Waste of Rapeseed from Biodiesel Production as a Potential Biosorbent for Heavy Metal Ions

Rapeseed waste from biodiesel production was explored as a biosorbent for the removal of Cu(II) and Cd(II) ions from aqueous solutions under batch conditions. The optimum value of the initial pH for the sorption of both metal ions was found to be 4.5 to 5. The efficiency of Cu(II) and Cd(II) removal from aqueous solutions varied from 49% to 91% and from 61% to 97%, respectively, by increasing the rapeseed waste dose from 5 to 30 g L. According to the evaluation using the Langmuir equation, the monolayer sorption capacity of copper (II) and cadmium (II) ions on rapeseed waste was found to be 15.43 mg g and 21.72 mg g, respectively at 293 K. The batch sorption systems under study were thermodynamically characterized by means of parameters such as ∆G, ∆H, and ∆S. The kinetic parameters derived from the pseudo-first-order and pseudo-second-order equations were calculated and compared.