238 pubs · 5,247 cites · h-index 42
The growing volume of textile waste increases the need for effective chemical recycling methods. The hydrochloric acid-based polycotton recycling process offers a route to valorize polycotton textiles (polyester/cotton blends in any ratio) in two steps. First, cotton is selectively hydrolyzed with superconcentrated hydrochloric acid at ambient temperature, enabling its separation from polyester. The resulting saccharides are then converted and simultaneously extracted at 91 °C as 5-chloromethylfurfural (CMF). This preliminary study examined whether dye molecules present in polycotton waste textiles affect the performance and product of the recycling process. The CMF production was not affected by the presence of dyes; however, the heat required for this step caused dye degradation. To prevent contamination of the product by the dye molecules and their degradation products, two types of activated carbon (AC) were evaluated as dye adsorbents. Both proved effective at removing dye molecules from hydrolysates produced from four types of post-consumer polycotton waste. However, although the use of ACs resulted in decolorized hydrolysates, it resulted in lower CMF yields in the subsequent conversion step. Therefore, the use of AC is not recommended in the current laboratory setup.
Experimental chemical process optimization demonstrates high-yield conversion of polycotton textile waste into 5-(chloromethyl)furfural, indicating a viable method for large-scale textile recycling.
Evaluates how different fibers impact CMF yield in polycotton recycling, suggesting best practices for optimal processes.
Research explores the impact of 2,3-butanediol stereochemistry on developing renewable polyesters, suggesting performance improvements.
Investigating Humins Foams Reveals Versatile Carbon Materials for Water Purification Applications.
As a result of the current high throughput of the fast fashion collections and the concomitant decrease in product lifetime, we are facing enormous amounts of textile waste. Since textiles are often a blend of multiple fibers (predominantly cotton and polyester) and contain various different components, proper waste management and recycling are challenging. Here, we describe a high-yield process for the sequential chemical recycling of cotton and polyester from mixed waste textiles. The utilization of 43 wt% hydrochloric acid for the acid hydrolysis of polycotton (44/56 cotton/polyester, room temperature, 24 h) results in a 75% molar glucose yield from the cotton fraction, whereafter the hydrolysate solution is easily separated from the solid polyester residue. The reaction is scalable, as similar results are obtained for experiments performed at 1 mL, 0.1, and 1.0 L and even in a 230 L pilot plant reactor, where mixed postconsumer polycotton waste textile is successfully recycled. The residual polyester is successfully converted via glycolysis to bis(2-hydroxyethyl) terephthalate in 78% isolated yield (>98% purity).
Every second, the equivalent of a garbage truck filled with textile waste is discarded. Due to the complex composition of clothing materials, more than 80 wt% of this waste is either incinerated or sent to landfills. Currently, only 15 wt% of textiles are recycled, and of that fraction, approximately 93 wt% undergoes downcycling, resulting in lower-value products. Generally, about 50 wt% of textile waste is composed of polycotton-a blend of cotton, a glucose-based polysaccharide, and polyester, primarily poly(ethylene terephthalate) (PET). Although this combination leverages the advantageous properties of both fibres, full valorisation of these materials is complex due to their blended structure. Simultaneously, there is an urgent need to transition away from fossil-based feedstocks. Cotton-rich textiles present a promising alternative as a non-food-based glucose source for the chemical industry, owing to their high cellulose content and widespread availability. Therefore, this review explores the current state-of-the-art methods for hydrolysing cotton into glucose through acid and/or enzymatic hydrolysis, while preserving the polyester component. These techniques enable the effective separation and subsequent valorisation of both cotton and PET fractions, facilitating their reuse in the production of new materials.
This study reviews saccharification technologies, focusing on HCl-based methods, their industrial evolution, and challenges in scaling, emphasizing the historical progress and ongoing need for innovation.
This study explores the synthesis and performance of novel copolyesters containing 2,3-butanediol (2,3-BDO) as a biobased secondary diol. This presents an opportunity for improving their thermal properties and reducing crystallinity, while also being more sustainable. It is, however, a challenge to synthesize copolyesters of sufficient molecular weight that also have high 2,3-BDO content, due to the reduced reactivity of secondary diols compared to primary diols. Terephthalate-based polyesters were synthesized in combination with different ratios of 2,3-BDO and ethylene glycol (EG). With a 2,3-BDO to EG ratio of 28:72, an Mn of 31.5 kDa was reached with a Tg of 88 °C. The Mn dropped with increasing 2,3-BDO content to 18.1 kDa for a 2,3-BDO to EG ratio of 78:22 (Tg = 104 °C) and further to 9.8 kDa (Tg = 104 °C) for the homopolyester of 2,3-BDO and terephthalate. The water and oxygen permeability both increased significantly with increasing 2,3-BDO content and even the lowest content of 2,3-BDO (28% of total diol) performed significantly worse than PET. The incorporation of 2,3-BDO had little effect on the tensile properties of the polyesters, which were similar to PET. The results suggest that 2,3-BDO can be potentially applied for polyesters requiring higher Tg and lower crystallinity than existing materials (mainly PET).
This study proposes a chemical recycling pathway for valorizing the cellulosic component of municipal waste streams such as textile, cleaning wipes, corrugated cardboard, contaminated cardboard (i.e. a pizza box), paper-plastic laminate (PPL) coffee cups and cigarette butts (CBs). The goal of this study is to establish an experimental procedure that allows to test a broad range of cellulose-containing waste materials, laying the groundwork for commercial deployment of their chemical recycling. The cellulose contained in these materials is transformed into 5-chloromethylfurfural (CMF), a precursor for bio-based plastics, without affecting the plastic counterpart (if present). We employ a biphasic system concept using aqueous HCl solutions for CMF formation and in situ extraction from the reaction medium using immiscible organic solvents, enabling straightforward product separation. This method allows to hydrolyze cellulosic materials from waste without affecting PET or polyolefin plastic also present, facilitating the subsequent recycling of this plastic as well. This study serves as a foundation to assess the feasibility of using cellulose-containing waste streams for chemical recycling and to offer recommendations on selecting optimal reaction procedures.
The synthesis of 5-(halomethyl)furfurals (XMFs, X=F, Cl, Br, I), including 5-(chloromethyl)furfural (CMF), 5-(bromomethyl)furfural (BMF), 5-(iodomethyl)furfural (IMF), and 5-(fluoromethyl)furfural (FMF), from biomass represents a pivotal advancement in renewable chemistry and engineering. Harnessing waste biomass as a raw material offers a sustainable alternative to fossil-based resources, mitigating environmental degradation and addressing pressing energy needs. CMF and BMF, characterized by their enhanced stability over the hydroxyl analog, 5-(hydroxymethyl)furfural (HMF), exhibit promise as renewable building blocks for scale-up and commercialization. The surge in research interest, particularly from 2010 to 2024, reflects a growing recognition of XMFs' potential as novel platform chemicals. This review highlights the evolution of XMF synthesis methods, focusing on their transformation from saccharides and lignocellulosic biomass. Mechanistic insights and experimental setups are scrutinized for industrial feasibility and scalability, shedding light on technical challenges and avenues for further research. The analysis underscores the burgeoning significance of XMFs in the transition towards sustainable chemical production, emphasizing the importance of process optimization and mechanistic understanding for commercial deployment.
Post-modification of a series of NCN-pincer platinum(II) complexes [PtX(NCN-R-4)] (NCN = [C6H2(CH2NMe2)2-2,6]–, R = C(O)H, C(O)Me and C(O)Et), X = Cl– or Br–) at the para-position using the McMurry reaction was studied. The synthetic route towards two new [PtCl(NCN-R-4)] (R = C(O)Me and C(O)Et) complexes used above is likewise described. The utility and limitations of the McMurry reaction involving these pincer complexes was systematically evaluated. The predicted “homo-coupling” reaction of [PtBr(NCN-C(O)H-4)] led to the unexpected formation of 3,3′,5,5′-tetra[(dimethylamino)methyl]-4,4′-bis(platinum halide)-benzophenone (halide = Br or Cl), referred to hereafter as the bispincer-benzophenone complex 13. This material was further characterized using X-ray crystal structure determination. The applicability of the pincer complexes in the McMurry reaction is shown to open a route towards the synthesis of tamoxifen-type derivatives of which one phenyl ring of Tamoxifen® itself is replaced by an NCN arylplatinum pincer fragment. The newly synthesized derivatives can be used as potential candidates in anti-cancer drug screening protocols. Two NCN-arylpincer platinum tamoxifen type derivatives, 5 and 6, were successfully synthesized and of 5 the separation of the diastereomeric E-/Z-forms was achieved. Compound 6, which is the pivaloyl protected NCN pincer platinum hydroxy-Tamoxifen® derivative, was obtained as a mixture of E-/Z-isomers. The new derivatives were further analyzed and characterized with 1H-, 13C{1H}- and 195Pt{1H}-NMR, IR, exact mass MS and elemental analysis.
Humins as biorefineries by-product can be converted with a direct heating treatment into new rigid porous carbon materials known as humins foams. Currently, not many informations about this new material are known. Here, a preparation protocol in two steps involving foaming and carbonization is reported, while the materials have been investigated in terms of morphology, elemental content, water adsorption–desorption, stability to solvents and high temperatures, and thermal conductivity. In order to evaluate their potential uses in applications such as water purification, the pH associated to the zero charge point has been identified. Foams prepared under air ventilated condition revealed an extremely negative surface, which can be used in cation exchange applications. The surface's groups have been identified by Boehm titration, showing that this behavior can be associated to the presence of acid moieties, while the basic species result absent. The humins foams have been also tested through CO2 adsorption tests at realistic operation conditions, revealing that their performances can compete with materials reported in literature. Finally, activated carbon monoliths from carbonized humins foams using CO2 activation were tested, reaching a surface area of 1347 m2 g−1 after 20 min and 1482 m2 g−1 after 40 min of activation. These monoliths have been characterized in terms of morphology and elemental content. The results prove that the humins foams are very versatile materials, cost effective and easy to produce, with promising properties that can be further tailored for foreseen applications.
We report a highly efficient and 100% atom economic synthesis of methyl acrylate and acetic acid via gas phase pyrolysis of methyl 3-acetoxypropionate at 600 °C. The latter can be produced in a single step from methyl levulinate, a side product of Avantium’s FDCA process.
A new macroporous foam-like material is presented based on autocross-linking humins, an industrial biorefinery byproduct. Humins foams are obtained by a simple heating process, without any pretreatment and with high control of morphology, porosity, and carbon content. Untreated humins have been characterized by GC, ultra-performance liquid chromatography (UPLC), elemental analysis, and FTIR, whereas the mechanism of foaming was elucidated by a combination of thermal and rheological analyses. A preliminary screening of conditions was conducted to identify the parameters controlling this foaming process. A foam was produced in a controlled way with open and/or closed cells with cell diameters between 0.2 and 3.5 mm. Humins foams were characterized by Raman spectroscopy, FTIR, SEM, nitrogen adsorption, pycnometry, and mechanical tests. The results show that, based on humins, it is possible to obtain porous materials with controlled architectures and a range of parameters that can be tailored, depending on the foreseen applications.
A series of organometallic octupolar 1,3,5-substituted-2,4,6-styryl-benzene complexes was synthesized by post-modification of parent [PtCl(NCN-CHO-4)], i.e. 1,3,5-tri-R-2,4,6-tris[(4-(PtCl)(3,5-bis[(dimethylamino)methyl]styryl)]benzene (NCN = [C6H2(CH2NMe2)2-2,6]– in which R = OMe, H, Br (1–3). Their synthesis involved a triple Horner-Wadsworth-Emmons reaction of [PtCl(NCN-CHO-4)] with the appropriate tris[(diethoxyphosphoryl)]methyl]benzene derivative. The 195Pt{1H} NMR chemical shift reflects the electronic properties of the π-system to which it is connected. The UV/Vis bands of the octupolar platinum complexes are only slightly red-shifted (by 5–12 nm) with respect to those of corresponding stilbenoid Pt-Cl pincer compounds (i.e., the separate branches), suggesting that there is only a limited electronic interaction between these branches. The fluorescence Stokes shift, quantum yields and lifetimes of 1–3 also are of the same order of magnitude as those of stilbenoid Pt-Cl pincer compounds, indicating that a dipolar excited state is formed, which is localized on one of the three branches. The hyper-Rayleigh scattering technique revealed hyperpolarizabilites βHRS of 430, 870 and 183 × 10−30 esu for 1, 2 and 3, respectively, which are among the highest for transition metal complexes. The highest value was found for the compound lacking a donor or acceptor group at the central core, lending support to the idea that dispersion overwhelms charge transfer in determining the magnitude of the first hyperpolarizability in octupolar compounds.
The objective of this paper is to investigate the anti-knock quality of sugar-derived levulinic esters (methyl levulinate (ML) and ethyl levulinate (EL)) and cyclic ethers (furfuryl ethyl ether (FEE) and ethyl tetrahydrofurfuryl ether (ETE)). To this end, combustion experiments were carried out in both an engine and a constant volume autoignition device (modified ignition quality tester (IQT)). The results from both apparatuses demonstrate that ML, EL and FEE have superior anti-knock quality to the reference Euro95 gasoline. ETE, conversely, performed markedly worse than the reference fuel on both setups and might therefore be a more appropriate fuel additive for compression ignition engines. The main reason of the distinctions in anti-knock quality can be found in the molecular structure of the neat biofuels. ML and EL are levulinic esters, with a ketone (CO) functionality and an ester (C(O)–O) group on the carbon chain. They can readily produce stable intermediates during the auto-ignition process, thereby slowing down the overall reaction rate. The unsaturated cyclic ether (FEE) has very strong ring C–H bonds. However, the saturated cyclic ether (ETE) has weak ring C–H bonds, which facilitate more readily ring opening reactions. Ethyl side chains on the cyclic ethers further accelerate the reaction rate. Importantly for future research, our results suggest that the modified (IQT) and engine experiments are interchangeable setups with respect to qualitative anti-knock quality evaluation of novel compounds.
A series of organometallic 4,4'-substituted benzylidene aniline complexes 4-ClPt-3,5-(CH2NMe2)2C6H2CH[double bond, length as m-dash]NC6H4R'-4', abbreviated as PtCl[NCN(CH[double bond, length as m-dash]NC6H4R'-4')-4], with R' = NMe2, Me, H, Cl, CN (, respectively), was synthesized via a Schiff-base condensation reaction involving reaction of PtCl[NCN(CH[double bond, length as m-dash]O)-4] () with the appropriate 4-R'-substituted aniline derivative () in toluene. The resulting arylplatinum(ii) products were obtained in 75-88% yield. Notably, product was also obtained in 68% yield from a reaction in the solid state by grinding solid with aniline . The structures of , , and in the solid state (single crystal X-ray diffraction) showed a non-planar geometry, in particular for compound . The electronic interaction between the donor benzylidene fragment PtCl(NCN-CH) and the para-R' aniline substituent through the azomethine bridge was studied with NMR and UV/Vis spectroscopy. Linear correlations were found between the azomethine (1)H, the (195)Pt NMR and various (13)C NMR chemical shifts, and the substituent parameters σF and σR of R' at the aniline site. In common with organic benzylidene anilines, the azomethine (1)H NMR chemical shift showed anomalous substituent behavior. The (195)Pt NMR chemical shift of the platinum center can be used as a probe for the electronic properties of the delocalized π-system of the benzylidene aniline framework, to which it is connected. The dual substituent parameter treatment of the azomethine (13)C NMR shift gave important insight into the unique behaviour of the Pt-pincer group as a substituent. Inductively, it is a very strong electron-withdrawing group, whereas mesomerically it behaves like a very strong electron donating group.
We have prepared the dinuclear ruthenium complexes [(R 3 -tpy)Ru(N ∧ C ∧ N-tpy)Ru(tpy)] 3+ (R = H ([ 5a ] 3+ ), CO 2 Me ([ 6a ] 3+ ), N ∧ C(H) ∧ N-tpy = 4′-(3,5-dipyridylphenyl)-2,2′:6′,2′′-terpyridine, tpy = 2,2′:6′,2′′-terpyridine) and [(R 3 -tpy)Ru(N′ ∧ C ∧ N′-tpy)Ru(tpy)] 3+ (R = H ([ 5b ] 3+ ), CO 2 Me ([ 6b ] 3+ ), N′ ∧ C(H) ∧ N′-tpy = 4′-(3,5-di(4- tert- butylpyridyl)phenyl)-2,2′:6′,2′′-terpyridine) in a stepwise manner. The directional nature of the bridging ligand, which is potentially cyclometalating on one side, induces large redox asymmetry in the resulting dinuclear complexes. One-electron oxidation gives rise to a strong metal-to-metal charge transfer transition from the [Ru(tpy 2 )] 2+ moiety to the cycloruthenated group, centered at 1034 nm for [ 6b ] 4+ . The localized nature of the oxidation processes, the shape of the NIR band, and TD-DFT calculations allow assignment of these systems to localized Robin−Day class II. Exclusive substitution of the terminal tpy ligand on the cyclometalated ruthenium with acid moieties allows selective attachment of the dye to a semiconductor surface, whereby a possible two-step upconversion path is created in dye-sensitized solar cells for the utilization of low-energy photons.
To investigate the viability of cyclometalation as a general tool in the design of new sensitizers for dye-sensitized solar cells, a series of (cyclometalated) ruthenium complexes was prepared. To this purpose we have prepared the carboxylate-functionalized 2,2′:6′,2′′-terpyridine (tpy)-based tridentate ligands 4′-ethoxycarbonyl-2,2′:6′,2′′-terpyridine (EtO 2 C-N ∧ N ∧ N, 5 ), methyl-3,5-di(2-pyridyl)benzoate (MeO 2 C-N ∧ C(H) ∧ N, 6 ), 4-ethoxycarbonyl-6-phenyl-2,2′-bipyridine (EtO 2 C-C(H) ∧ N ∧ N, 7 ), and 4,4′-bis(methoxycarbonyl)-6-phenyl-2,2′-bipyridine ((EtO 2 C) 2 -C(H) ∧ N ∧ N, 8 ), and the ruthenium complexes thereof, [Ru(EtO 2 C-tpy)(tpy)](PF 6 ) 2, 1a, [Ru(MeO 2 C-N ∧ C ∧ N)(tpy)](PF 6 ), 2a, [Ru(EtO 2 C-C ∧ N ∧ N)(tpy)](PF 6 ), 3a, and [Ru((MeO 2 C) 2 -C ∧ N ∧ N)(tpy)](PF 6 ) 2, 4a . In this series, cyclometalation results in a red shift as well as in a broadening of the electronic absorption features and is accompanied by a cathodic shift in the Ru II /Ru III redox process. The complexes are photostable in both the Ru(II) and the Ru(III) state. Deprotection of the esters and grafting onto TiO 2 resulted in a small additional red shift of the absorption features. Incorporation of the free acids of the complexes into a standardized solar cell shows efficient sensitization for the complexes 3b and 4b, with the C,N,N′-bonding motif. The dicarboxylated complex 4b showed short circuit currents similar to those obtained for the benchmark compound N719 . In contrast, for the free acid of 1a, with the N,N′,N′′-bonding motif, and for 2a, with the N,C,N′-bonding motif, low efficiencies were observed. To put these results into perspective, we have applied TD-DFT calculations. The optical assignments based on these calculations correlated well with the spectral changes observed during p K a determinations. The complexes with the C,N,N′-bonding motif possess an excited state associated with the cyclometalated ligand, allowing efficient charge injection, while the complex with the N,C,N′-bonding motif possesses a more isolated excited state located on the remote tpy ligand and, as a result, is not capable of efficient charge injection into the TiO 2 conduction band. This shows that the covalent carbon-to-ruthenium bond can be utilized as a tool to shift the operational threshold of the individual sensitizer for dye-sensitized solar cells toward lower energy, as long as care is taken that the nature of the excited state is appropriate for electron injection.