Exploring new DGT samplers containing a polymer inclusion membrane for mercury monitoring

Abstract

A polymer inclusion membrane (PIM) made of cellulose triacetate as a polymer and the task specific ionic liquid (IL) trioctylmethylammonium thiosalicylate (TOMATS) was assembled as a new Diffusive Gradients in Thin film (DGT) device to test its efficiency as a binding phase for mercury (Hg) monitoring. The effect of IL content was assessed, showing that higher TOMATS percentage is better for short deployment studies (up to hours), whereas for long-term exposure (up to days), a lower content can be more suitable. Different configurations of PIM-DGT samplers have been tested under controlled conditions and compared with in-house DGT conventional ones, manufactured with thiol groups as resin layer, for the determination of labile Hg. According to our results, a nonlinear accumulation profile of Hg with deployment time for the different designs of PIM-DGT was observed, limiting the range of applicability of the DGT technique. Promising results for the efficient removal of Hg from aqueous solutions and/or environmental monitoring studies were obtained with TOMATS.

System for mercury preconcentration in natural waters based on a polymer inclusion membrane incorporating an ionic liquid

“…Moreover, this PIM composition was found to result in a stable membrane, since an insignificant mass loss was found for each solution tested (1.4% for milli-Q water, 1.8% for a 10 -3 M cysteine solution and 2.5% for sea water). These results are in agreement of those reported in [17] where a mass loss of 2.4% was found for a PIM made of 50%CTA-50% TOMATS immersed in 0.1 M NaCl solution.…”

“…The effectiveness of TOMATS incorporated in a polymeric matrix was demonstrated in our previous studies, where a PIM with a composition of 50% CTA-50% TOMATS extracted Hg from natural waters [17,18]. In the present study, with the aim of comparing the extraction efficiency of both IL, we used PIMs containing 50% TOMATS or 50% TOMAS to test their ability to extract Hg from a SNW sample.…”

“…However, the desorption process was not possible. This IL has also been incorporated into a polymeric matrix of cellulose triacetate (CTA) to form a polymeric sorbent used as a binding phase in a Diffusive Gradient of Thin Films (DGT) device for Hg monitoring in river water [17]. Moreover, this CTA-TOMATS sorbent was also investigated to extract Hg from different natural water samples to facilitate its detection by EDXRF [18].…”

Diffusive gradients in thin films for the measurement of labile metal species in water and soils: a review

“…Therefore, the DGT allows in situ evaluation of labile fractions and by approximation, bioavailability of metal species in aqueous environments, including natural waters (Zhang et al 1998;Clarisse et al 2009;Lucas et al 2012;Turull et al 2017aTurull et al , 2018Bratkič et al 2019;Gao et al 2019c), sediments (Harper et al 1998(Harper et al , 2000Gao et al 2009;Yin et al 2014) and soils (Docekalová et al 2012;Song et al 2015;Turull et al 2019a, b;Babalola and Zhang 2021), based on the behavior of the labile species in the diffusive layer is similar to the behavior in the proximity of biological membrane (Clarisse et al 2012;Amirbahman et al 2013;Fernández-Gómez et al 2015). The DGT passive sampler houses a binding gel and a diffusive gel protected by a membrane filter, that permits the diffusion of free ions and labile complexes through the diffusive layer that are irreversibly uptake by the specific binding layer.…”

Speciation of Inorganic Compounds in Aquatic Systems Using Diffusive Gradients in Thin-Films: A Review

“…However, many of them are not or no longer commercially available due to interrupted production; only 3-mercaptopropylsilica (3-MFS) and Purolite S924 are still commercially available (Gao et al, 2011;Bratkic et al, 2019;Reichstädter et al, 2020). However, individual research groups have synthesized new home-made resins for assessment of Hg and other trace metal in aquatic systems (Gao et al, 2011;Turull et al, 2017a;Elias et al, 2020;Reichstädter et al, 2021). Due to the very strong binding between the functional groups of the resin and Hg, the elution procedures for Hg are also different from those for other trace metals (elution procedures can be found in Table 5).…”