Thiol-ethylene bridged PMO: A high capacity regenerable mercury adsorbent via intrapore mercury thiolate crystal formation

Abstract

Highly ordered thiol-ethylene bridged Periodic Mesoporous Organosilicas were synthesized directly from a homemade thiol-functionalized bis-silane precursor. These high surface area materials contain up to 4.3mmol/g sulfur functions in the walls and can adsorb up to 1183mg/g mercury ions. Raman spectroscopy reveals the existence of thiol and disulfide moieties. These groups have been evaluated by a combination of Raman spectroscopy, Ellman's reagent and elemental analysis. The adsorption of mercury ions was evidenced by different techniques, including Raman, XPS and porosimetry, which indicate that thiol groups are highly accessible to mercury. Scanning transmission electron microscopy combined with EDX showed an even homogenous distribution of the sulfur atoms throughout the structure, and have revealed for the first time that a fraction of the adsorbed mercury is forming thiolate nanocrystals in the pores. The adsorbent is highly selective for mercury and can be regenerated and reused multiple times, maintaining its structure and functionalities and showing only a marginal loss of adsorption capacity after several runs.

Protection of Thiol Groups on the Surface of Magnetic Adsorbents and Their Application for Wastewater Treatment

“…It has been known that all thiols have an affinity for mercury ions as well as sulphides 25 , 41 . Therefore, it is not surprising that Me/Lig ratio is almost 1/1 for all studied samples.…”

“…This urges a requirement for application of single-step methods in preparation of magnetite particles functionalized by 3-mercaptopropyl groups 24 . Moreover, it is known that thiol groups are easily oxidized to form disulfide bonds 25 , 26 that are no longer capable of ion-exchange interactions, which decrease their sorption capacity towards many metal ions 27 . Recently it has been demonstrated that introduction of an additional alkyl function into the ligand layer is capable to limit the unwanted interactions and stabilize single functional groups 28 .…”

Thiol-Functionalized Ethylene Periodic Mesoporous Organosilica as an Efficient Scavenger for Palladium: Confirming the Homogeneous Character of the Suzuki Reaction

“…In this context, an option that allows thiol groups to be obtained without involving the use of grafting or co-condensation processes is the use of the precursor 1-thiol-1,2-bis(triethoxysilyl)ethane, synthesized by Van Der Voort et al by thiol acid-ene chemistry [13]. This yielded a 100% thiol-functionalized PMO, which proved to have a high adsorption capacity and selectivity towards mercury ions [14].…”

Environmental Applications of Diatomite Minerals in Removing Heavy Metals from Water

“…Large-scale application of the biological method is limited by parameters such as pH, temperature, and the content of oxygen for a microorganism. Among the numerous techniques, adsorption is the most widely utilized because of its advantages of cost-effectiveness, easy operation, and high efficiency at trace quantities, − but its problems such as regeneration, poor selectivity, and secondary pollution still need further improvement.…”