One-step preparation of emulsion-templated amino-functionalized porous organosilica monoliths for highly efficient Cr(VI) removal

Abstract

In this study, we reported that the amino-functionalized organosilica monoliths (amino-OSMs) without need post-synthesis functionalization were prepared in one-step emulsion-templated method. Herein, formation of organosilica skeleton and amino-functionalization of skeleton surface can be simultaneously realized by addition of ammonia. The SEM images showed that the amino-OSMs had a rich pore structures with high adjustability via the simple change in formulation of the emulsions. The successful graft of amino groups on the surface of the organosilica monolith was confirmed by EDS and XPS measurements. The amino-OSMs prepared in this work show the excellent Cr(VI)-removal capacity from the aqueous solution. It is demonstrated that Cr(VI) adsorption on amino-OSM-3 was best described by Langmuir models and pseudo-second-order kinetic. The adsorption efficiency of amino-OSM-3 for Cr(VI) was measured to be 92.8% at room temperature, still remained as high as 85.1% after five recycles as indicative of the good durability. Furthermore, the treated capacity of amino-OSM-3 is 4.25 kg·g−1 with initial concentration of 200 μg·L−1 through the column with a height of 0.5 cm. Correspondingly, Cr(VI) aqueous solution after treatment meet the requirement of the World Health Organization water discharge standard with Cr(VI) concentration as low as 50 μg·L−1. This work paves the way for the scale-up production of amino-OSMs using emulsion-templated technique for potential application in heavy metal removal.