Preparation and Properties of Cellulose-Based Films Regenerated from Waste Corrugated Cardboards Using [Amim]Cl/CaCl2

Threading the needle: Achieving simplicity and performance in cellulose alkanoate ω-carboxyalkanoates for amorphous solid dispersion

Most active pharmaceutical ingredients (APIs) suffer from poor water solubility, often keeping them from reaching patients. To overcome the issues of poor drug solubility and subsequent low bioavailability, amorphous solid dispersions (ASDs) have garnered much attention. Cellulose ester derivatives are of interest for ASD applications as they are benign, sustainable-based, and successful in commercial drug delivery systems, e.g. in osmotic pump systems and as commercial ASD polymers. Synthesis of carboxy-pendant cellulose esters is a challenge, due in part to competing reactions between carboxyls and hydroxyls, forming ester crosslinks. Herein we demonstrate proof-of-concept for a scalable synthetic route to simple, yet highly promising ASD polymers by esterifying cellulose polymers through ring-opening of cyclic succinic or glutaric anhydride. We describe the complexity of such ring-opening reactions, not previously well-described, and report ways to avoid gelation. We report synthesis, characterization, and preliminary in vitro ASD evaluations of fifteen such derivatives. Synthetic routes were designed to accommodate these criteria: no protecting groups, no metal catalysts, mild conditions with standard reagents, simple purification, and one-pot synthesis. Finally, these designed ASD polymers included members that maintained fast-crystallizing felodipine in solution and release it from an ASD at rather high 20 % drug loading (DL).

Tailoring Hydronium ion Driven Dissociation-Chemical Cross-Linking for Superfast One-Pot Cellulose Dissolution and Derivatization to Build Robust Cellulose Films

Concepts of sustainability must be developed to overcome the increasing environmental hazards caused by fossil resources. Cellulose derivatives with excellent properties are promising biobased alternatives for petroleum-derived materials. However, a one-pot route to achieve cellulose dissolution and derivatization is very challenging, requiring harsh conditions, high energy consumption, and complex solubilizing. Herein, we design a one-pot tailoring hydronium ion driven dissociation-chemical cross-linking strategy to achieve superfast cellulose dissolution and derivatization for orderly robust cellulose films. In this strategy, there is a powerful driving force from organic acid with a pKa below 3.75 to dissociate H+ and trigger the dissolution and derivatization of cellulose under the addition of H2SO4. Nevertheless, the driving force can only trigger a partial swelling of cellulose but without dissolution when the pKa of organic acid is above 4.26 for the dissociation of H+ is inhibited by the addition of inorganic acid. The cellulose film has high transmittance (up to ∼90%), excellent tensile strength (∼122 MPa), and is superior to commercial PE film. Moreover, the tensile strength is increased by 400% compared to cellulose film prepared by the ZnCl2 solvent. This work provides an efficient solvent, which is of great significance for emerging cellulose materials from renewable materials.

Laser-cum-KOH activation allows interfacial engineering of cardboard-derived carbon, tunable ionic states, and universal dye adsorption

In this study, we demonstrate the preparation of laser-cum KOH-activated porous carbon with tunable ionic states, unique surface chemistry, and physical texture from renewable and environmentally friendly precursors (waste cardboard boxes). The adsorption performance of the engineered adsorbents is examined on the adsorption of methyl blue (MB, anionic) and methylene blue (MeB, cationic). The adsorption mechanism was determined using detailed batch adsorption, and the MB was adsorbed via the formation of ternary complexes, whereas the MeB was adsorbed through cation-π interaction. Furthermore, the non-activated laser-induced carbon (LIC100) and the KOH-activated carbon (KAC(L)) exhibit superior dye adsorption capacities of 9610 (MB) and 1882 mg g-1 (MeB), respectively. To the best of our knowledge, this is the highest ever reported at dye removal in the field of adsorptive dye removal. Langmuir isotherm model and pseudo-second-order are fitted well for both MB and MeB adsorption. Lastly, the carbons generated through this modern technique can be remodeled into a more secure device to obtain clean and microorganism-free water. This study showed the potential of laser-induced carbonization of KOH-activated substrate and provided unique insights into future development for universal dye adsorption and other possible applications.

Commercial paper as a promising carrier for biofilm cultivation of Chlorella sp. for the treatment of anaerobic digestate food effluent (ADFE): Effect on the photosynthetic efficiency

Microalgal technology is still economically unattractive due to the high cost associated with microalgal cultivation and biomass recovery from conventional suspension cultures. Biofilm-based cultivation is a promising alternative for higher biomass yield and cheap/easy biomass harvesting opportunities. Additionally, using anaerobic digestate food effluent (ADFE) as a nutrient source reduces the cultivation cost and achieves ADFE treatment as an added value. However, the search for locally available, inexpensive, and efficient support materials is still open to research. This study evaluates the potential of commercially available, low-cost papers as support material for biofilm cultivation of Chlorella sp. and treatment of ADFE. Among the four papers screened for microalgal attachment, quill board paper performed better in higher biomass yield and stability throughout the study period. The attached growth study was done in a modular food container vessel, using anaerobic digestate food effluent (ADFE) as a nutrient source and a basal medium as a control. The microalgae grew well on the support material with higher biomass yield and productivity of 108.64 g(DW) m-2 and 9.96 g (DW) m-2 d-1, respectively, in the ADFE medium compared with 85.87 g (DW) m-2 and 4.99 g (DW) m-2 d-1, respectively in the basal medium. Chlorophyll, a fluorescence (ChlF) probe, showed that cell density in the biofilm significantly changes the photosynthetic apparatus of the algae, with evidence of stress observed as the culture progressed. Also, efficient nutrient removal from the ADFE medium was achieved in the 100 %, 85 %, and 40.2 % ratios for ammoniacal nitrogen, phosphate, and chemical oxygen demand (COD). Therefore, using quill board paper as carrier material for microalgal cultivation offers promising advantages, including high biomass production, easy biomass harvesting (by scrapping or rolling the biomass with the paper), and efficient effluent treatment.

Wood waste valorization: Ethanol based organosolv as a promising recycling process

Wood waste is a valuable material that could constitute an abundant and inexpensive source for the production of new materials the recovery of energy. In Europe, about 46% of wood waste is recycled to particleboard and fiberboard, while the other fraction is incinerated. However, a considerable quantity of wood waste shows potential for its transformation into value-added products due to its compositional quality. In this work, wood waste collected at a mechanical treatment plant underwent organosolv treatment to produce a cellulose pulp suitable for manufacturing containerboard. Three variables (temperature, acid concentration, and ethanol concentration) were investigated to find an optimal solution to produce wood pulp by means of Design of Experiment. Wood waste was microwave-heated at 160 °C for 15 min using an acidified ethanol-water solution (2% w/w H2SO4 and 0.8 w/w ethanol concentration), producing pulp with an average cellulose content of 76% where 93% of initial cellulose was retained. Thanks to a one-pot approach, ethanol was totally recovered, 62% of initial lignin was precipitated, and 20 g/l of hemicellulose-derived sugars solution was obtained. Finally, three wood waste samples collected in different periods of the year yielded comparable outcomes, suggesting a good reproducibility of the organosolv process. ANOVA test with a significance level of 0.01 showed a p-value of 0.029 and 0.235 for cellulose content and cellulose recovery, respectively. This study paves the way for an industrial symbiosis between recycling centers and paper mills located in the same territory.

Criteria for Assessing Sustainability of Lignocellulosic Wastes: Applied to the Cellulose Nanofibril Packaging Production in the UK

Extensive use of petrochemical plastic packaging leads to the greenhouse gas emission and contamination to soil and oceans, posing major threats to the ecosystem. The packaging needs, hence, are shifting to bioplastics with natural degradability. Lignocellulose, the biomass from forest and agriculture, can produce cellulose nanofibrils (CNF), a biodegradable material with acceptable functional properties, that can make packaging among other products. Compared to primary sources, CNF extracted from lignocellulosic wastes reduces the feedstock cost without causing an extension to agriculture and associated emissions. Most of these low value feedstocks go to alternative applications, making their use in CNF packaging competitive. To transfer the waste materials from current practices to the packaging production, it is imperative to assess their sustainability, encompassing environmental and economic impacts along with the feedstock physical and chemical properties. A combined overview of these criteria is absent in the literature. This study consolidates thirteen attributes, delineating sustainability of lignocellulosic wastes for commercial CNF packaging production. These criteria data are gathered for the UK waste streams, and transformed into a quantitative matrix, evaluating the waste feedstock sustainability for CNF packaging production. The presented approach can be adopted to decision scenarios in bioplastics packaging conversion and waste management.

Bacterial Cellulose-Based Blends and Composites: Versatile Biomaterials for Tissue Engineering Applications

Cellulose of bacterial origin, known as bacterial cellulose (BC), is one of the most versatile biomaterials that has a huge potential in tissue engineering due to its favourable mechanical properties, high hydrophilicity, crystallinity, and purity. Additional properties such as porous nano-fibrillar 3D structure and a high degree of polymerisation of BC mimic the properties of the native extracellular matrix (ECM), making it an excellent material for the fabrication of composite scaffolds suitable for cell growth and tissue development. Recently, the fabrication of BC-based scaffolds, including composites and blends with nanomaterials, and other biocompatible polymers has received particular attention owing to their desirable properties for tissue engineering. These have proven to be promising advanced materials in hard and soft tissue engineering. This review presents the latest state-of-the-art modified/functionalised BC-based composites and blends as advanced materials in tissue engineering. Their applicability as an ideal biomaterial in targeted tissue repair including bone, cartilage, vascular, skin, nerve, and cardiac tissue has been discussed. Additionally, this review briefly summarises the latest updates on the production strategies and characterisation of BC and its composites and blends. Finally, the challenges in the future development and the direction of future research are also discussed.

3D carbon aerogel from waste corrugated cardboard as a photothermal reservoir for solar steam generation

Three-dimensional carbon aerogel (CA800) was prepared from waste corrugated cardboard (WCC) by the procedure of slurrying, solvent replacement, drying, and carbonization in turn, and the product was explored as an all-in-one evaporator for solar steam generation without bulk water. Carbonization of the precursor was investigated using thermogravimetric analyzer coupled with Fourier transform infrared spectrometer. Results showed that CO2, CO, furfural, and levoglucosan were released during pyrolysis of WCC within the range of 300 to 390 °C, while polymerization of newly formed char between 390 and 580 °C mainly resulted in the formation of CO2 and CO. Both pyrolysis and polymerization reactions can be described by diffusion-controlled mechanisms, and the activation energies were 155.62 and 11.17 kJ mol-1, respectively. CA800 possessed a BET surface area of 210 m2 g-1. Light can be effectively absorbed and converted into heat by CA800, and its surface temperature achieving 73 °C under 1 kW m-2 irradiation. CA800 had outstanding wettability due to the presence of hydrophilic minerals in carbon matrix, and it was able to store as much as 15 times its own weight in water due to its abundant interconnected channels and hierarchical nanopores. Solar-driven water evaporation rate over CA800 achieved 1.72 kg m-2 (normalized to projection area), which was nearly 6 times higher than the value achieved by the bare water system. The photothermal conversion efficiency was calculated to be 118 %, and the overestimated efficiency was caused by the environmental energy gained by the cold evaporation surface of CA800.

Detection of nanoplastics based on surface-enhanced Raman scattering with silver nanowire arrays on regenerated cellulose films

Plastic pollution has steadily become a global issue due to its ubiquity and degradation into micro and nanoparticles. Herein, we report the construction of surface-enhanced Raman scattering (SERS)-active array substrates with regenerated cellulose (RC) and plasmonic nanoparticles (AuNRs and AgNWs) via a simple vacuum-assisted filtration method using a silicon mask for rapid nanoplastic detection. The AgNWs/RC film exhibited a SERS intensity of crystal violet approximately six times higher than that of the AuNRs/RC film with a high enhancement factor of 1.8 × 10⁷. Moreover, the AgNWs/RC film exhibits a better SERS activity for polystyrene nanoplastic detection than the AuNRs/RC film because the dense AgNW network structures are well suited for nanoplastic detection. The AgNWs/RC film can detect PS nanoplastics down to 0.1 mg/mL with a good reproducibility of the SERS signal. The low-cost, flexible, and highly sensitive AgNWs/RC films could provide an efficient and rapid SERS-based method for nanoplastic detection.

Biodegradable Cellulose Film Prepared From Banana Pseudo-Stem Using an Ionic Liquid for Mango Preservation

The excessive use and disposal of plastic packaging materials have drawn increasing concerns from the society because of the detrimental effect on environment and ecosystems. As the most widely used fruit packing material, polyethylene (PE) film is not suitable for long-term preservation of some tropical fruits, such as mangos, due to its inferior gas permeability. Cellulose based film can be made from renewable resources and is biodegradable and environmental-friendly, which makes it a promising alternative to PE as a packaging material. In this study, cellulose film synthesized from delignified banana stem fibers via an ionic liquid 1-Allyl-3-methylimidazolium chloride ([AMIm][Cl]) were evaluated as packing material for mangos preservation. The moisture vapor transmission rate and gas transmission rate of the synthesized cellulose film were 1,969.1 g/(m²⋅24 h) and 10,015.4 ml/(m²⋅24 h), respectively, which are significantly higher than those of commercial PE films. The high permeability is beneficial to the release of ethylene so that contribute to extend fruit ripening period. As a result, cellulose film packaging significantly decreased the disease and color indexes of mangos, while prolonged the storage and shelf life of marketable fruits. In addition, the cellulose film was decomposed in soils in 4 weeks, indicating an excellent biodegradability as compared to the PE plastic film.

Valorization of Wheat Straw for the Paper Industry: Pre-extraction of Reducing Sugars and Its Effect on Pulping and Papermaking Properties

Cleaner production of sugars and pulp from renewable feedstocks has captured significant scientific attention in the recent past because they can be used for various end applications. In the papermaking industry, a major fraction of hemicellulosic sugars is lost during the pulping. The present study aims at retrieving these hemicellulosic sugars through alkali-, hot-water-, and acid-mediated extraction prior to pulping, which otherwise would have been lost during pulping and washing of pulp. These retrieved sugars can be used as feedstocks for renewable energy and value-added products. Different pretreatments were applied, aided with varying temperature, chemical concentrations, and time. Substantial amounts of total reducing sugars (TRSs) up to 21.98, 13.2, and 15.01% were extracted prior to pulping by acid, alkali, and hot-water pretreatments. Compositions of mono sugars present in the treated liquor were also characterized and confirmed by high-performance liquid chromatography analysis. The morphological changes in the wheat straw after pre-extraction were studied using the field emission gun scanning electron microscopy technique. Pulping of untreated and pretreated wheat straw was carried out at different alkali charges (12, 14, and 16% NaOH). Among all, acid-pretreated straw showed an increase in pulp yield by 10.9% at a 16% alkali charge. Physical strength properties of different pulps were further examined. Alkali- and hot-water-pretreated straw pulp retained 94.26 and 83.16% tensile indices and 92.43 and 87.02% burst indices, respectively. An increase in tear index up to 4.32, 2.01, and 2.30% for alkali-, hot-water-, and acid-pretreated straw pulp was achieved, respectively. Hot-water- and alkali-pretreated wheat straw was observed to be conducive for paper production. The integrated use of wheat straw for extraction of underutilized sugars and pulp production in this way may serve as a key stepping stone for future biorefinery designs in pulp and paper mills.