Dehydrated Carbon Fiber for the Recovery of Pd(II) and Pt(II) From Chloride Aqueous Solution

Cellulose fiber was separated from date palm leaflets and was carbonized by dehydration using dilute sulfuric acid at 150°C. Produced dehydrated carbon fiber (DCF) was tested for the sorption of Pd(II) and Pt(II) at different pH, contact time, metal concentration, and temperature. With the rise in pH, sorption was found to increase for Pd(II) but decreases for Pt(II). The optimum pH ranges of 1-3 for Pt(II) and 3-3.5 for Pd(II). Approximate equilibrium was obtained within 50 hr for both metals with sorption data fitting the pseudo second order model well. Activation energy, Ea, was found to be higher than 40 kJ/mol for the sorption of both metals, indicating the involvement of chemical processes in metal sorption. The Langmuir isotherm was found to fit the sorption data more than other isotherms. Thermodynamic parameters were calculated and showed an involvement of chemical processes in metal sorption with stronger interaction for the carbon with Pb(II) than with Pt(II). Both of Pd(II) and Pt(II) were reduced to their respective elemental forms on the surface of the fiber as confirmed by scanning electron microscopy and x-ray diffraction.