Preparation of high-efficiency ceramic planar membrane and its application for water desalination

Abstract

Highly efficient Si 3 N 4 ceramic planar membrane for water desalination process using membrane distillation was prepared by the dual-layer phase inversion tape casting and sintering method. In comparison with typical phase inversion tape casting method, the green tape was formed using Si 3 N 4 slurry on the top and graphite slurry on the bottom. After consuming away the graphite structure, a ceramic membrane consisting of a two-layered structure (skin and finger-like layers) was obtained. The skin layer was relatively tight, and thus could act as a functional layer for separation, while the finger-like layer contained straight open pores with a diameter of 100 μm, acting as a support with low transport resistance. For comparison, typical Si 3 N 4 ceramic membrane was fabricated by phase inversion technique without graphite substrate, resulting in a three-layered structure (skin, finger-like, and sponge layers). After membrane modification from hydrophilic to hydrophobic with polymer derived nanoparticle method, the water desalination performance of the membranes was tested using the sweeping gas membrane distillation (SGMD) with different NaCl feed solutions. With the increase of salt content from 4 to 12 wt%, the water flux decreased slightly while rejection rate maintained over 99.99%. Comparing with typical three-layered Si 3 N 4 membrane, an excellent water flux enhancement of over 83% was resulted and the rejection rate remained over 99.99%.

Ceramic membranes applied to membrane distillation: A comprehensive review

“…Moreover, the decline of the permeate flux may be the result of the driving force decrease in MD due to concentration polarization caused by the increasing concentration of solute in the feed solution. However, even at higher solute concentration, a high permeate flux is still obtained . On the other hand, Garofalo et al obtained a reduction of solute rejection when increasing solute concentration …”

“…Many authors reported that feed temperature showed a remarkable influence on the permeate flux with ceramic membranes applied to MD, regardless of configuration and feed solution. This propensity is explained by the Antoine equation, which predicts an exponential relationship between the vapor pressure difference and temperature due to the higher latent heat of water evaporation and higher heat transfer coefficient, without affecting the permeate quality.…”

“…Hubadillah et al and Kujawa et al proved that ceramic‐based MD can be applied to high concentrated solutions without affecting its performance because of lower fouling effect . On the other hand, many authors observed that when increasing the solute concentration at the feed side results in a decrease in permeate flux . This phenomenon is explained by Raoult's law, which states that higher solute concentrations lead to decrease in water vapor pressure.…”

Energy for desalination: A state-of-the-art review

“…New generation RO membranes can bring about reduction in feed pressures by increasing more fresh water production per membrane element and compact membrane packing [424]. Though most of the research on such membranes is directed towards carbon nanotubes (CNTs) [425] and aquaporin [426] membranes, several other novel membrane concepts based on ceramic materials have also been reported [427][428][429]. Table 21 compares the most prominent next generation RO membranes.…”

Membrane separation as a pre-treatment process for oily saline water

“…The tape casting was used to prepare MF alumina [366,367], UF zirconia [368], silicon nitride [369,370], and Kaolin [371] ceramic membranes. It was also used to prepare MF metal membranes [372].…”