Fabrication of tetraethylenepentamine functionalized alginate beads for adsorptive removal of Cr (VI) from aqueous solutions.

In this study, an innovative adsorbent based on tetraethylenepentamine (TEPA) functionalized alginate (Alg) beads (TEPA-Alg) was developed for the adsorptive removal of Cr (VI) from aqueous solutions. Chemical modification of alginate surface was carried out using p-benzoquinone (PBQ) as a coupling agent followed by functionalization with TEPA. The prepared functionalized beads were characterized using FTIR, TGA, SEM, and XPS tools. Results showed that the ion exchange capacity (IEC) significantly increased from 6.34 to 10.32 meq g-1 with increasing TEPA concentration up to 0.05 M. Furthermore, removal (%) of Cr (VI) increased gradually from 38 to 86% with rising TEPA concentration from 0.0125 M to 0.05 M. While only 22% was recorded using native alginate beads. The gained equilibrium data were fitted to Langmuir isotherm model with maximum adsorption capacity ~ 77 mg/g and the adsorption kinetics were well-expressed by pseudo-first-order model. Reusability studies showed good adsorption properties after 5 consecutive cycles. Results achieved by this study imply that the prepared functionalized TEPA-Alg beads could be efficiently utilized for the removing Cr (VI) ions from their aqueous solutions.