The ability of an unconventional bio-adsorbent, pineapple leaf powder (PLP) for the adsorption of methylene
blue (MB) from aqueous solution was studied. It was observed that intra-particle diffusion was
involved in the adsorption process and that the kinetic data fitted well with a pseudo-second-order
equation. Fitting parameters revealed that the rate of adsorption increased with decrease in dye concentration
and decrease in ionic strength while the mixing speed did not have a significant effect on
adsorption. The adsorption was favorable at higher pH and lower temperature, and the equilibrium data
were well fitted by the Langmuir isotherm. The maximum adsorption capacity varied from 4.68×10−4
to 9.28×10−4 mol/g when pH increases from 3.5 to 9.5. Thermodynamic parameters suggest that the
adsorption is a typical physical process, spontaneous, and exothermic in nature. The results revealed that
this agricultural waste has potential to be used as an economical adsorbent for the removal ofmethylene
blue from aqueous solution.