XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 755
Of the different adsorption systems, fixed-bed column
studies are conducted for heavy metal removal due to their
practical applicability. Aside from the simple operation and
design, large volumes of wastewater can be treated effec-
tively (Malik, Jain, and Yadav 2018), as needed by the min-
erals industry.
A low-cost adsorbent that has shown potential in heavy
metal adsorption is goethite, a stable iron oxide abundant
in the natural environment. Goethite has a role in the
immobilization of heavy metal ions in soils, and its pres-
ence contributes to defining the eventual fate of these pol-
lutants. (Liu, Chen, and Frost 2014) Goethite is also one
of the iron oxides that dominates the limonite layer of the
nickel laterite profile, of which the Philippines has abun-
dant deposits.
This research aims to describe the performance of a goe-
thite fixed-bed column in the adsorption of arsenic, through
simulation. Mining operations can use this in the treatment
of their wastewater to meet both local and international
water quality standards, as well as contribute towards the
2030 Agenda for Sustainable Development through meet-
ing the United Nations Sustainable Development Goals 6
(Clean Water and Sanitation) and 14 (Life Below Water).
METHODOLOGY
Background
COMSOL Multiphysics version 5.3 was used to solve
the model equations numerically. To begin the column
adsorption modeling, the Transport of Diluted Species
in Porous Media (TDS) sub-module under the Chemical
Species Transport (CST) module was used for the time-
dependent study. A three-dimensional column geometry
was built to represent the adsorption column, with dimen-
sions of 0.1 m in radius and a maximum of 1 m in height.
This methodology used in this study was patterned after the
approach taken by (Cirio et al., 2020).
It was assumed that there is no accumulated fluid on
top of the column, and there is only a continuous dripping
inflow, similar to a heap leaching model. (McBride et al.,
2018)
The information shown in Table 1 and Table 2 are the
characteristics of the goethite adsorption column and the
porous media transport properties. This information was
input to the software.
The maximum adsorption capacities and adsorption
constants obtained by (Lakshmipathiraj et al., 2006) was
used as a basis for As(V) adsorption. These values are listed
in Table 3. This particular study yielded a 103 m2/g surface
area for their synthesized goethite, and adsorption isotherm
studies were conducted under a pH of 5. The values in this
table were also input to the software.
Simulation Study Design
A fixed-bed column adsorption system with varying col-
umn bed height, flow rate, and initial concentration was
investigated. The simulation range and levels are defined
in Table 4.
Table 1. Characteristics of goethite adsorption column for COMSOL Multiphysics simulation
Characteristic Value
Radius of goethite column 0.1 m
Maximum height of goethite column 1 m
Density of synthetic goethite (ρ) 1350 kg/m3 (Lehmann, Zouboulis, and Matis 2001)
Bed porosity (ε
p )0.3
Table 2. Porous media transport properties
Property Value Unit
Fluid diffusion coefficient, (D
F,C )1 × 10–9 m2/s
Effective diffusivity model Millington and Quirk model —
Temperature (T) 298.15 K
Table 3. Maximum adsorption capacity and adsorption constant for As(V) adsorption onto
synthesized goethite
Maximum adsorption capacity 0.0627322 mol/kg
Calculation method, Adsorption constant Langmuir, 0.194 m3/mol
Of the different adsorption systems, fixed-bed column
studies are conducted for heavy metal removal due to their
practical applicability. Aside from the simple operation and
design, large volumes of wastewater can be treated effec-
tively (Malik, Jain, and Yadav 2018), as needed by the min-
erals industry.
A low-cost adsorbent that has shown potential in heavy
metal adsorption is goethite, a stable iron oxide abundant
in the natural environment. Goethite has a role in the
immobilization of heavy metal ions in soils, and its pres-
ence contributes to defining the eventual fate of these pol-
lutants. (Liu, Chen, and Frost 2014) Goethite is also one
of the iron oxides that dominates the limonite layer of the
nickel laterite profile, of which the Philippines has abun-
dant deposits.
This research aims to describe the performance of a goe-
thite fixed-bed column in the adsorption of arsenic, through
simulation. Mining operations can use this in the treatment
of their wastewater to meet both local and international
water quality standards, as well as contribute towards the
2030 Agenda for Sustainable Development through meet-
ing the United Nations Sustainable Development Goals 6
(Clean Water and Sanitation) and 14 (Life Below Water).
METHODOLOGY
Background
COMSOL Multiphysics version 5.3 was used to solve
the model equations numerically. To begin the column
adsorption modeling, the Transport of Diluted Species
in Porous Media (TDS) sub-module under the Chemical
Species Transport (CST) module was used for the time-
dependent study. A three-dimensional column geometry
was built to represent the adsorption column, with dimen-
sions of 0.1 m in radius and a maximum of 1 m in height.
This methodology used in this study was patterned after the
approach taken by (Cirio et al., 2020).
It was assumed that there is no accumulated fluid on
top of the column, and there is only a continuous dripping
inflow, similar to a heap leaching model. (McBride et al.,
2018)
The information shown in Table 1 and Table 2 are the
characteristics of the goethite adsorption column and the
porous media transport properties. This information was
input to the software.
The maximum adsorption capacities and adsorption
constants obtained by (Lakshmipathiraj et al., 2006) was
used as a basis for As(V) adsorption. These values are listed
in Table 3. This particular study yielded a 103 m2/g surface
area for their synthesized goethite, and adsorption isotherm
studies were conducted under a pH of 5. The values in this
table were also input to the software.
Simulation Study Design
A fixed-bed column adsorption system with varying col-
umn bed height, flow rate, and initial concentration was
investigated. The simulation range and levels are defined
in Table 4.
Table 1. Characteristics of goethite adsorption column for COMSOL Multiphysics simulation
Characteristic Value
Radius of goethite column 0.1 m
Maximum height of goethite column 1 m
Density of synthetic goethite (ρ) 1350 kg/m3 (Lehmann, Zouboulis, and Matis 2001)
Bed porosity (ε
p )0.3
Table 2. Porous media transport properties
Property Value Unit
Fluid diffusion coefficient, (D
F,C )1 × 10–9 m2/s
Effective diffusivity model Millington and Quirk model —
Temperature (T) 298.15 K
Table 3. Maximum adsorption capacity and adsorption constant for As(V) adsorption onto
synthesized goethite
Maximum adsorption capacity 0.0627322 mol/kg
Calculation method, Adsorption constant Langmuir, 0.194 m3/mol