Copper ion removal from aqueous media using banana peel biochar/Fe3O4/branched polyethyleneimine

Abstract

To address the severe pollution caused by heavy metals, adsorbents have attracted considerable attention based on the idea of energy conservation, emission reduction, and waste utilization. In this work, magnetic nanocomposites were employed as an adequate source for Cu2+ adsorption. Fe3O4 nanoparticles were modified using branched polyethyleneimine and biochar produced from banana peels. The magnetic nanocomposites (BPB/Fe3O4/BPEI) were prepared by chemical coprecipitation. The resulting adsorbents were characterized using SEM, TEM, EDS, XRD, and FTIR, and it was also indicated that BPB/Fe3O4/BPEI was successfully prepared by stepwise modification with BPB, Fe3O4, and branched polyethyleneimine. VSM result shows the BPB/Fe3O4/BPEI exhibit a paramagnetic behavior (21.22 emu/g). A mesoporous structure can be confirmed by BET analysis (BPB/Fe3O4/BPEI: 68.72 m2/g). The effects of contact time, pH, concentration of copper ions, and adsorbent dose on the efficiency of copper ion adsorption were investigated. The optimal adsorption efficiencies for BPB(81.99%), Fe3O4(20.18%), BPB/Fe3O4(82.15%), Fe3O4/BPEI(87.37%), and BPB/Fe3O4/BPEI(99.46%) were determined. Furthermore, D-R, Temkin, Freundlich, Langmuir, Redlich-Peterson, Toth, Sips, and Hill isotherm models, Weber-Morris intraparticle diffusion, and Elovich, PSO, PFO, and Boyd kinetic models were conducted to better understand the removal process. The BPB/Fe3O4/BPEI adsorbents fit the PSO kinetic model and the Sips isotherm model best. The maximum capacities for Cu2+ adsorption with BPB, Fe3O4, BPB/Fe3O4, Fe3O4/BPEI, and BPB/Fe3O4/BPEI are determined to be 15.14 mg/g, 2.75 mg/g, 24.65 mg/g, 32.66 mg/g, and 73.23 mg/g, respectively. Furthermore, the effect of other metal ions and the reusability of BPB/Fe3O4/BPEI were studied, indicating that BPB/Fe3O4/BPEI has good stability even in the presence of other influential heavy metal ions in solution and can be effectively reused for wastewater treatment.