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Keywords = direct dye recovery

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20 pages, 4874 KiB  
Article
Preparation of pH-Responsive PET TeMs by Controlled Graft Block Copolymerisation of Styrene and Methacrylic Acid for the Separation of Water–Oil Emulsions
by Indira B. Muslimova, Dias D. Omertassov, Nurdaulet Zhumanazar, Nazerke Assan, Zhanna K. Zhatkanbayeva and Ilya V. Korolkov
Polymers 2025, 17(16), 2221; https://doi.org/10.3390/polym17162221 - 14 Aug 2025
Viewed by 252
Abstract
To develop membranes capable of efficient and switchable emulsion separation under variable pH conditions, pH-responsive surfaces were engineered on poly(ethylene terephthalate) track-etched membranes (PET TeMs) via a two-step UV-initiated RAFT graft polymerization process. Initially, polystyrene (PS) was grafted to render the surface hydrophobic, [...] Read more.
To develop membranes capable of efficient and switchable emulsion separation under variable pH conditions, pH-responsive surfaces were engineered on poly(ethylene terephthalate) track-etched membranes (PET TeMs) via a two-step UV-initiated RAFT graft polymerization process. Initially, polystyrene (PS) was grafted to render the surface hydrophobic, followed by the grafting of poly(methacrylic acid) (PMAA) to introduce pH-responsive carboxyl groups. Optimized conditions (117 mM MAA, RAFT:initiator 1:10, 60 min UV exposure at 10 cm) resulted in PET TeMs-g-PS-g-PMAA surfaces exhibiting tunable wettability, with contact angles shifting from 90° at pH 2 to 65° at pH 9. Successful grafting was confirmed by FTIR, AFM, SEM, TGA, and TB dye sorption. The membranes showed high degree of rejection (up to 98%) for both direct and reverse emulsions. In direct emulsions, stable flux values (70 ± 2.8 to 60 ± 2.9 L m−2 h−1 for cetane-in-water and 195 ± 8.2 to 120 ± 6.9 L m−2 h−1 for o-xylene-in-water) were maintained over five cycles at 900 mbar, indicating excellent antifouling performance. Reverse emulsions initially exhibited higher flux, but stronger fouling; however, flux recovery reached 91% after cleaning. These findings demonstrate the potential of PET TeMs-g-PS-g-PMAA as switchable, pH-responsive membranes for robust emulsion separation. Full article
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33 pages, 6152 KiB  
Review
A Comprehensive Guide to Enzyme Immobilization: All You Need to Know
by Marina Simona Robescu and Teodora Bavaro
Molecules 2025, 30(4), 939; https://doi.org/10.3390/molecules30040939 - 18 Feb 2025
Cited by 21 | Viewed by 8697
Abstract
Enzyme immobilization plays a critical role in enhancing the efficiency and sustainability of biocatalysis, addressing key challenges such as limited enzyme stability, short shelf life, and difficulties in recovery and recycling, which are pivotal for green chemistry and industrial applications. Classical approaches, including [...] Read more.
Enzyme immobilization plays a critical role in enhancing the efficiency and sustainability of biocatalysis, addressing key challenges such as limited enzyme stability, short shelf life, and difficulties in recovery and recycling, which are pivotal for green chemistry and industrial applications. Classical approaches, including adsorption, entrapment, encapsulation, and covalent bonding, as well as advanced site-specific methods that integrate enzyme engineering and bio-orthogonal chemistry, were discussed. These techniques enable precise control over enzyme orientation and interaction with carriers, optimizing catalytic activity and reusability. Key findings highlight the impact of immobilization on improving enzyme performance under various operational conditions and its role in reducing process costs through enhanced stability and recyclability. The review presents numerous practical applications of immobilized enzymes, including their use in the pharmaceutical industry for drug synthesis, in the food sector for dairy processing, and in environmental biotechnology for wastewater treatment and dye degradation. Despite the significant advantages, challenges such as activity loss due to conformational changes and mass transfer limitations remain, necessitating tailored immobilization protocols for specific applications. The integration of immobilization with modern biotechnological advancements, such as site-directed mutagenesis and recombinant DNA technology, offers a promising pathway for developing robust, efficient, and sustainable biocatalytic systems. This comprehensive guide aims to support researchers and industries in selecting and optimizing immobilization techniques for diverse applications in pharmaceuticals, food processing, and fine chemicals. Full article
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29 pages, 1445 KiB  
Review
Algal-Based Carbonaceous Materials for Environmental Remediation: Advances in Wastewater Treatment, Carbon Sequestration, and Biofuel Applications
by Lázaro Adrián González Fernández, Nahum Andrés Medellín Castillo, Manuel Sánchez Polo, Amado Enrique Navarro Frómeta and Javier Ernesto Vilasó Cadre
Processes 2025, 13(2), 556; https://doi.org/10.3390/pr13020556 - 16 Feb 2025
Cited by 7 | Viewed by 1548
Abstract
Water pollution from industrial, municipal, and agricultural sources is a pressing global concern, necessitating the development of sustainable and efficient treatment solutions. Algal biomass has emerged as a promising feedstock for the production of carbonaceous adsorbents due to its rapid growth, high photosynthetic [...] Read more.
Water pollution from industrial, municipal, and agricultural sources is a pressing global concern, necessitating the development of sustainable and efficient treatment solutions. Algal biomass has emerged as a promising feedstock for the production of carbonaceous adsorbents due to its rapid growth, high photosynthetic efficiency, and ability to thrive in wastewater. This review examines the conversion of algal biomass into biochar and hydrochar through pyrolysis and hydrothermal processes, respectively, and evaluates their potential applications in wastewater treatment, carbon sequestration, and biofuel production. Pyrolyzed algal biochars typically exhibit a moderate to high carbon content and a porous structure but require activation treatments (e.g., KOH or ZnCl2) to enhance their surface area and adsorption capabilities. Hydrothermal carbonization, conducted at lower temperatures (180–260 °C), produces hydrochars rich in oxygenated functional groups with enhanced cation exchange capacities, making them effective for pollutant removal. Algal-derived biochars and hydrochars have been successfully applied for the adsorption of heavy metals, dyes, and pharmaceutical contaminants, with adsorption capacities significantly increasing through post-treatment modifications. Beyond wastewater treatment, algal biochars serve as effective carbon sequestration materials due to their stable structure and high carbon retention. Their application as soil amendments enhances long-term carbon storage and improves soil fertility. Additionally, algal biomass plays a key role in biofuel production, particularly for biodiesel synthesis, where microalgae’s high lipid content facilitates bio-oil generation. Hydrochars, with energy values in the range of 20–26 MJ/kg, are viable solid fuels for combustion and co-firing, supporting renewable energy generation. Furthermore, the integration of these materials into bioenergy systems allows for waste valorization, pollution control, and energy recovery, contributing to a sustainable circular economy. This review provides a comprehensive analysis of algal-derived biochars and hydrochars, emphasizing their physicochemical properties, adsorption performance, and post-treatment modifications. It explores their feasibility for large-scale wastewater remediation, carbon capture, and bioenergy applications, addressing current challenges and future research directions. By advancing the understanding of algal biomass as a multifunctional resource, this study highlights its potential for environmental sustainability and energy innovation. Full article
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13 pages, 1960 KiB  
Article
Asymmetric Membranes Obtained from Sulfonated HIPS Waste with Potential Application in Wastewater Treatment
by Marcial Alfredo Yam-Cervantes, Rita Sulub-Sulub, Mauricio Hunh-Ibarra, Santiago Duarte, Erik Uc-Fernandez, Daniel Pérez-Canales, Manuel Aguilar-Vega and Maria Ortencia González-Díaz
Membranes 2024, 14(12), 247; https://doi.org/10.3390/membranes14120247 - 22 Nov 2024
Cited by 1 | Viewed by 1388
Abstract
The recovery and reuse of high-impact polystyrene (HIPS) into high-value products is crucial for reducing environmental thermoplastics waste and promoting sustainable materials for various applications. In this study, asymmetric membranes obtained from sulfonated HIPS waste were used for salt and dye removals. The [...] Read more.
The recovery and reuse of high-impact polystyrene (HIPS) into high-value products is crucial for reducing environmental thermoplastics waste and promoting sustainable materials for various applications. In this study, asymmetric membranes obtained from sulfonated HIPS waste were used for salt and dye removals. The incorporation of sulfonic acid (-SO3H) groups into HIPS waste by direct chemical sulfonation with chlorosulfonic acid (CSA), at two different concentrations, was investigated to impart antifouling properties in membranes for water treatment. Asymmetric membranes from recycled HIPS, R-HIPS, R-HIPS-3, and R-HIPS-5 with 3 and 5% sulfonation degrees, respectively. Sulfonated HIPS shows a decrease in water contact angle (WCA) from 83.8° for recycled R-HIPS to 66.1° for R-HIPS-5, respectively. A WCA decrease leads to an increase in antifouling properties for R-HIPS-5, compared to non-sulfonated R-HIPS, which leads to a higher flux recovery ratio (FRR) and enhanced separation properties for sulfonated membranes. The HIPS-5 membrane exhibited the highest rejection rates for Reactive Black 5 dye (94%) and divalent salts (72% for MgSO4 and 67% for Na2SO4). The performance of the recycled HIPS asymmetric membranes is well correlated with porosity, water uptake, and the higher negative charge from the sulfonic acid groups present, which enhance the electrostatic repulsions of salts and dyes. Full article
(This article belongs to the Special Issue Recent Advances in Polymeric Membranes—Preparation and Applications)
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18 pages, 1949 KiB  
Review
Unraveling the Potential of Microbial Flocculants: Preparation, Performance, and Applications in Wastewater Treatment
by Yang Yang, Cancan Jiang, Xu Wang, Lijing Fan, Yawen Xie, Danhua Wang, Tiancheng Yang, Jiang Peng, Xinyuan Zhang and Xuliang Zhuang
Water 2024, 16(14), 1995; https://doi.org/10.3390/w16141995 - 14 Jul 2024
Cited by 10 | Viewed by 3815
Abstract
Microbial flocculants (MBFs), a class of eco-friendly and biodegradable biopolymers produced by various microorganisms, have gained increasing attention as promising alternatives to conventional chemical flocculants in wastewater treatment and pollutant removal. This review presents a comprehensive overview of the current state of MBF [...] Read more.
Microbial flocculants (MBFs), a class of eco-friendly and biodegradable biopolymers produced by various microorganisms, have gained increasing attention as promising alternatives to conventional chemical flocculants in wastewater treatment and pollutant removal. This review presents a comprehensive overview of the current state of MBF research, encompassing their diverse sources (bacteria, fungi, and algae), major categories (polysaccharides, proteins, and glycoproteins), production processes, and flocculation performance and mechanisms. The wide-ranging applications of MBFs in removing suspended solids, heavy metals, dyes, and other pollutants from industrial and municipal wastewater are critically examined, highlighting their superior efficiency, selectivity, and environmental compatibility compared to traditional flocculants. Nonetheless, bioflocculants face significant challenges including high substrate costs, low production yields, and intricate purification methodologies, factors that impede their industrial scalability. Moreover, the risk of microbial contamination and the attendant health implications associated with the use of microbial flocculants (MBFs) necessitate thorough evaluation. To address the challenges of high production costs and variable product quality, strategies such as waste valorization, strain improvement, process optimization, and biosafety evaluation are discussed. Moreover, the development of multifunctional MBF-based flocculants and their synergistic use with other treatment technologies are identified as emerging trends for enhanced wastewater treatment and resource recovery. Future research directions are outlined, emphasizing the need for in-depth mechanistic studies, advanced characterization techniques, pilot-scale demonstrations to accelerate the industrial adoption of MBF, and moreover, integration with novel wastewater treatment processes, such as partial nitrification and the anammox process. This review is intended to inspire and guide further research and development efforts aimed at unlocking the full potential of MBFs as sustainable, high-performance, and cost-effective bioflocculants for addressing the escalating challenges in wastewater management and environmental conservation. Full article
(This article belongs to the Special Issue Water Quality Engineering and Wastewater Treatment III)
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14 pages, 4197 KiB  
Article
Bioactive Lyocell Fibers with Inherent Antibacterial, Antiviral and Antifungal Properties
by Frank Wendler, Thomas Schulze, Janine Bauer and Benjamin Redlingshöfer
Molecules 2024, 29(9), 2054; https://doi.org/10.3390/molecules29092054 - 29 Apr 2024
Cited by 2 | Viewed by 1649
Abstract
Functional Lyocell fibers gain interest in garments and technical textiles, especially when equipped with inherently bioactive features. In this study, Lyocell fibers are modified with an ion exchange resin and subsequently loaded with copper (Cu) ions. The modified Lyocell process enables high amounts [...] Read more.
Functional Lyocell fibers gain interest in garments and technical textiles, especially when equipped with inherently bioactive features. In this study, Lyocell fibers are modified with an ion exchange resin and subsequently loaded with copper (Cu) ions. The modified Lyocell process enables high amounts of the resin additive (>10%) through intensive dispersion and subsequently, high uptake of 2.7% Cu throughout the whole cross-section of the fiber. Fixation by Na2CO3 increases the washing and dyeing resistance considerably. Cu content after dyeing compared to the original fiber value amounts to approx. 65% for reactive, 75% for direct, and 77% for HT dyeing, respectively. Even after 50 household washes, a recovery of 43% for reactive, 47% for direct and 26% for HT dyeing is proved. XRD measurements reveal ionic bonding of Cu fixation inside the cellulose/ion exchange resin composite. A combination of the fixation process with a change in Cu valence state by glucose/NaOH leads to the formation of Cu2O crystallites, which is proved by XRD. Cu fiber shows a strong antibacterial effect against Staphylococcus aureus and Klebsiella pneumonia bacteria, even after 50 household washing cycles of both >5 log CFU. In nonwoven blends with a share of only 6% Cu fiber, a strong antimicrobial (CFU > log 5) and full antiviral effectiveness (>log 4) was received even after 50 washing cycles. Time-dependent measurements already show strong antiviral behavior after 30 s. Further, the fibers show an increased die off of the fungal isolate Candida auris with CFU log 4.4, and nonwovens made from 6% Cu fiber share a CFU log of 1.7. Findings of the study predestines the fiber for advanced textile processing and applications in areas with high germ loads. Full article
(This article belongs to the Special Issue Biopolymers and Biohybrids for Human Health)
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16 pages, 2930 KiB  
Article
Feasibility of Forward Osmosis to Recover Textile Dyes Using Single Salts and Multicomponent Draw Solutions
by Magdalena Cifuentes-Cabezas, Laura García-Suarez, José Luis Soler-Cabezas, Beatriz Cuartas-Uribe, Silvia Álvarez-Blanco, José Antonio Mendoza-Roca and María-Cinta Vincent-Vela
Membranes 2023, 13(12), 911; https://doi.org/10.3390/membranes13120911 - 18 Dec 2023
Cited by 5 | Viewed by 2793
Abstract
The textile industry generates large volumes of water characterized mainly by an intense color coming from dyes that are difficult to process due to their synthetic base and the presence of aromatic components. Due to the stricter regulation on the discharge of these [...] Read more.
The textile industry generates large volumes of water characterized mainly by an intense color coming from dyes that are difficult to process due to their synthetic base and the presence of aromatic components. Due to the stricter regulation on the discharge of these effluents, in order to reduce dye waste before discharge into natural channels, alternatives are being sought to manage this wastewater. In this work, the concentration of dyes in simulated wastewater from the textile industry was studied by forward osmosis (with a cellulose triacetate CTA membrane), with the aim of concentrating the dye for its future recovery and reincorporation into the production process. Two dyes of different nature were evaluated to study the efficiency of the proposed process, using NaCl and reverse osmosis brine from a model seawater desalination solution as extraction solutions. It was observed that dye type (reactive or direct) and their charge influence the color rejection with the forward osmosis membrane used. It was able to concentrate the dyes in the feed solution up to approximately 55% with the reverse osmosis brine from the model seawater desalination solution. Finally, the results demonstrate that the FO process is a promising option for concentrating dyes present in wastewater from the textile industry in order to reuse them in the dyeing process. Full article
(This article belongs to the Section Membrane Processing and Engineering)
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23 pages, 3124 KiB  
Review
Toward Climate Neutrality: A Comprehensive Overview of Sustainable Operations Management, Optimization, and Wastewater Treatment Methods
by Vasileios Alevizos, Ilias Georgousis and Annamaria Kapodistria
Pollutants 2023, 3(4), 521-543; https://doi.org/10.3390/pollutants3040036 - 15 Nov 2023
Cited by 11 | Viewed by 2499
Abstract
Various studies have been conducted in the fields of sustainable operations management (SOM), optimization, and wastewater treatment, yielding unsubstantiated recovery. In the context of Europe’s climate neutrality vision, this paper reviews effective decarbonization strategies and proposes sustainable approaches to mitigate carbonization in various [...] Read more.
Various studies have been conducted in the fields of sustainable operations management (SOM), optimization, and wastewater treatment, yielding unsubstantiated recovery. In the context of Europe’s climate neutrality vision, this paper reviews effective decarbonization strategies and proposes sustainable approaches to mitigate carbonization in various sectors such as buildings, energy, industry, and transportation and how these interlink with wastewater management. The study also explores the role of digitalization in decarbonization and reviews policies that can direct governments’ actions towards a climate-neutral society. This paper presents a review of optimization approaches applied in the fields of science and technology, incorporating modern optimization techniques based on various peer-reviewed published research papers. It emphasizes non-conventional energy and distributed power-generating systems along with the deregulated and regulated environment. Additionally, this paper critically reviews the performance and capability of the micellar-enhanced ultrafiltration (MEUF) process in the treatment of dye wastewater. The review presents evidence of the simultaneous removal of co-existing pollutants and explores the feasibility and efficiency of biosurfactants instead of chemical surfactants. Lastly, the paper proposes a novel Firm–Regulator–Consumer-Technology Enablers/Facilitators interaction framework to study operations, decisions and interactive cooperation considering the relationships between the four agents through a comprehensive literature review of SOM. The proposed framework provides support for exploring future research opportunities and holistic sustainability initiatives. Full article
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29 pages, 4645 KiB  
Review
Review in Waste Tire Management—Potential Applications in Mitigating Environmental Pollution
by Dorota Czarna-Juszkiewicz, Piotr Kunecki, Justyna Cader and Magdalena Wdowin
Materials 2023, 16(17), 5771; https://doi.org/10.3390/ma16175771 - 23 Aug 2023
Cited by 45 | Viewed by 8878
Abstract
Increasing year-by-year vehicle production is related to the expanding volume of used tires; therefore, exploring waste management strategies is strongly recommended. The global tire market reached 2.27 billion units in 2021 and is expected to reach 2.67 billion units by 2027. Dumping tires [...] Read more.
Increasing year-by-year vehicle production is related to the expanding volume of used tires; therefore, exploring waste management strategies is strongly recommended. The global tire market reached 2.27 billion units in 2021 and is expected to reach 2.67 billion units by 2027. Dumping tires in landfills can cause significant environmental impacts, so waste tire utilisation plays an important role. Predominantly, the following three directions are employed for waste tire disposal: retreading, energy recovery and material recovery. The review shows that used tires can remove environmental pollution from both aqueous solutions containing heavy metal ions, dyes, pharmaceutical compounds, and benzene, toluene, ethylbenzene and xylene (BTEX). Particularly high efficiency was achieved in the removal of dyes (72%), taking into account the high initial concentration of impurities. The adsorption process depends on multiple factors, including, in particular, the following: pH, initial concentration of pollution, contact time and the properties of the sorbent used. The optimal pH range was identified to be between 6 and 7. Considering the principles of circular economy as well as based on the current state of knowledge, it can be concluded that the solid fraction obtained from the combustion of waste tires can be practically utilised for various environmental purposes. Full article
(This article belongs to the Special Issue Mineral Composite Materials Produced with Waste/Recycled Components)
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13 pages, 3074 KiB  
Article
Seamless Coupling of Chemical Glycan Release and Labeling for an Accelerated Protein N-Glycan Sample Preparation Workflow
by Mumtaz Kasim, Anja Griebel, Grit Sandig, Robert Höltzel, Akshay Malhotra, Stephan Hinderlich, Volker Sandig, Barbara Müller and Hans Henning von Horsten
Bioengineering 2023, 10(6), 651; https://doi.org/10.3390/bioengineering10060651 - 26 May 2023
Viewed by 2074
Abstract
Analytical methods fr direct quantitative N-glycan analysis require a sequence of sample preparation and clean-up steps that result in reduced glycan recovery. Therefore, we aimed to combine glycan release and labeling steps. Based on the hypothesis that the reaction mechanism for oxidative [...] Read more.
Analytical methods fr direct quantitative N-glycan analysis require a sequence of sample preparation and clean-up steps that result in reduced glycan recovery. Therefore, we aimed to combine glycan release and labeling steps. Based on the hypothesis that the reaction mechanism for oxidative chemical glycan release comprises a stable glycan isocyanate intermediate, we investigated whether this could be exploited for the in-situ preparation of fluorescent glycan conjugates. ANTS-labeled N-glycans were derived from chicken ovalbumin via an in-situ chemical release/coupling approach and by standard Peptide-N-Glycosidase F (PNGase F) digestion/reductive amination. Synoptic fluorescence-assisted carbohydrate electrophoresis with UV detection (FACE-UV) analysis yielded matching patterns of fluorescent N-glycan bands in the expected electrophoretic mobility range between hexose units GU-5 and GU-11 of the standard. Anthranilamide (2-AB)-glycan conjugates prepared from a test glycoprotein carrying a predominant Core-F glycan gave single predominant peaks in hydrophilic interaction chromatography with fluorescence detection (HILIC-FLD) and electrospray ionization mass spectrometry (ESI-MS) spectra in agreement with sodiated triply charged Core-F-AB conjugates for both the standard and the in-situ coupling methods. The Core-F-AB conjugate prepared by the in-situ coupling approach had a slightly elevated retention time on HILIC-FLD and an ESI-MS m/z peak in line with a urea-bonded glycan-AB conjugate, with closed pyran ring structures on the glycan moiety. Glycan isocyanates intermittently formed during chemical glycan release, which could be utilized to prepare labeled glycan samples directly from glycoproteins and fluorescent dyes bearing a primary amine functional group. Full article
(This article belongs to the Special Issue Glycans in Therapy and Diagnostics)
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16 pages, 2279 KiB  
Article
Development and Optimization of Chromatographic Conditions for the Determination of Selected B Vitamins in Pharmaceutical Products
by Joanna Żandarek, Żaneta Binert-Kusztal, Małgorzata Starek and Monika Dąbrowska
Processes 2023, 11(3), 937; https://doi.org/10.3390/pr11030937 - 19 Mar 2023
Cited by 6 | Viewed by 5918
Abstract
Vitamins are a unit of organic chemical substances that are essential for the adequate working of the human body. Water-soluble B vitamins are involved in the regulation of many metabolic and regulatory processes. Due to the inability to synthesize endogenously, they must be [...] Read more.
Vitamins are a unit of organic chemical substances that are essential for the adequate working of the human body. Water-soluble B vitamins are involved in the regulation of many metabolic and regulatory processes. Due to the inability to synthesize endogenously, they must be supplied to the body with edibles or in the form of supplementation as drugs or dietary supplements. Maintaining the correct level of vitamins is extremely important in the treatment of various diseases. In the presented work, the qualitative and quantitative procedure of the assay of vitamins B1, B2, B5, B6 and B12 in pharmaceutical products by chromatographic technique coupled with densitometric detection was developed, optimized and validated. During the optimization process, TLC Silica gel 60 F254 plates were chosen as a suitable stationary, and the mixture consisted of chloroform: ethanol: water: glacial acetic acid (2:8:2:0.5 v/v/v/v) as a mobile phase. Densitometric detection was conducted at a maximum absorbance λ = 254 nm for vitamins B1, B2, B6 and B12 and λ = 550 nm for vitamin B5 (after dyeing with ninhydrin). In the next step, the developed procedure was validated in accordance with the ICH guidelines. The recorded correlation coefficients obtained in all tested concentrations of B vitamins, ranging from 0.9947 to 0.9996, confirmed good linearity. The method is characterized by good precision, RSD data ranging from 0.62 to 1.52% for direct precision and from 0.84 to 1.4% for intermediate precision. Accuracy was proven by a recovery test at three concentration levels, with values close to 100% with RSD less than 1%. The calculated LOD and LOQ data for all tested vitamins B1, B2, B5, B6 and B12 were belove 1 μg/spot. The developed method was then used to quantitatively and qualitatively assess the content of B vitamins in medicinal products and dietary supplements with satisfactory results. Full article
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18 pages, 4858 KiB  
Article
Dyeing with Hydrotalcite Hybrid Nanoclays and Disperse, Basic and Direct Dyes
by Daniel López-Rodríguez, Jorge Jordán-Núñez, Jaime Gisbert-Paya, Pablo Díaz-García and Eva Bou-Belda
Int. J. Mol. Sci. 2023, 24(1), 808; https://doi.org/10.3390/ijms24010808 - 3 Jan 2023
Cited by 4 | Viewed by 2966
Abstract
Textile effluents are among the most polluting industrial effluents in the world. Textile finishing processes, especially dyeing, discharge large quantities of waste that is difficult to treat, such as dyes. By recovering this material from the water, in addition to cleaning and the [...] Read more.
Textile effluents are among the most polluting industrial effluents in the world. Textile finishing processes, especially dyeing, discharge large quantities of waste that is difficult to treat, such as dyes. By recovering this material from the water, in addition to cleaning and the possibility of reusing the water, there is the opportunity to reuse this waste as a raw material for dyeing different textile substrates. One of the lines of reuse is the use of hybrid nanoclays obtained from the adsorption of dyes, which allow dye baths to be made for textile substrates. This study analyses how, through the use of the nanoadsorbent hydrotalcite, dyes classified by their charge as anionic, cationic and non-ionic can be adsorbed and recovered for successful reuse in new dye baths. The obtained hybrids were characterised by X-ray diffraction and infrared spectroscopy. In addition, the colour was analysed by spectrophotometer in the UV-VIS range. The dyes made on cotton, polyester and acrylic fabrics are subjected to different colour degradation tests to assess their viability as final products, using reflection spectroscopy to measure the colour attribute before and after the tests, showing results consistent with those of a conventional dye. Full article
(This article belongs to the Special Issue Recent Advances in Nanomaterials Science)
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45 pages, 1945 KiB  
Review
Recent Progress on Emerging Applications of Hydrochar
by Md Tahmid Islam, Al Ibtida Sultana, Cadianne Chambers, Swarna Saha, Nepu Saha, Kawnish Kirtania and M. Toufiq Reza
Energies 2022, 15(24), 9340; https://doi.org/10.3390/en15249340 - 9 Dec 2022
Cited by 42 | Viewed by 5796
Abstract
Hydrothermal carbonization (HTC) is a prominent thermochemical technology that can convert high-moisture waste into a valuable product (called hydrochar) at a relatively mild treatment condition (180–260 °C and 2–10 MPa). With rapidly growing research on HTC and hydrochar in recent years, review articles [...] Read more.
Hydrothermal carbonization (HTC) is a prominent thermochemical technology that can convert high-moisture waste into a valuable product (called hydrochar) at a relatively mild treatment condition (180–260 °C and 2–10 MPa). With rapidly growing research on HTC and hydrochar in recent years, review articles addressing the current and future direction of this research are scarce. Hence, this article aims to review various emerging applications of hydrochars, e.g., from solid fuel to soil amendment, from electron storage to hydrogen storage, from dye adsorption, toxin adsorption, heavy metal adsorption to nutrient recovery, and from carbon capture to carbon sequestration, etc. This article further provides an insight in the hydrochar’s working mechanism for various applications and how the applications can be improved through chemical modification of the hydrochar. Finally, new perspectives with appropriate recommendations have been made to further unveil potential applications and its improvement through hydrochar and its modified version. Full article
(This article belongs to the Special Issue Hydrothermal Carbonization II)
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16 pages, 2951 KiB  
Article
Advanced Design of Integrated Heat Recovery and Supply System Using Heated Water Storage for Textile Dyeing Process
by Juyeong Seo, Haneul Mun, Jae Yun Shim, Seok Il Hong, Hee Dong Lee and Inkyu Lee
Energies 2022, 15(19), 7298; https://doi.org/10.3390/en15197298 - 4 Oct 2022
Cited by 6 | Viewed by 1902
Abstract
Heat recovery from a high-temperature wastewater is the major concern in the conventional textile industry. However, limited space in the textile plant is an important constraint for the process enhancement. Therefore, an easily applicable heat recovery system with a small amount of additional [...] Read more.
Heat recovery from a high-temperature wastewater is the major concern in the conventional textile industry. However, limited space in the textile plant is an important constraint for the process enhancement. Therefore, an easily applicable heat recovery system with a small amount of additional equipment to the existing dyeing process is required. To meet the needs from the industry, this study suggests an integrated heat recovery and supply system consisting of single heat exchanger and single storage tank using freshwater as a thermal carrier to utilize the reusable heat in the wastewater. Freshwater is stored in a tank after direct heat exchange with wastewater and is supplied to the next dyeing process. Three different designs of the integrated system were compared based on the lower limit of the wastewater temperature: above 50 °C, 40 °C, and 30 °C for Cases 1, 2, and 3, respectively. The energy and energy flow analyses showed Case 2 to be well balanced between the quality and quantity of the recovered heat, and there was no heat loss via drainage. The heat demand for Case 2 was 795.5 kW, which was the lowest among all cases. Furthermore, an economic analysis showed that the total cost for Case 2 was reduced by 63.2% compared with the base case. Despite the use of an additional heat exchanger and water storage tank, the proposed system was more economical because of the reduced operating costs. Finally, a detailed analysis was conducted by determining the more efficient temperature for heat recovery and supply. Full article
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24 pages, 8598 KiB  
Article
The Optimal Concentration of Nanoclay Hydrotalcite for Recovery of Reactive and Direct Textile Colorants
by Daniel López-Rodríguez, Bàrbara Micó-Vicent, Marilés Bonet-Aracil, Francisco Cases and Eva Bou-Belda
Int. J. Mol. Sci. 2022, 23(17), 9671; https://doi.org/10.3390/ijms23179671 - 26 Aug 2022
Cited by 4 | Viewed by 2451
Abstract
Concerns about the health of the planet have grown dramatically, and the dyeing sector of the textile industry is one of the most polluting of all industries. Nanoclays can clean dyeing wastewater using their adsorption capacities. In this study, as a new finding, [...] Read more.
Concerns about the health of the planet have grown dramatically, and the dyeing sector of the textile industry is one of the most polluting of all industries. Nanoclays can clean dyeing wastewater using their adsorption capacities. In this study, as a new finding, it was possible to analyze and quantify the amount of metal ions substituted by anionic dyes when adsorbed, and to determine the optimal amount of nanoclay to be used to adsorb all the dye. The tests demonstrated the specific amount of nanoclay that must be used and how to optimize the subsequent processes of separation and processing of the nanoclay. Hydrotalcite was used as the adsorbent material. Direct dyes were used in this research. X-ray diffraction (XRD) patterns allowed the shape recovery of the hydrotalcite to be checked and confirmed the adsorption of the dyes. An FTIR analysis was used to check the presence of characteristic groups of the dyes in the resulting hybrids. The thermogravimetric (TGA) tests corroborated the dye adsorption and the thermal fastness improvement. Total solar reflectance (TSR) showed increased radiation protection for UV-VIS-NIR. Through the work carried out, it has been possible to establish the maximum adsorption point of hydrotalcite. Full article
(This article belongs to the Special Issue Recent Advances in Nanomaterials Science)
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