Simultaneous sorption of heavy metals on Algerian Bentonite: mechanism study

Abstract

Industrialization has induced tremendous environmental problems, particularly surface and underground water pollution by harmful heavy metals. In this work, we attempt to eliminate simultaneously iron and cadmium from aqueous solutions by adsorption on Algerian Bentonite. This abundant material was used without any modification. The sorption mechanism was investigated, and effects of pH, initial adsorbate and adsorbent concentrations were studied. The kinetics study revealed that equilibrium was reached after 120 min for both metals, and maximal adsorbed quantities of cadmium (76 mg/g) and iron (55 mg/g ) were obtained at pH = 10 and 8 respectively. Different kinetic models were tested, such as pseudo first-order, pseudo second-order, film and intraparticle diffusion models. The pseudo second-order model fits well the experimental data. Biot number values (2–39) show that the simultaneous sorption process is controlled by film diffusion due to electrostatic interactions between negatively charged surface and cations, then by the internal diffusion and formation of bonds between cations and adsorbent constituents. Also, compared to iron, the high and rapid sorption of cadmium reflects the selective nature of the sorption process. These results show that raw bentonite could be used without further treatment as an efficient sorbent for heavy metal mixtures.

Facile Synthesis of Sodium Dodecyl Sulfate Intercalated Mg‐Al LDH and its Excellent Adsorption Performances for Cu2+ from Aqueous Solution

“…[11] Among these diverse techniques, adsorption stands out as a widely recognized and efficient approaches for heavy metal removal, owing to its simplicity, high efficiency and cost-effectiveness. [12] Commonly utilized adsorbents mainly include activated carbon, [13] kaolin, [14] bentonite [15] and attapulgite. [16] Notably, researchers have demonstrated the effectiveness of various adsorbents in heavy metal removal.…”