Irina Smirnova

• Prof. Dr.-Ing
• Head of Department at Hamburg University of Technology

Bioaerogels bear high potential in the development of fat-replacers, due to their oil-structuring capacity. However, current aerogel preparation from biopolymeric gels requires a complex and resource-intensive processes, which might limit their adoption as oil-structuring food ingredients. A simpler and more sustainable process to produce bioaeroge...

Aerogels are exceptionally lightweight materials characterized by their high open porosity and remarkable specific surface area, currently used across a wide array of industrial sectors from construction to energy storage and have great potential for expanding their applicability and unlocking new market opportunities. Driven by global economic gro...

The global demand for aerogels is constantly growing, thus, optimizing and scaling up the production processes have become increasingly important in the last decade. The utilization of millimeter-sized aerogel particles for such purposes is typically preferred due to inherent advantages in handling and production compared to other geometries. The p...

The aim of this study is to investigate the activity and stability of carbon aerogel‐supported platinum electrocatalysts in the hydrogen evolution reaction, compared to current solutions based on carbon black. Self‐synthesized carbon aerogels (pyrolyzed cellulose, and chitosan‐based aerogels) with multiscale porosity and high overall specific surfa...

The prevalence of bacterial infections in wounds is a significant challenge to successful wound healing. This study investigates the antibacterial effect of hyaluronic acid and alginate aerogel loaded with zinc oxide nanoparticles as a potential dressing for wound healing. The aerogel composite was synthesized via supercritical gel drying and chara...

The direct production of aerogels from natural tissues/waste with high specific surface areas and properties comparable to synthesized biopolymer aerogels and their application in oil-structuring are possible.

This study explores the innovative potential of native lignin as a sustainable biopolyol for synthesizing polyurethane aerogels with variable microstructures, significant specific surface areas, and high mechanical stability. Three types of lignin—Organosolv, Aquasolv, and Soda lignin—were evaluated based on structural characteristics, Klason ligni...

Redox biocatalysis is an essential pillar of the chemical industry. Yet, the enzymes’ nature restricts most reactions to aqueous conditions, where the limited substrate solubility leads to unsustainable diluted biotranformations. Non‐aqueous media represent a strategic solution to conduct intensified biocatalytic routes. Deep eutectic solvents (DES...

Miniature actuators are utilized in various application fields, from robotics to medical devices, where compact dimensions, precise movements, and cost-effectiveness are crucial factors. Particularly for applications like braille displays, there is a critical demand for lightweight, portable, and affordable actuators to integrate into daily life fo...

In this work, nanostructured and transparent cellulose aerogels are synthesized via a purely salt induced approach from non‐modified microcrystalline cellulose type II. The production process requires in contrast to state of the art methods no pretreatment of cellulose or use of expensive cellulose‐solvents: it consists of hydrogel formation via cr...

The accurate prediction of solvation free energies is critical for understanding various phenomena in the liquid phase, including reaction rates, equilibrium constants, activity coefficients, and partition coefficients. Despite extensive research, precise prediction of solvation free energies remains challenging. In this study, we introduce openCOS...

Hydrophilicity is one important drawback of bio‐based aerogels. To overcome this issue, a novel approach for the preparation of mesoporous, water repellent aerogels is introduced, which combines synthesis of crosslinked bio‐based copolymers from methacrylate copolymerizations, followed by solvent exchange and supercritical drying steps. The influen...

The COSMO-RS (Conductor-like Screening Model for Real Solvents) is a predictive thermodynamic model that has found diverse applications in various domains like chemical engineering, environmental chemistry, nanotechnology, material science, and biotechnology. Its core concept involves calculating the screening charge density on the surface of each...

Subject. This article deals with the issues related to the stability of the region's electricity system. Objectives. The article aims to develop an original approach to monitoring the stability of the region's electric power system. Methods. For the study, we used a fuzzy logic approach. Results. The article proposes an algorithm for monitoring the...

Deep eutectic solvents (DESs) have recently gained increased attention for their potential in biotechnological applications. DESs are binary mixtures often consisting of a hydrogen bond acceptor and a hydrogen bond donor, which allows for tailoring their properties for particular applications. If produced from sustainable resources, they can provid...

Today’s labor market, in line with the pace of life of the society, is changeable, oriented towards economic, social and technical development, open to qualitative modernization, ready to implement new ideas and tools. Reorganizations of requirements, trends and methods in labor market sectors related to data analysis and processing are especially...

Today, the ICT market is developing rapidly. At the same time, a number of studies have proved that the human potential in this market does not always keep pace with the development of the technological component. The aim of the current study is to identify what environmental external factors have an impact on the development of the ICT market. The...

Aerogels are remarkable nanoporous materials with unique properties such as low density, high porosity, high specific surface area, and interconnected pore networks. In addition, their ability to be synthesized from various precursors such as inorganics, organics, or hybrid, and the tunability of their properties make them very attractive for many...

In the present work, a series of metal nanoparticle-decorated carbogels (M-DCs) was synthesized starting from beads of parent metal-crosslinked alginate aerogels (M-CAs). M-CAs contained Ca(ii), Ni(ii), Cu(ii), Pd(ii) and Pt(iv) ions and were converted to M-DCs by pyrolysis under a N2 atmosphere up to pyrolysis temperatures of TP = 600 °C. The text...

At present, an interest has grown in the field of biocompatible aerogels and composite aerogel materials in life sciences, especially in biomedical and pharmaceutical applications. Due to their large surface area, open pore structure, and biocompatibility, aerogels are very promising candidates for drug delivery systems. The use of inorganic, organ...

In this chapter, we discuss the process of supercritical drying as it relates to the production of aerogels. What was once a heuristic technique typically performed using overly conservative process rules can now be quantitatively designed and efficiently implemented. Herein, thermodynamic and kinetic considerations of supercritical drying are revi...

Several important unit operations involved in aerogel production pertain to the formation and processing of gels. Formation of a gel typically occurs in a mold, and accordingly, important considerations should be given to gel molding. Furthermore, after a gel has been formed, additional processing steps are typically required before its pore fluid...

Thermodynamic models and, in particular, SAFT-type equations are vital in characterizing complex systems. This paper presents a framework for sampling parameter distributions in PC-SAFT and SAFT-VR Mie equations of state to understand parameter confidence intervals and correlations. We identify conserved quantities contributing to significant corre...

Heat transfer affects many industrial processes that manipulate particle temperatures due to cyclic temperature fluctuations throughout processing. Despite its importance, there is no thorough understanding of heat transfer on moist particle beds. In this contribution, a novel experimental setup was developed to evaluate the temperature evolution o...

Animal-based whey protein isolate (WPI) and plant-based potato protein isolate (PPI) aerogel microparticles (particle size ∼40–77 μm) were produced via top-down wet milling of alcogels followed by supercritical–CO2–drying and used as matrices for structuring of liquid sunflower oil. pH variation (pH 3.0, 7.0, 9.0) during heat-induced gelation was u...

Recently an improved long-range model for electrolyte solutions was developed that is applicable from infinite dilution to pure salt. This paper tests this claim for the first time applying it to the calculation of liquid-liquid equilibria for mixtures of different ionic liquids (ILs) and water. The conventional Pitzer-Debye-H\"uckel (PDH) equation...

The analogy between the restricted primitive model and capacitor circuits, originally described decades ago for the Mean Spherical Approximation, is explored and applied to other electrolyte theories to demonstrate its transferability in linearized electrolyte theories. On this basis, we offer an explanation of why scaling the salt diameter blurs d...

Deep eutectic solvents (DESs) have gained attention in recent years as attractive alternatives to traditional solvents. There is a growing number of publications dealing with the thermodynamic modeling of DESs highlighting the importance of modeling the solutions' properties. In this review, we summarize the state-of-the-art in DES modeling as well...

We present a novel, generalized and thermodynamically consistent modification of the Pitzer-Debye-H\"uckel term that can include concentration dependent density, molar mass and relative permittivity within the derivation. In contrast to similar developments, this extension is applicable to simple salts with small spherical ions as well as ionic liq...

The predictive electrolyte model COSMO-RS-ES is refined to improve the description of systems at 25{\deg}C in which strong ion pairing is expected due to a low static permittivity of the liquid phase. Furthermore, the short-range ion energy interaction equations have been modified to better describe the misfit and energy interaction terms between i...

Brief introduction of four coating approaches for biopolymer aerogels: - spray coating of aerogel particles - cold plasma coating with hydrophobic layers - supercritical deposition - coating during solvent exchange

In this study, for the first time, polyphenols are extracted using microwave-assisted deep eutectic solvents (MW-DES) from supercritical CO2 defatted date seeds under variable operating conditions. The best conditions consisted of choline chloride: formic acid (1:2 molar ratio), a solid to solvent ratio of 1/20 (g/mL) (0.75 g of dry biomass in 15 m...

We present a novel, thermodynamically consistent modification of the Pitzer-Debye-Hückel term and its extension for concentration dependent density, molar mass and relative permittivity. This extension is validated for ionic liquids by comparison with a reference model from the literature and, in contrast to similar extensions, also applied to conv...

The model COSMO-RS (Conductor-like screening model for realistic solvation) is based on the approximation of molecular interactions by the interactions of surface segments from the molecular cavities. These segment interactions are functions of the segment properties i.e. descriptors, with the most important descriptor being the screening charge de...

CO2 induced gelation of aqueous biopolymer systems results in stable and homogeneous hydrogels with a wide field of potential applications in food and pharmaceutical industry. For the application of the process in industry, good understanding of process parameters and their impact on the overall process and the gel properties is necessary. The mech...

Buildings are responsible for 40% of energy consumption annually in Europe, along with the respective greenhouse gas emissions. To mitigate these impacts, intensive research is ongoing in the sector of the Nearly Zero-Energy Buildings (NZEBs). However, as it is expected that the operational energy of future buildings becomes greener and more effici...

Natural compounds include a boundless diversity of molecules and functionalities that represent an excellent pool of materials for production of functional foods, food additives, and pharmaceuticals. Research on lignin functional and bioactive properties has recently become the center of interest for research centers worldwide, chasing for the comp...

Three concepts for a 3000 t/a continuous autohydrolysis plant aiming at a full fractionation of agricultural residues (wheat straw as model substrate) into streams rich in xylose, glucose, and lignin, respectively, are developed. For this purpose, two kinetic models based on batch liquid-hot water experiments (30 mL, 170–230 °C, 10–60 min) were inv...

In this work, the potential of lignin as a filler additive and anti-aging agent in a pressure-sensitive adhesive (PSA) based on natural rubber (NR) was investigated. Herein, different approaches to incorporate lignin into NR matrix by adaptation of a two-step compounding process were evaluated. At first, a twin-screw extruder (TSE) was utilized to...

The application range of aerogels, especially in the life-science sector, can be extended by utilizing biocompatible polymers such as polylactic acid (PLA). However, the low glass transition temperature (Tg) of PLA and the challenging gelation techniques limit the application of supercritical CO 2 (scCO 2 ) drying and thus the PLA-aerogel productio...

Denaturation, aggregation, and gelation of protein solutions can be induced through increased temperatures and the presence of organic solvents. Depending on the molecular features of the involved proteins, the denaturation conditions lead to very different gel properties. However, it is poorly understood how organic solvents in combination with he...

Protein aerogel particles prepared by supercritical-CO2-drying (SCD) of ground whey protein (WP) hydrogels (20% w/w, pH 5.7) were converted into oleogels by dispersion in selected edible oils (castor, cod liver, corn, flaxseed, MCT, peanut and sunflower oil). The obtained oleogels were analysed for oil content, microstructure, rheological propertie...

The aim of this work was to evaluate the potential of cold plasma polymerization as a simple, fast and versatile technique for deposition of protective hydrophobic and oleophobic polymer layers on hydrophilic biopolymer aerogels. Polymerization of different fluorinated monomers (octafluorocyclobutane C4F8 and perfluoro-acrylates PFAC-6 and PFAC-8)...

The processing of large quantities of water in biorefining processes can lead to immense costs for heating, evaporation, and wastewater disposal. These costs may prohibit the exploitation of alternative products, e.g., xylooligosaccharides from straw, which are regarded as too costly. A new counter-current extractions method is proposed that aims a...

BACKGROUND Ginsenoside Rb1 is one of the major bioactive components of Panax ginseng C.A. Meyer (Araliaceae), a medicinal plant that has been used for therapeutic purposes for thousands of years in Asian countries. The pharmaceutical activity of ginsenoside Rb1 highly depends on molecular structure and its deglycosylated metabolites are known to be...

Aim of this work is to apply protective and homogeneous shellac coating layers on the surface of hydrophilic open-pore cellulose aerogel particles with low densities of approx. 0.1 g/cm3 and high specific surface areas in the range of 400-450 m2/g while keeping the aerogels' microstructure intact during processing. For this purpose, an innovative m...

Aerogels are a class of open nonfluid porous solid materials known for their low density, high specific surface area, and accessible pores. This combination of characteristics makes them highly promising for a wide gamut of applications ranging from thermal and acoustic insulation, catalysts and sensors, adsorbents and absorbents, energy storage, c...

The present study evaluates the effect of calcium alginate aerogel as a potential drug carrier, on the liver and kidney functions, and on the gut microbiota of Wistar rats. The studied alginate aerogel was prepared in the form of nanoparticles using the jet cutting technique, and they were characterized in terms of specific surface areas, outer mor...

In this work the feasibility of continuous cloud point extraction in packed columns was evaluated. Therefore, extraction of phenylacetic acid with aqueous micellar two-phase systems containing the nonionic surfactant Triton X-114 was chosen as a model system. Raschig rings and structured packing CY from Sulzer were evaluated in terms of HETP, extra...

In this work, a continuous, heterogeneous extractive biocatalysis was realized with penicillin G hydrolysis as a model reaction. Therefore, commercially available structured packing CY from Sulzer were coated with enzyme‐containing gels and their catalytic activity was examined. Thereby, the potential of aqueous micellar two‐phase systems (ATPMS) a...

In the present study the aerogel technology was used to prepare pulmonary drug carriers consisting of alginate and alginate-hyaluronic acid by an emulsion gelation technique and supercritical CO2 drying. During the preparation process, the emulsification rate and inner phase viscosity were varied to control the diameter of aerogel microspheres. Res...

AS (Aquasolv) Lignin produced via Liquid Hot Water Pretreatment and Enzymatic Hydrolysis has shown potential as an active pharmaceutical ingredient and/or excipient in solid dosage forms. Moreover, lignin is safe to consume and presents antioxidant and antidiabetic capacity, properties that can add to solid dosage forms in pharmaceuticals. This wor...

Reported approach aims for the synthesis of spherical cellulose beads with high production rates (0.7-4.1 kg/h of hydrogel) via the so-called jet cutting method. To form particles, jets of aqueous cellulose/sodium hydroxide solutions were cut into pieces and collected in a gelation bath (30 wt% aqueous H2SO4 , 20°C). After solvent exchange with eth...

Polyurea-crosslinked alginate (X-M-alginate; M: Co, Ni, Cu) aerogels, prepared from the corresponding M-alginate wet-gels and the aromatic triisocyanate Desmodur RE, are precursors for metal- and nitrogen-doped carbon (X-M-C) aerogels.

The analogy between the restricted primitive model and capacitor circuits, originally described decades ago for the Mean Spherical Approximation, is explored to demonstrate its transferability in linearized electrolyte theories. On this basis, we offer an explanation of why treating the salt diameter as a free adjustable parameter blurs differences...

Different numerical solutions of a previously developed mass transport model for supercritical drying of aerogel particles in a packed bed [Part 1: Selmer et al. 2018, Part 2: Selmer et al. 2019] are compared. Two finite difference discretizations and a finite volume method were used. The finite volume method showed a higher overall accuracy, in th...

Chronic non-healing wounds represent a substantial economic burden to healthcare systems and cause a considerable reduction in quality of life for those affected. Approximately 0.5–2% of the population in developed countries are projected to experience a chronic wound in their lifetime, necessitating further developments in the area of wound care m...

Polyurea-crosslinked calcium alginate (X-Ca-alginate) and chitosan (X-chitosan) aerogel beads have been prepared via reaction of an aliphatic triisocyanate (Desmodur N3300) with the –OH groups of calcium alginate or the –NH2 groups of chitosan preformed wet gels, forming surface urethane or urea groups, respectively, and the subsequent formation of...

Smart materials possess a high potential for application in process engineering. Among these smart materials, stimuli-responsive hydrogels exhibit the chemically inherent characteristic to significantly change their macroscopic properties through shifts in environmental conditions. This enables response-triggered actuation caused by a reaction or p...

This study aims at investigating the effect of ethanol (EtOH) on the textural properties of whey protein and egg white protein hydrogels. The hydrogels were produced by thermally induced gel formation of aqueous protein solutions. The water contained in the gel network was subsequently exchanged by EtOH to assess structural changes upon exposure of...

In this work, the ability of several solvents to induce gel formation from amylomaize starch solubilized in dimethyl sulfoxide (DMSO) was investigated. The formed gels were subjected to solvent exchange using ethanol and dried with supercritical carbon dioxide (sc-CO2) to obtain the aerogels. The influence of starch concentration (3–15 wt%) and sol...

Aerogels are highly porous structures created from hydrogels by solvent exchange and supercritical CO2 drying. They can be produced from proteins and used for encapsulation of active ingredients. In this work, the structural relationship between various protein based hydrogels and aerogels was investigated. We compare egg white protein (EWP) and pa...

This work presents two novel methods to investigate in situ the carbon dioxide (CO2)-induced gelation of biopolymer-based solutions. The CO2-induced gelation is performed in a viewing cell at room temperature under CO2 pressure (20 to 60 bar), whereby calcium precursors are used as cross-linkers. The novel methods allow the in situ optical observat...

Pretreatment is necessary to increase the enzymatic digestibility of lignocellulosic biomass. Here, degradation reactions of solubilized pentoses to furfural and others are undesired regarding the reduced product yield and increasing downstream processing efforts. In this work, the use of the unit operation configuration was successfully shown to r...

Pea and amylomaize starches were used to produce aerogel in form of monoliths and microparticles. The formation of starch gel was investigated, and we showed that each starch needed a different pasting temperature for its complete dissolution. The gelation kinetics was investigated with oscillatory rheometry for both systems as a function of the st...

The prediction of solvation free energies is essential for a variety of applications. Solvation free energies of neutral systems can be predicted quit accurately. The accuracy of predictions for solvation free energies of ionic solutes dissolved in neutral solvents, however, has been reported to be worse by at least one order of magnitude. In this...

Particle size and morphology are of high industrial importance due to the fact that product properties and performance can be affected by this factors. For instance, bulk properties, processability and appearance of the final product are given by particle size and shape. In this regard, the optimization of process parameters for particle developmen...

Biopolymer-based aerogels can be obtained by supercritical drying of wet gels and endowed with outstanding properties for biomedical applications. Namely, polysaccharide-based aerogels in the form of microparticles are of special interest for wound treatment and can also be loaded with bioactive agents to improve the healing process. However, the p...

Different pretreatments strategies have been developed over the years mainly to enhance enzymatic cellulose degradation. In the new biorefinery era, a more holistic view on pretreatment is required to secure optimal use of the whole biomass. Hydrothermal pretreatment technology is regarded as very promising for lignocellulose biomass fractionation...

Reactor design and development are key disciplines in process engineering. In order to keep up with modern-day production demands, new reactor concepts have to be conceived, which transcend the mere purpose of a reaction vessel. With the availability of improved fabrication methods and insight into new materials, novel process integration measures...

Jedes Gel lässt sich in ein Aerogel verwandeln. Das funktioniert sogar bei gekochten Eiern. Das europäische Forschungsprojekt Cost Action Aerogel wird nun Anwendungen für Umwelt‐ und Lebenswissenschaften untersuchen lassen.