Tailored Janus silica nanosheets integrating bispecific artificial receptors for simultaneous adsorption of 2,6-dichlorophenol and Pb()

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2019, Vol.7 (27), p.16161-16175
• Main Authors: Liu, Jinxin, Wang, Pan, Zhou, Mengdie, Ma, Yue, Niu, Xiangheng, Pan, Guoqing, Pan, Jianming
• Format: Article
• Language: English
• Subjects: 2,6-Dichlorophenol; Adsorption; Chelation; Endothermic reactions; Health risks; Heavy metals; Kinetics; Lead; Metal ions; Molecular imprinting; Nanoparticles; Nanosheets; Planar structures; Pollutants; Public health; Receptors; Recognition; Regeneration; Sewage; Sewing; Silica; Silicon dioxide; Surface chemistry
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c9ta01116a

Potentially toxic dichlorophenols and heavy metal ions commonly coexist in industrial sewage, posing a serious threat to public health and the environment and making the treatment more challenging. Inspired by Suzhou bifacial embroidery, whereby the Janus-like planar structure allows different compositions to be compartmentalized onto two distinct surfaces, Janus silica nanosheets partitioning bispecific artificial receptors ( i.e. , molecularly imprinted sites and thiol groups) onto distinct recognition surfaces (J-MIPs/cys) were designed to independently take up 2,6-dichlorophenol (DCP) and Pb( ii ). For J-MIPs/cys, the thiol groups are expected to capture Pb( ii ) via chelating action and molecularly imprinted cavities act as highly specific recognition sites for DCP. J-MIPs/cys possessed uniform cross-sectional dimensions and thickness (∼25.3 nm), and a particle-like surface imprinted layer (∼21.8 nm). In the monocomponent system, J-MIPs/cys displayed fast binding kinetics (60 min and 45 min), large monolayer adsorption capacity (129.4 mg g −1 and 82.95 mg g −1 ), high affinity, and excellent regeneration after five reuse cycles (9.134% and 12.16% loss in adsorption amounts) for DCP and Pb( ii ), respectively. Additionally, a spontaneous and endothermic adsorption process was also confirmed. In a binary system, the presence of Pb( ii ) produced a prominent increase in DCP adsorption at high initial concentrations and a decrease at low initial concentrations, owing to the partial complexation of Pb( ii ) with excess DCP and occupation of imprinted sites by Pb( ii ). However, the uptake of Pb( ii ) was inhibited over the whole range of concentration in the presence of DCP due to the competitive adsorption onto thiol groups. In summary, J-MIPs/cys integrating novel bispecific receptors open wide possibilities for efficient and specific treatment of coexisting toxic pollutants. Potentially toxic dichlorophenols and heavy metal ions commonly coexist in industrial sewage, posing a serious threat to public health and the environment and making the treatment more challenging.