Herein

we present a simple strategy for preparing monolithic sodalite adsorbents

via

sequential additive manufacturing and post-treatments. In detail

the method includes (i) 3D printing of cylindrical monoliths using clay as the base material; (ii) thermal activation of the 3D-printed clay monoliths by calcination (to produce reactive alumina and silica species and enable mechanical stabilization); (iii) conversion of the activated clay monoliths to hierarchical porous sodalite monoliths

via

hydrothermal alkaline treatment. Parametric studies on the effect of calcination temperature

alkaline concentration and hydrothermal treatment time on the property of the resulting materials (such as phase composition and morphology) at different stages of preparation was conducted. Under the optimal conditions (

i.e.

calcination temperature of 850℃

NaOH concentration of 3.3 mol·L

-1

reaction temperature of 150℃

and reaction time of 6 h)

a high-quality pure sodalite monolith was obtained

which possesses a relatively high BET surface area (58 m

2

·g

-1

) and hierarchically micro-meso-

macroporous structure. In the proposed application of continuous removal of heavy metals (chromium ion as the model) from wastewater

the developed 3D-printed sodalite monolith showed excellent Cr

3+

removal performance and fast kinetics (~98% removal efficiency within 25 cycles)

which outperformed the packed bed using sodalite pellets (made by extrusion).