Influence of coal properties on mercury uptake from aqueous solution

The uptake of mercury (II) from aqueous solution by a range of coals has be en studied and the results have been compared to those for a number of othe r sorbents, including commercial active carbons and cation-exchange resins. At pH 5 in a buffer medium, the capacities for mercury removal of the low- rank coals and the oxidized bituminous coals investigated are comparable to those of the other sorbents tested. For the lignites investigated, a high content of organic sulfur does not markedly affect the capacity for mercury uptake in relatively neutral and low chloride media, owing to redox reacti ons being the most likely mechanism involved. However, in highly acidic sol utions, the capacities for mercury uptake are considerably greater for the high-sulfur coals investigated than for their low-sulfur counterparts due t o chelation being the major sorption process involved.