Geosynthetic Clay Liner Permeated with Acid Rock Drainage:The Role of Iron in Arsenic Immobilization

Naka, Angelica; Kattsumi, Takeshi; Ohta, Takehiro; Flores, Giancarlo; Inui, Tomoyuki; Takai, Atsushi

doi:10.5030/jcigsjournal.27.39

Cited by 1 publication

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“…Therefore arsenic, an oxyanion, cannot be sorbed by GCLs. Previous studies by the authors have shown that great amount of As was retained into GCLs mainly due to the high concentration of Fe present in ARD (Naka et al, 2012), and Lange et al (2007) proposed an hypothesis of As retention due to the gypsum precipitation observed in XRD analysis after ARD permeation through GCLs. Abollino et al (2003) reported that at pH < 3.5 metals are adsorbed on Na-montmorillonite following the order: Cu 2+ < Pb 2+ < Cd 2+ < Zn 2+ < Mn 2+ = Cr 3+ = Ni 2+ .…”

Section: Effects Of Type Of Metalmentioning

confidence: 99%

Factors influencing hydraulic conductivity and metal retention capacity of geosynthetic clay liners exposed to acid rock drainage

Naka

Flores

Tanaka

et al. 2016

JGS Special Publication

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Evaluating the factors that affect hydraulic conductivity and metal retention in geosynthetic clay liners (GCLs) becomes crucial in order to decide whether or not GCLs can be used as a barrier material in rock containments with potential for acid rock drainage (ARD) generation. This study presents a state-of-the-art review of the factors that impact the hydraulic conductivity and heavy metal retention on GCLs: effect of the type of bentonite inside GCLs, prehydration, confining pressure, pH, metal concentration, and type of metal ion in ARDs. ARDs affect the hydraulic performance of GCLs because of their characteristic low pH (usually lower than pH 3) and presence of different heavy metals and concentrations (especially the presence of divalent and trivalent metals). The retention of metals present in ARD through GCLs are governed by the pH (higher retention at pH higher than 3.5), the metals that are present in the ARD as well as the buffering capacity of the bentonite (determined by the cation exchange capacity of bentonite). Ion exchange constitutes the main mechanism for metal uptake, but other mechanisms also take place. Secondary sorption on ferrihydrite or gypsum (formed through precipitation of metals present in ARD) of metalloids such as As, which cannot be sorbed by bentonite directly, may also occur.

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Section: Effects Of Type Of Metalmentioning

confidence: 99%