Facile utilization of magnetic MnO2@Fe3O4@sulfonated carbon sphere for selective removal of hazardous Pb(II) ion with an excellent capacity: Adsorption behavior/isotherm/kinetic/thermodynamic studies

Magnetic MnO2@Fe3O4@sulfonated carbon sphere (CS-S-Fe-Mn) was used as a magnetic adsorbent for selective removal of Pb2+ ion from aqueous solution via co-creation between electrostatic force along with co-ordinate covalent bond. The CS-S-Fe-Mn was prepared via hydrothermal carbonization/sulfonation and followed by facile precipitation processes. The physical and chemical properties of CS-S-Fe-Mn and other adsorbents were characterized by BET-BJH, XRD, FTIR, VSM, SEM-EDS, pHpzc and Boehm titration techniques. As observed, the CS-S-Fe-Mn exhibited a spherical (petal-like walls) shape with a good dispersion of Fe3O4 and MnO2 particles, which had surface area of 146 m(2)/g, total acidity-basicity of 7.87 mmol/g and negative surface charge (pH < pHpzc). The paramagnetic properties of CS-S-Fe-Mn was well found with a saturation magnetization value of 21.8 emu/g, resulting in facile separation from water system using an external magnetic field. A maximum adsorption capacity (qmax) of Pb2+ over CS-S-Fe-Mn was 147.76 mg/g which had higher performance than previous references, resulting from synergetic effects of oxygen containing functional groups such as -C--O/C-O, -COOH and -SO3H as well as MnO2. Moreover, the adsorption behaviors of Pb2+ onto CS-S-Fe-Mn were in good agreement with rapid monolayer-physisorption (E = 2.93 kJ/mol)/spontaneous-endothermic (Delta H = 49.12 kJ/mol) nature processes as well as intra-particle diffusion via two step mechanisms, supporting by isotherm, kinetic, thermodynamic and Weber-Morris models. This research provided a handy strategy for Pb2+ removal with high adsorption capacity from environmental wastewater.

Automated summary

The study focused on the selective removal of Pb2+ ions from aqueous solutions using a magnetic adsorbent, CS-S-Fe-Mn, with good dispersion and magnetic properties. The adsorbent showed a high surface area, strong adsorption capacity, and conformed to rapid monolayer-physisorption and spontaneous-endothermic processes.