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Adsorption of ferric ions onto natural feldspar: kinetic modeling and adsorption isotherm
Al-Anber, M.A.
Abstract
The removing of ferric ions (Fe3+) from
aqueous solution using natural feldspar (NF) has been
studied in a batch operation mode. The factors affecting of
the sorption equilibrium, such as contact time, initial
concentration of the ferric ions (Fe3+), feldspar dosage
concentration and temperature, were investigated. The
maximum removal is 93 % (approx.) using low-level
concentration of Fe3+ ions (30 mg L-1) and high dosage
concentration (40 g L-1). The adsorption equilibrium is
achieved during the first 90 min. Freundlich model has
successfully analyzed the equilibrium of isotherms with
R2 = 1. The adsorption mechanism of aqueous ferric ion
on NF follows Freundlich isotherm models (R2 = 0.997).
The capacity (Kf) and intensity (1/n) of Freundlich
adsorption are 1.70 and 0.621, respectively. The results
reveal that the adsorption mechanism of ferric ion on NF is
chemisorptions, heterogeneous multilayer and spontaneous
in nature (δG = -19.778 kJ mol-1). Adsorption reaction
kinetic models, such as pseudo-first order and pseudosecond
order, and adsorption diffusion model, such as
Weber–Morris intraparticle diffusion model, have been
used to describe the adsorption rate and mechanism of the
ferric ion onto NF surface. Adsorption of ferric ion on the
NF has achieved Lagergren pseudo-second-order model
(R2 = 1.0 approx.) more than Lagergren pseudo-first-order
model. The kinetic parameters, rate constant and sorption
capacities have been calculated. The new information in
this study suggests that NF could be used as a novel filtering
materials for removing ferric ions from water.
Keywords
Ferric ion; Feldspar; Adsorption; Freundlich; Kinetic; Thermodynamic
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