Superselective Removal of Lead from Water by Two-Dimensional MoS2 Nanosheets and Layer-Stacked Membranes

• Published in: Environmental science & technology Vol. 54; no. 19; pp. 12602 - 12611
• Main Authors: Wang, Zhongying, Tu, Qingsong, Sim, Alison, Yu, Julie, Duan, Yanghua, Poon, Sidney, Liu, Bei, Han, Qi, Urban, Jeffrey J, Sedlak, David, Mi, Baoxia
• Format: Journal Article
• Language: English
• Published: Easton American Chemical Society 06.10.2020; American Chemical Society (ACS)
• Subjects: Adsorption; Cadmium; Calcium; Calcium ions; Cations; Contamination; Copper; Density functional theory; Drinking water; ENVIRONMENTAL SCIENCES; Lead; Magnesium; Membrane filters; Membranes; Molybdenum disulfide; Nanosheets; Selectivity; Treatment and Resource Recovery; Two dimensional materials; Water pollution; Water treatment; Waterborne diseases; Zinc
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/acs.est.0c02651

Point-of-use (POU) devices with satisfactory lead (Pb2+) removal performance are urgently needed in response to recent outbreaks of lead contamination in drinking water. This study experimentally demonstrated the excellent lead removal capability of two-dimensional (2D) MoS2 nanosheets in aqueous form and as part of a layer-stacked membrane. Among all materials ever reported in the literature, MoS2 nanosheets exhibit the highest adsorption capacity (740 mg/g), and the strongest selectivity/affinity toward Pb2+ with a distribution coefficient K d that is orders of magnitude higher than that of other lead adsorption materials (5.2 × 107 mL/g). Density functional theory (DFT) simulation was performed to complement experimental measurements and to help understand the adsorption mechanisms. The results confirmed that the cation selectivity of MoS2 follows the order Pb2+ > Cu2+ ≫ Cd2+ > Zn2+, Ni2+ > Mg2+, K+, Ca2+. The membrane formed with layer-stacked MoS2 nanosheets exhibited a high water flux (145 L/m2/h/bar), while effectively decreasing Pb2+ concentration in drinking water from a few mg/L to less than 10 μg/L. The removal capacity of the MoS2 membrane is a few orders of magnitude higher than that of other literature-reported membrane filters. Therefore, the layer-stacked MoS2 membrane has great potential for POU removal of lead from drinking water.