Solid-state polymer membranes for simple, sensitive, and low-cost monitoring of mercury in water

Abstract

Solid-state Hg(II) selective membranes were produced and assessed by means of X-ray absorption near edge structure in the total reflection X-ray fluorescence (XANES-TXRF) setup and by the energy dispersive X-ray fluorescence (EDXRF) technique. Membranes were functionalized using four promising ligands for mercury complexation, i.e.: i) 4-(2-Pyridylazo) resorcinol (PAR), ii) thiourea, iii) calconcarboxylic acid (CCS), and iv) dithizone. A simple analytical procedure was followed, using miniscule reagent quantities, thus suggesting the process is also cost-effective. XANES-TXRF revealed that mercury complexes with the ligands, and not simply adsorbed onto the PVC matrix, while the complexation was not affected by the matrix existence. Mercury exhibited an increased oxidation grade and was covalently bound to it was preferably bound with Cu in tap water, indicating limited usefulness for mercury preconcentration. Therefore, it is suggested that, depending on the ligand, the solid-state membranes could also possibly used for multi-elemental heavy metals analysis in water.

First Synthesis of 2-Amino-5-hydroxy-4H-chromene-3-carbonitriles from 4-(2-Pyridylazo)resorcinol

“…4-(2-Pyridylazo)resorcinol (PAR, 4), available in the form of sodium salt monohydrate, has long been actively used in analytical chemistry as a non-selective tridentate complexing agent for the extraction and concentration of heavy metal ions, as a metallochromic indicator for complexometric titration, reagent for the photometric determination of analytes (for reviews, see [19][20][21][22][23]). In recent years, PAR has been actively used to create optical sensors and test materials for the determination and extraction of heavy metals [24][25][26][27], spectrophotometric analysis of transition metals in catalysts [28], extraction of Rh 3+ [29], Ga 3+ [30], Ir 4+ [31], and Co 2+ ions [32], obtaining charge-transfer complexes with aromatic nitro compounds [33], etc. However, as far as we know, 4-(2-pyridylazo)resorcinol has not yet been used as a reagent for fine organic synthesis.…”