en |
Adsorptive desulfurization of feed diesel using chemically impregnated coconut coir waste
Ahmed, Md. J. K. & Ahmaruzzaman, M.
Abstract
This study reports the usage of chemically
impregnated coconut coir waste (CICCW) as a low-cost
adsorbent for the desulfurization of feed diesel. The characterization
of the developed adsorbent was focused on
quantitative analysis (carbon yield %, proximate, ultimate,
carbon surface functionalities, BET surface area and
porosity distribution, and particle size analysis), qualitative
analysis (FTIR), and optical analysis (SEM). Batch
experiments with feed diesel having a total sulfur concentration
of 2,050 mg L-1 were conducted to optimize the
adsorption parameters such as adsorbent dose, temperature,
and contact time. The adsorption process shows an optimum
dose of 1 g/20 mL, and the equilibrium is attained in
3 h. The adsorption of sulfur onto the adsorbent at optimum
temperature 293 K is regulated by external mass
transfer (diffusion into mesopores) followed by a steady
adsorption phase with intra-particle diffusion in micropores.
A Fickian mechanism controls the diffusion of sulfur
molecules from the solution onto the surface of the
adsorbent. Freundlich adsorption isotherm illustrates the
equilibrium adsorption data very well. The negative value
of ΔGº (-27.61 kJ mol-1) and ΔSº (-44.56 J K-1 mol-1)
indicates the feasibility, spontaneity of the adsorption
process and justified the decrease in the randomness of
adsorbed sulfur molecules onto the adsorbent surface,
respectively. The exhausted CICCW can be effectively
regenerated by methanol and reutilized for three
adsorption–desorption cycles. The approximate cost of
preparation of the adsorbent was USD 10.714 per kg. These
results clearly proved the feasibility of the developed lowcost
adsorbent (CICCW) as a good candidate for the
desulfurization of feed diesel.
Keywords
Adsorption; Adsorption; Batch experiments; Freundlich isotherm
|