Development of a heavy metal sorption system through the PS functionalization of coconut (Cocos nucifera) fibers

Lignocellulosic residues are interesting materials for the production of heavy metal adsorbents for aquatic systems. Whole fibers taken from coconut (Cocos nucifera) husks were functionalized with the thiophosphoryl (PS) group by means of the direct reaction with Cl3PS, (CH3O)2ClPS or (CH3CH2O)2ClPS in order to obtain an adsorptive system for 'soft' metal ions, particularly Cd2+. These functionalized fibers (FFs) were characterized by means of elemental analysis, infrared spectroscopy, thermal analysis and acid-base titration. Adsorption isotherms for Cd2+ fitted the Langmuir model, with binding capacities of 0.2-5 mmol g−1 of FF at 25 °C.