Purification doi: 10.3390/purification2020006

Authors: Vasileios M. Pappas

Pulsed electric field (PEF) extraction studies often report yield gains but less consistently translate them into purification-relevant metrics. This study re-analyzed a locked comparability tier of 56 solvent-matched control (CTR)-PEF contrasts from five leaf-biomass studies to map total phenolic content (TPC) uplift onto first-order downstream duty proxies. The tier was not designed as a field-wide survey, and audit logs plus dependence-aware analyses were used to reduce author bias. Across the 56 pairs, median ΔTPC% was 26.7% (IQR 12.1–35.0), with positive values in 55 of 56 contrasts. The strongest gains were concentrated at low specific energy (Wspec ≤ 0.15 kJ kg−1 treated biomass) and 0–25% ethanol within this dataset. PLRI translated these uplifts into first-order processed-volume scaling at fixed capture criteria, and Pareto screening identified PLRI values of 1.18–1.73, corresponding to approximately 15–42% lower processed volume under the stated assumptions. Marker-level data were limited to two matrices (three paired observations), but SSF values > 1 (1.06–2.89) were consistent with possible composition steering. No new experiments were performed, and ballast, fouling, and downstream performance were not measured; conclusions are therefore limited to the operating envelope and are intended for screening, reporting standardization, and subsequent purification validation.

Purification doi: 10.3390/purification2020005

Authors: Stylianos Spathariotis Eirini Zagoraiou Anastasia-Maria Moschovi Ekaterini Polyzou Iakovos Yakoumis

Platinum group metals (PGMs), platinum (Pt), palladium (Pd) and rhodium (Rh), are critical for automotive emission control, chemical manufacturing and emerging energy technologies, yet their supply is limited and geographically concentrated. Their designation as critical raw materials (CRMs) in the EU has intensified recycling efforts, especially from spent automotive catalysts. Conventional pyrometallurgical and acid-based hydrometallurgical routes achieve high recovery efficiencies but rely on aggressive reagents and energy-intensive processing. Deep eutectic solvents (DESs) have emerged as greener leaching media capable of dissolving PGMs under milder and tunable conditions. This review outlines the conventional hydrometallurgical framework, summarizes DES fundamentals relevant to metals dissolution, and critically assesses recent advances in DES-based leaching of PGMs from spent catalysts. The influence of solvent composition, oxidants and complexing ligands on PGMs speciation and recovery is discussed, together with emerging reporting guidelines and research priorities. Overall, DES-based leaching offers a promising and potentially safer route for autocatalyst recycling but the technology remains at an early stage of development, requiring further mechanistic insight and sustainability evaluation.

Purification doi: 10.3390/purification2020004

Authors: Simona Serban Yanjun Li Gang Li Tongnian Gu Long Liu Xiaoju Lei Caroline Tinsley Xiaokang Kou Alessandra Basso

Native Staphylococcus aureus protein A exhibits strong affinity to the Fc and VH regions of human IgG1, IgG2, and IgG4, making it a valuable tool for monoclonal antibody (mAb) purification. However, its low stability under conditions such as increased alkaline concentrations during cleaning-in-place (CIP), protease exposure, thermal stress, and shear forces limits its usability for large-scale industrial applications. Recombinant Protein A (rProtein A) can be modified to improve key properties, including alkaline stability. In this study, we present targeted modifications to the C domain of native Protein A, evaluating multimeric variants for structural and functional improvements. The selected variant demonstrated extremely high stability after 60 h incubation at 0.5 M NaOH by maintaining more than >90% initial dynamic binding capacity (DBC) and up to 80% DBC after 40 h in 1.0 M NaOH. However, the most impressive result obtained was the stability of the ligand in 1.5 M NaOH, retaining 80% DBC after 22 h and 60% DBC after 40 h. To the best of our knowledge, this is the first time that such high alkaline stability is reported for a rProtein A. To assess its application in monoclonal antibody purification, the optimized rProtein A ligand was immobilized on agarose resin and tested in chromatography processes. The resulting chromatography resin functionalized with the CmZmb ligand (now commercialized by Sunresin, China under the name of rProtein A Seplife Suno) exhibited a high dynamic binding capacity of 70 mg/mL, minimal ligand leaching under operational conditions (~15 ppm), and extended lifecycle performance (88% DBC retained after 120 purification cycles with 0.5 M NaOH CIP), making it well-suited for industrial-scale applications.

Purification doi: 10.3390/purification2010003

Authors: Messan Justin Kessouagni Moursalou Koriko Koffi Fiaty Catherine Charcosset Gado Tchangbedji

Paracetamol (PAR) was selected as an emerging micropollutant model to evaluate the effectiveness of the photo-Fenton process using natural Bandjéli ore (BO) as a heterogeneous source of iron. An aliquot of 1 mL of the activated product was introduced into 200 mL of an aqueous solution of paracetamol at a defined concentration. The tests were conducted in a double-jacketed glass photoreactor (0.2 L), continuously stirred and equipped with two UVA PL-L lamps (36 W, λ = 365 nm), with the temperature maintained at 20 °C and the pH around 2.4. The photo-Fenton process was applied with different initial paracetamol concentrations (10–50 mg/L), different H2O2/PAR initial molar ratios (10:1 and 5:1), and different ferric ion concentrations (2.84–4.73 mg/L). Under these conditions, complete disappearance of the parent compound (paracetamol) was achieved in less than 3 h for iron contents below 5 mg/L, in compliance with the discharge standards applicable in France and Togo. Inhibition tests with propan-2-ol highlighted the predominant role of hydroxyl radicals and the secondary involvement of superoxide radicals in the subsequent stages. Taken together, these results demonstrate that Bandjéli iron ore is an effective, sustainable, and economically advantageous alternative to commercial iron salts for implementing the photo-Fenton process in the decontamination of water polluted by organic micropollutants.

Purification doi: 10.3390/purification2010002

Authors: Sagar Roy

The demand for global energy consumption, driven by population expansion and economic development, has intensified significantly over the decades and created substantial momentum for the development of sustainable energy technologies [...]

Purification doi: 10.3390/purification2010001

Authors: Bastian Greisner Magnus Rienäcker Frank Rögener André Lerch

Industrial whey dewatering via membrane processes remains challenging due to the rapid increase in viscosity, strong fouling tendencies from proteins and minerals, and the steep rise in osmotic pressure during concentration. These effects restrict operating windows and complicate energy-efficient process control. This study addresses the application of forward osmosis (FO) technology for industrial-scale dewatering of sweet whey using an Aquaporin Inside® HFFO14 module. Various feed- and draw-side cross flow velocities (0.0397 to 0.0524 m s−1 and 0.0127 to 0.0190 m s−1, respectively) and draw solution (DS) osmotic pressures of 20 bar and 60 bar were investigated using a production-scale prototype plant. Sweet whey had an initial osmotic pressure of 7 bar and an electrical conductivity of 5.7 mS cm−1. DS pressures of 20 bar and 60 bar resulted in a total recovery of 50% and over 80%, respectively. Water flux rates initially ranged from 10.1 to 11.6 L m−2 h−1 (LMH) and ceased at 3.3 LMH. Specific energy demand ranged from 0.15 to 1.1 kWh m−3. These findings support the feasibility of industrial-scale FO technology and underscore the potential of FO as an energy-efficient, sustainable solution for the dairy industry. However, frequent rinsing and cleaning routines are crucial to maintain membrane performance.

Purification doi: 10.3390/purification1030008

Authors: Yuying Wang Tianqi Wang Jin Shang

Despite significant progress in renewable energy development, nitrogen oxides (NOx) remain a persistent air pollutant [...]

Purification doi: 10.3390/purification1020007

Authors: Verena Hilgenfeldt Katrin Rübner Andreas Hahn Heidrun Steinmetz

Although various special materials have been studied for their potential for phosphorus removal in constructed wetlands, varying methodologies make direct comparisons of adsorption capacities observed in laboratory experiments difficult. This paper aims to establish a methodology for determining the optimal ratio of phosphate to material mass for different materials and for achieving the necessary contact time for adsorption isotherms. To minimise the number of experiments required, pretests over 24 h should be repeated to determine the phosphate-specific ratios until they show around 60% of the initial concentration. The tested materials included lava sand and expanded sand (ExS), which showed saturating kinetics curves after 24 to 48 h. However, aggregates containing calcium silicate hydrate (CSH) phases (autoclaved aerated concrete AAC, sand–lime brick SLB, and hydrothermal granules HTG) did not show saturating curves, complicating contact time determination. Consequently, adsorption velocity is proposed to identify the phase with the lowest adsorption rate, which is then used as the contact time in adsorption isotherm experiments. Using this method, adsorption times of 48 h were observed for HTG and SLB, while that for AAC was 24 h. This methodology is intended as an initial approach to establish a common basis for researchers investigating novel materials and make the results comparable.

Purification doi: 10.3390/purification1020006

Authors: Laiba Butt Anushree Das Alireza Tabibi Mousab Rehmani Benson Karimi

Heparin, an essential plasma-derived therapy, acts as a naturally occurring anticoagulant and is essential in various physiological processes. Due to its complex structure, repeating units of sulfated glycosaminoglycan, it attracts attention in the field of commercial pharmaceuticals. In recent decades, significant advancements have been made in the development of economical adsorbents designed especially for the extraction of heparin from the intestinal mucosa of pigs, as evidenced by investments from various pharmaceutical industries. This requirement arises from the demand for efficient, scalable extraction methods for natural sources. In this study, we investigated the application of beta zeolites to increase the recovery of heparin from real porcine mucosa samples, emphasizing materials with greater adsorption surfaces, higher thermal stability, and increased porosity. According to our research, the zeolite CP814E’s macropores and huge surface area allow it to adsorb up to 20.6 mg·g−1 (39%) of heparin from actual mucosa samples. We also investigated the adsorbent’s surface conditions, which are essential for efficient heparin recovery, and adjusted temperature and pH to enhance heparin uptake. These findings demonstrate that zeolite-based adsorbents can enhance the extraction of heparin effectively for use in medicinal applications.

Purification doi: 10.3390/purification1010005

Authors: Francesco Vegliò

Purification (ISSN 3042-6197) is an international, peer-reviewed, open access journal offering a platform for theories, emerging technologies, and practical applications of purification across chemistry, biology, chemical and environmental engineering, materials science, pharmaceutical technology, food engineering, and related areas [...]

Purification doi: 10.3390/purification1010004

Authors: Monika Gwadera Pawel Brzoskwinia Szymon Hnatyk Gabriela Kazberuk

In this study, the adsorption of a textile dye from water onto activated carbon is considered and the results of our own experimental studies on adsorption equilibrium and kinetics are presented. The adsorption isotherm and kinetic curves were found to reflect the possibility of removing the dye from water by adsorption onto activated carbon. Kinetic studies were conducted using a fixed bed of adsorbent grains. The water and dye solution flowed through the column with the adsorbent. The main aim of this study was to determine diffusion coefficients and mass transfer coefficients. The values of the external mass transfer coefficient and external diffusion coefficient of the dye in water were calculated for different flow rates of the solution, i.e., for different external resistance values. The external diffusion coefficient was DAB = 2.21·10−10 m2/s and the external mass transfer coefficient was between kc = 4.813·10−8 m/s for the lowest solution velocity in the adsorber equal to 0.0693 m/s and kc = 5.623·10−8 m/s for the highest velocity equal to 0.185 m/s. The internal diffusion coefficient and internal mass transfer coefficient, i.e., the coefficients of the transfer from the external surface of a grain to its interior, were determined with the use of the analytical solution of the diffusion and adsorption equation For the apparent solution velocity of 0.0693 m/s the internal diffusion coefficient was Ds = 0.57·10−10 m2/s and the internal mass transfer coefficient was ks = 1.89·10−10 m/s. For the velocity of 0.163 m/s, the internal diffusion coefficient was Ds = 0.84·10−10 m2/s and the internal mass transfer coefficient was ks = 9.00·10−10 m/s. The results of the calculations presented are a measure of the efficiency of a given adsorbent in a given system. The values obtained for the mass transfer coefficients can be used as data for further calculations of this process.

Purification doi: 10.3390/purification1010003

Authors: Ivan Notardonato Cristina Di Fiore Pasquale Avino

Indoor air quality (IAQ) has emerged as a critical area of research, reflecting growing concerns regarding occupant health, well-being, and comfort in enclosed environments. The increasing complexity of modern indoor spaces, coupled with rapid advancements in sensing technologies and data analysis methodologies, has intensified scientific interest in effective IAQ assessment and management. This review aims to examine current technologies and methodologies for monitoring key indoor air quality indicators. Furthermore, it offers practical recommendations for enhancing IAQ in diverse built environments and explores the integration of artificial intelligence (AI) into monitoring systems. The findings underscore the potential of AI-enhanced approaches to optimize indoor environmental conditions and support proactive air quality management strategies.

Purification doi: 10.3390/purification1010002

Authors: Lelum Duminda Manamperuma Janka Dibdiakova Ocelie Kjønnø Bjørn Rusten Josipa Matic Sileshi Gizachew Wubshet Eilen Arctander Vik

Crossflow membrane separation was used as a scalable downstream process for the up concentrate of low-molecular-weight peptides and for the removal of salt (NaCl) from Calanus finmarchicus hydrolysate. Membrane processes are increasingly used for various applications in both upstream and downstream processing. The C. finmarchicus hydrolysate was prepared by enzymatic hydrolysis, followed by crossflow separation. The stepwise membrane nanofiltration of hydrolysate contributed to a progressive reduction in salt in the hydrolysate. The salt concentration in the concentrates decreased by 34%, 53%, and 75%, highlighting the efficiency of the filtration process in separating NaCl from peptides. This gradual reduction in salt concentration suggests that the membrane effectively facilitated NaCl removal while retaining peptides. Briefly, 75% NaCl removal was achieved, with peptide recovery reaching 57% using an NFX membrane in crossflow filtration.

Purification doi: 10.3390/purification1010001

Authors: Karol Chilmon Maciej Kalinowski Wioletta Jackiewicz-Rek

This study investigates the relationship between surface properties and microstructural characteristics of photocatalytic composites and their impact on air purification efficiency. High-resolution energy-dispersive X-ray spectroscopy (EDS) mapping and mercury intrusion porosimetry (MIP) were employed to analyze photocatalyst distribution and pore structure quantitatively. The findings demonstrated a strong correlation between TiO2 coverage on the photoactive surface and NO removal rates and between pore structure characteristics and NO2 generation rates. Two predictive models were developed to link NOx removal rates with photocatalytic cementitious mortars’ surface and structural properties. A stepwise regression approach produced a second-degree polynomial model with an adjusted R2 of 0.98 and a Mean Absolute Percentage Error (MAPE) of 8.34%, indicating high predictive accuracy. The results underscore the critical role of uniform photocatalyst distribution and optimized pore structure in enhancing NOx removal efficiency while promoting the generation of desirable products (NO3−) and minimizing the formation of undesirable byproducts (NO2).