Hexavalent chromium removal by various adsorbents: Powdered activated carbon, chitosan, and single/multi-walled carbon nanotubes

Chanil Jung; Jiyong Heo; Jonghun Han; Namguk Her; Sung Jae Lee; Jeill Oh; Jaena Ryu; Yeomin Yoon

doi:10.1016/j.seppur.2012.12.028

Hexavalent chromium removal by various adsorbents: Powdered activated carbon, chitosan, and single/multi-walled carbon nanotubes

Chanil Jung, Jiyong Heo, Jonghun Han, Namguk Her, Sung Jae Lee, Jeill Oh, Jaena Ryu, Yeomin Yoon

Department of Environmental Science & Engineering

Research output: Contribution to journal › Article › peer-review

319 Scopus citations

Abstract

The adsorption behavior of ppb-level aqueous solutions of hexavalent chromium [Cr(VI)] on four different adsorbents was investigated as a function of pH, contact time, initial Cr(VI) concentration, adsorbent dose, and the copresence of competing anions. The adsorbents selected were powered activated carbon (PAC), chitosan, single-walled carbon nanotubes (SWNTs), and multi-walled carbon nanotubes (MWNTs). Each adsorbent was characterized by Fourier transform infrared spectroscopy and measurements of zeta potential to determine its suitability for Cr(VI) adsorption. The adsorption of Cr(VI) was found to be favored at low pH because all adsorbents were positively charged under acidic conditions (pH 4), while a dosage of 100 mg/L resulted in efficient adsorption behavior. PAC and chitosan provided the best removal performance. The highly functionalized and porous PAC and the protonated amines on chitosan enabled a better performance and resulted in high Cr(VI) removal efficiencies of 99.4% and 94.7%, respectively, while the removal efficiencies of SWNTs and MWNTs were 72.9% and 51.9%, respectively. Isotherm and kinetic studies were undertaken to evaluate the characteristics of the Cr(VI) adsorption process. A well-fitted Langmuir isotherm model suggested that monolayer adsorption was the main process operating with an adsorption capacity (q_m) of 46.9, 35.6, 20.3, and 2.48 mg/g for PAC, chitosan, SWNTs, and MWNTs, respectively. Pseudo second-order fitted models revealed the importance of kinetic parameters (apart from adsorption capacity) in understanding the transport of Cr(VI) in the solution, while an intra-particle diffusion model fitted well for μg/L levels of Cr(VI) adsorption. This indicated that both physisorption and chemisorption were dominant, particularly for SWNTs. Anions such as Cl^- and SO42- in the solution competed with HCrO4- and this phenomenon resulted in negative effects on Cr(VI) adsorption.

Original language	English
Pages (from-to)	63-71
Number of pages	9
Journal	Separation and Purification Technology
Volume	106
DOIs	https://doi.org/10.1016/j.seppur.2012.12.028
State	Published - 2013

Bibliographical note

Funding Information:
This research was supported by the Korea Ministry of Environment, ‘Project, 414-111-004’ and ‘GAIA Project, 2012000550022’.

Keywords

Chitosan
Hexavalent chromium
Multi-walled carbon nanotubes
Powdered activated carbon
Single-walled carbon nanotubes

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10.1016/j.seppur.2012.12.028

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@article{9702319209cd4d5f9b410cfe3e6e42d9,

title = "Hexavalent chromium removal by various adsorbents: Powdered activated carbon, chitosan, and single/multi-walled carbon nanotubes",

abstract = "The adsorption behavior of ppb-level aqueous solutions of hexavalent chromium [Cr(VI)] on four different adsorbents was investigated as a function of pH, contact time, initial Cr(VI) concentration, adsorbent dose, and the copresence of competing anions. The adsorbents selected were powered activated carbon (PAC), chitosan, single-walled carbon nanotubes (SWNTs), and multi-walled carbon nanotubes (MWNTs). Each adsorbent was characterized by Fourier transform infrared spectroscopy and measurements of zeta potential to determine its suitability for Cr(VI) adsorption. The adsorption of Cr(VI) was found to be favored at low pH because all adsorbents were positively charged under acidic conditions (pH 4), while a dosage of 100 mg/L resulted in efficient adsorption behavior. PAC and chitosan provided the best removal performance. The highly functionalized and porous PAC and the protonated amines on chitosan enabled a better performance and resulted in high Cr(VI) removal efficiencies of 99.4% and 94.7%, respectively, while the removal efficiencies of SWNTs and MWNTs were 72.9% and 51.9%, respectively. Isotherm and kinetic studies were undertaken to evaluate the characteristics of the Cr(VI) adsorption process. A well-fitted Langmuir isotherm model suggested that monolayer adsorption was the main process operating with an adsorption capacity (qm) of 46.9, 35.6, 20.3, and 2.48 mg/g for PAC, chitosan, SWNTs, and MWNTs, respectively. Pseudo second-order fitted models revealed the importance of kinetic parameters (apart from adsorption capacity) in understanding the transport of Cr(VI) in the solution, while an intra-particle diffusion model fitted well for μg/L levels of Cr(VI) adsorption. This indicated that both physisorption and chemisorption were dominant, particularly for SWNTs. Anions such as Cl- and SO42- in the solution competed with HCrO4- and this phenomenon resulted in negative effects on Cr(VI) adsorption.",

keywords = "Chitosan, Hexavalent chromium, Multi-walled carbon nanotubes, Powdered activated carbon, Single-walled carbon nanotubes",

author = "Chanil Jung and Jiyong Heo and Jonghun Han and Namguk Her and Lee, {Sung Jae} and Jeill Oh and Jaena Ryu and Yeomin Yoon",

note = "Funding Information: This research was supported by the Korea Ministry of Environment, {\textquoteleft}Project, 414-111-004{\textquoteright} and {\textquoteleft}GAIA Project, 2012000550022{\textquoteright}.",

year = "2013",

doi = "10.1016/j.seppur.2012.12.028",

language = "English",

volume = "106",

pages = "63--71",

journal = "Separation and Purification Technology",

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T1 - Hexavalent chromium removal by various adsorbents

T2 - Powdered activated carbon, chitosan, and single/multi-walled carbon nanotubes

AU - Jung, Chanil

AU - Heo, Jiyong

AU - Han, Jonghun

AU - Her, Namguk

AU - Lee, Sung Jae

AU - Oh, Jeill

AU - Ryu, Jaena

AU - Yoon, Yeomin

N1 - Funding Information: This research was supported by the Korea Ministry of Environment, ‘Project, 414-111-004’ and ‘GAIA Project, 2012000550022’.

PY - 2013

Y1 - 2013

N2 - The adsorption behavior of ppb-level aqueous solutions of hexavalent chromium [Cr(VI)] on four different adsorbents was investigated as a function of pH, contact time, initial Cr(VI) concentration, adsorbent dose, and the copresence of competing anions. The adsorbents selected were powered activated carbon (PAC), chitosan, single-walled carbon nanotubes (SWNTs), and multi-walled carbon nanotubes (MWNTs). Each adsorbent was characterized by Fourier transform infrared spectroscopy and measurements of zeta potential to determine its suitability for Cr(VI) adsorption. The adsorption of Cr(VI) was found to be favored at low pH because all adsorbents were positively charged under acidic conditions (pH 4), while a dosage of 100 mg/L resulted in efficient adsorption behavior. PAC and chitosan provided the best removal performance. The highly functionalized and porous PAC and the protonated amines on chitosan enabled a better performance and resulted in high Cr(VI) removal efficiencies of 99.4% and 94.7%, respectively, while the removal efficiencies of SWNTs and MWNTs were 72.9% and 51.9%, respectively. Isotherm and kinetic studies were undertaken to evaluate the characteristics of the Cr(VI) adsorption process. A well-fitted Langmuir isotherm model suggested that monolayer adsorption was the main process operating with an adsorption capacity (qm) of 46.9, 35.6, 20.3, and 2.48 mg/g for PAC, chitosan, SWNTs, and MWNTs, respectively. Pseudo second-order fitted models revealed the importance of kinetic parameters (apart from adsorption capacity) in understanding the transport of Cr(VI) in the solution, while an intra-particle diffusion model fitted well for μg/L levels of Cr(VI) adsorption. This indicated that both physisorption and chemisorption were dominant, particularly for SWNTs. Anions such as Cl- and SO42- in the solution competed with HCrO4- and this phenomenon resulted in negative effects on Cr(VI) adsorption.

AB - The adsorption behavior of ppb-level aqueous solutions of hexavalent chromium [Cr(VI)] on four different adsorbents was investigated as a function of pH, contact time, initial Cr(VI) concentration, adsorbent dose, and the copresence of competing anions. The adsorbents selected were powered activated carbon (PAC), chitosan, single-walled carbon nanotubes (SWNTs), and multi-walled carbon nanotubes (MWNTs). Each adsorbent was characterized by Fourier transform infrared spectroscopy and measurements of zeta potential to determine its suitability for Cr(VI) adsorption. The adsorption of Cr(VI) was found to be favored at low pH because all adsorbents were positively charged under acidic conditions (pH 4), while a dosage of 100 mg/L resulted in efficient adsorption behavior. PAC and chitosan provided the best removal performance. The highly functionalized and porous PAC and the protonated amines on chitosan enabled a better performance and resulted in high Cr(VI) removal efficiencies of 99.4% and 94.7%, respectively, while the removal efficiencies of SWNTs and MWNTs were 72.9% and 51.9%, respectively. Isotherm and kinetic studies were undertaken to evaluate the characteristics of the Cr(VI) adsorption process. A well-fitted Langmuir isotherm model suggested that monolayer adsorption was the main process operating with an adsorption capacity (qm) of 46.9, 35.6, 20.3, and 2.48 mg/g for PAC, chitosan, SWNTs, and MWNTs, respectively. Pseudo second-order fitted models revealed the importance of kinetic parameters (apart from adsorption capacity) in understanding the transport of Cr(VI) in the solution, while an intra-particle diffusion model fitted well for μg/L levels of Cr(VI) adsorption. This indicated that both physisorption and chemisorption were dominant, particularly for SWNTs. Anions such as Cl- and SO42- in the solution competed with HCrO4- and this phenomenon resulted in negative effects on Cr(VI) adsorption.

KW - Chitosan

KW - Hexavalent chromium

KW - Multi-walled carbon nanotubes

KW - Powdered activated carbon

KW - Single-walled carbon nanotubes

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DO - 10.1016/j.seppur.2012.12.028

M3 - Article

AN - SCOPUS:84873843585

SN - 1383-5866

VL - 106

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EP - 71

JO - Separation and Purification Technology

JF - Separation and Purification Technology

ER -

Hexavalent chromium removal by various adsorbents: Powdered activated carbon, chitosan, and single/multi-walled carbon nanotubes

Abstract

Bibliographical note

Keywords

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