Fluoride removal by palm shell waste based powdered activated carbon vs. functionalized carbon with magnesium silicate: Implications for their application in water treatment

Choe Earn Choong; Kien Tiek Wong; Seok Byum Jang; In Wook Nah; Jaeyoung Choi; Shaliza Ibrahim; Yeomin Yoon; Min Jang

doi:10.1016/j.chemosphere.2019.124765

Fluoride removal by palm shell waste based powdered activated carbon vs. functionalized carbon with magnesium silicate: Implications for their application in water treatment

Chemosphere. 2020 Jan:239:124765. doi: 10.1016/j.chemosphere.2019.124765. Epub 2019 Sep 7.

Authors

Choe Earn Choong¹, Kien Tiek Wong¹, Seok Byum Jang¹, In Wook Nah², Jaeyoung Choi³, Shaliza Ibrahim⁴, Yeomin Yoon⁵, Min Jang⁶

Affiliations

¹ Department of Environmental Engineering, Kwangwoon University, 20 Kwangwoon-Ro, Nowon-Gu, Seoul, 01897, Republic of Korea.
² Center for Energy Convergence, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-Gu, Seoul, 02792, Republic of Korea.
³ Green City Technology Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-Gu, Seoul, 02792, Republic of Korea.
⁴ Institute of Ocean and Earth Sciences (IOES), University of Malaya, Kuala Lumpur, 50603, Malaysia.
⁵ Department of Civil and Environmental Engineering, University of South Carolina, Columbia, 300 Main Street, SC, 29208, USA.
⁶ Department of Environmental Engineering, Kwangwoon University, 20 Kwangwoon-Ro, Nowon-Gu, Seoul, 01897, Republic of Korea. Electronic address: minjang@kw.ac.kr.

PMID: 31520981
DOI: 10.1016/j.chemosphere.2019.124765

Abstract

In this study, palm shell activated carbon powder (PSAC) and magnesium silicate (MgSiO₃) modified PSAC (MPSAC) were thoroughly investigated for fluoride (F^-) adsorption. F^- adsorption isotherms showed that PSAC and MPSAC over-performed some other reported F^- adsorbents with adsorption capacities of 116 mg g^-1 and 150 mg g^-1, respectively. Interestingly, the MgSiO₃ impregnated layer changed the adsorption behavior of F^- from monolayer to heterogeneous multilayer based on the Langmuir and Freundlich isotherm models verified by chi-square test (X²). Thermodynamic parameters indicated that the F^- adsorption on PSAC and MPSAC was spontaneous and exothermic. PSAC and MPSAC were characterized using FESEM-EDX, XRD, FTIR and XPS to investigate the F^- adsorption mechanism. Based on the regeneration tests using NaOH (0.01 M), PSAC exhibited poor regeneration (<20%) while MPSAC had steady adsorption efficiencies (∼70%) even after 5 regeneration cycles. This is due to highly polarized C-F bond was found on PSAC while Mg-F bond was distinguished on MPSAC, evidently denoting that the F^- adsorption is mainly resulted from the exchange of hydroxyl (-OH) group. It was concluded that PSAC would be a potential adsorbent for in-situ F^- groundwater remediation due to its capability to retain F^- without leaching out in a wide range pH. MPSAC would be an alternative adsorbent for ex-situ F^- water remediation because it can easily regenerate with NaOH solution. With the excellent F^- adsorption properties, both PSAC and MPSAC offer as promising adsorbents for F^- remediation in the aqueous phase.

Keywords: Adsorption; Fluoride; Magnesium silicate; Palm-shell activated carbon.

MeSH terms

Adsorption
Charcoal / chemistry*
Fluorides / chemistry
Fluorides / isolation & purification*
Hydrogen-Ion Concentration
Kinetics
Magnesium Silicates / chemistry*
Microscopy, Electron, Scanning
Phoeniceae
Photoelectron Spectroscopy
Spectroscopy, Fourier Transform Infrared
Thermodynamics
Waste Products
Water Pollutants, Chemical / chemistry
Water Pollutants, Chemical / isolation & purification*
Water Purification / methods
X-Ray Diffraction

Substances

Magnesium Silicates
Waste Products
Water Pollutants, Chemical
Charcoal
Fluorides