Design Equilibrium Parameters for Recovery of Chromium(III) from Concentrated Saline Sulfate Media via Room-Temperature Cloud-Point Extraction Process Using a Mixture of Multidentate Schiff Base Ligand/Tergitol 15-S-7 as a Novel Biodegradable Extracting System

Abstract

A new eco-friendly cloud-point extraction process (CPEP) involving Tergitol 15-S-7 as a biodegradable nonionic surfactant and N,N′-bis(salicylideneaminoethyl)amine multidentate Schiff base, namely H 2 Saldien, as chelating extractant was performed for the removal of chromium(III) from concentrated aqueous sulfate medium. The phase diagram of the Tergitol 15-S-7/water micellar system was first established. Then, the effect of sodium sulfate (Na 2 SO 4 ) on the cloud points (T cp ) was determined. Chromium(III) extraction efficiency was maximized through an optimization process in which the influence of each parameter (i.e., equilibrium pH, extractant concentration, and nonionic surfactant concentration) on the chemical recoveries of Cr(III) was investigated. At optimum experimental conditions, nearly 94% extraction efficiency with a minimal volume fraction of surfactant-rich phase (ϕ s = 0.25), and ambient separation temperature (T s = 17 °C) was achieved at pH 4, in one stage. The analysis of the extraction data revealed that the cloud-point process of chromium(III) proceeds via a cation exchange mechanism. The stoichiometry of the complex extracted into the surfactant-rich phase was ascertained to have a composition of 1:2 [Cr/H 2 Saldien]. A higher extraction constant was obtained for CPE compared with conventional solvent extraction, confirming the feasibility and usefulness of the CPE for Cr(III) recovery. Overall, the rational-designed H 2 Saldien/Tergitol 15-S-7 biodegradable extractant system exhibited superior extractability for Cr(III) in the CPE process.

Improvement in the Chromium(VI)-Diphenylcarbazide Determination Using Cloud Point Microextraction; Speciation of Chromium at Low Levels in Water Samples

“…In recent years, this methodology has been used for the extraction of various Cr 6+ complexes, measuring the final concentration of the metal in the condensed phase by means of an atomic [ 26 , 27 , 28 , 29 , 30 , 31 ] or molecular techniques [ 11 , 16 , 26 , 32 , 33 , 34 ].…”

Reverse Micellar Dyeing of Cotton Fabric with Reactive Dye Using Biodegradable Non-Ionic Surfactant as Nanoscale Carrier: An Optimisation Study by One-Factor-at-One-Time Approach

“…Our previous works focused on the use of non-ionic polyethylene glycol (PEG)based [22] and alkyl polyglucoside (APG)-based [23] surfactants and rhamnolipid biosurfactant [24] for reverse micellar dyeing of cotton fabric in a different non-aqueous solvent medium. Compared with poly(ethylene glycol) (12) tridecyl ether (PEG-12), which is a mixture of C 11 to C 14 iso-alkyl ethers, Tergitol type 15-S-12 (T15S12) is a secondary alcohol ethoxylate (SAE) with distinctive branched hydrophobic tails [25], and it is readily biodegradable and specially created to meet the "designed to degrade" principle [21,26]. To the best of our knowledge, using T15S12 SAE-based biodegradable non-ionic surfactant (HLB value of 14.5) as a dye carrier for reverse micellar dyeing of cotton fabric is unknown and has not yet been explored and found in the literature.…”