Efficient removal of mercury (II) from water by use of cryogels and comparison to commercial adsorbents under environmentally relevant conditions

Mercury is a toxic element, which can be found in air, water and soil in several inorganic and organic forms. Mercury pollution comes from a variety of industrial sources, including vinyl-chloride, pulp and paper, fertilizers and pharmaceuticals industry, gold mining and cement production. Gels have increasingly attracted the interest over the past decades and one of the investigated applications is the fast removal of organic substances, metals and other cations and anions from water. In this work, two types of cryogels were synthesized at sub-zero temperature by free-radical polymerization technique, characterized by using a set of complimentary methods and used for the removal of mercury from aqueous solutions of different chemistry. Kinetics and equilibrium studies were performed in ultra-pure water solutions in order to study the mechanisms in the presence nitrate and chloride ions. The cryogels exhibited excellent efficiency towards mercury removal from all model solutions. Moreover, the cryogels were tested in different water matrixes (tap, river and sea water) and compared to commercial adsorbents (activated carbon, strong acid resin and zeolite Y). Cryogels were able to remove mercury much faster than commercial adsorbents with the exception of seawater where activated carbon was superior.