Sorption and desorption of mercury(II) in saline and alkaline soils of Bahía Blanca, Argentina

DANIELA LAFONT; OLGA E. SOULAGES; SILVIA G. ACEBAL; ALFREDO G. BONORINO

ENVIRONMENTAL EARTH SCIENCES

SPRINGER-VERLAG

Lugar: Berlín-Heidelberg; Año: 2012 p. 1 - 10

1866-6280

Abstract The objective of this work was to study sorption– desorption and/or precipitation–dissolution processes of Hg(II) compounds considering an eventual contact of soils with Hg-bearing wastes. In addition, this study contributes new data about Hg(II) chemistry in alkaline systems. Saline and alkaline soils with low organic matter (1 %) and high clay content (60–70 %) were obtained near a chlor-alkali plant. Batch techniques were used to perform the experiments using 0.1 M NaNO3 solutions. Total Hg(II) concentrations ranged from 6.2 9 10-8 to 6.3 9 10-3 M. Sorption of Hg(II) was evaluated at two concentration ranges: (a) 6.2 9 10-8 to 1.1 9 10-4 M, and (b) 6.4 9 10-4 to 6.3 9 10-3 M. At low Hg(II) concentrations, adsorption occurred with a maximum sorption capacity ranging from 4 to 5 mmol/kg. At high Hg(II) concentrations, sorption–precipitation reactions occurred and maximum sorption capacity ranged from 17 to 31 mmol/kg. The distribution of Hg(II) hydrolysis products showed that Hg(OH)2 was the predominant species under soil conditions. According to sorption experiments, X-ray diffraction and chemical speciation modelling, the presence of Hg(OH)2 in the interlayer of the interstratified clay minerals can be proposed. Hg(OH)2 was partially desorbed by repeated equilibrations in 0.1 M NaNO3 solution. Desorption ranged from 0.1 to 0.9 mmol/kg for soils treated with 5.8 9 10-5 M Hg(II), whereas 2.1–3.8 mmol/ kg was desorbed from soils treated with 6.3 9 10-3 M Hg(II). Formation of soluble Hg(II) complexes was limited by low organic matter content, whereas neutral Hg(OH)2The objective of this work was to study sorption– desorption and/or precipitation–dissolution processes of Hg(II) compounds considering an eventual contact of soils with Hg-bearing wastes. In addition, this study contributes new data about Hg(II) chemistry in alkaline systems. Saline and alkaline soils with low organic matter (1 %) and high clay content (60–70 %) were obtained near a chlor-alkali plant. Batch techniques were used to perform the experiments using 0.1 M NaNO3 solutions. Total Hg(II) concentrations ranged from 6.2 9 10-8 to 6.3 9 10-3 M. Sorption of Hg(II) was evaluated at two concentration ranges: (a) 6.2 9 10-8 to 1.1 9 10-4 M, and (b) 6.4 9 10-4 to 6.3 9 10-3 M. At low Hg(II) concentrations, adsorption occurred with a maximum sorption capacity ranging from 4 to 5 mmol/kg. At high Hg(II) concentrations, sorption–precipitation reactions occurred and maximum sorption capacity ranged from 17 to 31 mmol/kg. The distribution of Hg(II) hydrolysis products showed that Hg(OH)2 was the predominant species under soil conditions. According to sorption experiments, X-ray diffraction and chemical speciation modelling, the presence of Hg(OH)2 in the interlayer of the interstratified clay minerals can be proposed. Hg(OH)2 was partially desorbed by repeated equilibrations in 0.1 M NaNO3 solution. Desorption ranged from 0.1 to 0.9 mmol/kg for soils treated with 5.8 9 10-5 M Hg(II), whereas 2.1–3.8 mmol/ kg was desorbed from soils treated with 6.3 9 10-3 M Hg(II). Formation of soluble Hg(II) complexes was limited by low organic matter content, whereas neutral Hg(OH)21 %) and high clay content (60–70 %) were obtained near a chlor-alkali plant. Batch techniques were used to perform the experiments using 0.1 M NaNO3 solutions. Total Hg(II) concentrations ranged from 6.2 9 10-8 to 6.3 9 10-3 M. Sorption of Hg(II) was evaluated at two concentration ranges: (a) 6.2 9 10-8 to 1.1 9 10-4 M, and (b) 6.4 9 10-4 to 6.3 9 10-3 M. At low Hg(II) concentrations, adsorption occurred with a maximum sorption capacity ranging from 4 to 5 mmol/kg. At high Hg(II) concentrations, sorption–precipitation reactions occurred and maximum sorption capacity ranged from 17 to 31 mmol/kg. The distribution of Hg(II) hydrolysis products showed that Hg(OH)2 was the predominant species under soil conditions. According to sorption experiments, X-ray diffraction and chemical speciation modelling, the presence of Hg(OH)2 in the interlayer of the interstratified clay minerals can be proposed. Hg(OH)2 was partially desorbed by repeated equilibrations in 0.1 M NaNO3 solution. Desorption ranged from 0.1 to 0.9 mmol/kg for soils treated with 5.8 9 10-5 M Hg(II), whereas 2.1–3.8 mmol/ kg was desorbed from soils treated with 6.3 9 10-3 M Hg(II). Formation of soluble Hg(II) complexes was limited by low organic matter content, whereas neutral Hg(OH)23 solutions. Total Hg(II) concentrations ranged from 6.2 9 10-8 to 6.3 9 10-3 M. Sorption of Hg(II) was evaluated at two concentration ranges: (a) 6.2 9 10-8 to 1.1 9 10-4 M, and (b) 6.4 9 10-4 to 6.3 9 10-3 M. At low Hg(II) concentrations, adsorption occurred with a maximum sorption capacity ranging from 4 to 5 mmol/kg. At high Hg(II) concentrations, sorption–precipitation reactions occurred and maximum sorption capacity ranged from 17 to 31 mmol/kg. The distribution of Hg(II) hydrolysis products showed that Hg(OH)2 was the predominant species under soil conditions. According to sorption experiments, X-ray diffraction and chemical speciation modelling, the presence of Hg(OH)2 in the interlayer of the interstratified clay minerals can be proposed. Hg(OH)2 was partially desorbed by repeated equilibrations in 0.1 M NaNO3 solution. Desorption ranged from 0.1 to 0.9 mmol/kg for soils treated with 5.8 9 10-5 M Hg(II), whereas 2.1–3.8 mmol/ kg was desorbed from soils treated with 6.3 9 10-3 M Hg(II). Formation of soluble Hg(II) complexes was limited by low organic matter content, whereas neutral Hg(OH)29 10-8 to 6.3 9 10-3 M. Sorption of Hg(II) was evaluated at two concentration ranges: (a) 6.2 9 10-8 to 1.1 9 10-4 M, and (b) 6.4 9 10-4 to 6.3 9 10-3 M. At low Hg(II) concentrations, adsorption occurred with a maximum sorption capacity ranging from 4 to 5 mmol/kg. At high Hg(II) concentrations, sorption–precipitation reactions occurred and maximum sorption capacity ranged from 17 to 31 mmol/kg. The distribution of Hg(II) hydrolysis products showed that Hg(OH)2 was the predominant species under soil conditions. According to sorption experiments, X-ray diffraction and chemical speciation modelling, the presence of Hg(OH)2 in the interlayer of the interstratified clay minerals can be proposed. Hg(OH)2 was partially desorbed by repeated equilibrations in 0.1 M NaNO3 solution. Desorption ranged from 0.1 to 0.9 mmol/kg for soils treated with 5.8 9 10-5 M Hg(II), whereas 2.1–3.8 mmol/ kg was desorbed from soils treated with 6.3 9 10-3 M Hg(II). Formation of soluble Hg(II) complexes was limited by low organic matter content, whereas neutral Hg(OH)29 10-3 M. Sorption of Hg(II) was evaluated at two concentration ranges: (a) 6.2 9 10-8 to 1.1 9 10-4 M, and (b) 6.4 9 10-4 to 6.3 9 10-3 M. At low Hg(II) concentrations, adsorption occurred with a maximum sorption capacity ranging from 4 to 5 mmol/kg. At high Hg(II) concentrations, sorption–precipitation reactions occurred and maximum sorption capacity ranged from 17 to 31 mmol/kg. The distribution of Hg(II) hydrolysis products showed that Hg(OH)2 was the predominant species under soil conditions. According to sorption experiments, X-ray diffraction and chemical speciation modelling, the presence of Hg(OH)2 in the interlayer of the interstratified clay minerals can be proposed. Hg(OH)2 was partially desorbed by repeated equilibrations in 0.1 M NaNO3 solution. Desorption ranged from 0.1 to 0.9 mmol/kg for soils treated with 5.8 9 10-5 M Hg(II), whereas 2.1–3.8 mmol/ kg was desorbed from soils treated with 6.3 9 10-3 M Hg(II). Formation of soluble Hg(II) complexes was limited by low organic matter content, whereas neutral Hg(OH)29 10-8 to 1.1 9 10-4 M, and (b) 6.4 9 10-4 to 6.3 9 10-3 M. At low Hg(II) concentrations, adsorption occurred with a maximum sorption capacity ranging from 4 to 5 mmol/kg. At high Hg(II) concentrations, sorption–precipitation reactions occurred and maximum sorption capacity ranged from 17 to 31 mmol/kg. The distribution of Hg(II) hydrolysis products showed that Hg(OH)2 was the predominant species under soil conditions. According to sorption experiments, X-ray diffraction and chemical speciation modelling, the presence of Hg(OH)2 in the interlayer of the interstratified clay minerals can be proposed. Hg(OH)2 was partially desorbed by repeated equilibrations in 0.1 M NaNO3 solution. Desorption ranged from 0.1 to 0.9 mmol/kg for soils treated with 5.8 9 10-5 M Hg(II), whereas 2.1–3.8 mmol/ kg was desorbed from soils treated with 6.3 9 10-3 M Hg(II). Formation of soluble Hg(II) complexes was limited by low organic matter content, whereas neutral Hg(OH)29 10-4 to 6.3 9 10-3 M. At low Hg(II) concentrations, adsorption occurred with a maximum sorption capacity ranging from 4 to 5 mmol/kg. At high Hg(II) concentrations, sorption–precipitation reactions occurred and maximum sorption capacity ranged from 17 to 31 mmol/kg. The distribution of Hg(II) hydrolysis products showed that Hg(OH)2 was the predominant species under soil conditions. According to sorption experiments, X-ray diffraction and chemical speciation modelling, the presence of Hg(OH)2 in the interlayer of the interstratified clay minerals can be proposed. Hg(OH)2 was partially desorbed by repeated equilibrations in 0.1 M NaNO3 solution. Desorption ranged from 0.1 to 0.9 mmol/kg for soils treated with 5.8 9 10-5 M Hg(II), whereas 2.1–3.8 mmol/ kg was desorbed from soils treated with 6.3 9 10-3 M Hg(II). Formation of soluble Hg(II) complexes was limited by low organic matter content, whereas neutral Hg(OH)22 was the predominant species under soil conditions. According to sorption experiments, X-ray diffraction and chemical speciation modelling, the presence of Hg(OH)2 in the interlayer of the interstratified clay minerals can be proposed. Hg(OH)2 was partially desorbed by repeated equilibrations in 0.1 M NaNO3 solution. Desorption ranged from 0.1 to 0.9 mmol/kg for soils treated with 5.8 9 10-5 M Hg(II), whereas 2.1–3.8 mmol/ kg was desorbed from soils treated with 6.3 9 10-3 M Hg(II). Formation of soluble Hg(II) complexes was limited by low organic matter content, whereas neutral Hg(OH)22 in the interlayer of the interstratified clay minerals can be proposed. Hg(OH)2 was partially desorbed by repeated equilibrations in 0.1 M NaNO3 solution. Desorption ranged from 0.1 to 0.9 mmol/kg for soils treated with 5.8 9 10-5 M Hg(II), whereas 2.1–3.8 mmol/ kg was desorbed from soils treated with 6.3 9 10-3 M Hg(II). Formation of soluble Hg(II) complexes was limited by low organic matter content, whereas neutral Hg(OH)22 was partially desorbed by repeated equilibrations in 0.1 M NaNO3 solution. Desorption ranged from 0.1 to 0.9 mmol/kg for soils treated with 5.8 9 10-5 M Hg(II), whereas 2.1–3.8 mmol/ kg was desorbed from soils treated with 6.3 9 10-3 M Hg(II). Formation of soluble Hg(II) complexes was limited by low organic matter content, whereas neutral Hg(OH)23 solution. Desorption ranged from 0.1 to 0.9 mmol/kg for soils treated with 5.8 9 10-5 M Hg(II), whereas 2.1–3.8 mmol/ kg was desorbed from soils treated with 6.3 9 10-3 M Hg(II). Formation of soluble Hg(II) complexes was limited by low organic matter content, whereas neutral Hg(OH)29 10-5 M Hg(II), whereas 2.1–3.8 mmol/ kg was desorbed from soils treated with 6.3 9 10-3 M Hg(II). Formation of soluble Hg(II) complexes was limited by low organic matter content, whereas neutral Hg(OH)29 10-3 M Hg(II). Formation of soluble Hg(II) complexes was limited by low organic matter content, whereas neutral Hg(OH)22 was retained by adsorption on clay mineral surfaces.