Modified clays for barriers: a review

Abstract

The aim of this Specialized Lecture is to present the recent advances and issues, as well as original research, on Modified Clays for Barriers. Topics of interest include:(1) long-term hydraulic performance of modified clays for GCLs, (2) chemico-osmotic and diffusion efficiency of modified clays, (3) modeling coupled chemical-hydraulicmechanical behavior of modified clays, (4) wet and dry ageing of modified clays, (5) use of novel bentonites for vertical barrier applications, and (6) organoclays for various barrier applications. In addition, the possible reuse of dredged sediments after polymer treatment will also be discussed. Environmental management and handling of dredged sediments are important worldwide because enormous amounts of dredged material emerge from maintenance, construction and remedial works within water systems. Usually these materials after temporary upland disposal in lagoons are disposed in landfills. The aim of this study is to analyse the possible reuse of these sediments as a low-cost alternative material for landfill covers. The mechanisms through which polymers can improve the efficiency of dredged sediments for waste containment low permeable barriers are discussed.

The Role of Natural Clays in the Sustainability of Landfill Liners

“…• Lab or field measurements (Allen, 2000;Benson et al, 1999;Shackelford and Javed, 1991); • Compaction (Herrmann et al, 2009); • (liquid) saturation ratio (Benson et al, 1999;Widomski et al, 2018); • Other minor construction variables (Benson et al, 1999); • Permeating liquid (di Emidio et al, 2017;Francisca and Glatstein, 2010;Jo et al, 2001;Lee et al, 2005;Singh and Prasad, 2007;Stepniewski et al, 2011; Uma Shankar and Muthukumar, 2017); • Methodology (Sandoval et al, 2017); • Passing of time and wet-dry seasonal variations (di Emidio et al, 2017;Egloffstein, 2001;Mitchell and Jaber, 1990;Stepniewski et al, 2011;Widomski et al, 2016).…”

“…This results in measurements of unsaturated K whose values are typically lower than those of saturated K as the water would be strongly attracted by the tension of the dry soil. The possible loss of the hydraulic connection when the pore water at the bottom of the model liner is transferred to the collector during spinning would also promote unsaturated conditions with lower K. Additionally, there are other processes that can also be affecting K. The leachate, with a high concentration and valence of ions, would decrease the net particle charge (Chorom and Rengasamy, 1995) and thickness of the Diffuse Double Layer (di Emidio et al, 2017;Schmitz, 2006;Stepniewski et al, 2011) in an initial stage. The former is due to the decrease in the dispersion of clays and the latter is relevant for the high porosity of freshly compacted soils.…”

The role of natural clays in the sustainability of landfill liners

“…• Lab or eld measurements (Allen, 2000;Benson et al, 1999;Shackelford and Javed, 1991); • Compaction (Herrmann et al, 2009); • (liquid) saturation ratio (Benson et al, 1999;Widomski et al, 2018); • Other minor construction variables (Benson et al, 1999); • Permeating liquid (di Emidio et al, 2017;Francisca and Glatstein, 2010;Jo et al, 2001;Lee et al, 2005;Singh and Prasad, 2007;Stepniewski et al, 2011;Uma Shankar and Muthukumar, 2017);…”

“…• Passing of time and wet-dry seasonal variations (di Emidio et al, 2017;Egloffstein, 2001;Mitchell and Jaber, 1990;Stepniewski et al, 2011;Widomski et al, 2016).…”

Gaseous Heptanethiol Removal by a Fe3+-Phenanthroline–Kaolinite Hybrid Material

“…Usually, these materials are grouped based on the type of host (i.e., the layered mineral) and guest molecule involved in the interaction. Three main types of functionalized layer silicates can be identified, namely, (i) organoclays, which are layered silicates (typically smectites) bound to an organic molecule (or to an organo-metallic complex) that imparts peculiar properties to the modified minerals; − (ii) pillared clays, which are layered silicates intercalated with small organic or inorganic complexes (i.e., “pillars”), partially filling the interlayer space; − and (iii) clay mineral-nanocomposites, which are fine-particulate materials, heterogeneous at the nanoscale level, made at least from one clay mineral and from other materials such as polymers, pharmaceuticals, inorganic molecules, or carbon. − …”