Abstract
We report the selective engineering of hybrid organic mesoporous silica monolith adsorbents for the recovery of silver (Ag) ions from e-waste samples. The Ag-I multithiolated adsorbent scales were synthesized through dense and continuous surface modifications of hierarchically ordered mesoporous (HOM) monoliths by active organic moieties. Captured subsets were created on the monolithic surfaces and in the orderly pore cavities for suitable Ag-I trapping. In addition, HOM monolithic carriers, with unique surface dominants, micrometer-sized particles, high surface-area/pore-volume ratios, and uniform groove-like cage cavities, form neat rooms for target ions. The decoration and depression of the extraordinary micrometer-sized surface monoliths and the orderly neat grooves enable the adsorption of large quantities and well-dispersed coverage of the multithiolated layers. These layers include sulfur- and nitrogen-active sites that selectively improve Ag-I adsorption/trapping/capture among competitive matrices. Results indicate that the adsorption of Ag-I is strong at pH 6.5 and it appears to follow the Langmuir adsorption model, with a maximum capacity of 179.23 mgg(-1). The hierarchical multithiolated adsorbent scales exhibit selectivity for Ag ions in the presence of coexisting cations. The retention of the organic structure and orientation along the HOM monoliths enables multiple-use recovery, collection, and management of Ag-I, without altering their functionality and capacity. The results suggest that the hierarchical adsorbent scales are suitable for Ag-I recovery from aquatic samples.