Abstract
The different species of nickel present in natural waters exhibit different transport behaviour through bulk liquid membranes (BLMs). This fact has been used to design and optimise a separation/pre-concentration system applicable to separate labile and non-labile nickel fractions. A hydrazone derivative—1,2-cyclohexanedione bis-benzoyl-hydrazone (1,2-CHBBH) dissolved in toluene/dimethyl formamide (2% DMF)—was used as a chemical carrier of nickel species, from an aqueous source solution (sample) to a receiving acidic solution. Both chemical and hydrodynamic conditions controlling the transport system were studied and optimised. Under optimum conditions, variations in the transport of nickel ions as a function of organic (humic acids) and inorganic (chloride ions) ligands were studied. Relationships between the permeability coefficient (P) or recovery efficiency (%R) and the concentrations of ligands and nickel species were analysed using Winhumic V software. A negative correlation between P and the concentration of organic nickel complexes was found, suggesting that only labile nickel species are transported through the liquid membrane, with non-labile complexes remaining in the water sample; allowing for their separation and subsequent quantification in natural waters.
Highlights
Chemical speciation of trace metals in natural waters is currently a hot topic in environmental chemistry
We evaluated a novel bulk liquid membrane system to separate nickel fractions from natural waters
The permeability coefficient and recovery efficiency were dependent on the humic acid concentration, resulting in a decrease in nickel transport as ligand concentration increased
Summary
Chemical speciation of trace metals in natural waters is currently a hot topic in environmental chemistry. Its importance is due to trace metals are no biodegradable remaining in the environment for long periods distributed between the different environmental compartments [1]. Once they reach the aquatic media, dissolved trace metals mainly appear as free hydrated ions or complexed with organic or inorganic ligands. The distribution of these chemical forms depends mainly on the total metal concentration, pH and redox potential, as well as the concentration of ligands.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
