Selective ion separation
from brines is pivotal for attaining
high-purity
lithium, a critical nonrenewable resource. Conventional methods encounter
substantial challenges, driving the quest for streamlined, efficient,
and swift approaches. Here, we present a graphene oxide (GO)-based
ternary heterostructure membrane with a unique design. By utilizing
Zn2+-induced confinement synthesis in a two-dimensional
(2D) space, we incorporated two-dimensional zeolitic imidazolate framework-8
(ZIF-8) and zinc alginate (ZA) polymers precisely within layers of
the GO membrane, creating tunable interlayer channels with a ternary
heterostructure. The pivotal design lies in ion insertion into the
two-dimensional (2D) membrane layers, achieving meticulous modulation
of layer spacing based on ion hydration radius. Notably, the ensuing
layer spacing within the hybrid ionic intercalation membrane occupies
an intermediary realm, positioned astutely between small-sized hydrated
ionic intercalation membrane spacing and their more extensive counterparts.
This deliberate configuration accelerates the swift passage of diminutive
hydrated ions while simultaneously impeding the movement of bulkier
ions within the brine medium. The outcome is remarkable selectivity,
demonstrated by the partitioning of K+/Li+ =
20.9, Na+/K+ = 31.2, and Li+/Mg2+ = 9.5 ion pairs. The ZIF-8/GO heterostructure significantly
contributes to the selectivity, while the mechanical robustness and
stability, improved by the ZA/GO heterostructure, further support
its practical applicability. This report reports an advanced membrane
design, offering promising prospects for lithium extraction and various
ion separation processes.