Biosorption of Cu(II), Pb(II), Ni(II), and Fe(II) on Alkali Treated Coir Fibers

Batchwise adsorption of Cu(II), Pb(II), Ni(II) and Fe(II) ions on coconut coir was studied. Coir fiber was subjected to alkali treatment (18% (w/v) NaOH) in order to enhance its metal adsorption capacity and rate of uptake. The maximum metal ion uptake capacity of Cu(II), Pb(II), Ni(II), and Fe(II) on alkali treated coir increased by nearly 3 times to 9.43, 29.41, 8.84, and 11.11 mg g-1, respectively. The solution pH played a crucial role in metal adsorption and the optimum pH for maximum adsorption was found to be different for each metal ion. The adsorption followed pseudo second-order kinetics and the isotherm data fits to the Langmuir adsorption isotherm. Repeated desorption-adsorption cycles explored the potential of reuse of alkali treated coir fibers upto 3 times with negligible loss of adsorption capacity.