A Novel Coordination Polymer as Adsorbent Used to Remove Hg(II) and Pb(II) from Water with Different Adsorption Mechanisms

Anion-encapsulating, discrete prism and extended frusta, from trimetallated triangular macrocycles and linkers

Reaction of a trinuclear triangular macrocyclic complex Pb3L(CF3SO3)6 with bidentate linkers in a ratio of 3 equiv. of linker per 2 equiv. of complex, produces a prismatic structure with 4,4'-dipyridyl, and two unprecedented, extended 3D frustum-like structures with 1,2-di(4-pyridyl)ethylene and 1,4-di(4-pyridyl)benzene. The cavities of these structures encapsulate triflate anions.

One-step synthesis of thiol-functionalized metal coordination polymers: effective and superfast removal of Hg (II) in the different matrices to ppb level

The mercury in water bodies has posed a great threat to the environment and humans, and removing mercury and purifying wastewater has become a global environmental issue. Adopting Zn(II) coordination polymers (Zn-CPs) emerged as a new approach, however, the kind of Zn-CPs, which solely consisted of amino groups, exhibited unsatisfactory performance in capturing Hg(II) at a low level and causing the subsequent leaching of Zn(II) after adsorption. In this study, we fabricated the thiol-modified Zn-based coordination polymers (Zn-CPs-SH) through a one-step solvothermal reaction to efficiently capture Hg(II) from wastewater. Its preeminent adsorption performance could be maintained across a broad range of pH (2-7), ion strength (Cl-, SO42-, and NO3- at 0-10,000 mg/L), and dissolved organic matter (0-100 mg/L). The impressive properties, including fast kinetics (k2∼1.01 × 10-4 L/min), outstanding adsorption capacity (1278.72 mg/g, 298 K), superior selectivity (Kd∼2.3 × 104 mL/g), and excellent regeneration capability (Re = 93.54% after 5 cycles), were attributed to the ultra-abundance of adsorption sites donating from thiol groups, which was revealed by XPS analysis, DFT calculations, and molecular orbital theory. Noteworthy, the high practical application potential of Zn-CPs-SH was demonstrated by its outstanding Hg(II) removal efficiency (Re ≥ 99.10%) in various Hg(II)-spiked water matrices, e.g., tap water, river water, and industrial wastewater. Importantly, the residual Hg(II) in the treated water declined to the ppb level without any Zn(II) leaching. Overall, it is highly anticipated that the incorporation of Zn-CPs-SH would facilitate the practical implementation of highly efficient Hg(II) removal in wastewater treatment owing to its exhibiting high selective affinity, superior adsorption capacity, and enhanced efficiency.

Novel Zn metal-organic framework with the thiazole sites for fast and efficient removal of heavy metal ions from water

Pollution of water by heavy metal ions such as Pb2+ and Hg2+ is considered as an important issue, because of the potential toxic effects these ions impose on environmental ecosystems and human health. A new Zn-based metal-organic framework, [Zn2(DPTTZ) (OBA)2] (IUST-2), was synthesized through a solvothermal method by the reaction of 2, 5-di (4- pyridyl) thiazolo [5, 4-d] thiazole ligand (DPTTZ), the "V-shape" 4,4'-oxybis (benzoic acid) ligand (OBA) and zinc nitrate (Zn(NO3)2·6H2O). This novel MOF has been characterized by several analysis techniques such as fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA), powder x-ray diffraction (PXRD), thermogravimetry analysis (TGA), differential thermal analysis (DTA), field emission scanning electron microscopy (FE-SEM), Brunauer-Emmett-Teller (BET) surface area analysis and single-crystal X-ray diffraction (SXRD). This 3D MOF was tested for removing Pb2+ and Hg2+ ions from water. The factors that were investigated on the elimination of Pb2+ and Hg2+ ions were of pH, adsorption time, and the effect of initial ions concentration. According to the results, this particular Zn-MOF had significant performance in eliminating Pb2+ and Hg2+ ions from water with a removal efficiency of more than 97% and 87% within 3 min, respectively.

One-pot facile approach to design an efficient macro-porous polymeric matrix to remediate Hg(II)and Pb(II) from aqueous medium and its performance evaluation study by mathematical modelling

In the present scenario discharge of heavy-metal ions into water bodies is a global threat that is causing serious health hazards even in low concentrations. Thus, in order to remediate the heavy-metal [Hg(II) and Pb(II)] toxicity, an organic-inorganic hybrid functional porous metallo-polymeric network i. e, poly(Zirconyl methacrylate-co-1-vinyl imidazole) (pZrVIm) was fabricated via one-pot facile synthesis approach. The pZrVIm architecture has shown high removal efficiency for Hg(II) and Pb(II) aqueous medium even in extremely low quantities. Advanced instrumental techniques were used to characterize the structural and morphological characteristics of pZrVIm. Different experimental variables i.e., reaction time, pH, initial feed concentration, co-ion effects etc. were explored to examine adsorption behaviour. The maximum adsorption capacities (q_max) of pZrVIm5 were calculated as 168.06 and 162.34 mg g^-1 for Hg(II) and Pb(II) respectively by the Langmuir isotherm model. Data from isotherms showed that monolayer adsorption on a homogeneous surface is the rate-limiting stage and followed pseudo-second-order kinetic process. The Artificial Neural Network (ANN) modelling was used to validate kinetics and isotherm data which revealed high accuracy of the model with correlation coefficient values (R = 0.99). Various types of isotherm models such as Langmuir, Freundlich, Dubinin-Radushkevich, Temkin, Redlich-Peterson, Toth and Koble-Corigen have been studied to determine the adsorption phenomena. The pore diffusion model revealed breakthrough time of 91 h and 84 h, Hg(II) and Pb(II) with the feed concentration of 15 mg L^-1 respectively. The study revealed that pZrVIm5 has great potential for heavy metal ions remediation for water treatment.