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Achieving Controllable MoS₂ Nanostructures with Increased Interlayer Spacing for Efficient Removal of Pb(II) from Aquatic Systems

Kumar, Neeraj, Fosso-Kankeu, Elvis, Ray, Suprakas Sinha
ACS applied materials & interfaces 2019 v.11 no.21 pp. 19141-19155
adsorbents, adsorption, antibiotics, batteries, chemical composition, ciprofloxacin, electrostatic interactions, ions, lead, microparticles, moieties, molybdenum disulfide, nanosheets, pH, photolysis, sorption isotherms, wastes, water analysis, water treatment
The development of new synthesis approaches for MoS₂ is necessary to achieve controlled morphologies and unique physicochemical properties that can improve its efficiency in particular applications. Herein, a facile one-step hydrothermal route is proposed to prepare controllable MoS₂ micro/nanostructures with an increased interlayer using sodium diethyldithiocarbamate trihydrate as the new S source at different pH values. To investigate the morphology, chemical composition, and structure of the MoS₂ micro/nanostructures, various characterization techniques were used. The obtained microrods, microspheres, and microrods with hairlike structures (denoted as MoS₂-N-H) were composed of MoS₂ nanosheets with increased interlayer spacing (∼1.0 nm) and utilized for the removal of Pb(II) from aquatic systems. Among the structures, MoS₂-N-H demonstrated the highest adsorption capacity (303.04 mg/g) for Pb(II) due to the existence of −S/–C/–N/–O-comprised functional groups on its surface, which led to strong Pb–S complexation and electrostatic attractions. The uptake of Pb(II) onto MoS₂-N-H followed pseudo-second-order kinetics and Freundlich isotherm. To evaluate its practical applicability, the adsorbent was employed in real mine water analysis; it was found that MoS₂-N-H could adsorb almost 100% of the Pb(II) ions in the presence of various coexisting ions. Additionally, after Pb(II) adsorption, MoS₂-N-H was transformed into PbMoO₄₋ₓSₓ spindlelike nanostructures, which were further used for photodegradation of an antibiotic, viz., ciprofloxacin (CIP), to avoid secondary environment waste. Thus, this investigation provides an effective one-pot approach to fabricate controllable MoS₂ micro/nanostructures with increased interlayer spacing for water treatment. The utility of these nanostructures in related supercapacitor/battery applications may also be envisaged because of their unique structural properties.