Effective extraction of lithium from high Mg

2+

/Li

+

ratio brine lakes is of great challenge. In this work

organic- inorganic hybrid silica nanofiltration (NF) membranes were prepared by dip-coating a 1

2-bis(triethoxysilyl)ethane (BTESE)-derived separation layer on tubular TiO

2

support

for efficient separation of LiCl and MgCl

2

salt solutions. We found that the membrane calcinated at 400 ℃ (M1-400) could exhibit a narrow pore size distribution (0.63-1.66 nm) owing to the dehydroxylation and the thermal degradation of the organic bridge groups. All as-prepared membranes exhibited higher rejections to LiCl than to MgCl

2

which was attributed to the negative charge of the membrane surfaces. The rejection for LiCl and MgCl

2

followed the order: LiCl N MgCl

2

revealing that Donnan exclusion effect dominated the salt rejection mechanism. In addition

the triplecoated membrane calcined at 400 ℃ (M3-400) exhibited a permeability of about 9.5 L·m

-2·

h

-1

·bar

-1

for LiCl or MgCl

2

solutions

with rejections of 74.7% and 20.3% to LiCl and MgCl

2

respectively

under the transm

embrane pressure at 6 bar. Compared with the previously reported performance of NF membranes for Mg

2+

/Li

+

separation

the overall performance of M3-400 is highly competitive. Therefore

this work may provide new insight into designing robust silica-based ceramic NF membranes with negative charge for efficient lithium extraction from salt lakes.