic, including bulk density, apparent porosity, mechanical and thermal shock resistance were measured. It was found that excessive reaction temperature could decompose the mullite, and a suitable temperature for pure urchin‐like mullite whiskers was found to be 900°C. To achieve oil‐water separation, bionic surface grafting technology was used for coating a hydrophobic and lipophilic material (octadecylamine, ODA) on mullite ceramic. Oil adsorption capacities of the ceramic/ODA for various oils, that is, .27 and .24 g/g for cooking and motor oil, respectively, were successfully achieved.

Influence of additive contents on the properties of SiC ceramic membranes and their performance in oil‐water separation

“…The bionic surface grafting technology was used for coating with hydrophobic and lipophilic material like octadecylamine and reported very good oil adsorption capacities for various oils. 15 Recently Pittruff et al evaluated the filtration efficiency of a complete module (core and membrane) in a real filtration device, where the core of the discs was prepared using the Rauschert RaFo-MF-401 and membrane was manufactured using mixture of alumina and SiO 2 powders. The material exhibited good microfiltration efficiency, resistance against acids, alkalis and thermal-shocks, as well as moderate three-point mechanical strength.…”

“…prepared the porous urchin‐like mullite ceramics with high porosity using Si/SiC solid waste and Al 2 (SO 4 ) 3 , by the traditional pressing‐sintering process. The bionic surface grafting technology was used for coating with hydrophobic and lipophilic material like octadecylamine and reported very good oil adsorption capacities for various oils 15 . Recently Pittruff et al.…”

Analysis of Influencing Factors in the Preparation of Mullite Whiskers from Recovering Silicon-Rich Waste under Low-Temperature Conditions

“…Among the inorganic whiskers, mullite whiskers belong to the composition series of orthogonal aluminosilicates with a general composition of Al 2 (Al 2+2x Si 2−2x )O 10−x , x between about 0.2 and 0.9 (about 55 to 90 mol% Al 2 O 3 ) [ 1 ]. They effectively improve the mechanical properties of materials and prevent the development of cracks by significantly increasing flexural strength and fracture toughness, which enables them to be widely used in the field of ceramic and metal matrix composites [ 2 , 3 , 4 , 5 , 6 ]. The crystallographic direction parallel to the c-axis, in which mullite crystals grow much faster than in other directions, is advantageous for the synthesis of mullite whiskers with a high degree of orientation [ 7 , 8 ].…”

Preparation of Self-Coating Al2O3 Bonded SiAlON Porous Ceramics Using Aluminum Dross and Silicon Solid Waste under Ambient Air Atmosphere

“…Moreover, this can be achieved without any separation treatment for aluminum dross. Coincidentally, massive amounts of silicon solid waste are generated in the process of crystal silicon cutting during the development of the photovoltaic industry [ 27 , 28 ]. Researchers have focused on the effective recovery of high purity Si from silicon solid wastes for the sustainable development of photovoltaic industry, and various methods have been developed [ 29 , 30 , 31 , 32 ].…”