Cellulosic fibers — Biosorptive materials and indicators of heavy metals pollution

Challenges of Green Transition in Polymer Production: Applications in Zero Energy Innovations and Hydrogen Storage

The green transition in the sustainable production and processing of polymers poses multifaceted challenges that demand integral comprehensive solutions. Specific problems of presences of toxic trace elements are often missed and this prevents shifting towards eco-friendly alternatives. Therefore, substantial research and the development of novel approaches is needed to discover and implement innovative, sustainable production materials and methods. This paper is focused on the most vital problems of the green transition from the aspect of establishing universally accepted criteria for the characterization and classification of eco-friendly polymers, which is essential to ensuring transparency and trust among consumers. Additionally, the recycling infrastructure needs substantial improvement to manage the end-of-life stage of polymer products effectively. Moreover, the lack of standardized regulations and certifications for sustainable polymers adds to the complexity of this problem. In this paper we propose solutions from the aspect of standardization protocols for the characterization of polymers foreseen as materials that should be used in Zero Energy Innovations in Hydrogen Storage. The role model standards originate from eco-labeling procedures for materials that come into direct or prolonged contact with human skin, and that are monitored by different methods and testing procedures. In conclusion, the challenges of transitioning to green practices in polymer production and processing demands a concerted effort from experts in the field which need to emphasize the problems of the analysis of toxic ultra trace and trace impurities in samples that will be used in hydrogen storage, as trace impurities may cause terrific obstacles due to their decreasing the safety of materials. Overcoming these obstacles requires the development and application of current state-of-the-art methodologies for monitoring the quality of polymers during their recycling, processing, and using, as well as the development of other technological innovations, financial initiatives, and a collective commitment to fostering a sustainable and environmentally responsible future for the polymer industry and innovations in the field of zero energy applications.

Adsorbents for water decontamination: A recycling alternative for fiber precursors and textile fiber wastes

The exponential growth in textile fiber production and commensurate release of textile waste-based effluents into the environment has significant impacts on human wellbeing and the long-term planetary health. To abate these negative impacts and promote resource circularity, efforts are being made to recycle these waste materials via conversion into adsorbents for water decontamination. This review critically examines plant- and regenerated cellulose-based fibers for removing water pollutants such as heavy metals, dyes, pharmaceutical and petrochemical wastes. The review reveals that chemical modification reactions such as grafting, sulfonation, carboxymethylation, amination, amidoximation, xanthation, carbon activation, and surface coating are normally employed, and the adsorption mechanisms often involve Van der Waals attraction, electrostatic interaction, complexation, chelation, ion exchange, and precipitation. Furthermore, the adsorption processes and thus the adsorption mechanisms are influenced by factors such as surface properties of adsorbents, pollutant characteristics including composition, porosity/pore size distribution, specific surface area, hydrophobicity/hydrophobicity, and molecular interactions. Besides, feasibility of the approaches in terms of handling and reuse, environmental fate, and economic impact was evaluated, in addition to the performances of the adsorbents, the prospects, and challenges. As current cost analysis is non-exhaustive, it is recommended that researchers focus on extensive cost analysis to fully appreciate the true cost effectiveness of employing these waste materials. In addition, more attention must be paid to potential chemical leaching, post-adsorption handling, and disposal. Based on the review, fiber precursors and textile fiber wastes are viable alternative adsorbents for sustainable water treatment and environmental management, and government entities must leverage on these locally accessible materials to promote recyclability and circularity.

Modification Strategies of Kapok Fiber Composites and Its Application in the Adsorption of Heavy Metal Ions and Dyes from Aqueous Solutions: A Systematic Review

Kapok fiber (Ceiba pentandra) belongs to a group of natural fibers that are mainly composed of cellulose, lignin, pectin, and small traces of inorganic compounds. These fibers are lightweight with hollow tubular structure that is easy to process and abundant in nature. Currently, kapok fibers are used in industry as filling material for beddings, upholstery, soft toys, and nonwoven materials. However, kapok fiber has also a potential application in the adsorptive removal of heavy metal ions and dyes from aqueous systems. This study aims to provide a comprehensive review about the recent developments on kapok fiber composites including its chemical properties, wettability, and surface morphology. Effective and innovative kapok fiber composites are analyzed with the help of characterization tools such as scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and Brunauer-Emmett-Teller analysis. Different pre-treatment methods such as alkali and acid pre-treatment, oxidation pre-treatment, and Fenton reaction are discussed. These techniques are applied to enhance the hydrophilicity and to generate rougher fiber surfaces. Moreover, surface modification and synthesis of kapok fiber-based composites and its environmental applications are examined. There are various methods in the fabrication of kapok fiber composites that include chemical modification and polymerization. These procedures allow the kapok fiber composites to have higher adsorption capacities for selective heavy metal and dye removal.

Geo-environmental approach to assess heavy metals around auto-body refinishing shops using bio-monitors

The vehicular industry is looking for continuous challenges to develop the sustainability of its manufacturing, maintenance processes, and vehicle emissions due to marketability, environmental, economic, and policy concerns. The present study focuses on the impact of these processes on the environment. In Pakistan, most of the auto-body refinishing processes are carried out in an open atmosphere. The shades of Azadirachta indica (Neem Tree) are generally used for the outdoor practice of scrapping, grinding, and painting in auto-body refinishing shops of Pakistan. Azadirachta indica leaves were selected as bio-indicator. For the present work, 26 affected sites and 10 control sites were selected from Karachi city, which is the financial hub and biggest city of Pakistan. Concentrations of different metals (Fe, Co, Cd, Cr, Cu, Mn, Mo, Ni, Pb, and Zn) were determined by atomic absorption spectrophotometer. A geographic information system (GIS) is used to present the variation in concentrations within Karachi city. The only positive correlation was observed in Pb and Mn (0.750). Principal component analysis (PCA) is applied to identify the anthropogenic effect between auto-body refinishing areas and control areas. Almost all analyzed metals show higher concentration at affected sites but Pb (87.14 mg/kg), Mn (46.47 mg/kg) and Fe (146.95 mg/kg) were leading the values, as compared to their concentration at control sites, Pb (48.83 mg/kg), Mn (15.23 mg/kg) and Fe (43.07 mg/kg). All analyzed metals are frequently present in different color pigments, whereas Pb, Mn, and Fe may also come from other sources, like the anti-knocking agent, vehicular exhaust, and scraping of car surface.

Use of Chènevotte, a Valuable Co-Product of Industrial Hemp Fiber, as Adsorbent for Pollutant Removal. Part I: Chemical, Microscopic, Spectroscopic and Thermogravimetric Characterization of Raw and Modified Samples

FINEAU (2021–2024) is a trans-disciplinary research project involving French, Serbian, Italian, Portuguese and Romanian colleagues, a French agricultural cooperative and two surface-treatment industries, intending to propose chènevotte, a co-product of the hemp industry, as an adsorbent for the removal of pollutants from polycontaminated wastewater. The first objective of FINEAU was to prepare and characterize chènevotte-based materials. In this study, the impact of water washing and treatments (KOH, Na₂CO₃ and H₃PO₄) on the composition and structure of chènevotte (also called hemp shives) was evaluated using chemical analysis, X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, X-ray computed nanotomography (nano-CT), attenuated total reflectance–Fourier transform infrared (ATR-FTIR) spectroscopy, solid state NMR spectroscopy and thermogravimetric analysis. The results showed that all these techniques are complementary and useful to characterize the structure and morphology of the samples. Before any chemical treatment, the presence of impurities with a compact unfibrillated structure on the surfaces of chènevotte samples was found. Data indicated an increase in the crystallinity index and significant changes in the chemical composition of each sample after treatment as well as in surface morphology and roughness. The most significant changes were observed in alkaline-treated samples, especially those treated with KOH.

Utilization of Jengkol Peel (Pithecellobium jiringa (Jack) Prain) as Lead (II) Ions Bio-sorbent with Column Method

Problems arising from laboratory waste include the content of lead metal ions in it, which can affect health. While on the other hand, Jengkol peel is a market waste and has no economic value. Jengkol peel contains hydroxyl groups and carboxylates to bind heavy metals such as lead (II) ions. So, this study aims to determine the effect of variations in flow rate, adsorbent height, and solution acidity and determine the ability of Jengkol peel in adsorbing lead (II) ions in the laboratory liquid by the column method. Organic groups that include active sides can be removed using 1N sodium hydroxide to increase the adsorption ability. Sodium hydroxide functions to dissolve lignin in lignocellulose compounds so that carboxylic groups are formed in cellulose, which has a role in binding metal ions. The determination of functional groups was carried out by Fourier-transform Infrared Spectroscopy. The identification of the adsorbent morphology was carried out by Scanning Electron Microscope. The adsorption of lead (II) ions by Jengkol peel was determined by calculating the difference between the lead (II) ions in the solution after and before passing through the column. The amount of lead metal remaining in solution was determined using Atomic Absorption Spectroscopy. Sodium hydroxide solution with a concentration of 1N can separate lignin from cellulose contained in lignocellulose to enhance the bio-sorbent ability of the Jengkol peel in binding metal ions. The smaller the flow rate in the column, the higher the amount of lead (II) ions adsorbed in the bio-sorbent. The acidity of the solution has the best adsorption at pH 5. The metal ions from the simulation sample can reduce the number of lead (II) metal ions adsorbed by 11%.

Synthesis, Modification and Characterization of Antimicrobial Textile Surface Containing ZnO Nanoparticles

In this research, a textile surface was modified by the sol–gel methodology with a new antimicrobial coating containing nanoparticles active against bacteria resistant to antibiotics. The effect of ultrasonic irradiation power (40 to 90 kHz), the concentration of reagents (nanoparticles, precursor and acids) and time (15 to 72 min) were investigated in relation to the structure, morphology and antimicrobial activity of coatings with zinc oxide nanoparticles. The relationship between the sonocatalytic performance and structure of the resultant modification was established by using various techniques, such as FTIR spectroscopy (FTIR) and scanning electron microscopy with an EDX detector (SEM-EDX), thin-layer chromatography (TLC) and antimicrobial effects were determined on selected model microorganisms. The homogeneity of layers with ZnO nanoparticles on samples was increased by increasing the ultrasonic irradiation power and time. The ultrasonic irradiation unify did not only unify both the structure and the morphology of samples, it also prevented the agglomeration of the nanoparticles. Moreover, under optimal conditions, an antimicrobial coating with ZnO nanoparticles, active against bacterial species S. aureus and E. coli was efficiently prepared. Results of the Time-kill methodology revieled excellent results starting after 6 hours of exposal to antimicrobialy functionalized cellulose polymer.

Biosorption of Elements

Biosorption is a unique ability of living or dead biomass to interact with substances such as metals where reduction of sorbate concentration can be achieved. Thus, it has been widely proposed as a promising alternative for metal remediation and recovery owing to its low cost and sustainable “green” nature. Despite considerable biosorption‐related research performed in the past few decades, no significant commercial success has been achieved so far. This chapter starts with discussion of the basic science of biosorption and the potential of some selected biomasses such as yeast, algae, agro‐based waste and vermicompost to be used as biosorbent material. Following this, some important issues regarding the practical application of biosorption are highlighted, including the advantages and disadvantages of using dead or living biomass, the availability of biosorption reactors, immobilization techniques, metal recovery and post‐treatment of spent biosorbent. Lastly, current challenges that limit the commercial success of biosorption as well as the direction of future research are discussed.