Adsorption of Cu(II), Ni(II) and Zn(II) on modified jute fibres

The potential of a lignocellulosic fibre, jute, was assessed for adsorption of heavy metal ions like Cu(II), Ni(II) and Zn(II) from their aqueous solutions. The fibre was also used as adsorbent after chemically modifying it by two different techniques viz, loading of a dye with specific structure, C.I. Reactive Orange 13, and oxidising with hydrogen peroxide. Both the modified jute fibres gave higher metal ion adsorption. Thus, the dye loaded jute fibres showed metal ion uptake values of 8.4, 5.26 and 5.95 mg/g for Cu(II), Ni(II) and Zn(II), respectively, while the corresponding values for oxidised jute fibres were 7.73, 5.57 and 8.02 mg/g, as against 4.23, 3.37 and 3.55 mg/g for unmodified jute fibres. Adsorption isotherm models indicated best fit for Langmuir model for the modified jute fibres. The adsorption values decreased with lowering of pH. The desorption efficiency, regenerative and reuse capacity of these adsorbents were also assessed for three successive adsorption-desorption cycles. The adsorptive capacity was retained only when the caustic soda regeneration is carried out as an intermediate step after desorption. Possible mechanism has been given.