Efficient Removal of Toxic mMetal Ions (Pb(II) and Hg(II) Ions in Single Component Systems by Adsorption on Romanian Clay Material

Abstract

In this study, a local natural clay material was used for the efficient removal of Pb(II)ions and Hg(II) ions from aqueous media, in batch system. The adsorptive potential of clay material was testes at different initial solution pH, adsorbent dosage, contact time and initial heavy metal ions concentration and room temperature (20  2C). The highest adsorption efficiency of clay material was found at initial pH of 7.0 in case of Pb(II) ions, and 2.0 in case of Hg(II) ions, while the adsorbent dosage had the same value (4 g/L) for both metal ions. The adsorption equilibrium is very fast and was reach within 10 min. The modelling of experimental data showed that the adsorption processes followed the Freundlich isotherm model and pseudo-second order kinetic model. Detailed analysis of the experimental data indicate that the retention of Pb(II) and Hg(II) ions from aqueous solution on clay materials involves two processes, one of adsorption and the other of precipitation, whose succession depends on the speciation form of the metal ion in aqueous solution. However, the high adsorption capacity and short contact time are important characteristics which suggest the potential use of this clay material in environmental remediation processes.

Adsorption Behavior of Lead Ions from Wastewater on Pristine and Aminopropyl-Modified Blast Furnace Slag

“…The R 2 value of pseudo-second-order model (0.999) is larger than those of pseudo-first-order (0.957) and intraparticle diffusion (0.921) model and the equilibrium adsorption capacity derived from pseudo-second-order kinetic equation (40.62 mg•g −1 ) is much more similar to the experimental value (38.55 mg•g −1 ), indicating that the pseudo-second-order model is more suitable for describing the adsorption of lead ions on the slag. This observation suggests that the limiting step in the adsorption is predominantly controlled by a chemical adsorption mechanism, in other words, electronic transfer and electronic sharing between the adsorbate and adsorbent are involved in the adsorption process [18,49,50]. Therefore, any strategies that may enhance the chemical interaction between lead ions and the superficial functional groups of the slag are highly advantageous to the removal efficiency of the lead ions from wastewater.…”

“…Amongst these techniques, adsorption has received increasing attention due to its ease of operation and abundance of adsorbents [15][16][17]. Zeolites, ordered mesoporous silica, activated carbon, clay minerals [18], etc. are considerably effective for metal ions removal by adsorption due to their high porosity and surface area, but most of these adsorbents are quite expensive because of the complex synthesis process, involving high energy consumption and large depletion of raw material sources [10], thus limiting their widespread use in wastewater treatment.…”