Reactively sintered porous MgAl2O4 for water-purification filter with controlled particle morphology

Abstract

Porous MgAl 2 O 4 filters were prepared by reactive sintering of a MgCO 3 (basic) powder and 4-type Al 2 O 3 source powders with different particle size and phases (-Al 2 O 3 , fine and coarse boehmite AlOOH, and -Al 2 O 3). The mixed powder compacts were reactively sintered in air at 1200, 1400 or 1600 °C for 2 h to obtain MgAl 2 O 4. Single-phase porous MgAl 2 O 4 was successfully obtained by the reactive sintering at 1400 and 1600 °C. From the SEM observation, the initial particle sizes of Al 2 O 3 sources strongly affected the final microstructure of porous MgAl 2 O 4 , rather than the phases of Al 2 O 3 sources. The porous MgAl 2 O 4 filter made from fine boehmite source exhibited good performance to remove submicron-sized colloidal particles (simulating bacteria) from a suspension. Possibility of the thermal recovery of porous MgAl 2 O 4 filter was demonstrated.

Reactive sintering and particle morphology control of β″-alumina-based water purification filters

“…The pore-size distribution was determined by mercury intrusion porosimetry (PoreMaster-60-GT, Quantachrome). Washburn equation was used to calculate the pore size, where mercury surface tension is 480 dyne/cm and mercury contact angle is 140° [30].…”

“…The effective filtration area was 22 mm in diameter. bacteria-contaminated water [29,30]. The turbidity of the initial suspension was 894.4 NTU.…”

“…It is note-worthy that water purification filters consisting of MgAl2O4 spinel equiaxed grains were suitable for more precise filtration, but the filtration-rate became much slower (~0.20 mL/min in the similar experimental conditions of Ref. 29) [30].…”

Reactive synthesis of porous MgAl₂O₄ membranes on a macroporous Al₂O₃-based ceramic tube toward cross-flow ultrafiltration

“…For the nanofiltration and the reverse osmosis, porous membranes made of zeolite or polycrystalline TiO 2 on macroporous ceramics are currently used. 13)19) Recently, our group has focused on porous ceramic filters made of MgAl 2 O 4 spinel, 20) due to its excellent thermal and chemical stability. 21)23) In the previous study, porous MgAl 20) Rod-like MgCO 3 (basic) micrometer-sized particles thermally decompose into MgO nanoparticles at ³500°C, which are chemically active for the double-oxide synthesis.…”

“…13)19) Recently, our group has focused on porous ceramic filters made of MgAl 2 O 4 spinel, 20) due to its excellent thermal and chemical stability. 21)23) In the previous study, porous MgAl 20) Rod-like MgCO 3 (basic) micrometer-sized particles thermally decompose into MgO nanoparticles at ³500°C, which are chemically active for the double-oxide synthesis. 24) Even with a simple dead-end type setting, the porous MgAl 2 O 4 filter made from a fine boehmite source exhibited good microfiltration performance to remove submicron-sized colloidal particles (i.e., simulating bacteria) from a suspension.…”