TITLE:
Kinetics, Equilibrium and Thermodynamics Studies of Fe3+ Ion Removal from Aqueous Solutions Using Periwinkle Shell Activated Carbon
AUTHORS:
Akpa Jackson Gunorubon, Nduka Chukwunonso
KEYWORDS:
Adsorption, Iron Ions, Kinetics, Isotherm, Thermodynamics
JOURNAL NAME:
Advances in Chemical Engineering and Science,
Vol.8 No.2,
March
22,
2018
ABSTRACT:
Iron (III) adsorption from aqueous solutions unto periwinkle shell carbon
(PSC) was studied using batch experiments. Activated periwinkle shell carbon
was prepared (pyrolysed at 300°C and activated with nitric acid) and characterized
to determine its physiochemical properties. Batch adsorption experiments
were conducted to investigate the effects of process parameters (contact
time, particle size, carbon dosage and pH of stock solution) on adsorption
rate. Adsorption kinetics was tested using pseudo first and second order models.
Adsorption Isotherms were analyzed using the Langmuir, Freundlich and
Temkin isotherms while Thermodynamics parameters such as Enthalpy
change (ΔH°), Entropy change (ΔS°) and Gibbs-free energy change (ΔG°)
were determined. Results showed that adsorption rate increase with increase
in contact time, adsorbent dose and pH and decreased with increase in particle
size. Batch adsorption Kinetics experiments revealed that the mechanism
of adsorption followed pseudo-second-order kinetic model. Isotherm data
showed that the Langmuir isotherm accurately described the adsorption data
indicating that adsorption process was mainly monolayer on a homogeneous
adsorbent surface. Thermodynamic parameters results showed that adsorption
process was endothermic with Enthalpy change (ΔH°): 222.91 kJ/mol; a
positive Entropy change (ΔS°) of 19.19 kJ/mol, indicating an increase in the
degree of freedom (or disorder) of the adsorbed species and a negative Gibb’s
free energy (ΔG°) at all temperature indicating that the adsorption process
was spontaneous and favorable at high temperature.