Nicolas Schaeffer

Nicolas Schaeffer
University of Aveiro | UA · Division of Chemistry

PhD

About

32
Publications
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631
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Introduction
Research interests center around the recovery of critical metals from complex matrices using alternative solvents through a mixed experimental and computational approach. For more information as well as all our articles, please visit the following website http://path.web.ua.pt/publications.asp.

Publications

Publications (32)
Article
Full-text available
Bio-based ionic liquids (ILs) are being increasingly sought after, as they are more sustainable and eco-friendly. Purines are the most widely distributed, naturally occurring N-heterocycles, but their low water-solubility limits their application. In this work, four purines (theobromine, theophylline, xanthine, and uric acid) were combined with the...
Article
In this work, the challenging solvent extraction (SX) separation of Pt(iv) from Pd(ii) is investigated using non-ionic hydrophobic type V deep eutectic solvents (DES) incorporating trioctylphosphine oxide (TOPO) as a constituent. Type V DES are highly structured solvents characterised by the existence of an intermolecular hydrogen bonded network, t...
Article
An acidic aqueous biphasic system (AcABS) presenting a desired and reversible phase transition with HNO 3 concentration and temperature is presented herein as an integrated platform for metal separation. The simple, economical, and fully incinerable (C,H,O,N) AcABS composed of tetrabutylammonium nitrate ([N 4444 ][NO 3 ]) + HNO 3 + H 2 O is charact...
Article
In a circular economy context, there is a growing need for more sustainable waste management options to recover elements from end-of-life materials. These “secondary ores” represent a source of critical elements that are often present in higher concentration compared to their primary ore. In this work, the recovery of lanthanum (La) from waste nick...
Article
This study is aimed to enhance the understanding of the interaction between ionic liquids (ILs) and non-ionic Pluronic triblock copolymers in aqueous two-phase micellar systems (ATPMS) used for selective separation/purification of hydrophobic biomolecules. The ILs allow a precise control of the cloud point phase separation temperatures (CPT), parti...
Article
Full-text available
In this work, the aqueous phase diagram for the mixture of the hydrophilic tributyltetradecyl phosphonium ([P44414]Cl) ionic liquid with acetic acid (CH3COOH) is determined, and the temperature dependency of the biphasic region established. Molecular dynamic simulations of the [P44414]Cl + CH3COOH + H2O system indicate that the occurrence of a clos...
Article
Full-text available
Solubilizing agents are widely used to extract poorly soluble compounds from biological matrices. Aqueous solutions of surfactants and hydrotropes are commonly used as solubilizers, however, the underlying mechanism that determines their action is still roughly understood. Among these, ionic liquids (IL) are often used not only for solubilization o...
Article
Starting from a real Proton Exchange Membrane Fuel Cell (PEMFC) leachate, separation of the strategic metals platinum(IV) and cobalt(II) was carried out using two distinct strategies applying ionic liquids (ILs), either via solvent extraction (SX) or acidic aqueous biphasic system (AcABS). The versatility of ILs and their ability to provide origina...
Article
Full-text available
The tuneable properties of surface-active ionic liquids (SAIL) and Pluronics are dramatically magnified by combining them in aqueous solutions. The thermo-controlled character of both, essential in the extraction of valuable compounds, can be fine-tuned by properly selecting the Pluronic and SAIL nature. However, further understanding of the nanosc...
Article
Full-text available
The continued electrification of society and the related growing demand for rechargeable batteries requires in turn the elaboration of efficient and sustainable recycling strategies for their recovery and valorization. An important separation relevant to Nickel Metal Hydride (NiMH) and Lithium-Ion battery recycling is the inter-transition elements...
Article
Hypothesis: Imidazolium-based ionic liquids (ILs) in water exhibit a surfactant-like behavior that is only partially characterized by experimental techniques with molecular dynamic (MD) simulations emerging as a complimentary tool to study their phase behavior. However, while atomistic models suffer of time and size scale limitations, higher-level...
Article
In comparison to the well-described ionic eutectic mixtures, hydrophobic eutectic solvents (HES) composed of two non-ionic compounds represent a relatively new class of eutectic. In this work, a number of non-ionic HES liquid at room temperature were identified from a large initial screening of potential mixtures. Three new HES based on Thymol+TOPO...
Article
Full-text available
It was recently shown that tetramethylammonium chloride presented negative deviations to ideality when mixed with tetraethylammonium chloride or tetrapropylammonium chloride, leading to a strong decrease of the melting points of these salt mixtures, in a behavior akin to that observed in the formation of deep eutectic solvents. To better rationaliz...
Article
Natural products can be the basis for the development of green solvents, relevant for the advancement of new, more sustainable, processes and products. In this work, ten binary mixtures constituted by terpenes are prepared and characterized. Their solid-liquid phase diagrams show that room temperature solvents can be prepared from solid terpenes in...
Article
Full-text available
In this paper, we develop a new coarse-grained model, under the MARTINI framework, for Pluronic block copolymers that is able to describe the self-assembly mechanism and reproduce experimental micelle sizes and shapes. Previous MARTINI-type Pluronic models were unable to produce realistic micelles in aqueous solution, and thus our model represents...
Article
Mixtures of non-ionic compounds have been reported as DES but most are just ideal mixtures. In the thymol–menthol system, an abnormal strong interaction was identified stemming from the acidity difference of the phenolic and aliphatic hydroxyl groups. This type of interaction is found to be the key to prepare non-ionic DES, that may be classified a...
Article
A tuneable thermoresponsive system based on combinations of sodium dodecyl sulfate surfactant with tetrabutylammonium chloride salt is presented as an integrated process for the solid-liquid extraction of violacein from bio-engineered...
Article
The temperature responsive solubility of ionic liquids with ‘bulky’ polar regions, such as tributyltetradecyl phosphonium chloride [P44414]Cl, in acidic aqueous solutions, is elucidated through a combined experimental and computational approach. The temperature effect in the acidic aqueous biphasic system HCl/[P44414]Cl/H2O was characterised in the...
Article
An acidic aqueous biphasic system (AcABS), in which the inorganic salt component of a traditional aqueous biphasic system (ABS) is replaced by the inorganic acid inherently present in typical hydrometallurgical leachate solution, is shown to selectively separate cobalt from nickel, a separation relevant to the recycling of nickel metal hydride (NiM...
Article
A sustainable and flexible approach for the extraction and separation of rhenium and molybdate species based on a polymeric aqueous two-phase system (ATPS) is proposed in which the high metal content in concentrated copper effluents is directly used as the driver of phase demixing. The partition coefficient and selectivity of Re, Mo, and Cu are stu...
Article
Full-text available
Waste electrical and electronic equipment (WEEE) is the fastest growing type of waste globally and is an important challenge due to its heterogeneity, intrinsic toxicity and potential environmental impact. However, WEEE also represents an important secondary source of critical and valuable elements and must be viewed as a resource within the contex...
Article
Sustainable hydrophobic eutectic solvents, composed of low-priced and biodegradable terpenes and fatty acids, were used for the extraction and separation of Cu(II) from other transition metals in mildly acidic solutions....
Article
Ionic-liquid-based aqueous biphasic systems (IL-based ABS) have demonstrated exceptional performance in bioseparation processes. However, IL-based ABS are of limited interest for metal extraction as most metals are not stable in their neutral or alkaline pH conditions. In the quest for better extraction systems for metals, the development of IL-bas...
Article
Ionic liquid-based acidic aqueous biphasic systems (AcABS) represent a promising alternative to solvent extraction process for the recovery of critical metals in which the substitution of the inorganic salt by an acid allows for the ‘one pot’ approach to the leaching and separation of metals. However, a more fundamental understanding of AcABS forma...
Article
The first instance of an acidic aqueous biphasic system (AcABS) based on tributyltetradecylphosphonium chloride ([P44414][Cl]) and an acid is here reported. This AcABS exhibits pronounced thermomorphic behavior and is shown to be applicable to the extraction of metal ions from concentrated acidic solutions. Metal ions such as cobalt(II), iron(III),...
Article
The first instance of an acidic aqueous biphasic system (AcABS) based on tributyltetradecylphosphonium chloride ([P44414][Cl]) and an acid is here reported. This AcABS exhibits pronounced thermomorphic behavior and is shown to be applicable to the extraction of metal ions from concentrated acidic solutions. Metal ions such as cobalt(II), iron(III),...
Article
Spent fluorescent lamps, classified as hazardous waste in the EU, are segregated at source. Processes for the recovery of critical rare-earth (RE) elements from the phosphor powder waste, however, often involve use of aggressive acid or alkali digestion, multi-stage separation procedures, and production of large aqueous waste streams which require...
Article
Phosphors and optoelectronic thin film electronic device layers contain critical metals including lanthanides and indium that should be recycled. Solvent impregnated resins (SIRs) containing (i) DEHPA (ii) DODGAA and (iii) DODGAA with the ionic liquid [C4mim][Tf2N] are investigated in extraction chromatography methodologies to recover and separate...
Article
The factors, including ionic liquid:water ratios, temperature, solvent:solute contact times, and the effect of dissolved rare earth metal ions on the [Hbet][Tf2N]:H2O thermometric phase change are determined to develop a process for separating the light from the heavy rare earth metal oxides in [Hbet][Tf2N]:H2O mixtures. The relative solubility dat...

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Project
Metals are primary yet finite commodities, necessary for the continued growth of modern society, and are at the forefront of the green economy transition. However, the mining rates of most metals are at a historical maximum, while their recovery from waste, where these metals are newly concentrated and can therefore be considered as urban ores, remains low. The imbalance between supply and demand, compounded by the unequal geographical concentration of exploitable deposits, results in an unsustainable situation. For this Special Issue in Metals, we welcome innovative contributions in the area of metal recycling and recovery using any metallurgical processing route. Articles addressing either the theoretical or practical understanding of metal processing are encouraged, as well as a critical comparison of process options and literature reviews. We would also appreciate receiving articles dealing with the wider context of metal recovery and criticality, such as global flows of critical metals or the environmental impacts of recycling using life cycle assessment methodology.