Recent Advancements in Plastic Packaging Recycling: A Mini-Review

Today, the scientific community is facing crucial challenges in delivering a healthier world for future generations. Among these, the quest for circular and sustainable approaches for plastic recycling is one of the most demanding for several reasons. Indeed, the massive use of plastic materials over the last century has generated large amounts of long-lasting waste, which, for much time, has not been object of adequate recovery and disposal politics. Most of this waste is generated by packaging materials. Nevertheless, in the last decade, a new trend imposed by environmental concerns brought this topic under the magnifying glass, as testified by the increasing number of related publications. Several methods have been proposed for the recycling of polymeric plastic materials based on chemical or mechanical methods. A panorama of the most promising studies related to the recycling of polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and polystyrene (PS) is given within this review

Catalizzatori idrosolubili contenenti il sale sodico dell’acido diidrotiottico come legante

L’uso di specie catalitiche a base di metalli di transizione modificate con opportuni leganti idrosolubili consente di condurre reazioni in sistemi bifasici (acqua/solvente organico) così da permettere una semplice separazione e riciclo del catalizzatore. La nostra ricerca, improntata all’uso di leganti idrosolubili semplici e a basso costo, si è indirizzata da tempo verso l’utilizzo del sale sodico dell’acido diidrotiottico (DHTANa), forma ridotta dell’acido tiottico (TA) o acido α-lipoico, un composto facilmente reperibile ed economico. In uno studio preliminare erano state preparate soluzioni del precursore catalitico ottenute per reazione di [Rh(COD)Cl]2 con DHTANa in H2O in presenza di Na2CO3 in eccesso. Queste soluzioni, utilizzate tal quali, avevano mostrato alta attività e selettività in reazioni di idrogenazione e di idroformilazione. 1,2 Sulla base di questi risultati promettenti ci siamo riproposti di indagare meglio sia la struttura che l’attività del catalizzatore, estendendo la ricerca anche a derivati dell’iridio. Sono stati pertanto preparati complessi a base di Rh e di Ir partendo da [Rh(COD)Cl]2 e [Ir(COD)Cl]2, rispettivamente. In entrambi i casi si forma una specie idrosolubile, presumibilmente di struttura [M(DHTANa)Cl]2 (M = Rh o Ir) ed una specie, probabilmente di natura polimerica, solubile in acqua ma solo a pH alcalino. Tutte queste specie hanno mostrato una buona attività catalitica in ambiente bifasico acquoso sia nella riduzione di doppi legami carbonio-carbonio che di nitroderivati aromatici. Infine, nell’ottica di migliorare la sostenibilità del processo, stiamo valutando la possibilità di studiare la riduzione di TA a DHTA per via elettrochimica, evitando così l’uso del NaBH4, e di usare precursori metallici più economici. Riferimenti 1. S. Paganelli, O. Piccolo, P. Pontini, R. Tassini, V.D. Rathod, Catal. Today, 247 (2015) 64-69. 2. V.D. Rathod, S. Paganelli, O. Piccolo, Catal. Commun., 84 (2016) 52-55

Boosting physical-mechanical properties of adipic acid/chitosan films by DMTMM cross-linking

In this paper we present a novel strategy to easily prepare biodegradable chitosan derived films as new packaging systems. Combination of chitosan, adipic acid and 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methyl-morpholinium chloride (DMTMM) allowed to obtain high-performing cross-linked films. Biobased glycerol was employed as plasticizer. An in-depth study was performed on ten different samples in order to evaluate the role of DMTMM as cross-linking agent. Experimental data showed that 15 wt% of DMTMM enhanced moisture content and moisture uptake (10.42% and 11.11%), water vapor permeability (0.13 10− 7 g m− 1 h− 1 Pa− 1) and good UV barrier properties. Additionally, 30 wt% of DMTMM significantly increased the tensile strength of films up to 83 MPa and elongation at break values reached 39.7%. Thermogravimetric, IR, XRD and SEM analysis confirmed that physical-mechanical properties of the obtained films were considerably improved, due to cross-linking by DMTMM, demonstrating promising properties for packaging applications

Recyclable Ir Nanoparticles for the Catalytic Hydrogenation of Biomass-Derived Carbonyl Compounds

The valorisation of biomass-derived platform chemicals via catalytic hydrogenation is an eco-friendly tool which allows us to recover bio-based building blocks and produce fine chemicals with high industrial appeal. In the present study, a novel surfactant-type triazolyl-thioether ligand was prepared, showing excellent catalytic activity in the presence of bis(1,5-cyclooctadiene)diiridium(I) dichloride [Ir(COD)Cl]2 for the hydrogenation of furfural, cinnamaldehyde, levulinic acid, 5-hydroxymethylfurfural, vanillin, and citral. Easy recovery by liquid/liquid extraction allowed us to recover the catalyst, which could then be efficiently recycled up to 11 times for the hydrogenation of furfural. In-depth analysis revealed the formation of spherical structures with metal nanoparticles as big as 2–6 nm surrounded by the anionic ligand, preventing iridium nanoparticle degradation

Substrate and Product Selective Supramolecular Catalysis by Pillar[5]arene in the Alkylation of Primary Linear Amines with Allyl Bromide

We report the supramolecular catalysis exerted by the cavity of pillar[5]arene on the classic nucleophilic substitution reaction of primary alkyl amines on allyl bromide. The tubular nanocatalyst imparts both substrate selectivity for linear amines and product selectivity in favor of secondary amine products. The reaction turned out to be very sensitive to the size of the cavity and the nature of the alkoxy residues on the rim of the cylindrical nanometric catalyst. The acceleration observed was due to the stabilization of the developing charge on the N atom by an electrostatic interaction with the aromatic units of the cavity of the pillararene. Recycling of the supramolecular organocatalyst was also demonstrate

Development of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride cross-linked carboxymethyl cellulose films

First example of the use of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methyl-morpholinium chloride (DMTMM) as cross-linking agent for the development of carboxymethyl cellulose (CMC) films for food packaging is reported. Influence of different wt % of DMTMM and glycerol on the physical-mechanical properties of CMC films was investigated. The presence of DMTMM effectively improved moisture uptake, moisture content, water vapour permeability, water solubility of the films, oil resistance together with good biodegradability. Best compromise between high water resistance, vapour permeability and mechanical properties was accomplished with 5 wt % DMTMM and 50 wt % glycerol giving tensile strength and elongation at break of 52.25 ± 4.33 and 37.32 ± 2.04 respectively. DSC, TGA and SEM analysis further confirmed CMC cross-linking by DMTMM. All films prepared showed low opacity and high transparencies. Therefore, data reported show that DMTMM can efficiently crosslink CMC to produce films for food packaging.First example of the use of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methyl-morpholinium chloride (DMTMM) as cross-linking agent for the development of carboxymethyl cellulose (CMC) films for food packaging is reported. Influence of different wt % of DMTMM and glycerol on the physical-mechanical properties of CMC films was investigated. The presence of DMTMM effectively improved moisture uptake, moisture content, water vapour permeability, water solubility of the films, oil resistance together with good biodegradability. Best compromise between high water resistance, vapour permeability and mechanical properties was accomplished with 5 wt % DMTMM and 50 wt % glycerol giving tensile strength and elongation at break of 52.25 ± 4.33 and 37.32 ± 2.04 respectively. DSC, TGA and SEM analysis further confirmed CMC cross-linking by DMTMM. All films prepared showed low opacity and high transparencies. Therefore, data reported show that DMTMM can efficiently cross-link CMC to produce films for food packaging

Synthesis of Amidation Agents and Their Reactivity in Condensation Reactions

Nowadays, the development of new approaches which smartly bypass the use of harsh reaction conditions and hazardous chemicals covers a pivotal role. In this research paper the synthesis, characterization, and application of novel libraries of triazine bis-quaternary ammonium salts, employed as coupling agents to produce amides is reported. Full characterization of the novel compounds by 1H and 13C NMR, FT-IR spectroscopy, ESI-HRMS, and elemental analysis is provided. Furthermore, a comparison in terms of activity of the preformed triazine compounds versus in situ formulations has been evaluated for the formation of amides in the presence of phenylethylamine and different aliphatic or aromatic acids. A possible correlation between the chemical structure of the triazine and their reactivity for the formation of the triazine bis-quaternary ammonium salts is also reported. Moreover, best performing condensation agents have been further tested for the cross-linking of collagen powder as possible wet white tanning systems, for sustainable and environmentally friendly leather tanning