Sulfurized activated carbons and their mercury adsorption/desorption behavior in aqueous phase

Abstract

Sulfurized activated carbons (SACs) are of the most recent forms of modified sorbents with high affinity toward mercury. The adsorption/desorption behavior of SACs has not been studied in detail in liquid phases. The study was carried out with the aim of recognition of similarities and differences in the properties and performances of SACs and activated carbons (ACs) exposing to aqueous-phase mercury. In this study, three different sulfurizing agents including dimethyl disulfide (DMDS), elemental sulfur (S), and sulfur dioxide (SO 2 ) were tested for AC sulfurization (each under the optimal conditions). Sulfurization with DMDS at room temperature led to the formation of elemental sulfur and sulfide/disulfide on the AC surface; however, sulfurization at higher temperatures with SO 2 and powdered S resulted in the formation of more stable organic forms such as thiophene and oxidized sulfur. The equilibrium mercury adsorption capacity of AC-DMDS was so larger than AC and other SACs. On the other hand, the largest surface area drop and consequently the slowest mercury adsorption rate belonged to this sample. However, AC-S and AC-SO 2 led to moderate increase in mercury equilibrium adsorption capacity; they showed several advantages resulted from their extended porosities and more stable sulfur functionalities. The more accelerated adsorption especially at initial stages of contact in batch modes and negligible entry of sulfur compounds into the treating wastewater were of their important advantages. Mercury desorption was also studied and compared using several acidic and potassium halide solvents. The possibility of applicability of SACs in consecutive mercury adsorption/desorption cycles was also investigated.

Influence of Different Sulfur Forms on Gas-Phase Mercury Removal by SO2-Impregnated Porous Carbons

“…This study therefore set out to find the relationships between Hg 0 adsorption performance and different sulfur species in SO 2 -impregnated activated carbons. Previous studies in SO 2 -impregnated porous carbons dealing with aquatic Hg 2+ adsorption suggest that elemental sulfur and disulfide seemed particularly effective in Hg 2+ uptake. , Then, the hypothesis that will be tested is that the reduced sulfur form is more effective than other sulfur groups in SO 2 -impregnated sorbents for Hg 0 adsorption. It is hoped that this study will contribute to the development of SO 2 impregnation in mercury emission control technologies.…”

Caracterización computacional de ligandos orgánicos derivados de ácido fumárico para la adsorción selectiva de mercurio inorgánico

“…Una vez seleccionado el confórmero más estable de AF, éste se funcionalizó con uno y dos grupos -SH, -SCH3, -NH2 y -PH2, estos grupos actúan como funciones dadoras de electrones que pueden presentar afinidad por el mercurio, basadas en sus características de bases blandas que interaccionan adecuadamente con metales como ácidos blandos (Asasian y Kaghazchi, 2015;Hendrickx et al, 2015). Muchos de los contaminantes acuosos inorgánicos son metales con bajas densidades de carga, como Cd, Hg y Pb.…”

“…Con la aproximación de diferencias finitas, dichos índices de reactividad fueron más variados, así por ejemplo el Con_A con un grupo -SH, un grupo -NH2 y un grupo -PH2 son un poco más duros que el AF, pero con un grupo -SCH3 es un poco menos duro. En general, aunque hay cierta pérdida de reactividad al funcionalizar el CON_A eliminando su doble enlace, se espera que de manera global estos grupos aumenten la afinidad por el mercurio, basadas en sus características de bases blandas que interaccionan adecuadamente con metales ácidos blandos (Asasian y Kaghazchi, 2015;Hendrickx et al, 2015). Adicionalmente, con Koopmans no se evidencian diferencias significativas entre modificar con uno o dos grupos al CON_A; por ejemplo, los valores 0.119 -0.117 de la dureza química de los compuestos modificados con uno y dos -NH2 solo se diferencian por 0.002.…”

Sorption profile of mercury (II) from aqueous solution onto low-rank Pakistani coal

“…Among these treatment processes, the mercury adsorption method at the solid-liquid interface is a promising and dominant method with some advantages of high efficiency, simplicity, low cost and the availability of diverse adsorbents [23,24] such as activated carbon [25], silicates of aluminum and titanium [26,27], oxides of silicon and aluminum α-Al 2 O 3 [28,29], mesoporous SBA-15 [30], carbon aerogel [31], fly ash [32], activated carbon [33], clay [34] and various other adsorbents.…”