ABSTRACT
The present study is aimed to optimized diluent type, tri-n-butyl phosphate (TBP) composition and temperature for the reactive extraction of p-nitro phenol (PNP) in two different PNP concentration ranges [(0.00036–0.00646) kmol·m−3 and (0.00646–0.01437) kmol·m−3] as found in industrial effluents. 1-Octanol is investigated as the best diluent with TBP based on COSMO-RS theory. Equilibrium study based on mass action law is performed to find the insights of extraction mechanisms, equilibrium constant (K = 295.12 k·mol−1) and stoichiometry (m:n = 1:1) as also confirmed by FTIR. Thermodynamic parameters, enthalpy (ΔH°), and entropy (ΔS°) are determined 27.51 K J mol−1 and −50.21 J mol−1 K−1, respectively.
Nomenclature
PNP | = | p-nitro phenol |
TBP | = | tri-n- butyl phosphate |
% E | = | degree of extraction |
K | = | equilibrium constant |
n | = | Complex ratio |
(Emisfit) | = | hydrogen bonding free energy |
(EHB) | = | Van der Waals energy |
= | coefficient for electrostatic misfit interactions | |
= | effective contact area between two surface segments | |
CHB | = | Coefficient for hydrogen bond strength |
= | threshold for hydrogen bonding | |
= | element-specific vdws coefficient | |
= | element-specific vdws coefficient | |
ΔH° | = | change in enthalpy |
ΔS° | = | change in entropy |
HPh | = | concentration of undissociated PNP in aqueous phase |
= | concentration of PNP in organic phase | |
= | TBP concentration in organic phase | |
Ka | = | dissociation constant |
pKa | = | acidic strength of phenol |
p | = | partition coefficient |
KD | = | distribution coefficient |
φ | = | volume fraction of solvent |
Z | = | loading ratio |
R | = | universal gas constant, 8.314 J−1mol·K |
T | = | temperature in K |
H- bond | = | hydrogen bond |
Acknowledgments
The authors thank director, Motilal Nehru National Institute of Technology, for providing the research facility to carry out the experiments. The authors also thank Ewing Christian College, Allahabad University, for providing the FTIR facility.
Conflict of interest
The authors declare no conflict of interest.
Correction Statement
This article has been republished with minor changes. These changes do not impact the academic content of the article.