Cellulose Samples Research Articles

Reconstruction of drought and long-rain chronologies since the 17th century in central Japan using intra-annual tree-ring oxygen isotope ratios and documentary records

Abstract. Oxygen isotope ratios (δ18O) of tree-ring cellulose and historical documentary records are widely used to explore the hydroclimatic conditions of the past. In this study, we attempted to reconstruct chronologies of local climate disasters spanning 4 centuries in central Japan using these proxy data. For tree-ring δ18O measurements, we prepared cellulose samples from a long-living cedar tree with continuously broad ring widths. To enhance the temporal resolution, we divided each annual ring into several (mainly six) segments. Analysis of the correlations with observed relative humidity and precipitation data revealed that the intra-ring δ18O variations in the sample tree reflected the hydroclimatic conditions from April to July in each year. Subsequently, we chronologically listed the occurrence of eight types of disasters in the 17th to 19th centuries in the area adjacent to the sample tree according to 20 titles of “Town/City history”, which is a compilation of historical documentary records from the local municipality. By comparison with the intra-ring δ18O data, we found that most of the major droughts and long rains recorded in the historical documents occurred in the Baiu rainy season (typically June–July) or pre-Baiu season, corresponding to the growing season of the sample tree. Based on an analysis of the intra-ring δ18O variation for documentary-based drought and long-rain years, we set thresholds of intra-ring δ18O values to identify and extract drought and long-rain years. Drought and long-rain chronologies obtained by applying these thresholds were temporally continuous, complementing those based on documentary records. They depicted the relationships between the frequency of these climate disasters and the occurrence of major famines and the long-term tendency of length and magnitude of the Baiu rainy season in historical times.

Towards understanding and directing the nitration of cellulose

AbstractNitrocellulose is industrially produced from cellulose by treatment with nitric and sulfuric acid. While sulfuric acid is known to catalyse the hydrolysis of cellulose, its effect on nitrated cellulose has not been reported before. Herein we show by gel permeation chromatography that hydrolysis of nitrocellulose derived from cotton linters over a one-week timescale reduces the length of the polymer chains via a two-stage reaction process similar to that observed for cellulose. Powder X-ray diffraction patterns and scanning electron microscopy images of nitrated cellulose samples originating from plant and bacterial sources are compared with highly processed nitrocellulose membranes and show a variation in morphology and an enhancement of sample crystallinity. This highlights a selective mechanism where the amorphous domains are preferentially hydrolysed over the crystalline domains, which is also common behaviour with cellulose. Overall, this work shows that the timescale for nitration exerts control over the resulting product crystallinity, morphology and polymer chain length. Graphical abstract

Oxidized cellulose 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) for Mn(II) adsorption

The presence of excess Mn²⁺ in water can result in unpleasant odors and tastes, and its consumption can lead to neurological disorders in humans. Adsorption using oxidized cellulose is an efficient method for removing Mn²⁺ ions. In this study, cellulose was oxidized using the TEMPO/NaOCl/NaBr system with varying NaOCl concentrations (5, 15, and 30 mmol/g) to identify the optimum conditions for Mn²⁺ adsorption. The carboxyl group content in the oxidized cellulose samples was 0.2393, 0.2435, and 0.2664 mmol/g, respectively. The adsorption efficiencies were 92.40%, 91.71%, and 91.43%, with the highest efficiency observed at 5 mmol/g NaOCl. The decrease in adsorption efficiency at higher NaOCl concentrations was attributed to the oxidation of secondary hydroxyl groups, forming undesirable ketone groups and disrupting the reaction pathway. FTIR analysis confirmed successful oxidation with a new absorption band at 1646 cm⁻¹. XRD analysis showed an increase in the crystalline index to 82.8%, 83.1%, and 83.13% for NaOCl concentrations of 5, 15, and 30 mmol/g, respectively. This study highlights the potential of TEMPO/NaOCl/NaBr-oxidized cellulose as an effective adsorbent for Mn²⁺ removal under optimized conditions.

Fluorescence analysis of wood chips and their constituents

Abstract Micro-spectral analysis and fluorescence decay experiments of beech and oak chips as well as their main constituents lignin and cellulose are reported. While the lignin spectrum shows two fluorescence bands of almost identical intensity around 500 nm and 560 nm, the cellulose spectrum is dominated by a band around 500 with a less pronounced shoulder at 560 nm, whose intensity increases with the amount of residual lignin. Fluorescence decay kinetics are bi-exponential with lifetimes around 0.5 ns and 2.5 ns and an increasing contribution of the short-lived component with an increasing amount of lignin. Both data sets indicate that a quantification of residual lignin in cellulose samples obtained after decomposition of beech wood appears possible in a concentration range of 2–10 %. This may provide a non-destructive and label-free test of the quality of decomposition.

Formation of disordered regions is caused by drying in cellulose microfibrils of Egeria densa

Periodically disordered regions can be induced by drying in cellulose microfibrils of several plant species. In this study, cellulose nanocrystals were prepared from never-dried and oven-dried cellulose samples from Egeria densa by sulfuric acid hydrolysis and observed with transmission electron microscopy. Cellulose nanocrystals from never-dried samples were long (> 1 μm in length), curved smoothly, and had very few kinks. In contrast, cellulose nanocrystals from oven-dried samples were shorter (50–600 nm in length) and were almost entirely straight. These results indicated that never-dried cellulose microfibrils lacked the disordered regions along the microfibril and exhibited a continuous, low bending rigidity. Never-dried and oven-dried cellulose samples from E. densa were subjected to acid hydrolysis, dissolution in 1% LiCl/dimethylacetamide, and size-exclusion chromatography–multi-angle laser-light scattering analysis. After acid hydrolysis, oven-dried samples showed a significantly lower degree of polymerization than never-dried samples. In addition, oven-dried samples showed a unimodal and narrow molar mass distribution, whereas never-dried samples showed a bimodal distribution after acid hydrolysis. These results indicated that oven-drying induces the disordered regions along the cellulose microfibril and that the disordered regions are cleaved by acid hydrolysis.

In-situ X-ray analysis of cold alkali dissolution of cellulose pulps of various origin

This article elucidates the dissolution of cellulose from different raw materials in NaOH aqueous solution via the combination of synchrotron-radiation-based SAXS/WAXS characterization. The X-ray measurements probed the mesostructure of the cellulose samples during the freeze-thawing cycle allowing tracking the initial swelling of the structure, the kinetics of disintegration of the cellulose crystallites as well as controlling the final state of the cellulose solution, i.e. presence or absence of cellulose aggregates. The individual SAXS and WAXS measurements were fitted and modelled to enable visualisation and tracking of the changes in the structure in relation to temperature during cooling and warming phases. To further increase the understanding of the parameters affecting dissolution different cellulose samples and solution compositions were considered. For this purpose the effect of increasing the concentration of NaOH and adding Zn2+ has been carefully investigated as well as the importance of the cellulose origin. We found consistent development that the dissolution occurs faster at higher concentrations of NaOH and with Zn2+ regardless the origin. Nevertheless, SAXS data show that materials with a larger amount of cellulose I show more apparent swelling in mesoscopic structure than bleached agricultural containing cellulose II. Despite few crystalline residues after the complete cooling-heating cycle shown by WAXS, some cellulose was not completely dissolved as some network structure remained in the samples under the test condition as suggested by SAXS.

Chemical thermodynamics of biomass, cellulose, and cellulose derivatives: A review

This article provides a review of the research on the chemical thermodynamics and thermochemistry of biomass, cellulose, and its derivatives such as ethers, esters, and oxycelluloses. For diverse biomass types, gross and net heating values were studied. It has been established that these energetical characteristics of biomass can be calculated using a superposition of the energetical characteristics of the main components of biomass such as cellulose, hemicelluloses, lignin, lipids, proteins, etc. The pelletization of biomass improves its fuel performance. It was shown that, if the ultimate goal is to generate the maximum amount of thermal energy, then it is more profitable to directly burn the initial biomass in the form of pellets than to burn the amount of solid or liquid biofuel that can be extracted from this biomass. After the cellulose study, the direct and exact thermochemical method for determining the crystallinity degree of this biopolymer was proposed. In addition, the standard combustion and formation enthalpies of various cellulose samples were studied. As a result, the thermodynamic characteristics of four crystalline allomorphs of cellulose, CI, CII, CIII, and CIV, were obtained and their thermodynamic stability was evaluated. The thermochemistry of enzymatic hydrolysis of cellulose was studied. In addition. The thermodynamical characteristics of various cellulose derivatives were determined, and the thermochemistry of the reactions of cellulose alkalization, etherification, esterification, and oxidation was studied.

Dynamic nuclear polarization solid-state NMR spectroscopy as a tool to rapidly determine degree of modification in dialcohol cellulose

Dialcohol cellulose can be prepared by periodate-mediated oxidation of cellulose followed by reduction with borohydride. The two-step reaction creates a modified cellulose polymer which is ring-opened between the C2 and C3 carbons in the glucose unit. This material has attracted both scientific and commercial interest, due to its potential role in the transition towards a fossil-fuel-free society. In order to become a reliable component in the materials of tomorrow, chemical properties such as degree of modification must be accurately quantified. In this work we describe how solid-state NMR spectroscopy, enhanced by dynamic nuclear polarization (DNP), can be used for this purpose. Our results illustrate that it is possible to obtain high sensitivity enhancements in dialcohol cellulose with the DNP enhanced solid-state NMR technique. Enhancements above a factor of fifty, on a 400 MHz/263 GHz DNP system in the presence of 12 mM AMUPol radical were achieved. This allows us to quantify the degree of modification in dialcohol cellulose samples in time spans as short as 20 min using DNP enhanced multiple-contact cross polarization experiments. We also exemplify how DNP enhanced, 13C-13C dipolar recoupling experiments can be used for the same purpose and for studying chemical shift correlations in dialcohol cellulose.Graphical abstract

Physico-chemical properties and lipid binding capacity of bacterial cellulose synthesized on whey

Bacterial cellulose (BC) has significant potential for applications in the food industry due to its ability to stabilize food dispersion systems. In this work, the efficiency of BC biosynthesis on dairy industry waste was investigated, and these process parameters were studied: amount of substrate, titratable acidity, mass of synthesized cellulose. The physico-chemical properties and lipid binding capacity of the obtained gel films and dehydrated polysaccharide samples were determined. Bacterial cellulose was obtained under static conditions, in a liquid nutrient medium – whey. Lactose from whey was preliminarily hydrolysed with the enzyme preparation LACTA FREE to a glucose content of 1.93%. The mass of cellulose produced under static conditions by the symbiotic consortium Medusomyces gisevii was 3.84 g/l over 21 days at T=31°C. A correlation was noted between low amounts of glucose in the culture fluid on the 6th day of biosynthesis and a decrease in titratable acidity. The degree of conversion of glucose from fermented whey to the mass of produced bacterial cellulose was 22.6%. The maximum biosynthesis rate of 0.181 gL-1×day-1 (dry weight) was established on the 15th day of the process. The water retention capacity of the synthesized bacterial cellulose gel films was determined to be 82.35 ± 0.63 g/g. Lyophilized samples of bacterial cellulose were characterized by a higher water absorption capacity (22.44 g/g) compared to samples dehydrated at T=50°C (5.42 g/g). It was found that rehydrated samples of lyophilized cellulose had a 3.43 times higher ratio of free and bound moisture compared to dried BC samples. The bulk density of disaggregated cellulose was determined: lyophilized - 20 kg/m3, thermally dried - 170 kg/m3. The work provides a comparative analysis of the lipid binding capacity of BC and chitosan. Microbiological parameters of disaggregated bacterial cellulose were determined.

A soft processing technology for the extraction of cellulose from plant residues and agri-food wastes

In this study, cellulose was extracted from giant cane (GC), Posidonia oceanica seagrass (PO), coffee silverskin (CS), and brewer's spent grain (BSG) as alternatives to conventional sources of cellulose. The extraction protocol involved three steps: i) hemicellulose and lignin removal through alkaline hydrolysis in a 5% (w/v) NaOH solution (solid-to-liquid ratio = 1:100 g/mL, T = 25 °C, t = 2 h, ω = 300 rpm), ii) removal of organic compounds and ashes through a 95% (v/v) ethanol solution (solid-to-liquid ratio = 1:25 g/mL, T = 25 °C, t = 0.5 h, ω = 500 rpm), and iii) double bleaching in a 1% (w/v) acidic (pH = 4) NaClO2 solution (solid-to-liquid ratio = 1:50 g/mL, T = 90 °C, t = 1.5 h, ω = 500 rpm). Yield, purity, crystallinity degree, and morphology of cellulose extracted through a soft-chemical cascade process were assessed by gravimetric, infrared (FT-IR), nuclear magnetic resonance (NMR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses. Averaged cellulose extraction yields of 36.4, 38.6, 23.1, and 22.2% for GC, PO, CS, and BSG were obtained, respectively. All cellulose samples had high purity, though lower than the ultra-pure bacterial cellulose, which was due to the slight contamination from unremoved hemicellulose and lignin residues. Cellulose samples exhibited similar chemical features and the typical fibril-like morphology of microcrystalline cellulose (6–13 μm in width). The versatility of the proposed extraction procedure supports the sustainable conversion of low-cost organic biomasses to valuable products with manifold industrial applications (e.g., food packaging).

Chemical resistance in acidic environments of alkali-activated lightweight composites based on secondary raw materials

The durability problems in Portland cement are related to decalcification of C–S–H; alkali-activated composites are proposed as alternative, focusing on acid exposure and resistance. They were prepared from recycled materials, basic oxygen furnace carbonated and desulfurization slags. The standard material is 100% metakaolin geopolymer compared to slag-based alkali-activated materials (AAMs) with and without reinforcement of fibers (basalt, and cellulose), added in 4 wt%. The acidic environments are H2SO4, HCl, and HNO3 N = 2.14 (10, 7.5, and 12.5 wt%, respectively). The chemical resistance is improved by the addition of basalt fibers. The decrease in weight loss is 48% in HNO3 and 47% in HCl for AAM-Bas sample, while for AAM-Cell it is 9% in HCl and 34% in HNO3. The compressive strength of the AAM and AAM-Bas samples remains constant after HCl attack, while this acid attacks cellulose samples, which are stable in HNO3 and have a compressive strength of 10 MPa.

The presence of nanoparticles in aqueous droplets containing plant-derived biopolymers plays a role in heterogeneous ice nucleation.

Organic matter can initiate heterogeneous ice nucleation in supercooled water droplets, thereby influencing atmospheric cloud glaciation. Predicting the ice nucleation ability of organic matter-containing cloud droplets is challenging due to the unknown mechanism for templating ice. Here, we observed the presence of nanoparticles in aqueous samples of known ice-nucleating biopolymers cellulose and lignin, as well as in newly identified ice-nucleating biopolymers xylan and laminarin. Using our drop Freezing Ice Nuclei Counter (FINC), we measured the median ice nucleation temperature (T50) of xylan and of laminarin droplets of 2 μl to be -14.2 and -20.0 °C, respectively. Next, we characterized these samples using nanoparticle tracking analysis, and we detected and quantified nanoparticles with mean diameters between 132 and 267nm. Xylan contained the largest nanoparticles and froze at higher temperatures. Xylan also dictated the freezing in a 1:1:1:1 mixture with cellulose, lignin, laminarin, and xylan. Filtration experiments down to 300 kDa with the xylan sample indicated that the presence of nanoparticles triggered freezing. Overall, only samples with mean diameters above 150nm froze above -20 °C. Furthermore, we determined the ice-active site densities normalized to particle concentrations, surface area, and mass of the nanoparticles to show that the samples' nucleation site densities are similar to sea spray aerosols and nanometer-sized dust. The identification and characterization of xylan and laminarin as nanometer-sized ice-nucleating substances expands the growing list of organic matter capable of impacting cloud formation and thus climate.

Impact of Silver Nanoparticle Treatment and Chitosan on Packaging Paper's Barrier Effectiveness.

In this study, a comparative analysis of silver nanoparticles treatment and chitosan coating on packaging paper barrier properties was carried out. In order to examine the water, grease, and antibacterial barrier properties of silver nanoparticle-treated and chitosan-coated laboratory-obtained paper samples, a mixture of bleached softwood and hardwood celluloses was used. In order to conduct the comparative analysis SEM, water contact angle, Cobb60, and Kit tests were carried out on a cellulose sample, and four paper samples (three of them treated with silver nanoparticles-1, 2, and 3 mL/20 cm2 or chitosan coated-0.5, 1, and 2 g/m2) together with the inhibition activity against nine Gram-positive and Gram-negative bacteria, yeast, and fungal strains. The study found out that increasing the silver nanoparticle treatment and chitosan coating led to improved water resistance, while grease resistance was improved only for chitosan coated paper samples. Additionally, paper treated with 3 mL/20 cm2 of silver nanoparticles had the highest antibacterial protection (81.6%) against the Gram-positive bacterium Staphylococcus aureus, followed by Gram-negative Escherichia coli (75.8%). For the rest of the studied microorganisms, the average efficiency of the treated paper was 40.79%. The treatment of the paper with 1 and 2 mL/20 cm2 of silver nanoparticles was less effective-27.13 and 39.83%, respectively. The antibacterial protection of 2 g/m2 chitosan-coated paper samples was the most effective (average 79%) against the tested bacterial, yeast, and fungal strains. At 1 and 0.5 g/m2 chitosan coatings, the efficiency was 72.38% and 54.67%, respectively. Gram-positive bacteria, yeasts, and fungal strains were more sensitive to chitosan supplementation.

Investigating the Effects of the Physicochemical Properties of Cellulose-Derived Biocarbon on Direct Carbon Solid Oxide Fuel Cell Performance.

This paper presents a study of the characteristic effects of the physicochemical properties of microcrystalline cellulose and a series of biocarbon samples produced from this raw material through thermal conversion at temperatures ranging from 200 °C to 850 °C. Structural studies revealed that the biocarbon samples produced from cellulose had a relatively low degree of graphitization of the carbon and an isometric shape of the carbon particles. Based on thermal investigations using the differential thermal analysis/differential scanning calorimeter method, obtaining fully formed biocarbon samples from cellulose feedstock was possible at about 400 °C. The highest direct carbon solid oxide fuel cell (DC-SOFC) performance was found for biochar samples obtained via thermal treatment at 400-600 °C. The pyrolytic gases from cellulose decomposition had a considerable impact on the achieved current density and power density of the DC-SOFCs supplied by pure cellulose samples or biochars derived from cellulose feedstock at a lower temperature range of 200-400 °C. For the DC-SOFCs supplied by biochars synthesised at higher temperatures of 600-850 °C, the "shuttle delivery mechanism" had a substantial effect. The impact of the carbon oxide concentration in the anode or carbon bed was important for the performance of the DC-SOFCs. Carbon oxide oxidised at the anode to form carbon dioxide, which interacted with the carbon bed to form more carbon oxide. The application of biochar obtained from cellulose alone without an additional catalyst led to moderate electrochemical power output from the DC-SOFCs. The results show that catalysts for the reverse Boudouard reactions occurring in a biocarbon bed are critical to ensuring high performance and stable operation under electrical load, which is crucial for DC-SOFC development.

β-(1 → 4)-Polyglucuronic acids with C2/C3-ketones prepared from regenerated cellulose by catalytic oxidation using solid NaOCl·5H2O

Three commercial regenerated cellulose samples were subjected to TEMPO-catalyzed oxidation using solid NaOCl·5H2O as the primary oxidant for structural analyses of the oxidized products (TEMPO = 2,2,6,6-tetramethylpiperidine-1-oxyl). The regenerated cellulose/water slurries became transparent solutions after oxidation for 60 min. The yields of the oxidized products were almost 100 % when they were isolated as precipitates in ethanol/water mixtures. The solution-state NMR spectra revealed that the oxidized products were almost pure water-soluble β-(1 → 4)-polyglucuronic acids; the reaction conditions described herein ensured the complete oxidation of the C6–OH groups in the regenerated cellulose samples to C6-carboxy groups. However, the solid-state 13C NMR spectra of the oxidized products indicated that C2/C3-ketones (<20 % of the total units) were formed during side reactions, which is characteristic for oxidized products prepared from regenerated cellulose with the C2/C3-glycol structure. These ketones were likely to form intermolecular hemiacetal linkages in the oxidized products. During conductivity titration of the oxidized products, it is necessary to control the sample masses to accurately determine the carboxy contents. The mass-average degree of polymerization decreased from 330 to 890 for the original regenerated cellulose samples to 65–79 for the oxidized products; substantial depolymerization is inevitable during TEMPO-catalyzed oxidation of the regenerated cellulose samples.

Removal of Glyphosate with Nanocellulose for Decontamination Purposes in Aquatic Systems

(1) The excessive and incorrect use of agricultural pesticides has caused environmental pollution, with a final destination in aquatic environments. Among the widely used agricultural pesticides, glyphosate stands out for weed control, which according to the World Health Organization (WHO) is potentially carcinogenic in humans. Once in an aquatic environment, decontamination aimed at removing the pesticide is not always a simple task. In this sense, it is necessary to develop low-cost, sustainable procedures with a high remediation capacity. (2) In this context, a nanocellulose-based biopolymer was developed to removal glyphosate from aquatic environments. Nanocellulose was obtained from a cellulose sample from eucalyptus wood and was characterized by scanning and double-beam electron microscopy, scanning microscopy with an energy dispersive detector and Fourier transform infrared (FTIR) spectroscopy. Adsorption studies were carried out to evaluate the retention of glyphosate by nanocellulose. (3) Nanocellulose showed a value of 4.7 mg of glyphosate per gram of nanocellulose, and organomodified nanocellulose showed the removal of 6.1 mg of glyphosate per gram of nanocellulose, as evaluated in pseudo-first-order kinetic models. (4) The biomaterial has a sustainable and renewable origin, has potential for contaminant removal and can be applied to contaminated aquatic systems.

Evidence of a Rod-like Structure for Hydroxypropyl Cellulose Samples in Aqueous Solution.

Because hydroxypropyl cellulose (HpC) is a popular polymeric material that forms a liquid crystalline phase in solutions with various kinds of solvents, including water, it is commonly thought that HpC has a typical rod-like structure in solution. In this study, the structures of commercial HpC samples in aqueous solution with average molar substitution numbers (MS) ranging from 3.6 to 3.9 and weight-average molar masses (Mw) ranging from 36 to 740 kg mol-1 were investigated in detail. We first used multiple techniques, including standard static and dynamic light scattering (SLS and DLS), neutron and X-ray scattering experiments, and viscometric measurements, to obtain clear evidence of rod-like structures quantitatively. The dependence of excess scattering intensities for HpC samples under dilute conditions on the magnitude of the scattering vector over a wide range from 8.9 × 10-3 to 3.0 × 10 nm-1 was reasonably described by the form factor of rod particles with length (L) and diameter (d). Although the determined L value was close to the contour length (lc) calculated from the Mw values in the lower Mw range, L became obviously less than lc with increasing Mw. The radius of gyration (Rg) determined via SLS measurements was proportional to L by a factor of approximately 3.5 ∼ √12 over the Mw range examined. These observations revealed that the conformation of HpC molecules changes from an elongated single chain to a certain folded structure, maintaining the shape of the rod-shaped particles. Moreover, the Mw dependencies of the intrinsic viscosities and translational diffusion coefficients of the HpC samples resulting from DLS measurements were reasonably described with a theoretical rod-like particle model, assuming that L and d are identical to those resulting from the scattering behaviors.

Carbon Emission Pathways of Biodegradable Thermoplastic-based Species in Natural and Simulated Aqueous Conditions

This study assessed the carbon emission pathways of the biodegradation processes of bio-based thermoplastic moieties in two aqueous (surface and simulated marine water) environments and its implications on environmental quality. The physicochemical parameters of the aqueous media were determined using standard methods. The American Society for Testing and Materials’ standard was used to assess amount of CO2 evolved. Cellulose, bioplastic and polyethylene were inserted in two aquatic environments and arranged thrice in a randomized experimental arrangement of 2x4x3. Ultimate biodegradations of the test films were monitored using Scanning Electron Microscopy (SEM). The amount of CO2 evolved was assayed using the titration method. Data obtained were subjected to descriptive and inferential statistical analyses using Statistical Packages for Social Sciences (SPSS) version 25.0. After biodegradation, the initial values of the physicochemical parameters were within recommended values of the WHO standards with slight (less than 2%) differences. Moreover, CO2 captured from the two aqueous conditions were lower than the amount of CO2 evolved in aqueous solution with cellulose which is a natural polymer in this order: 88.725×102 mg from the soaked cellulose samples in marine &gt; 85.215×102 mg of CO2 evolved from cellulose entrenched in surface water &gt; 82.758×102 mg of CO2 evolved from bioplastic soaked in marine water &gt; 82.758×102 mg of CO2 evolved from bioplastic soaked in surface water &gt; 65.046×102 mg of CO2 evolved from polyethylene soaked in marine water &gt; 60.152×102 mg of CO2 evolved from polyethylene soaked in surface water. Moreover, the SEM results revealed high level of biodegradation and growth of biofilm on the biodegradable thermoplastics while the nylon 6 had little or no biofilm growth because of the recalcitrant nature. This study concluded that some biodegradable thermoplastics can biodegrade totally in aquatic environments without the release of greenhouse gases that could threaten the integrity of the aquatic environment as well as the release of toxic residues.

A New Concept for Interpretation of the Viscoelastic Behavior of Aqueous Sodium Carboxymethyl Cellulose Systems.

Viscoelastic behaviors of aqueous systems of commercially available sodium carboxymethyl cellulose (NaCMC) samples with the degrees of substitution (DS) of approximately 0.68 and 1.3, and the weight-average molar masses (Mw) higher than 200 kg mol-1 dissolved in pure water and aqueous sodium chloride solutions were investigated over a wide concentration (c) range of NaCMC samples. The dependencies of the specific viscosity (ηsp), the average relaxation time (τw), and the reciprocal of the steady-state compliance (Je-1) on c were discussed. The relationships ηsp ∝ c3, τw ∝ c2, and Je-1 ∝ c, characteristic of the rod particle suspensions, were clearly observed in a range lower than the c where the critical gel behavior was observed. Thus, a new concept based on the rheology of rod particle suspensions was employed to interpret the viscoelastic behaviors obtained in the c range. In this context, NaCMC polymer molecules are assumed to behave as extended rod particles with length (L) and diameter (d), including effective electrostatic repulsive distances, due to the dissociation of Na+ in aqueous systems. Thus, the number density of polymer molecules is given to be ν = c/Mw, and viscoelastic parameters such as ηsp, τw, and Je-1 are calculated using the theoretical model for rod particle suspensions proposed by Doi and Edwards. This concept reasonably described not only the viscoelastic data obtained in this study but also those from other groups using NaCMC samples with different DS and Mw values.

Juncus rigidus high biomass and cellulose productivity under wastewater salinity stress - A paradigm shift to the valorization of RO reject water

The use of water purifiers is intensively catching up and disposing of reverse osmosis reject water is of great concern. Reject water management using conventional methods is costly and harmful to the environment. To address this issue, the present study aims to utilize reverse osmosis reject wastewater using an eco-friendly approach. Juncus rigidus was treated with reject wastewater containing different salinity levels. Wastewater-treated plant dry biomass increased with increasing reject water salinity, and 625.3 g dry biomass recovered in treatment-B (~18,520 ppm). However, ~23,220 ppm wastewater salinity was lethal to the plants. The cellulose was extracted by alkali hydrolysis. The cellulose content in the wastewater-treated biomass was significantly higher in Treatment-B compared to both the control and Treatment-A (~12,744 ppm). The water salinity enhanced the cellulose (26.49 %) production in J. rigidus. Cellulose purity was confirmed using spectroscopic and thermogravimetric means. XRD shows highest crystallinity Index (77.29) with a d-spacing of 4.7 Å and 5.7 nm crystallite size in treatment-B. FTIR results reveal well-defined relevant peaks for OH, CH, CO, CH2, C-O-C, CO groups in treatment-B cellulose. Salinity impacts carboxyl groups in treatment B cellulose with a sharper and intense peak at 1644 cm−1 responsible for water absorption. Treatment-B exhibits higher thermal stability due to increased crystallinity. DSC shows endothermic depolymerization of cellulose with distinct peaks for different treatments. Morphological traits got better with increasing salinity with no adverse effect on cellulose. Salinity moderately affected the water absorption capacity of cellulose. All cellulose samples were devoid of gram-negative bacteria known by microbial test. This pioneering work underscores the plant's remarkable capacity not only to accomplish the circular economy by the valorization of wastewater obtained from various water purifiers for Juncus cultivation for cellulose production for diverse applications but also to generate income from wastewater.