Elsevier

Water Research

Volume 40, Issue 10, June 2006, Pages 2044-2054
Water Research

Interaction of trace elements in acid mine drainage solution with humic acid

https://doi.org/10.1016/j.watres.2006.03.009Get rights and content

Abstract

The release of metal ions from a coal mining tailing area, Lamphun, Northern Thailand, is studied by leaching tests. Considerable amounts of Mn, Fe, Al, Ni and Co are dissolved in both simulated rain water (pH 4) and 10 mg L−1 humic acid (HA) solution (Aldrich humic acid, pH 7). Due to the presence of oxidizing pyrite and sulfide minerals, the pH in both leachates decreases down to ∼3 combined with high sulfate concentrations typical to acid mine drainage (AMD) water composition. Interaction of the acidic leachates upon mixing with ground- and surface water containing natural organic matter is simulated by subsequent dilution (1:100; 1:200; 1:300; 1:500) with a 10 mg L−1 HA solution (ionic strength: 10−3 mol L−1). Combining asymmetric flow field-flow fractionation (AsFlFFF) with UV/Vis and ICP-MS detection allows for the investigation of metal ion interaction with HA colloid and colloid size evolution. Formation of colloid aggregates is observed by filtration and AsFlFFF depending on the degree of the dilution. While the average HA size is initially found to be 2nm, metal–HA complexes are always found to be larger. Such observation is attributed to a metal induced HA agglomeration, which is found even at low coverage of HA functional groups with metal ions. Increasing the metal ion to HA ratio, the HA bound metal ions and the HA entities are growing in size from <3 to >450 nm. At high metal ion to HA ratios, precipitation of FeOOH phases and HA agglomeration due to colloid charge neutralization by complete saturation of HA complexing sites are responsible for the fact that most of Fe and Al precipitate and are found in a size fraction >450nm. In the more diluted solutions, HA is more relevant as a carrier for metal ion mobilization.

Introduction

Approximately 20% of the total electricity in Thailand is generated by coal burning (Arbhabhirama et al., 1987). Most of the coal mines are the open-pit mines, where the tailings are placed around the mining area exposed to weathering and leaching by rain. It is well known that the tailings in mining areas are composed of various kinds of minerals containing high amounts of heavy metals (Kucukonder et al., 2003; Matlock et al., 2002; Lee et al., 2002; Dang et al., 2002). Residual waste crushed rock from mining activities represents a major source for metal rich acid mine drainage (AMD) water. The tailing minerals can release metal ions over long time scales due to oxidation of sulfide minerals leading to the production of sulfuric acid (e.g. Bunce et al., 2001) according to the overall equations:FeS2(s)+72O2(g)+H2OFe2+(aq)+2H+(aq)+2SO42-(aq),2Fe2+(aq)+12O2(g)+5H2O(l)2Fe(OH)3(s)+4H+(aq).Metals in the waste rock can be released by the low pH AMD (Kucukonder et al., 2003; Matlock et al., 2002; Lee et al., 2002; Dang et al., 2002; Bunce et al., 2001; Vigneault et al., 2001) and possibly be transported by rainwater and surface water away from the source. Quite a number of studies in many countries have been performed to study the release of metals from coal mine spoils, but only a few in Thailand. Those reports concerned the weathering process of the tailings using leaching experiment and sequential extraction (Yukselen and Alpaslan, 2001; Sun et al., 2001; Sahuquillo et al., 2002; Badulis, 1998). They focused on only how the metals are leached out. However, the mechanisms leading to the possible migration of heavy metals further away downstream from the mining site is still not clear. The geochemical behavior of metals released from the acidic tailing minerals depends on a number of different parameters. As soon as the AMD is diluted and pH increases, a number of precipitating phases have been observed: jarosite, schwertmannite, ferrihydrite (Hochella et al., 1999; Dinelli et al., 2001) and mixed amorphous gel like phases with more or less variable composition (Featherstone and O’Grady, 1997; Munka et al., 2002). Precipitation of those phases going along with metal adsorption and co-precipitation leads to the retention of released metal ions. The mobility of metal ions then is often determined by potentially forming particulate and colloidal species being stabilized and dispersed in the water. Particulate and colloidal species of metals such as Fe, As, Cd, Cu, Mn, Pb and Zn derived from tailing minerals have indeed been observed to migrate over long distances (Featherstone and O’Grady, 1997; Kimball et al., 1995; Zänker et al., 2002; Schemel et al., 2000). Purely inorganic colloidal species composed of high AlOOH and FeOOH amounts have their isoelectric point close to the pH of natural water and thus exhibit only low colloidal stability. Surface sorption or coating with silicate or natural organic matter as humic or fulvic acid is known to shift the isoelectrical point of colloidal particles to lower pH (e.g. Kretzschmar et al. 1998), and to increase inter-particle charge repulsion and thus colloidal stability. Humic and fulvic acids being present in natural water in concentrations ranging from 0.5 to 100 mg/L (Frimmel, 1998) can on the other hand form metal-complexes in certain pH ranges (Gundersen and Steinnes, 2003) and by this way enhance the metal mobility.

The aim of the present work is to study the colloid formation upon AMD dilution in presence of humic acid to simulate the interaction of acidic leachates upon mixing with ground- and surface water containing natural organic matter. Humic and fulvic acids are known to be major constituents of organic matter in most soils and groundwater (see e.g. Stevensen, 1994). Humic acid is thus taken to simulate the influence of natural organic matter on metal ion colloid formation. AMD is prepared by leaching of a tailing sample taken from a disposal of the Lamphun area with simulated rain water (RW) or humic acid containing solution. The solution compositions of the two leachates are compared with water samples taken from a pond fed by draining water from the mine. The leachate obtained with the humic acid solution (10 mg L−1, pH 7) is then subsequently diluted with 10 mg L−1 humic acid solution to final pH values ranging from 4.6 to 7.6 and the colloidal species formed are characterized by using the asymmetric flow field-flow fractionation (AsFlFFF) combined with UV/VIS absorbance and ICP-mass spectrometric detection. Humic acid concentration and pH values lie in the range of natural conditions.

Section snippets

Analysis of the tailings and water samples

AMD water samples from a coal mine disposal area in northern Thailand (Lamphun area) were collected from two sites of a pond during summer season (September: BP-S; LN-S) and rainy season (October: BP-O; LN-O). Tailing samples were taken from the same site. Grain particles with a size<1 mm were separated by sieving and used for characterization by X-ray diffraction (XRD-3000, Seifert, Germany), scanning electron microscopy (SEM-EDX, CamScan CS44 FE, England), X-ray fluorescence (XRF, Siemens, SRS

Characterization of solids and solutions

The elemental composition of the tailing sample used for leaching experiments is given in Table 1. Main mineral components as derived by XRD inspection are quartz (SiO2), jarosite (KFe3(SO4)2(OH)6) (an oxidation product of pyrite (FeS2)), gypsum (CaSO4·2H2O), and additionally muscovite (KAl3Si3O10(OH)2) and kaolinite (Al2Si2O5(OH)4). Analysis of minor components by SEM-EDX showed the presence of iron sulfides and gypsum. The composition of the solutions resulting from the leaching experiments

Conclusions

The experiments indicate that metal ions dissolved in AMD may experience either retention or mobilization when released from the source. When diluted in near neutral natural water, metal ions can be kept to a certain degree in solution by humic substances through complexation. Agglomeration to larger HA aggregates and thus precipitation, sedimentation or attachment to surfaces can predominate under conditions where polyvalent metal ions as Fe(III) and Al(III) saturate the complexing functional

Acknowledgements

The authors acknowledge the German Academic Exchange Service-Royal Golden Jubilee (DAAD-RGJ) Ph.D. Scholarship to S. S.. The Postgraduate Education and Research in Chemistry (PERCH) scholarship and the Thailand Research Fund (TRF) are grateful for partial financial support. S. S. would like to thank all the co-workers at Forschungszentrum Karlsruhe, Institut für Nukleare Entsorgung, for their help during performing the research in Germany notably assistance with analytical methods. The sample

References (49)

  • A.-V. Jung et al.

    Coagulation of humic substances and dissolved organic matter with ferric salt: an electron energy loss spectroscopy investigation

    Water Res.

    (2005)
  • B.A. Kimball et al.

    Effects of colloids on metal transport in a river receiving acid mine drainage, upper Arkansas River, Colorado, USA

    Appl. Geochem.

    (1995)
  • D.G. Kinniburgh et al.

    Ion binding to natural organic matter: competition, heterogeneity, stoichiometry and thermodynamic consistency

    Colloid. Surface. A,

    (1999)
  • R. Kretzschmar et al.

    Influence of pH and humic acid on coagulation kinetics of kaolinite: a dynamic light scattering study

    J. Coll. Interface Sci.

    (1998)
  • A. Kucukonder et al.

    Qualititative and quantitative analysis of lignite coal and its ash samples taken from Soma-Darkale region

    J. Quant. Spectrosc Radiat.

    (2003)
  • G. Lee et al.

    Removal of trace metals by coprecipitation with Fe, Al, and Mn from natural waters contaminated with acid mine drainage in the Ducktaown Mining District, Tennessee

    Appl. Geochem.

    (2002)
  • B. Lyven et al.

    Competition between iron- and carbon-based colloidal carriers for trace metals in a freshwater assessed using flow field-flow fractionation coupled to ICPMS

    Geochim. Cosmochim. Acta

    (2003)
  • M.M. Matlock et al.

    Chemical precipitation of heavy metals from acid mine drainage

    Water Res

    (2002)
  • L.E. Schemel et al.

    Colloid formation and metal transport through two mixing zones affected by acid mine drainage near Silverton

    Appl. Geochem.

    (2000)
  • M.E. Schimpf et al.

    Characterization of humic materials by field-flow fractionation

    Colloid Surface

    (1997)
  • B. Sun et al.

    Leaching of heavy metals from contaminated soils using EDTA

    Environ. Pollut.

    (2001)
  • B. Vigneault et al.

    Geochemical changes in sulfidic mine tailings under a shallow water cover

    Water Res

    (2001)
  • N.A. Wall et al.

    Humic acids coagulation: influence of divalent cations

    Appl. Geochem.

    (2003)
  • M.A. Yukselen et al.

    Leaching of metals from soil contaminated by mining activities

    J. Hazard. Mater.

    (2001)
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    Presently at School of Science, Mae Fah Luang University, 333 T.Tasud, Muang, Chiang Rai 57100 Thailand.

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