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We propose a new method for the extraction of cellulose nanocrystals (CNCs) from post-consumer cotton textiles through surface functionalization followed by mechanical treatment. Cotton-based textiles were esterified using an 85 wt% solution of citric acid at 100 °C, then further fibrillated in a microfluidizer. The final product, citrated cellulose nanocrystals (CitCNCs), was a dispersion of needle-like nanoparticles with high crystallinity. Up to 78 wt% of the cotton fabric was converted to CitCNCs that exhibited higher yields and a higher surface group content than CNCs extracted through H2SO4 hydrolysis, although CitCNCs showed a broader size distribution and decreased thermal stability. Experimental data supported by DFT calculations showed that the carboxyl groups on the CitCNC surface are bonded to cellulose by mono or diester linkages. An early-stage life cycle assessment (LCA) was performed to evaluate the environmental impact of using discarded textiles as a source of cellulose and analyze the environmental performance of the production of CitCNCs. Our work showed a significant reduction in the environmental burden of CNC extraction using post-consumer cotton instead of wood pulp, making clothing a good feedstock. The environmental impact of CitCNC production was mainly dominated by citric acid. As a proof of concept, around 58 wt% of the citric acid was recovered through evaporation and subsequent crystallization, which could reduce climate impact by 40%. With this work, we introduce a catalyst-free route to valorize textiles with the extraction of CitCNCs and how conducting LCA in laboratory-scale processes might guide future development and optimization.

Background: Bio-based nanomaterials such as cellulose nanocrystals (CNCs) have been increasingly explored in nanotechnology owing to their chemophysical properties, self-assembly, and low toxicity. Introduction: CNCs can be isolated from various cellulosic biomass sources. Textiles which are mostly made of cotton, are under-utilized biomass that after their lifetime is either burned or dumped into landfills. Method: In this study, cotton-based textiles are studied as a source of CNCs. CNCs were extracted from textiles with and without bleaching before the acid hydrolysis step, and further comparing them with the properties of industrial microcrystalline cellulose-derived CNCs. Nanocrystals were synthesized from the three different sources and their morphology, thermal properties, and colloidal stability were compared. Results: The result show similar thermal properties and morphological characteristics for the three synthesized CNCs, and similar colloidal stability between the two textile-based CNC dispersions, suggesting that the dyes on CNCs do not impact the quality of the product. Removing the bleaching pre-treatment -a water-demanding and toxically harmful step- before CNC extraction provides cost and environmental benefits without compromising on the CNC quality. Conclusion: This project seeks to streamline the CNC synthesis process with the long-term goal of eventually facilitating the textile recycling industry.

Iron nanoparticles are strong reducing agents with a variety of applications. Their reactivity is governed by their valence state as well as their available surface. As such their widespread use is limited by their colloidal instability. This work investigated the role of cellulose nanocrystal stabilizers on the shape, size, density, and colloidal stability of iron nanoparticles. Colloidally-stable zero-valent iron nanoparticles (nZVI) were synthesized through a classical redox reaction of iron sulfate using cellulose nanocrystals (CNCs) as stabilizers. Spherical nZVI nanoparticles were formed with high surface roughness and mean size of ~ 130 nm. CNC:nZVI nanoparticles made with greater amounts of CNCs were measured to have lower solidity, indicating that these nanocomposite nanoparticles are less compact. Low solidity nanoparticles were observed to be irregular aggregates composed of ~ 10 nm nZVI particles stabilized on CNCs. CNC:nZVI nanoparticles remained colloidally stable after more than 40 days. Mobility studies confirmed both their colloidal stability under flow conditions as well as the strong interaction between CNCs and nZVI as demonstrated by achieving over 97% breakthrough within 2 pore volumes and no measurable particle retention, respectively. It was hypothesized that cellulose nanocrystals play a triple role in nZVI stability: as a foreign surface to encourage stable nucleation over fast aggregation, as a capping agent to control particle growth, and as a stabilizer to prevent iron nanoparticles from aggregating into colloids. Our results highlight the impact of the presence of CNCs on the rates of nucleation, growth, aggregation, and aging of nZVI particles, demonstrating that CNCs have the potential to act as nZVI stabilizers.

The need for multifunctional, robust, reusable, and high-flux filters is a constant challenge for sustainable water treatment. In this work, fully biobased and biodegradable water purification filters were developed and processed by the means of three-dimensional (3D) printing, more specifically by fused deposition modelling (FDM).The polylactic acid (PLA) – based composites reinforced with homogenously dispersed TEMPO-oxidized cellulose nanofibers (TCNF) or chitin nanofibers (ChNF) were prepared within a four-step process; i. melt blending, ii. thermally induced phase separation (TIPS) pelletization method, iii. freeze drying and iv. single-screw extrusion to 3D printing filaments. The monolithic, biocomposite filters were 3D printed in cylindrical as well as hourglass geometries with varying, multiscale pore architectures. The filters were designed to control the contact time between filter’s active surfaces and contaminants, tailoring their permeance.All printed filters exhibited high print quality and high water throughput as well as enhanced mechanical properties, compared to pristine PLA filters. The improved toughness values of the biocomposite filters clearly indicate the reinforcing effect of the homogenously dispersed nanofibers (NFs). The homogenous dispersion is attributed to the TIPS method. The NFs effect is also reflected in the adsorption capacity of the filters towards copper ions, which was shown to be as high as 234 and 208 mg/gNF for TCNF and ChNF reinforced filters, respectively, compared to just 4 mg/g for the pure PLA filters. Moreover, the biocomposite-based filters showed higher potential for removal of microplastics from laundry effluent water when compared to pure PLA filters with maximum separation efficiency of 54 % and 35 % for TCNF/PLA and ChNF/PLA filters, respectively compared to 26 % for pure PLA filters, all that while maintaining their high permeance.The combination of environmentally friendly materials with a cost and time-effective technology such as FDM allows the development of customized water filtration systems, which can be easily adapted in the areas most affected by the inaccessibility of clean water.

Nanocellulose isolation fromlignocellulose is a tedious and expensive processwith high energy and harsh chemical requirements, primarily due to the recalcitrance of the substrate, which otherwise would have been costeffective due to its abundance. Replacing the chemical steps with biocatalytic processes offers opportunities to solve this bottleneck to a certain extent due to the enzymes substrate specificity and mild reaction chemistry. In this work, we demonstrate the isolation of sulphate-free nanocellulose from organosolv pretreated birch biomass using different glycosyl-hydrolases, along with accessory oxidative enzymes including a lytic polysaccharide monooxygenase (LPMO). The suggested process produced colloidal nanocellulose suspensions (zeta-potential-19.4 mV) with particles of 7-20 nm diameter, high carboxylate content and improved thermostability (T-o= 301 degrees C, T-max= 337 degrees C). Nanocelluloseswere subjected to post-modification using LPMOs of different regioselectivity. The sample from chemical route was the least favorable for LPMO to enhance the carboxylate content, while that from the C1-specific LPMO treatment showed the highest increase in carboxylate content. (c) 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).

Azo dyes and Chlorinated Organic Compounds (COCs) like trichloroethylene (TCE) are environmental contaminants found in textile industry effluents and groundwater sites respectively. Both compounds are carcinogenic to humans and hazardous to the environments they contaminate and are difficult to treat by conventional wastewater processes. In this study, electrocatalytically active nanocomposite membranes were fabricated and evaluated for their ability to remove azo dyes. Nano zero-valent iron (nZVI) particles were grown and stabilized within a network of dispersed single and double-walled carbon nanotubes (SW/DWCNTs), and this mixture was filtered onto the surface of a microfiltration polyethersulfone (PES) support membrane to form a porous, conductive, reactive surface nanocomposite. These catalytic surface nanocomposites were tested as a cathode alongside a graphite anode with -2 V applied for their ability to remove methyl orange (MO) dye in both a batch system and a continuous dead-end filtration system. In a well-mixed batch, it was found that complete removal of 0.25 mM MO (7.5 mMoles in 30 mL) by the charged membranes occurred within 2–3 h of operation. The performance of these nZVI-SW/DWCNT cathodes alongside controls suggests that the application of an applied current regenerates the spent reactivity of the embedded iron nanoparticles. Systems using nZVI-SW/DWCNT membranes achieved ∼ 87 mol % removal of methyl orange and demonstrated a 2.7 times greater removal rate than batch tests of analogous parameters, and 1.6 times greater than other continuous tests using membrane surface composites that lacked nZVI. Furthermore, the application of voltage to the membrane thin film surface composite increases the transmembrane flux through system, allowing for increased throughput at a given feed pressure. The results of these experiments show promise in the continuous removal of contaminants from wastewaters through reductive degradation, such as azo dyes and chlorinated organic compounds. Continuous regeneration of nZVI reactivity on a membrane surface offers substantial advantages over single-use approaches for the treatment of azo dyes and COCs in solution.