Adsorption–Desorption Behavior of Cadmium(II) and Copper(II) on the Surface of Nanoparticle Agglomerates of Hydrous Titanium(IV) Oxide

Abstract

The adsorption/desorption behavior of Cd 2þ and Cu 2þ on/from nanostructured hydrous titanium(IV) oxide (NHTO) surfaces was studied at 30 °C and pH 5.0 (( 0.1). The pseudosecond-order kinetics model described the metal ion adsorption reactions with NHTO very well (R 2 = 1.00). The isotherm equilibria were of a Langmuir type (R 2 Cd = 1.00, R 2 Cu = 0.95). The monolayer capacities evaluated were (0.15 and 0.46) mmol 3 g À1 for Cd 2þ and Cu 2þ , respectively. Investigations on the desorption of adsorbed metal ions from NHTO surfaces with a variation of complexions, ionic strength (I), and solution pH showed that ethylenediaminetetraacetic acid (EDTA; 0.01 M) and the HCl (0.1 M) solutions were the most efficient. Kinetic data of the desorption reactions between M 2þ -NHTO (M 2þ = Cd 2þ or Cu 2þ ) and EDTA (0.01 M) or HCl (0.1 M) were described by the first-order equation well (R 2 = 0.96À1.00), except the kinetic data for the Cu 2þ desorption by 0.01 M EDTA, which were described by the Elovich equation well (R 2 = 0.96). The kinetics of the desorption reactions indicated that the 0.1 M HCl could desorb metal ions from NHTO surface with more efficiency than 0.01 M EDTA. The desorption of metal ions with 0.1 M HCl could be described by an ion-exchange reaction type.

Rapid and efficient removal of fluoride ions from aqueous solution using a polypyrrole coated hydrous tin oxide nanocomposite

“…The effect of initial solution pH on the F À removal efficiency of PPy/HSnO NC 3 revealed that F À sorption by PPy/HSnO NC 3 is mainly governed by electrostatic interaction and ion-exchange mechanism which was further supported by the values of activation energy and thermodynamic parameters evaluated in Sections 3.3.2 and 3.3.6. The easy regenerability and reusability of the adsorbent with desorption efficiency of 95.8% as mentioned in Section 3.3.10. also signifies the physical nature of adsorption [59]. Eventually, it can be concluded that electrostatic interaction and ion-exchange are primarily underlying mechanisms of F À sorption on PPy/HSnO NC 3.…”

Pb2+ adsorption on TiO2@HF‐waste building bricks: Kinetics, thermodynamics, and mechanisms

“…Different kinds of adsorbents were studied for heavy metal ions removal, such as activated carbon, chitosan, zeolite, and so on. TiO 2 has the advantages of stable physical and chemical properties, nontoxic, and inexpensive (Chen, Wang et al., ; Chen et al., ; Chen, Yu, Wang, Feng, & Yan, ; Chen, Zhang et al., ; Cincotti, Mameli, Locci, Orrù, & Cao, ; Debnath, Nandi, & Ghosh, ; Kang, Lee, Moon, & Kim, ; Shen, Chen, & Wen, ). However, it also has some shortcomings which limit its application, such as the small particle size, agglomeration, also recycle problem (Chen, Yao, Yang, Wang, & Huang, ; Chen, Wang et al., ; Chen, Yu, Wang, Feng, & Yan, ; Chen, Zhang et al., ; Chen, Zhu, Wang, Feng, & Yan, ).…”

Matrix effects on the performance and mechanism of Hg removal from groundwater by MoS2 nanosheets

“…The Hg release behavior of the Hg-laden MoS 2 nanosheets and AC was examined with fresh groundwater, acid solution (mass ratio of H 2 SO 4 and HNO 3 at 2 : 1, pH = 3.20 ± 0.05), and EDTA solution, to simulate the natural state fluid, acid rain, and strong metal complexing agent, respectively. 69,70 Generally, as shown in Fig. 5a and b, the amount of released Hg from MoS 2 or AC increased slowly over 1 d, and then gradually reached an equilibrium in 2–4 d. Upon equilibrium, the desorption efficiencies of Hg-laden MoS 2 were 0.4%, 3.0%, and 28% (the ratio of desorbed Hg over the actual amount of Hg immobilized by MoS 2 estimated from Fig.…”

“…MoS2 used) has to be employed to achieve a similar Hg loading mass onto the remediation materials. The Hg release behavior of the Hg-laden MoS2 nanosheets and AC were examined with fresh groundwater, acid solution (mass ratio of H2SO4 and HNO3 at 2:1, pH = 3.20±0.05), and EDTA solution, to simulate natural state fluid, acid rain, and strong metal complexing agent, respectively 69,70. Generally, as shown in Figure5aand b, the amounts of released Hg from MoS2 or AC increased slowly in 1 d, and then gradually reached an equilibrium at 2-4 d. Upon equilibrium, the desorption efficiencies of Hg-laden MoS2 were 0.4%, 3.0%, and 28% (the ratio of desorbed Hg over the actual amount of Hg immobilized by MoS2 estimated from Figure 3f) in the simulated groundwater, acid solution, and EDTA solution, respectively, as compared to apparently higher desorption degree of 1.2%, 12%, and 60% in the case of AC (Figure 5b).…”