SORPTION OF PALLADIUM-THIOCYANATE COMPLEXES ONTO POLYURETHANE FOAM FROM AQUEOUS SOLUTION USING RADIOTRACER TECHNIQUE

SUMMARY The sorption of palladium-thiocyanate complex onto polyurethane foam (PUF) has been investigated and optimized from aqueous solution of different pHs (1–10) and of acids of varied concentration (0.01–0.5 M). Maximum sorption (∼99%) of palladium (9.4 × 10−5 M) in the presence of thiocyanate (1.25 × 10−2 M) ions has been achieved from 0.1 M hydrochloric acid solution within 5 min equilibrating time. The variation of palladium concentration (1.03 × 10−4 − 1.16 × 10−3 M) data were subjected to different sorption isotherms. The data followed both Freundlich and Dubinin-Radushkevich (D-R) isotherms very well, but Langmuir isotherm is not obeyed at very low concentration. The Freundlich parameters 1/n = 0.54 ± 0.02 and of Cm = 35 ± 7 mmol g−1 have been evaluated, whereas D-R isotherm yields β = -0.003277 ± 0.000193 kJ2 mol−2, Xm = 1.01 ± 0.16 mmol g−1, and of E = 12.3 ± 0.35 kJ mol−1. The Langmuir isotherm gives the value of Q = 0.27 ± 0.08 mmol g−1 and of b = (2.83 ± 0.06) × 104 L mol−1. The temperature...