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. 2020 Apr 16;25(8):1820.
doi: 10.3390/molecules25081820.

A Functionalized Silicate Adsorbent and Exploration of Its Adsorption Mechanism

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Free PMC article

A Functionalized Silicate Adsorbent and Exploration of Its Adsorption Mechanism

Hanzhi Lin et al. Molecules. .
Free PMC article

Abstract

Active silicate materials have good adsorption and passivation effects on heavy metal pollutants. The experimental conditions for the preparation of active silicate heavy metal adsorbent (ASHMA) and the adsorption of Cu(II) by ASHMA were investigated. The optimum preparation conditions of ASHMA were as follows: 200 mesh quartz sand as the raw material, NaOH as an activating agent, NaOH/quartz sand = 0.45 (mass fraction), and calcination at 600 °C for 60 min. Under these conditions, the active silicon content of the adsorbent was 22.38% and the utilization efficiency of NaOH reached 89.11%. The adsorption mechanism of Cu(II) on the ASHMA was analyzed by the Langmuir and Freundlich isotherm models, which provided fits of 0.99 and 0.98, respectively. The separation coefficient (RL) and adsorption constant (n) showed that the adsorbent favored the adsorption of Cu(II), and the maximum adsorption capacity (Qmax) estimated by the Langmuir isotherm was higher than that of 300 mg/L. Furthermore, adsorption by ASHMA was a relatively rapid process, and adsorption equilibrium could be achieved in 1 min. The adsorbents were characterized by FT-IR and Raman spectroscopy. The results showed that the activating agent destroyed the crystal structure of the quartz sand under calcination, and formed Si-O-Na and Si-OH groups to realize activation. The experimental results revealed that the adsorption process involved the removal of Cu(II) by the formation of Si-O-Cu bonds on the surface of the adsorbent. The above results indicated that the adsorbent prepared from quartz sand had a good removal effect on Cu(II).

Keywords: active silicate; adsorption mechanism; calcination-activation; heavy metal adsorption.

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Effect of preparation conditions on active silicon contents. (a) roasting temperature ranged from 100 °C to 700 °C, (b) ratio of NaOH to quartz sand ranged from 0.2 to 1.2, (c) roasting time ranged from 0 min to 150 min, (d) practice size ranged from 40 mesh to 400 mesh and (e) impurities: NaCl, Fe2O3, Al2O3, MgO, MnO2 and FeO.
Figure 2
Figure 2
FT-IR spectra of quartz and ASHMAs.
Figure 3
Figure 3
Raman spectra analysis of quartz sand (a) and ASHMA (b).
Figure 4
Figure 4
SEM images of quartz sand (a,b) and ASHMA (c,d), respectively.
Figure 5
Figure 5
Effect of (a) equilibrium time on the adsorption of Cu(II) by the ASHMA and (b) temperature.
Figure 6
Figure 6
Effect of unreacted NaOH in the adsorbents on the adsorption efficiency of the adsorbents.
Figure 7
Figure 7
The relationship between the amount of ASHMA added and the separation coefficient RL at different.
Figure 8
Figure 8
Scanning electron micrograph (a,b) and EDS pattern (c) for the ASHMA after the adsorption of Cu(II).

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References

    1. Li N., Kang Y., Pan W., Zeng L., Zhang Q., Luo J. Concentration and transportation of heavy metals in vegetables and risk assessment of human exposure to bioaccessible heavy metals in soil near a waste-incinerator site, South China. Sci. Total Environ. 2015;521:144–151. doi: 10.1016/j.scitotenv.2015.03.081. - DOI - PubMed
    1. Liu J., Yin M., Zhang W., Tsang D.C.W., Wei X., Zhou Y., Xiao T., Wang J., Dong X., Sun Y., et al. Response of microbial communities and interactions to thallium in contaminated sediments near a pyrite mining area. Environ. Pollut. 2019;248:916–928. doi: 10.1016/j.envpol.2019.02.089. - DOI - PubMed
    1. Liu X., Shi H., Bai Z., Zhou W., Liu K., Wang M., He Y. Heavy metal concentrations of soils near the large opencast coal mine pits in China. Chemosphere. 2020;244:125360. doi: 10.1016/j.chemosphere.2019.125360. - DOI - PubMed
    1. Bello O., Naidu R., Rahman M.M., Liu Y., Dong Z. Lead concentration in the blood of the general population living near a lead-zinc mine site, Nigeria: Exposure pathways. Sci. Total Environ. 2016;542:908–914. doi: 10.1016/j.scitotenv.2015.10.143. - DOI - PubMed
    1. Singh M., Thind P.S., John S. Health risk assessment of the workers exposed to the heavy metals in e-waste recycling sites of Chandigarh and Ludhiana, Punjab, India. Chemosphere. 2018;203:426–433. doi: 10.1016/j.chemosphere.2018.03.138. - DOI - PubMed
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