Efficient adsorption of organic dyes by two porous heterometallic metal–organic frameworks assembled with Schiff base ligands and Fe3+/Cd2+ ions

A copper(II)-based metal-organic framework: electrochemical sensing of Cd(II) and Pb(II) and adsorption of organic dyes

A new inorganic-organic hybrid complex, namely [Cu3L2(DMF)2]·H2O (Cu-L), has been synthesized using a sulfur-rich ligand, 3,3',3''-(1,3,5-triazine-2,4,6-triyltrisulfanediyl)tripropanoic acid (H3L) and metal cations under hydrothermal conditions. The metal atoms are interconnected to form a paddle-wheel-like structure, which is ultimately linked to the ligands to create a three-dimensional architecture. Cu-L, employed to fabricate an electrochemical sensor denoted as Cu-L@GCE (glassy carbon electrode), is capable of simultaneously detecting Cd2+ and Pb2+ at approximately -0.82 V and -0.58 V (vs. Ag/AgCl reference), exhibiting high sensitivity and selectivity. Cu-L@GCE demonstrates broad linear detection ranges of 8-28 μM for Cd2+ and 2-14 μM for Pb2+, along with low limit of detection (LOD) values of 0.01363 μM and 0.00212 μM, respectively. Furthermore, Cu-L@GCE achieves LOD values of 0.00209 μM and 0.000034 μM when detecting both ions simultaneously. The constructed sensor successfully detects Cd2+ and Pb2+ in mineral water, tap water, and river water with satisfactory recoveries. Additionally, the adsorption performance for organic dyes has been studied in detail using Cu-L as an adsorbent. The results indicate good adsorption selectivity for methylene blue (MB) and neutral red (NR) compared to methyl orange (MO) and rhodamine B (RhB) molecules.

Schiff base MOFs and their derivatives for sequestration and degradation of pollutants: present and future

Removal of contaminants via adsorption and catalysis have received a significant interest as energy and money-saving solutions for treating the world's wastewater. Metal-organic frameworks (MOFs), a newly discovered class of porous crystalline materials, have demonstrated tremendous promise in the removal and destruction of contaminants for water purification. In order to improve the interactions of MOFs with the target pollutants for their selective removal and degradation, the Schiff base functionalities emerged as promising active sites. Through pre- and post-synthetic alterations, Schiff base functionalities are integrated into the pore cages of MOF adsorbent materials. To understand the adsorptive/catalytic mechanism, potential interactions between the Schiff base sites and the target pollutants are discussed. Based on cutting-edge techniques for their synthesis, this paper examines current developments in the creation of Schiff base-functionalized MOFs as innovative materials for adsorptive removal and catalytic degradation of contaminants for water remediation.

Recent advances in metal-organic frameworks as adsorbent materials for hazardous dye molecules

Water is vital for the sustenance of all forms of life. Hence, water pollution is a universal crisis for the survival for all forms of life and a hurdle in sustainable development. Textile industry is one of the anthropogenic activities that severely pollutes water bodies. Inefficient dyeing processes result in thousands of tons of synthetic dyes being dumped in water bodies every year. Therefore, the efficient removal of synthetic dyes from wastewater has become a challenging research field. Owing to their tuneable structure-property aspects, metal-organic frameworks (MOFs) have emerged as promising adsorbents for the adsorptive removal of dyes from wastewater and textile effluents. In this perspective, we highlight recent studies involving the application of MOFs for the adsorptive removal of hazardous dye molecules. We also classify the developed MOFs into cationic, anionic, and neutral framework categories to comprehend their suitability for the removal of a given class of dyes.