Selective capture models and mechanisms of Pb(II) from wastewater using tannic-functionalized nickel-iron oxide Nanoparticles

It is of great importance to remove lead ions from wastewater as lead pollution is a serious problem. Hence, a new magnetic adsorbent (Tannic-Ni0.6Fe2.4O4) was synthesized by modifying nickel-iron oxide nanoparticles with tannic to selectively adsorb Pb(II) from wastewater. The adsorption capacity of Tannic-Ni0.6Fe2.4O4 for Pb(II) was investigated by batch experiment. The effects of pH, time, initial concentration and temperature on the sorption capacity were studied. The regenerated experiments and adsorption mechanisms have been also discussed. pH4 is the best condition for the adsorption experiment. The adsorption reaches equilibrium in 200 min and the maximum adsorption capacity is 139.8 mg/g. After five repetitive experiments, the adsorption capacity was reduced only from 70% to 61.5%. In addition, the entire adsorption process is based on monolayer chemisorptions because it conforms to the pseudo-second-order and Langmuir models. The thermodynamic data revealed that the adsorption is a spontaneous endothermic process. After 5 cycles, Tannic-Ni0.6Fe2.4O4 still maintained a good adsorption capacity. Tannic-Ni0.6Fe2.4O4 was successfully applied for selective adsorption of Pb(II) from wastewater with various metal ions. The uptake of Pb(II) by Tannic-Ni0.6Fe2.4O4 mainly followed ion exchange and chelation mechanism. Therefore, Tannic-Ni0.6Fe2.4O4 is a perfectly valid and useful adsorbent for the elimination of Pb(II) pollution.