Metal ion removal from aqueous solution using physic seed hull

The potential of physic seed hull (PSH), Jantropha curcas L. as an adsorbent for the removal of Cd2+ and Zn2+
metal ions from aqueous solution has been investigated. It has been found that the amount of adsorption
for both Cd2+ and Zn2+ increased with the increase in initial metal ions concentration, contact time,
temperature, adsorbent dosage and the solution pH (in acidic range), but decreased with the increase
in the particle size of the adsorbent. The adsorption process for both metal ions on PSH consists of
three stages—a rapid initial adsorption followed by a period of slower uptake of metal ions and virtually
no uptake at the final stage. The kinetics of metal ions adsorption on PSH followed a pseudo-secondorder
model. The adsorption equilibrium data were fitted in the three adsorption isotherms—Freundlich,
Langmuir and Dubinin–Radushkevich isotherms. The data best fit in the Langmuir isotherm indication
monolayer chemisorption of the metal ions. The adsorption capacity of PSH for both Zn2+ and Cd2+ was
found to be comparable with other available adsorbents. About 36–47% of the adsorbed metal could be
leached out of the loaded PSH using 0.1M HCl as the eluting medium.