Removal of lead and cadmium ions from wastewater using magnetic alginate impregnated sulfur

Abstract

A new adsorbent, magnetic Fe3O4 sulfonated nanoparticle caged alginate microbeads (S.MNPs@Alg), was developed for Cd(II) and Pb(II) ions removal from water, which could be effectively separated from the solution owing to the superparamagnetic property. This adsorbent was characterized using FTIR, FESEM, XRD, SEM, and VSM. The effect of parameters affecting sorption potential including pH, contact time, and adsorbent dosage was carried out. Under the best experimental condition, the Cd(II) and Pb(II) ions removal efficiencies were reported to be over 95%. To understand the nature of the sorption process, adsorption isotherms including Freundlich and Langmuir models were precisely investigated. The process is fitted well with the Langmuir model and the maximum adsorption capacity obtained was 37 mg. g−1 and 85 mg. g−1 for Cd(II) and Pb(II) ions, respectively. The as-prepared S.MNPs@Alg is easy to prepare and effective in the uptake of Cd(II) and Pb(II) ions with a physisorption mechanism, which adsorption rate is limited with the pseudo-second-order model. The adsorbent lost<5% of its removal efficiency in five adsorption–desorption cycles. Finally, the existence of sulfur groups increased adsorption capacity and decrease the toxicity of magnetic nanoparticles (MNPs) and the presence of magnetism part can facilitate the separation of the adsorbent from the solution.