High-flux water desalination with interfacial salt sieving effect in nanoporous carbon composite membranes

Abstract

Freshwater flux and energy consumption are two important benchmarks for the membrane desalination process. Here, we show that nanoporous carbon composite membranes, which comprise a layer of porous carbon fibre structures grown on a porous ceramic substrate, can exhibit 100% desalination and a freshwater flux that is 3-20 times higher than existing polymeric membranes. Thermal accounting experiments demonstrated that the carbon composite membrane saved over 80% of the latent heat consumption. Theoretical calculations combined with molecular dynamics simulations revealed the unique microscopic process occurring in the membrane. When the salt solution is stopped at the openings to the nanoscale porous channels and forms a meniscus, the vapour can rapidly transport across the nanoscale gap to condense on the permeate side. This process is driven by the chemical potential gradient and aided by the unique smoothness of the carbon surface. The high thermal conductivity of the carbon composite membrane ensures that most of the latent heat is recovered.

Electric‐Field‐Induced Ionic Sieving at Planar Graphene Oxide Heterojunctions for Miniaturized Water Desalination

“…[ 1 ] Nanomaterial‐based technologies, capable of effectively and affordably extracting potable water from unconventional water sources (such as, salt water, industrial waste water, and rain water), make critical contribution for sustainable water use. [ 2–5 ] Particularly, 2D‐material‐based nanofluidic membranes are considered as promising materials for next‐generation water desalination and purification. [ 6 ] For example, monolayer graphene with sub‐nanometer pores exhibits nearly 100% salt rejection and high water permeability, [ 7,8 ] with orders of magnitude greater than commercial reverse osmosis (RO) membranes (≈2 Lm −2 h −1 bar −1 ).…”

Structure and Transport Properties of Water and Hydrated Ions in Nano‐Confined Channels

“…Majumder et al [11] reported a flow rate of four to five orders of magnitude faster than conventional fluid flow through channels of 7 nm diameter in micro-fabricated membranes where aligned carbon nanotubes (CNTs) served as pores. [13] To achieve highly selective ion transmembrane transport, the microstructure of porous materials was optimized constantly. [12] On the other hand, ion selectivity of nanoporous materials has been revealed experimentally.…”

A Flexible, Self‐Floating Composite for Efficient Water Evaporation

“…Seawater desalination is a very promising means to gain fresh water . Osmosis membrane technology, solar desalination technology, and some other technologies have been used for desalination. Among them, efficient water evaporation technique has attracted tremendous attention due to its distinct advantages, such as inexhaustibility, safety, and environmental friendliness.…”