Highly effective remediation of Pb(II) and Hg(II) contaminated wastewater and soil by flower-like magnetic MoS2 nanohybrid.

The efficient enrichment and remediation of heavy metals from realistic wastewater and contaminated soil containing large excess of competitive ions remains a daunting challenge by far. In the present study, flower-like molybdenum disulfide decorated with iron oxide nanoparticles (MoS2/Fe3O4) is designed via a two-step hydrothermal method and mainly applied in the removal of Hg(II) and Pb(II) ions in aqueous environment. Exhaustive morphological, chemical and magnetic characterizations verify the successful formation of magnetic MoS2/Fe3O4. Batch adsorption experiments show that the obtained MoS2/Fe3O4 nanohybrid enables efficient capture of Hg(II) and Pb(II) ions, accompanied by ease-of-separation from solution by simply applying a magnet. In this respect, high adsorption capacities (263.6 mg g-1 for Pb(II) and 428.9 mg g-1 for Hg(II)) can be gained under optimized conditions (pH = 5.0; 298 K; nanohybrid dosage: 0.8 g L-1 and the contact time: 180 min). In addition, the effects of different parameters such as initial Pb(II)/Hg(II) concentration (50-500 mg L-1), temperature (298, 308 and 318 K) and co-existing ions (Zn(II), Cu(II), Cd(II) and Mg(II)) were systematically probed. The favorable adsorption capacity, selectivity and recyclability mainly originates from the strong Hg2+/Pb2+···S2- bonding interactions. Practical application potential of magnetic MoS2/Fe3O4 nanohybrid in realistic lead-acid battery industry wastewater and Pb(II)-contaminated soil is further explored, achieving promising results with high Pb(II) removal efficiency of 99.63% for wastewater and 57.15% for soil. Simple preparation, easy separation and high adsorption capacity would foster thus-designed sulfide-based nanohybrid a promising adsorbent for heavy metal removal from wastewater and contaminated soil.