Isotherms, kinetics and thermodynamics for adsorption of pyridine vapors on modified activated carbons

Abstract

The adsorption isotherms of pyridine have been determined gravimetrically on different samples of granulated, fibrous and spherical activated carbons. Several chemical treatments such as oxidation, degassing and impregnation have been carried out on as-received activated carbon cloth (ACC) so as to modify the surface characteristics of the activated carbon. The porous and chemical structure of modified and unmodified activated carbons has been characterised by XRD, TGA-DTG, SEM and pore size distribution techniques. The adsorption increases on oxidation while decreases on degassing which can be correlated to increase and decrease in the concentration of surface oxygen groups. Loading with Ag ? and Cu 2? increases the adsorption of pyridine compared with the unloaded sample while loading with Cr 6? decreases the adsorption of these vapors. The adsorption-desorption branches of pyridine vapors on metal impregnated do not meet even at zero relative vapor pressure indicating the chemisorption or other specific interactions. The adsorption kinetics data has been examined using the linear driving force and empirical diffusion models. The initial decrease in isosteric enthalpy of adsorption for modified and unmodified ACC indicates the effect of surface heterogeneity and later increase indicates the influence of lateral interactions between adsorbate molecules. The results suggest that the adsorption of pyridine involves the physisorption as well as specific interactions with carbon oxygen functional groups and metal complexes present on the carbon surface.

Site-specific functionalization for chemical speciation of Cr(III) and Cr(VI) using polyaniline impregnated nanocellulose composite: equilibrium, kinetic, and thermodynamic modeling

“…6b, c and Table 2, the values of correlation coefficient (R 2 ) attested by Langmuir model are greater than 0.99. Furthermore, the Langmuir sorption capacity is consistent with experimental values, indicative of the monolayer and homogenous uptake of chromium ions (Mittal et al 2009a;Gupta et al 2012a;Dhawan et al 2015), while the large value of b specifies electrostatic binding of chromium ions onto fabricated PANI-NCC (Renault et al 2008;Gupta et al 2014). The feasibility of Cr(III) and Cr(VI) sorption was determined with a dimensionless constant (R L ) known as separation factor which can be defined as…”

Analysis of Ammonium Adsorption Behavior and Mass Transfer Resistance From Aerated Lagoon Effluent Onto Activated Carbon

“…The XRD pattern of GAC has almost no diffraction lines; however, two broad peaks and one sharp peak have a diffraction maxima at diffraction angles 2θ of 23°, 2θ of 43° and 2θ of 81°, respectively. The peak 2θ of 23° denotes strong small angle indicating an amophorous structure with high porosity, and both the peaks 2θ of 23° and 2θ of 81° represent the graphitic basal plane [21]. These peaks pattern similar with mineralogy of activated carbon cloth [21] and coconut shell-activated carbon [3].…”

“…The peak 2θ of 23° denotes strong small angle indicating an amophorous structure with high porosity, and both the peaks 2θ of 23° and 2θ of 81° represent the graphitic basal plane [21]. These peaks pattern similar with mineralogy of activated carbon cloth [21] and coconut shell-activated carbon [3]. A peak at 2θ of 43° indicates the presence of minor phase of the quartz (SiO 2 ).…”

Separation of transglutaminase by thermo-responsive affinity precipitation using l-thyroxin as ligand

“…In consideration of the characters of the affinity polymer and target protein, the Freundlich isotherm and Langmuir–Freundlich (LF) isotherm equations which were used to describe heterogeneous adsorption systems were selected to correlate the experimental data of adsorption isotherm of affinity precipitation (Dhawan et al 2015 ).…”