Removal of mercury(II) and methylmercury from solution by tannin adsorbents

Abstract

Adsorption of mercury(ll) and methylmercury by two tannin sorbents was investigated using radiotracers. High sorption capacities for mercury are registered for both sorbents at pH 7. For Eucaliptus Saligna Sm sorbent (ETS) the maximum sorption capacity was 1.2_+.0.2 mmol/g and for Lysiloma latisiliqua sorbent (LTS) was 8.5+0.2 mmol/g. Methylmercury adsorption maximum was recorded at pH 4 and in buffered solutions at pH2. This species can be recovered in the presence of mercury(ll). Influence of different ions present in water was examined. High recoveries were reported for ETS in tap water samples but a decrease of uptake is observed for seawater.

DNA fragments assembled on polyamidoamine‐grafted core‐shell magnetic silica nanoparticles for removal of mercury(II) and methylmercury(I)

“…The percentage removal of MeHg(I) improved substantially with decreasing initial concentration, approaching 90% at 6 mg L −1 . Another interesting phenomenon is that, unlike other adsorbents requiring 24 h to reach equilibrium uptake, equilibrium sorption of MeHg(I) could be achieved in less than 5 s. We think the synthesized materials are promising for quick removal of MeHg(I).…”

“…The adsorption data of MeHg(I) fitted well with the pseudo‐second‐order kinetics (Table S4, Supporting Information). Although in most cases the coordination number of MeHg(I) is not greater than one, the chemical properties of MeHg(I) are affected by the environment: Hybridization of the mercuric ion might change from sp to sp , enabling MeHg(I) to bind more than one ligand . At an initial concentration of 100 mg L −1 , the adsorption capacity diminished significantly after 5 min (Fig.…”

“…The slight decreases in percentage removals with adsorbent dosages > 4 mg might be because the chance of contact between the nanoparticles is raised during stirring, leading to aggregation of the adsorbents and, consequently, a reduced number of active sites . Nonetheless, the nanoparticle assemblies had significantly higher percentage removal of both Hg(II) and MeHg(I) than the conventional adsorbents, suggesting relatively strong DNA‐mercury interaction.…”

“…To remove mercury species from water, numerous treatment technologies have been explored, including chemical precipitation, reverse osmosis, membrane filtration, ion exchange and adsorption. Among them, adsorption has become an attractive technique due to its low cost, superior efficiency and easy operation …”

“…Among them, adsorption has become an attractive technique due to its low cost, superior efficiency and easy operation. 3 Various new materials have been explored for their potential as adsorbents. Nanoparticles, such as gold, 4 TiO 2 , 5 silica, 6 Fe 3 O 4 7 and their composites, have drawn increasing interest because they have large surface areas facilitating efficient adsorption.…”