Intraparticle diffusion and adsorption of arsenate onto granular ferric hydroxide (GFH)

Mohammad Badruzzaman, Paul Westerhoff, Detlef R U Knappe

Research output: Contribution to journalArticle

259 Citations (Scopus)

Abstract

Porous iron oxides are being evaluated and selected for arsenic removal in potable water systems. Granular ferric hydroxide, a typical porous iron adsorbent, is commercially available and frequently considered in evaluation of arsenic removal methods. GFH is a highly porous (micropore volume ∼0.0394±0.0056 cm3 g-1, mesopore volume ∼0.0995±0.0096 cm3g-1) adsorbent with a BET surface area of 235±8 m2g-1. The purpose of this paper is to quantify arsenate adsorption kinetics on GFH and to determine if intraparticle diffusion is a rate-limiting step for arsenic removal in packed-bed treatment systems. Data from bottle-point isotherm and differential column batch reactor (DCBR) experiments were used to estimate Freundlich isotherm parameters (K and 1/n) as well as kinetic parameters describing mass transfer resistances due to film diffusion (kf) and intraparticle surface diffusion (Ds). The pseudo-equilibrium (18 days of contact time) arsenate adsorption density at pH 7 was 8 μg As/mg dry GFH at a liquid phase arsenate concentration of 10 μg As/L. The homogeneous surface diffusion model (HSDM) was used to describe the DCBR data. A non-linear relationship (DS=3.0-9 x Rp 1.4) was observed between Ds and GFH particle radius (RP) with Ds> values ranging from 2.98 x 10-12 cm2 s-1 for the smallest GFH mesh size (100 x 140) to 64 x 10-11 cm2 s-1 for the largest GFH mesh size (10 x 30). The rate-limiting process of intraparticle surface diffusion for arsenate adsorption by porous iron oxides appears analogous to organic compound adsorption by activated carbon despite differences in adsorption mechanisms (inner-sphere complexes for As versus hydrophobic interactions for organic contaminants). The findings are discussed in the context of intraparticle surface diffusion affecting packed-bed treatment system design and application of rapid small-scale column tests (RSSCTs) to simulate the performance of pilot- or full-scale systems at the bench-scale.

Original languageEnglish (US)
Pages (from-to)4002-4012
Number of pages11
JournalWater Research
Volume38
Issue number18
DOIs
StatePublished - 2004

Fingerprint

arsenate
Surface diffusion
hydroxide
adsorption
Adsorption
Arsenic
Batch reactors
Packed beds
Iron oxides
Adsorbents
Isotherms
arsenic
mesh size
iron oxide
Bottles
isotherm
Organic compounds
Kinetic parameters
Potable water
Activated carbon

Keywords

  • Adsorption
  • Arsenic
  • Iron
  • Surface diffusion
  • Water treatment

ASJC Scopus subject areas

  • Earth-Surface Processes

Cite this

Intraparticle diffusion and adsorption of arsenate onto granular ferric hydroxide (GFH). / Badruzzaman, Mohammad; Westerhoff, Paul; Knappe, Detlef R U.

In: Water Research, Vol. 38, No. 18, 2004, p. 4002-4012.

Research output: Contribution to journalArticle

Badruzzaman, Mohammad ; Westerhoff, Paul ; Knappe, Detlef R U. / Intraparticle diffusion and adsorption of arsenate onto granular ferric hydroxide (GFH). In: Water Research. 2004 ; Vol. 38, No. 18. pp. 4002-4012.
@article{44a885057d1143429d972eb5367da359,
title = "Intraparticle diffusion and adsorption of arsenate onto granular ferric hydroxide (GFH)",
abstract = "Porous iron oxides are being evaluated and selected for arsenic removal in potable water systems. Granular ferric hydroxide, a typical porous iron adsorbent, is commercially available and frequently considered in evaluation of arsenic removal methods. GFH is a highly porous (micropore volume ∼0.0394±0.0056 cm3 g-1, mesopore volume ∼0.0995±0.0096 cm3g-1) adsorbent with a BET surface area of 235±8 m2g-1. The purpose of this paper is to quantify arsenate adsorption kinetics on GFH and to determine if intraparticle diffusion is a rate-limiting step for arsenic removal in packed-bed treatment systems. Data from bottle-point isotherm and differential column batch reactor (DCBR) experiments were used to estimate Freundlich isotherm parameters (K and 1/n) as well as kinetic parameters describing mass transfer resistances due to film diffusion (kf) and intraparticle surface diffusion (Ds). The pseudo-equilibrium (18 days of contact time) arsenate adsorption density at pH 7 was 8 μg As/mg dry GFH at a liquid phase arsenate concentration of 10 μg As/L. The homogeneous surface diffusion model (HSDM) was used to describe the DCBR data. A non-linear relationship (DS=3.0-9 x Rp 1.4) was observed between Ds and GFH particle radius (RP) with Ds> values ranging from 2.98 x 10-12 cm2 s-1 for the smallest GFH mesh size (100 x 140) to 64 x 10-11 cm2 s-1 for the largest GFH mesh size (10 x 30). The rate-limiting process of intraparticle surface diffusion for arsenate adsorption by porous iron oxides appears analogous to organic compound adsorption by activated carbon despite differences in adsorption mechanisms (inner-sphere complexes for As versus hydrophobic interactions for organic contaminants). The findings are discussed in the context of intraparticle surface diffusion affecting packed-bed treatment system design and application of rapid small-scale column tests (RSSCTs) to simulate the performance of pilot- or full-scale systems at the bench-scale.",
keywords = "Adsorption, Arsenic, Iron, Surface diffusion, Water treatment",
author = "Mohammad Badruzzaman and Paul Westerhoff and Knappe, {Detlef R U}",
year = "2004",
doi = "10.1016/j.watres.2004.07.007",
language = "English (US)",
volume = "38",
pages = "4002--4012",
journal = "Water Research",
issn = "0043-1354",
publisher = "Elsevier Limited",
number = "18",

}

TY - JOUR

T1 - Intraparticle diffusion and adsorption of arsenate onto granular ferric hydroxide (GFH)

AU - Badruzzaman, Mohammad

AU - Westerhoff, Paul

AU - Knappe, Detlef R U

PY - 2004

Y1 - 2004

N2 - Porous iron oxides are being evaluated and selected for arsenic removal in potable water systems. Granular ferric hydroxide, a typical porous iron adsorbent, is commercially available and frequently considered in evaluation of arsenic removal methods. GFH is a highly porous (micropore volume ∼0.0394±0.0056 cm3 g-1, mesopore volume ∼0.0995±0.0096 cm3g-1) adsorbent with a BET surface area of 235±8 m2g-1. The purpose of this paper is to quantify arsenate adsorption kinetics on GFH and to determine if intraparticle diffusion is a rate-limiting step for arsenic removal in packed-bed treatment systems. Data from bottle-point isotherm and differential column batch reactor (DCBR) experiments were used to estimate Freundlich isotherm parameters (K and 1/n) as well as kinetic parameters describing mass transfer resistances due to film diffusion (kf) and intraparticle surface diffusion (Ds). The pseudo-equilibrium (18 days of contact time) arsenate adsorption density at pH 7 was 8 μg As/mg dry GFH at a liquid phase arsenate concentration of 10 μg As/L. The homogeneous surface diffusion model (HSDM) was used to describe the DCBR data. A non-linear relationship (DS=3.0-9 x Rp 1.4) was observed between Ds and GFH particle radius (RP) with Ds> values ranging from 2.98 x 10-12 cm2 s-1 for the smallest GFH mesh size (100 x 140) to 64 x 10-11 cm2 s-1 for the largest GFH mesh size (10 x 30). The rate-limiting process of intraparticle surface diffusion for arsenate adsorption by porous iron oxides appears analogous to organic compound adsorption by activated carbon despite differences in adsorption mechanisms (inner-sphere complexes for As versus hydrophobic interactions for organic contaminants). The findings are discussed in the context of intraparticle surface diffusion affecting packed-bed treatment system design and application of rapid small-scale column tests (RSSCTs) to simulate the performance of pilot- or full-scale systems at the bench-scale.

AB - Porous iron oxides are being evaluated and selected for arsenic removal in potable water systems. Granular ferric hydroxide, a typical porous iron adsorbent, is commercially available and frequently considered in evaluation of arsenic removal methods. GFH is a highly porous (micropore volume ∼0.0394±0.0056 cm3 g-1, mesopore volume ∼0.0995±0.0096 cm3g-1) adsorbent with a BET surface area of 235±8 m2g-1. The purpose of this paper is to quantify arsenate adsorption kinetics on GFH and to determine if intraparticle diffusion is a rate-limiting step for arsenic removal in packed-bed treatment systems. Data from bottle-point isotherm and differential column batch reactor (DCBR) experiments were used to estimate Freundlich isotherm parameters (K and 1/n) as well as kinetic parameters describing mass transfer resistances due to film diffusion (kf) and intraparticle surface diffusion (Ds). The pseudo-equilibrium (18 days of contact time) arsenate adsorption density at pH 7 was 8 μg As/mg dry GFH at a liquid phase arsenate concentration of 10 μg As/L. The homogeneous surface diffusion model (HSDM) was used to describe the DCBR data. A non-linear relationship (DS=3.0-9 x Rp 1.4) was observed between Ds and GFH particle radius (RP) with Ds> values ranging from 2.98 x 10-12 cm2 s-1 for the smallest GFH mesh size (100 x 140) to 64 x 10-11 cm2 s-1 for the largest GFH mesh size (10 x 30). The rate-limiting process of intraparticle surface diffusion for arsenate adsorption by porous iron oxides appears analogous to organic compound adsorption by activated carbon despite differences in adsorption mechanisms (inner-sphere complexes for As versus hydrophobic interactions for organic contaminants). The findings are discussed in the context of intraparticle surface diffusion affecting packed-bed treatment system design and application of rapid small-scale column tests (RSSCTs) to simulate the performance of pilot- or full-scale systems at the bench-scale.

KW - Adsorption

KW - Arsenic

KW - Iron

KW - Surface diffusion

KW - Water treatment

UR - http://www.scopus.com/inward/record.url?scp=4544343747&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=4544343747&partnerID=8YFLogxK

U2 - 10.1016/j.watres.2004.07.007

DO - 10.1016/j.watres.2004.07.007

M3 - Article

VL - 38

SP - 4002

EP - 4012

JO - Water Research

JF - Water Research

SN - 0043-1354

IS - 18

ER -