Synthesis of Magnetic Adsorbents Based Carbon Highly Efficient and Stable for Use in the Removal of Pb(II) and Cd(II) in Aqueous Solution.

Safa Benjedim,Luis A Romero-Cano,Agustín F Pérez-Cadenas,Francisco Carrasco-Marín,Hesham Hamad,Václav Slovák,Esther Bailón-García

doi:10.3390/ma14206134

Abstract

In this study, two alternative synthesis routes for magnetic adsorbents were evaluated to remove Pb(II) and Cd(II) in an aqueous solution. First, activated carbon was prepared from argan shells (C). One portion was doped with magnetite (Fe3O4+C) and the other with cobalt ferrite (CoFe2O4+C). Characterization studies showed that C has a high surface area (1635 m2 g−1) due to the development of microporosity. For Fe3O4+C the magnetic particles were nano-sized and penetrated the material’s texture, saturating the micropores. In contrast, CoFe2O4+C conserves the mesoporosity developed because most of the cobalt ferrite particles adhered to the exposed surface of the material. The adsorption capacity for Pb(II) was 389 mg g−1 (1.88 mmol g−1) and 249 mg g−1 (1.20 mmol g−1); while for Cd(II) was 269 mg g−1 (2.39 mmol g−1) and 264 mg g−1 (2.35 mmol g−1) for the Fe3O4+C and CoFe2O4+C, respectively. The predominant adsorption mechanism is the interaction between -FeOH groups with the cations in the solution, which are the main reason these adsorption capacities remain high in repeated adsorption cycles after regeneration with HNO3. The results obtained are superior to studies previously reported in the literature, making these new materials a promising alternative for large-scale wastewater treatment processes using batch-type reactors.

Highlights

Lead and cadmium are highly toxic metals evolved to the environment due to anthropogenic activities such as metal finishing, electroplating, plastics, pigments, and mining industries [1]
For the Fe3O4+C material, the pore size distribution is in a range of 10 to 100 nm, while for Materials 2021, 14, x FOR PEER REVIECWoFe2O4+C, the range is less than 10 nm, indicating that the precursor used to add ma6gnofet1i8c properties to the material directly influences the texture of the final material
Magnetic carbons were prepared from argan shells and supporting magnetite and cobalt ferrite particles

Summary

Introduction

Lead and cadmium are highly toxic metals evolved to the environment due to anthropogenic activities such as metal finishing, electroplating, plastics, pigments, and mining industries [1]. Various methods have been studied that allow Cd(II) and Pb(II) elimination from bodies and water effluents These methods range from precipitation, flocculation, electrochemical treatment, ion exchange, and membrane filtration processes [3,4,5]. These methods show very good results, but they are costly and, in most cases, not effective at low concentrations of the metal. The use of these processes generates high volumes of sludge, which is inefficient because they do not solve the environmental problem in its entirety. The adsorption process has been the most widely used method, as it avoids all of the above problems [6]

Methods

Results

Conclusion