Synthesis and characterization of adsorbent materials for the retention of elemental mercury from contaminated tropical soils

Abstract

Mercury is a toxic element that has the ability to volatilize at environment temperatures, and its vapors may be taken over long distances in the atmosphere. Research is needed to develop cheap technologies for capturing Hg emitted by soils and thus decreasing its soil-atmosphere flow. Thus, four materials were synthesized to evaluate the retention capacity of Hg emitted from soils: zeolite NaP (from ash wastes of coal combustion in thermoelectric plants), two biochars (Biochar P: from wood-W and Biochar P: PVC waste from construction), and hopcalite (from Mn and Cu oxides). Mercury volatilization was also evaluated from four typical Brazilian soils in dry and moist conditions. Hopcalite was the material with the highest Hg retention capacity with 97, 53, 93, and 7% of the Hg value volatilized by Typic Rhodustult, Humic Rhodic, Typic Ustifolist, and Oxic Dystrudept, in dry soil condition, respectively. Zeolite NaP retained 27, 8, 14, and 9% of the total Hg volatilized from Typic Rhodustult, Humic Rhodic, Typic Ustifolist, and Oxic Dystrudept, respectively, in the dry soil condition. The biochars W and P showed low Hg retention capacity (0.5 to 9%). The retention of elemental Hg of the adsorbent materials decreased as: hopcalite > zeolite > biochar W > biochar P.