Recovery of Au(III) from an aqueous solution by aminopropyltriethoxysilane-functionalized lignocellulosic based adsorbents

Lignocellulosic coconut pith (LCP) was functionalized with 3-aminopropyltriethoxysilane (APS) towards preparing aminopropyltriethoxysilane-functionalized lignocellulosic coconut pith (APS-LCP) adsorbents for high adsorption affinity towards Au(III) ions. The functionalization was confirmed by morphological, functional groups and thermal analyses. The Au(III) adsorption results show that the APS-LCP possessed much better Au(III) adsorption than LCP and both exhibited endothermic process. The Au(III) adsorption isotherm data fitted well to the Langmuir isotherm having the maximum adsorption capacity of 215.68 mg g(-1) and 261.36 mg g(-1) respectively, for the LCP and APS-LCP at 30 degrees C. The kinetic model analysis showed that the overall adsorption process was controlled by film diffusion, while the active site chemical interactions (e.g. ion exchange, chelation and reduction) were best described by the pseudo-second order kinetic model. Adsorption-desorption experiment revealed that the APS-LCP could be regenerated with minimum loss of the adsorption capacity. These results demonstrate the potential application of lignocellulosic materials as adsorbents through an appropriate modification for adsorptive recovery of Au(III) ions from an aqueous solution.