Calcium alginate encapsulated Ni/Fe nanoparticles beads for simultaneous removal of Cu (II) and monochlorobenzene.

Calcium alginate encapsulated Ni/Fe bimetallic nanoparticles beads (CA-Ni/Fe beads) were synthesized to simultaneously remove Cu (II) and monochlorobenzene (MCB) from aqueous solution. SEM, EDS, and XRD analyses confirmed that Ni/Fe bimetallic nanoparticles were not oxidized and successfully encapsulated by calcium alginate (CA). The experiments showed that the encapsulation process improved the simultaneous removal efficiency of Cu (II) and MCB, from 83.9% to 86.7% for Cu (II) and 94.7% to 99.1% for MCB compared with bare Ni/Fe nanoparticles after 120min treatment. Furthermore, the removal efficiency of Cu (II) and MCB increased with higher temperature, calcium alginate: Ni/Fe ratios and pH. Pseudo-second-order model for adsorption and pseudo-first-order model for the reduction process fitted the simultaneous removal of Cu (II) and MCB using CA-Ni/Fe beads. Based on the above results, it could be concluded that the simultaneous removal was a two-step process: firstly, the adsorption of Cu (II) and MCB on the CA-Ni/Fe beads; and secondly, reduction of Cu (II) and dehalogenation of MCB by Ni/Fe in CA-Ni/Fe beads. Finally, the efficiency of regenerated CA-Ni/Fe beads was tested using synthesized wastewater which showed a satisfactory removal efficiency of Cu (II) and MCB maintained at 83.8% and 91.7% after three times' regeneration.