Interaction of trace elements in acid mine drainage solution with humic acid
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: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)
- et al.
Aggregation of humic substances by metal ions measured by ultracentrifugation
Anal. Chim. Acta
(2001) - et al.
Electrochemical treatment of acidic aqueous ferrous sulfate and copper sulfate as models for acid mine drainage
Water Res
(2001) - et al.
Mobility of heavy metals associated with the natural weathering of coal mine spoils
Environ. Pollut.
(2002) - et al.
Metal distribution and environmental problems related to sulfide oxidation in the Libiola copper mine area (Ligurian Apennines, Italy)
J. Geochem. Explor.
(2001) - et al.
Removal of dissolved copper and iron at the freshwater-saltwater interface of an acid mine stream
Mar. Pollut.
(1997) Characterization of natural organic matter as major constituents in aquatic systems
J. Cont. Hydrol.
(1998)- et al.
Aquatic colloids relevant to radionuclide migration: characterization by size fractionation and ICP-mass spectrometric detection
Colloid Surface
(2003) - et al.
Inuence of pH and TOC concentration on Cu,Zn,Cd, and Al speciation in rivers
Water Res.
(2003) - et al.
Re-examination of cross-flow ultrafiltration for sampling aquatic colloids: evidence from molecular probes
Mar. Chem.
(2000) - et al.
A TEM study of samples from acid mine drainage systems: metal-mineral association with implications for transport
Geochim. Cosmochim. Acta
(1999)
Coagulation of humic substances and dissolved organic matter with ferric salt: an electron energy loss spectroscopy investigation
Water Res.
Effects of colloids on metal transport in a river receiving acid mine drainage, upper Arkansas River, Colorado, USA
Appl. Geochem.
Ion binding to natural organic matter: competition, heterogeneity, stoichiometry and thermodynamic consistency
Colloid. Surface. A,
Influence of pH and humic acid on coagulation kinetics of kaolinite: a dynamic light scattering study
J. Coll. Interface Sci.
Qualititative and quantitative analysis of lignite coal and its ash samples taken from Soma-Darkale region
J. Quant. Spectrosc Radiat.
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.
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
Chemical precipitation of heavy metals from acid mine drainage
Water Res
Colloid formation and metal transport through two mixing zones affected by acid mine drainage near Silverton
Appl. Geochem.
Characterization of humic materials by field-flow fractionation
Colloid Surface
Leaching of heavy metals from contaminated soils using EDTA
Environ. Pollut.
Geochemical changes in sulfidic mine tailings under a shallow water cover
Water Res
Humic acids coagulation: influence of divalent cations
Appl. Geochem.
Leaching of metals from soil contaminated by mining activities
J. Hazard. Mater.
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Presently at School of Science, Mae Fah Luang University, 333 T.Tasud, Muang, Chiang Rai 57100 Thailand.