Sorption behaviour of heavy metals in sand-bentonite-coal ash mixes for use as a liner material in landfills

Adsorption Property of Pb(II) by the Laterite‐Bentonite Mixture Used as Waste Landfill Liner

“…In this study, the adsorption of Pb(II) by laterite-bentonite mixture was investigated using the batch test under di erent conditions, including bentonite content (0-100%), contact time (5-480 min), solid to solution ratio (0.5-200 g•L −1 ), pH (2)(3)(4)(5)(6)(7)(8)(9)(10)(11), ion strength (0-1 mol•L −1 ), and temperature (328 K, 323 K). To evaluate the in uence of those conditions, three adsorption kinetic models and two adsorptive isotherm models are used to analyze the experiment data and the feasibility of di erent models in this research.…”

“…Because the existence of Pb(II) is highly dependent on the pH value, the batch test was carried out under different pH values [2][3][4][5][6][7][8][9][10][11], and the experiment results are shown in Figure 4. Clearly, the adsorption rate of Pb(II) increases significantly with the increase of the pH value, and this trend becomes evident when bentonite content decreases.…”

“…When applying equation (8) at two di erent temperatures, the prediction equation above can be plotted in Figure 10. As is shown in the gure, the predicted value of maximum adsorption by mixture is almost equal to the experiment results, indicating the practical application of this prediction equation.…”

“…For example, laterite, a kind of soil which is distributed wildly in tropical and subtropical regions of South China, is an expected source of liner material whose mechanical property is good. However, the tectonic fissure and low adsorption capacity bring some challenges for its safe application as the landfill liner for MSW [8][9][10]. erefore, a lot of additives have been studied to improve the property of natural materials such as lime, cement, fly ash, clay soils, and shale to improve their adsorption [6,8,[11][12][13].…”

“…However, the tectonic fissure and low adsorption capacity bring some challenges for its safe application as the landfill liner for MSW [8][9][10]. erefore, a lot of additives have been studied to improve the property of natural materials such as lime, cement, fly ash, clay soils, and shale to improve their adsorption [6,8,[11][12][13]. Among them, using bentonite as additive or the main material which has high cation exchange capacity (CEC) and specific surface area (SSA) can improve the adsorption property of the liner significantly and reduce its hydraulic conductivity effectively [14,15].…”