Band 39, Heft 1

To explore options for simple, safe, and compact chemical reactors that preserve wanted metastable initial products from sequential unwanted reactions, academic and industrial researchers have tried to repurpose reciprocating piston equipment or an “engine-like” design to be used as a chemical reactor. Piston reactors offer the benefit of achieving very high temperature and pressure conditions at very short and defined residence times. Such conditions offer promise for enhanced performance for several chemical conversions. This paper provides a review of the published literature and patents in the field of piston reactors to provide an overview of the current state-of-the-art. The review covers multiple aspects of piston reactors and their applications, reactor design options and their operation, catalyst and ignition placement, tested reactions, experimental setups as well as modeling and simulation. Several research gaps are highlighted as a motivation for future research in the field. To help interested readers into the topic, basic concepts and fundamentals of piston reactors are provided.

Chitosan is a biopolymer originating from renewable resources, with great properties which make it an attractive candidate for plenty of applications of contemporary interest. By manufacturing chitosan into nanofibers using the electrospinning method, its potential is amplified due to the enhancement of the active surface and the low preparation cost. Many attempts were made with the aim of preparing chitosan-based nanofibers with controlled morphology targeting their use for tissue engineering, wound healing, food packaging, drug delivery, air and water purification filters. This was a challenging task, which resulted in a high amount of data, sometimes with apparent contradictory results. In this light, the goal of the paper is to present the main routes reported in the literature for chitosan electrospinning, stressing the advantages and disadvantages of each of them. Special emphasis is placed on the influence of various electrospinning parameters on the morphological characteristics of the fibers and their suitability for distinct applications.

Fouling of heat exchangers (HEs) has become a major concern across the industrial sector. Fouling is an omnipresent phenomenon but is particularly prevalent in the dairy, oil, and energy industries. Reduced energy performance that results from fouling represents significant operating loss in terms of both maintenance and impact on product quality and safety. In most industries, cleaning or replacing HEs are currently the only viable solutions for controlling fouling. This review examines the latest advances in the development of innovative materials and coatings for HEs that could mitigate the need for costly and frequent cleaning and potentially extend their operational life. To better understand the correlation between surface properties and fouling occurrence, we begin by providing an overview of the main mechanisms underlying fouling. We then present selected key strategies, which can differ considerably, for developing antifouling surfaces and conclude by discussing the current trends in the search for ideal materials for a range of applications. In our presentation of all these aspects, emphasis is given wherever possible to the potential transfer of these innovative surfaces from the laboratory to the three industries most concerned by HE fouling problems: food, petrochemicals, and energy production.

Microfibrous composites (MCs) are novel materials with unique structures and excellent functional properties, showing great potential in industrial applications. The investigation of the physicochemical properties of MCs is significant for accommodating the rapid development of high-efficiency chemical engineering industries. In this review, the characteristics, synthesis and applications of different types of previously reported MCs are discussed according to the constituent fibres, including polymers, metals and nonmetals. Among the different types of MCs, polymer MCs have a facile synthesis process and adjustable fibre composition, making them suitable for many complex situations. The high thermal and electrical conductivity of metal MCs enables their application in strong exothermic, endothermic and electrochemical reactions. Nonmetallic MCs are usually stable and corrosion resistant when reducing and oxidizing environments. The disadvantages of MCs, such as complicated synthesis processes compared to those of particles or powders, high cost, insufficient thorough study, and unsatisfactory regeneration effects, are also summarized. As a result, a more systematic investigation of MCs remains necessary. Despite the advantages and great application potential of microfibrous composites, much effort remains necessary to advance them to the industrial level in the chemical engineering industry.

Superabsorbent polymers (SAP) and modified natural polymer hydrogels are widely and increasingly used in agriculture, health care textiles, effluent treatment, drug delivery, tissue engineering, civil concrete structure, etc. However, not many comprehensive reviews are available on this class of novel polymers. A review covering all the viable applications of SAP will be highly useful for researchers, industry persons, and medical, healthcare, and agricultural purposes. Hence, an attempt has been made to review SAPs with reference to their classifications, synthesis, modification by crosslinking, and physicochemical characterization such as morphology, swellability, thermal and mechanical properties, lifetime prediction, thermodynamics of swelling, absorption, release and transport kinetics, quantification of hydrophilic groups, etc. Besides, the possible methods of fine-tuning their structures for improving their absorption capacity, fast absorption kinetics, mechanical strength, controlled release features, etc. were also addressed to widen their uses. This review has also highlighted the biodegradability, commercial viability and market potential of SAPs, SAP composites, the feasibility of using biomass as raw materials for SAP production, etc. The challenges and future prospects of SAP, their safety, and environmental issues are also discussed.