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. 2024 Jun 12;14(1):13521.
doi: 10.1038/s41598-024-64337-5.

Understanding the relationship between pore size, surface charge density, and Cu2+ adsorption in mesoporous silica

Yanhui Niu  1 , Wenbin Yu  2 , Shuguang Yang  2 , Quan Wan  3
Affiliations

Understanding the relationship between pore size, surface charge density, and Cu2+ adsorption in mesoporous silica

Yanhui Niu et al. Sci Rep. .

Abstract

This research delved into the influence of mesoporous silica's surface charge density on the adsorption of Cu2+. The synthesis of mesoporous silica employed the hydrothermal method, with pore size controlled by varying the length of trimethylammonium bromide (CnTAB, n = 12, 14, 16) chains. Gas adsorption techniques and transmission electron microscopy characterized the mesoporous silica structure. Surface charge densities of the mesoporous silica were determined through potentiometric titration, while surface hydroxyl densities were assessed using the thermogravimetric method. Subsequently, batch adsorption experiments were conducted to study the adsorption of Cu2+ in mesoporous silica, and the process was comprehensively analyzed using Atomic absorption spectrometry (AAS), Fourier transform infrared (FTIR), and L3 edge X-ray absorption near edge structure (XANES). The research findings suggest a positive correlation between the pore size of mesoporous silica, its surface charge density, and the adsorption capacity for Cu2+. More specifically, as the pore size increases within the 3-4.1 nm range, the surface charge density and the adsorption capacity for Cu2+ also increase. Our findings provide valuable insights into the relationship between the physicochemical properties of mesoporous silica and the adsorption behavior of Cu2+, offering potential applications in areas such as environmental remediation and catalysis.

Keywords: Cu2+ adsorption; Mesoporous silica; Pore size; Surface charge density.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1
(a) N2 adsorption/desorption isotherm and (b) pore size distribution of MPS/.
Figure 2
Figure 2
TEM images of MPS (A), Acid–base titration curve of MPS (B),The change curves of Surface charge with pH of MPS (C) and TG curves of MPS (D).
Figure 3
Figure 3
(a) Langmuir adsorption isotherm and (b) Freundlich adsorption isotherm.
Figure 4
Figure 4
(a) Kinetics of Cu2+ adsorption according to the pseudo-first-order model (b) Kinetics of Cu2+ adsorption according to the pseudo-second-order model.
Figure 5
Figure 5
(a) ATR FT-IR sorption spectra of Cu2+ adsorption on MPS, (b) Cu L3-edge XANES spectra of MPS after Cu2+ adsorption, (c) Changes of relative absorption intensity and Cu2+adsorption capacity with surface charge density, (d) Changes of Cu2+adsorption capacity with pore size, (e) Changes of Cu2+adsorption capacity with surface charge density and (f) Changes of surface charge density with pore size.
Figure 6
Figure 6
Schematic diagram of potential superposition mechanism.
Figure 7
Figure 7
Schematic diagram of energy change in the adsorption process.
See this image and copyright information in PMC

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