Effects of microplastics on daphnia-associated microbiomes in situ and in vitro.

Microplastic pollution in aquatic environments is a growing global concern. Microplastics, defined as plastic fragments smaller than five millimetres, accumulate in freshwater reservoirs, especially in urban areas, impacting resident biota. This study examined the effects of microplastics on the performance and microbiome of Daphnia, a keystone organism in freshwater ecosystems, through both in situ sampling of freshwater ponds and a controlled 23-day in vitro exposure experiment.

Monitoring and controlling zeolite synthesis reactor-based solutions: a fed-batch strategy.

Most conventional zeolite synthesis takes place in closed batch autoclaves that cannot be monitored or controlled during the process. Moreover, the study of time-dependent parameters of the synthesis with the conventional "cooling-opening" procedure not only reduces accuracy as a series of reactors (never 100% identical) needs to be started in parallel (and stopped at different times), it is also labor intense. Furthermore, the classic batch concept does not permit the intermediate addition of species without disrupting synthesis and the cooling-reheating effects.

Ultrasound mechanisms and their effect on solid synthesis and processing: a review.

Ultrasound proves to be an effective technique for intensifying a wide range of processes involving solids and, as such, is often used to improve control over both solids formation and post-treatment stages. The intensifying capabilities of ultrasonic processing are best interpreted in the context of the chemical, transport, and mechanical effects that occur during sonication. This review presents an overview of how ultrasound influences the processing and synthesis of solids across various material classes, contextualized within an ultrasound effect framework.

Enhancing the Acidity Window of Zeolites by Low-Temperature Template Oxidation with Ozone.

Revisiting the impact of the first and often deemed trivial postsynthetic step, i.e., a high-temperature oxidative calcination to remove organic templates, increases our understanding of thermal acid site evolution and Al distributions.

Monothiolactide, a New Monomer for the Synthesis of Recyclable, Alternating Ester-Thioester Polymers.

Aliphatic polyesters and polythioesters are very interesting alternatives for current fossil-based and degradation-resistant plastics, due to their high (bio)degradability and (chemical) recyclability potential. Two important examples include polylactide (PLD), currently leading the synthetic bioplastics market, and its sulfur analog polythiolactide (PTLD). Both polymers can be made by ring-opening polymerization (ROP) of their corresponding (thio)dilactones, lactide (LD) and thiolactide (TLD) respectively.

Engineering Lewis Acidity in Zeolite Catalysts by Electrochemical Release of Heteroatoms during Synthesis.

The creation of heteroatom nodes in zeolite frameworks is a challenging but rewarding pathway to superior materials for numerous catalytic applications. Here, we present a novel method for precise control over heteroatom incorporation by in situ anodic release of a desired metal during hydrothermal zeolite synthesis. The generic character of the technique and the applicability of the new synthesis reactor are shown across 3 zeolite structures crystallized and 4 electrode metals in two pH zones and by offering access to a new mixed-metal zeolite.

Sustainable Polythioesters via Thio(no)lactones: Monomer Synthesis, Ring-Opening Polymerization, End-of-Life Considerations, and Industrial Perspectives.

As the environmental effects of plastics are of ever greater concern, the industry is driven towards more sustainable polymers. Besides sustainability, our fast-developing society imposes the need for highly versatile materials. Whereas aliphatic polyesters (PEs) are widely adopted and studied as next-generation biobased and (bio)degradable materials, their sulfur-containing analogs, polythioesters (PTEs), only recently gained attention.

Synthesis strategies to control the Al distribution in zeolites: thermodynamic and kinetic aspects.

The activity and selectivity of acid-catalyzed chemistry is highly dependent on the Brønsted and Lewis acid sites generated by Al substitutions in a zeolite framework with the desired pore architecture. The siting of two Al atoms in close proximity in the framework of high-silica zeolites can also play a decisive role in improving the performance of redox catalysts by producing exchangeable positions for extra-framework multivalent cations. Thus, considerable attention has been devoted to controlling the Al incorporation through direct synthesis approaches and post-synthesis treatments to optimize the performance as (industrial) solid catalysts and to develop new acid- and redox-catalyzed reactions.

Truly combining the advantages of polymeric and zeolite membranes for gas separations.

Mixed-matrix membranes (MMMs) have been investigated to render energy-intensive separations more efficiently by combining the selectivity and permeability performance, robustness, and nonaging properties of the filler with the easy processing, handling, and scaling up of the polymer. However, truly combining all in one single material has proven very challenging. In this work, we filled a commercial polyimide with ultrahigh loadings of a high-aspect ratio, CO-philic Na-SSZ-39 zeolite with a three-dimensional channel system that precisely separates gas molecules.

Catalytic amination of lactic acid using Ru-zeolites.

In this work we investigate the synthesis of alanine from lactic acid, a biobased platform chemical, using ammonia as a nitrogen source and Ru/zeolite catalysts. We report a high alanine selectivity when using Ru/BEA of 80-93%. Reaction side products were identified as ethanol, propionic acid or propanamide and the reaction mechanism was investigated.

On the key role of aluminium and other heteroatoms during interzeolite conversion synthesis.

Interzeolite conversion, a synthesis technique for several zeolite frameworks, has recently yielded a large amount of high-performing catalytic zeolites. Yet, the mechanisms behind the success of interzeolite conversion remain unknown. Conventionally, small oligomers with structural similarity between the parent and daughter zeolites have been proposed, despite the fact these have never been observed experimentally.

Selective Formation of α-Fe(II) Sites on Fe-Zeolites through One-Pot Synthesis.

α-Fe(II) active sites in iron zeolites catalyze NO decomposition and form highly reactive α-O that selectively oxidizes unreactive hydrocarbons, such as methane. How these α-Fe(II) sites are formed remains unclear. Here different methods of iron introduction into zeolites are compared to derive the limiting factors of Fe speciation to α-Fe(II).

A Cooperative OSDA Blueprint for Highly Siliceous Faujasite Zeolite Catalysts with Enhanced Acidity Accessibility.

A cooperative OSDA strategy is demonstrated, leading to novel high-silica FAU zeolites with a large potential for disruptive acid catalysis. In bottom-up synthesis, the symbiosis of choline ion (Ch ) and 15-crown-5 (CE) was evidenced, in a form of full occupation of the sodalite (sod) cages with the trans Ch conformer, induced by the CE presence. CE itself occupied the supercages along with additional gauche Ch , but in synthesis without CE, no trans was found.

Boosting PLA melt strength by controlling the chirality of co-monomer incorporation.

Bio-based and degradable polymers such as poly(lactic acid) (PLA) have become prominent. In spite of encouraging features, PLA has a low melt strength and melt elasticity, resulting in processing and application limitations that diminish its substitution potential classic plastics. Here, we demonstrate a large increase in zero shear viscosity, melt elasticity, elongational viscosity and melt strength by random co-polymerization of lactide with small amounts, 0.

Spectroscopic Identification of the α-Fe/α-O Active Site in Fe-CHA Zeolite for the Low-Temperature Activation of the Methane C-H Bond.

The formation of single-site α-Fe in the CHA zeolite topology is demonstrated. The site is shown to be active in oxygen atom abstraction from NO to form a highly reactive α-O, capable of methane activation at room temperature to form methanol. The methanol product can subsequently be desorbed by online steaming at 200 °C.

Small-Pore Zeolites: Synthesis and Catalysis.

In the past decade or so, small-pore zeolites have received greater attention than large- and medium-pore molecular sieves that have historically dominated the literature. This is primarily due to the commercialization of two major catalytic processes, NOx exhaust removal and methanol conversion to light olefins, that take advantage of the properties of these materials with smaller apertures. Small-pore zeolites possess pores that are constructed of eight tetrahedral atoms (Si and Al), each time linked by a shared oxygen These eight-member ring pores (8MR) provide small molecules access to the intracrystalline void space, e.

Catalytic Gas-Phase Production of Lactide from Renewable Alkyl Lactates.

A new route to lactide, which is a key building block of the bioplastic polylactic acid, is proposed involving a continuous catalytic gas-phase transesterification of renewable alkyl lactates in a scalable fixed-bed setup. Supported TiO /SiO catalysts are highly selective to lactide, with only minimal lactide racemization. The solvent-free process allows for easy product separation and recycling of unconverted alkyl lactates and recyclable lactyl intermediates.

CIT-9: A Fault-Free Gmelinite Zeolite.

A synthetic, fault-free gmelinite (GME) zeolite is prepared using a specific organic structure-directing agent (OSDA), cis-3,5-dimethylpiperidinium. The cis-isomers align in the main 12-membered ring (MR) channel of GME. Trans-isomer OSDA leads to the small-pore zeolite SSZ-39 with the OSDA in its cages.

Lactide Synthesis and Chirality Control for Polylactic acid Production.

Polylactic acid (PLA) is a very promising biodegradable, renewable, and biocompatible polymer. Aside from its production, its application field is also increasing, with use not only in commodity applications but also as durables and in biomedicine. In the current PLA production scheme, the most expensive part is not the polymerization itself but obtaining the building blocks lactic acid (LA) and lactide, the actual cyclic monomer for polymerization.

Potential and challenges of zeolite chemistry in the catalytic conversion of biomass.

Increasing demand for sustainable chemicals and fuels has pushed academia and industry to search for alternative feedstocks replacing crude oil in traditional refineries. As a result, an immense academic attention has focused on the valorisation of biomass (components) and derived intermediates to generate valuable platform chemicals and fuels. Zeolite catalysis plays a distinct role in many of these biomass conversion routes.

GREEN CHEMISTRY. Shape-selective zeolite catalysis for bioplastics production.

Biodegradable and renewable polymers, such as polylactic acid, are benign alternatives for petrochemical-based plastics. Current production of polylactic acid via its key building block lactide, the cyclic dimer of lactic acid, is inefficient in terms of energy, time, and feedstock use. We present a direct zeolite-based catalytic process, which converts lactic acid into lactide.

Review of old chemistry and new catalytic advances in the on-purpose synthesis of butadiene.

Increasing demand for renewable feedstock-based chemicals is driving the interest of both academic and industrial research to substitute petrochemicals with renewable chemicals from biomass-derived resources. The search towards novel platform chemicals is challenging and rewarding, but the main research activities are concentrated on finding efficient pathways to produce familiar drop-in chemicals and polymer building blocks. A diversity of industrially important monomers like alkenes, conjugated dienes, unsaturated carboxylic acids and aromatic compounds are thus targeted from renewable feedstock.

Top chemical opportunities from carbohydrate biomass: a chemist's view of the Biorefinery.

Cheap fossil oil resources are becoming depleted and crude oil prices are rising. In this context, alternatives to fossil fuel-derived carbon are examined in an effort to improve the security of carbon resources through the development of novel technologies for the production of chemicals, fuels, and materials from renewable feedstocks such as biomass. The general concept unifying the conversion processes for raw biomass is that of the biorefinery, which integrates biofuels with a selection of pivot points towards value-added chemical end products via so-called "platform chemicals".

Selective catalysis for cellulose conversion to lactic acid and other α-hydroxy acids.

This review discusses topical chemical routes and their catalysis for the conversion of cellulose, hexoses, and smaller carbohydrates to lactic acid and other useful α-hydroxy acids. Lactic acid is a top chemical opportunity from carbohydrate biomass as it not only features tremendous potential as a chemical platform molecule; it is also a common building block for commercially employed green solvents and near-commodity bio-plastics. Its current scale fermentative synthesis is sufficient, but it could be considered a bottleneck for a million ton scale breakthrough.