Superior single- and multi-component siloxane removal from water using a faulted silica DON zeolite adsorbent

Removal of monomeric siloxanes from water via adsorption poses a significant challenge, particularly during water reclamation in closed-volume systems. In this study, both faulted and faultless variants UTD-1 pure silica zeolites with a DON-type framework were considered for the removal of monomethylsilanetriol (MMST), dimethylsilanediol (DMSD), and trimethylsilanol (TMS), in single- and multi-component fashion. The results showed that UTD-1faulted exhibited the largest adsorption capacity for TMS, with a maximum adsorption uptake of 73.1 mg g-1 in the 1 to 140 mg L-1 aqueous concentration range. This is 7x larger than UTD-1faultless and at least one magnitude larger than other materials such as activated carbon. The interaction of TMS with UTD-1faulted is mainly with OH groups from siloxy-related faults present in the material, and multicomponent adsorption tests showed that TMS helps to drive the uptake of other siloxanes via co-adsorption. UTD-1 is a promising material platform for developing adsorption-based strategies for removing persistent monomeric siloxanes from aqueous environments. Pure porous silica zeolite adsorbents with framework surface faults, in the form of siloxy groups, are selective toward single- or multi-component linear siloxanes for removal from water.