Multicomponent Adsorption Models and the Kinetics of Deodourisation of Commercial DPK

ABSTRACT

The Multicomponent adsorption models and kinetics of deodorization of commercial kerosene (DPK) using conventional and non-conventional adsorbents have been investigated. The adsorbents used were bone char, limestone, silica gel and clay. The influence of contact time, adsorbent mass, pH, temperature, and adsorbent particle size on the rate percent aromatic and sulphur removal was evaluated. The experimental results were fitted to the Langmuir, Freundlich, Redlich-Peterson, Radke-Praustniz, and Temkin isotherms to obtain the measured sorption data. The characteristic parameters for each isotherm were determined:

The Kinetic modeling of the process was done using the first-order and second order rate models. Furthermore, the three main thermodynamic parameters namely, enthalpy of adsorption (ΔH), free energy (ΔG)and entropy (ΔS) were investigated, in order to determine what changes can be expected to occur during the sorption process.

Equilibrium studies showed that oxidized bone has the highest adsorption capacity from the list of adsorbent given above. The aromatic and sulphur content of DPK obtained after dearomatisation and desulphurization using oxidized bone and silica gel were 0.74 vol.% and 0.009 wtS, for oxidized bone and 0.65 Vol.% and 0.01 wtS for silica gel respectively. Langmuir and Redlich-Peterson models gave the best fit for the experimental data on the adsorption of sulphur and aromatics . The Pseudo- second-order rate

-1 .-1 constants for aromatic and sulphur were 0.0045min , 0.697min for

.-1 ,-1
oxidized bone, and 0.00358min , 0.672min for silica gel.The

thermodynamic parameters (entropy, enthalpy and Gibb`s free energy) of the system using oxidized bone were -46.35, -1,118 and 5,851 J/gK for aromatics, -34.50, -12,315 and 2,465J/gK for sulphur. Similarly, when silica gel was used were -48.30, -23,009, 6,832 J/gK for aromatics, -25.10, -11,259 and 2,562 J/gK for sulphur. Experimental results show that the rate of deodourisation of distillate DPK by adsorption techniques is second-order and reversible while the reaction itself is exothermic .