Abstract:
The kinetics and isotherm modeling of adsorption of Cr3+ ions onto unmodified coffee husk (UCH) and acid
modified coffee husk (MCH) biosorbent were successfully studied in batch experiments. Equilibrium data were
analyzed by Langmuir and Freundlich isotherm models. Equilibrium data best fitted to Langmuir isotherm. The
Langmuir adsorption capacity was higher in MCH (6.64 mg/g) compared to the UCH (3.85 mg/g). The
adsorption constant, b, was less than one in the two adsorption processes suggesting a high affinity of both the
UCH and MCH adsorbent for Cr3+ ions. The experimental data were fitted well with pseudo second order
kinetics with best fitness for both the UCH and MCH with regression coefficient (R2
) of 0.9792 and 0.9956,
respectively. The findings revealed that the unmodified and modified coffee husks have potential in removal of
Cr3+ from tannery wastewater
