Adsorption of methylantimony and methylarsenic on soils, sediments, and mine tailings from antimony mine area

• Methylarsenic sorption capacity and rate were greater than methylantimony sorption.
• Sorption isotherms for TMSb, MMA, and DMA exhibited Langmuir isotherms.
• The sorption capacity was proportional to the Fe/Al concentration in the environmental matrices.

Biogeochemical processes of antimony (Sb) – a chemically similar element as arsenic (As) – in a variety of environment is largely unexplored. Soil and sediment environment are known to control the geochemical fate of several contaminants via a multitude of processes, primarily adsorption. Here adsorption of organic Sb/As on soils, sediments, and mine tailings was investigated. Sorption studies showed that the methylarsenic sorption capacity and rate were greater than methylantimony sorption. For TMSb, MMA, and DMA sorption samples, the highest sorption capacity occurred in the Ferralsol, which contained the highest amount of Fe/Al-oxyhydroxides. The sorption capacity was proportional to the Fe/Al concentration in the environmental matrices (TMSb-Fe: R2 = 0.52, TMSb-Al: R2 = 0.69; MMA-Fe: R2 = 0.61, MMA-Al: R2 = 0.76; DMA-Fe: R2 = 0.42, DMA-Al: R2 = 0.59). The highest amount of TMSb, MMA, and DMA sorption rate was also observed for the Ferralsol with 82%, 97%, and 87%, respectively and that of the lowest values were the mine tailings. The other samples had similar amounts of TMSb/MMA/DMA sorption rate ranging from 5 to 60% of initially added organic species.