Controlling the Pore Size and Connectivity of Alumina-Particle-Stabilized Foams Using Sodium Dodecyl Sulfate: Role of Surfactant Concentration.

Herein, alumina foams were prepared from particle-stabilized foams, fabricated by direct foaming methods, that varied according to the concentration of sodium dodecyl sulfate (SDS). To confirm the formation mechanism of pore structures in alumina ceramic foams with varying SDS concentrations, the adsorption density, contact angle, ζ-potential, and surface tension of the alumina particles dispersed in SDS were analyzed. Additionally, model analysis was performed to confirm the interaction between alumina and air bubbles by applying the extended Derjaguin-Landau-Verwey-Overbeek model. The attachment of alumina particles to bubble surfaces at different SDS concentrations affected the pore structure of the ceramic foams; this confirmed that the attachment was significantly affected by the electrostatic interaction energy rather than hydrophobic interaction. Therefore, the pore size and connectivity of alumina foams could be controlled by varying the electrostatic interaction energy between alumina particles and air bubbles, which is determined by the SDS concentration.

Effect of Poly(vinyl alcohol) Concentration on the Micro/Mesopore Structure of SBA15 Silica.

In this work, a series of micro/mesoporous SBA15 silica materials were synthesized using P123 and poly(vinyl alcohol) (PVA) as co-templates. The pore structure of the prepared SBA15 was observed to be a function of the PVA concentration. When the amount of PVA was relatively small, the specific surface area, micropore volume, and pore wall thickness of the synthesized SBA15 were considerably large. By contrast, when a large amount of PVA was added, the pore wall thickness was greatly reduced, but the mesopore volume and size increased. This is because the added PVA interacted with the polyethylene oxide (PEO) in the shells of the P123 micelles. Furthermore, when the amount of PVA was increased, the core polypropylene oxide (PPO) block also increased, owing to the enhanced aggregation of the P123/PVA mixed micelles. This research contributes to a basic comprehension of the cooperative interactions and formation process underlying porous silica materials, assisting in the rational design and synthesis of micro/mesoporous materials.

Mesoporous Silica Derived from Municipal Solid Waste Incinerator (MSWI) Ash Slag: Synthesis, Characterization and Use as Supports for Au(III) Recovery.

In this study, the effect of NaOH on the synthesis of mesoporous silica (MS) by using municipal solid-waste incinerator (MSWI) ash slag was investigated. Moreover, the prepared MS was used as a support to evaluate its potential for the recovery of gold ions (Au(III)) from aqueous solution. The extraction process for the MSWI ash slag activated through mechanical grinding entailed alkali treatment, using varying concentrations of NaOH. The content of Si extracted from MSWI ash slag increased with the increasing grinding time and NaOH concentration. As the NaOH concentration increased, the pore structure (e.g., Brunauer-Emmett-Teller (BET) surface area and pore volume) of the synthesized MS improved. In addition, the amount of adsorbed Au(III) increased with increasing sulfur content immobilized on the support, and the sulfur content was in turn governed by the silanol content of the MS support. The adsorbent prepared by using the MS-3M support exhibited the highest Au(III) adsorption capacity (110.3 mg/g), and its adsorption-desorption efficiency was not significantly affected even after five adsorption-desorption cycles.