Rapid Microwave-promoted Synthesis of Zr-MOFs: An Efficient Adsorbent for Pb(II) Removal

Computational Investigation of Adsorptive Removal of Pb

“…[67] The need for desolvation may also be exacerbated in the presence of functional groups on the BDC linkers that would lead to even smaller or more crowded apertures. The partial desolvation hypothesis is consistent with the fact that experimental studies indicate using UiO-67 [25] and the presence of defects [26] can lead to increased Pb 2þ adsorption, likely owing to easier diffusion of Pb 2þ through the MOF. Furthermore, partial desolvation in order to pass through apertures in porous materials is a well-documented process, [68,69] and moderate dehydration only has a minor energy cost (see Fig.…”

“…We started our investigation of Pb 2þ adsorption by UiO-66 by focusing on the functionalised linkers as the adsorption sites, as the bulk of experimental work has been devoted to these systems. [22][23][24]26] We selected a variety of functionalised linkers that have either demonstrated success for adsorption of Pb 2þ (UiO-66-COOH/COO - [24] , UiO-66-NHCSNHCH 3 , [23] UiO-66-NCS, [23] UiO-66-NCO, [23] and UiO-66-NH 2 [22,23,26] ) or possess attributes that could improve Pb 2þ adsorption (UiO-66-SO 3 H/SO 3 -, UiO-66-CONH 2 , UiO-66-SH). For conciseness, throughout the manuscript we refer to the functionalised linkers by their functional groups (e.g.…”

“…adsorption, [23,24,26] even when the effects of potential Pb 2þ desolvation are taken into account. This indicates other factors such as the presence of defects should also be critically analysed.…”

“…A recent study using UiO-66-NH 2 found that an increased concentration of defects due to missing linkers connecting the metal oxide nodes led to enhanced Pb 2þ adsorption. [26] Defects might enhance adsorption performance simply by facilitating diffusion through the MOF but it is also possible that they might play an active role in adsorption. For instance, in another recent study, the defect sites created at the metal oxide nodes by absent linkers were directly functionalised to be capped by thiourea and amidinothiourea groups; these functional groups adsorbed Pb 2þ with a maximum adsorption capacity of 245.8 mg g À1 .…”

Highly Porous MOF Adsorbent for Wastewater Treatment

“…The maximum calculated (q e ) value for Pb(II) ions was 171.42 mg/g. Co-MOF [34] have a maximum adsorption capacity corresponding to 50 % of the adsorption capacity value obtained for Cd-H 4 bta while Cu-MOF [35], Fe-MOF [36] and Zr-MOF [37,38] have adsorption capacity corresponding to only 42, 53 and 79 % respectively. The maximum adsorption capacity values of Cd-MOF for Cu(II), Pb(II) and Ni(II) ion (183.43, 171.42 and 120.31 mg/g) respectively indicated that this material is a potential candidate for removing metal ions from aqueous solution.…”