keywords: Curcumin, equilibrium, isotherm, kinetic, sorption, metals, thermodynamic, turmeric
The performance of adsorbents, prepared from low cost tumeric for the removal of divalent metal ions was investigated. The adsorbents, coded as chemically modified biosorbent (MTB) and unmodified turmeric biosorbent (UTB) were characterized using Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). Protocols of batch experiment were followed for profiling several parametric factors. Equilibrium data were modeled using isotherm, kinetic, diffusion and thermodynamic equations. Results shows more developed pore size for the derived adsorbents which in turn presented higher sorption performance. In this study, sorption is best explained with the pseudo-second order model (R2>0.999), following more than one form of transport mode. Sorption process is thermodynamically spontaneous. The positive ΔS° reflected an irregular increase of the randomness at the adsorbent/solution interface. The activation energy (A) values were higher than 42 kJmol−1 indicating chemical reaction-based sorption processes (chemisorption) that also infer claims of the pseudo-second order model. The statistical test, comparing UTB and MTB indicates significant differences (p<0.5) for all the parametric factors. Overall, the study shows that MTB is a potential sorbent candidate for the uptake of divalent metal ions from wastewater, unveiling a removal efficiency of up to 95 % for divalent Cu, 94 % and 99 % Ni ions.
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