The kinetics of Cd2+, Cu2+ and Zn2+ adsorption onto pure and thioglycolic acid treated cassava tuber bark wastes (CTBW) were
investigated using a batch sorption technique at 30 C. Kinetic data suggested that the adsorption process was exothermic, the rate
limiting sorption step was physisorption and adsorption rates could be best described by a pseudo-second order model. Rate coefficients
were determined to range between 1.39 · 102 min1 and 5.94 · 102 min1, 1.46 · 103 min1 and 5.76 · 103 min1
and 0.69 · 103 min1 and 5.8 · 103 min1 for Cd2+, Cu2+ and Zn2+, respectively. The results from these studies indicated that
the sorption process is fast and stable. The adsorption equilibria were evaluated using the Langmuir equation and the monolayer
sorption capacity was found to range between 5.88–26.3 mg/g, 33.3–90.9 mg/g and 22.2–83.3 mg/g for Cd2+, Cu2+ and Zn2+, respectively.
Negative values of DG0
ads indicated that the adsorption process was spontaneous and exothermic in nature.
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