Research on Controlling Contact Electrification by Modification of Cellulose Molecule Surface with Amino Group

As a green material, cellulose is widely used in friction triboelectric nanogenerators (TENGs). However, the weak polarity of the cellulose surface leads to its weak contact electrification performance, which is not conducive to its utilization in TENGs. In this study, epoxy chloropropane and ethylenediamine were grafted onto cellulose to form paper and were assembled with an FEP film. The output voltage, current, and surface charge density were 34.9%, 26.7%, and 16.7% higher than those of ordinary paper, respectively. When 20% nano TiO2 filler was added to the paper made from amino-modified cellulose, the output voltage, current, and surface charge density of the TENG increased by 70.9%, 226.7%, and 122.2%, respectively, compared with ordinary paper. As the air humidity of the TENG increased from 60% to 90%, the output voltage, current, and surface charge density were maintained at 53.7%, 38.9%, and 61.0%, respectively. When a 5 × 107 Ω resistor was connected to the working circuit, its output power reached 13.78 μ W·cm2. This showed that cellulose as a green material has wide application prospects in the field of TENG.

Synthesis of Titanium Dioxide/Cellulose Derived from Banana Peel for Sonocatalytic Degradation of Methylene Blue

Banana peel was used as the source of cellulose and titanium dioxide (TiO2)/cellulose composites with different weight ratios were successfully synthesised by using sol-gel method. The composites were then characterised by using the scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The synthesised TiO2 was found to be in anatase phase. TiO2 particles were spherical in shape and consisted of both titanium (Ti) and oxygen (O) elements only. Meanwhile, the morphology of extracted cellulose was found to have a rough surface. TiO2 particles were found to be covering the cellulose surface when preparing the composite samples and clusters of agglomerated TiO2 particles on cellulose surface could be observed. FTIR results indicated that the absorption peaks intensity of cellulose slowly reduced as compared to the composite materials. The sonocatalytic degradation of methylene blue in the presence of TiO2/cellulose at weight ratio of 1:2 showed the highest degradation efficiency of 74.14 % at the optimum conditions (initial dye concentration of 10 ppm, catalyst dosage of 1.0 g/L and solution pH of 8). Study on the degradation kinetics of methylene blue at different solution pH proved that the reaction kinetics fitted well into pseudo first-order. Additionally, a chemical oxygen demand (COD) removal of 94.44 % was also achieved after 30 minutes of ultrasonic irradiation under the prescribed optimum conditions.

The Interaction of Cellulose Thin Films With Small Organic Molecules—Comparability of Two Inherently Different Methods

Paper is the material of choice for a large range of applications because it has many favorable environmental and economic characteristics. Especially in the packaging sector of dry goods and food products, paper has found unique applications. For that purpose, it has to fulfill certain requirements: Primarily it should protect the packaged goods. In order to ensure the compliance of a paper packaging, its interactions with the packaged goods should be investigated. Therefore, it is of utmost importance to understand how the paper interacts with chemicals of different nature and what factors influence these interactions—be that the nature of the paper or the characteristics of the substances. In this study, we investigated the surface interactions of cellulose thin films with n-decane and deuterated methanol using two different analytical methods: headspace solid-phase microextraction with gas chromatography and flame ionization detection (HS-SPME-GC/FID) and temperature-programmed desorption (TPD). Cellulose thin films were characterized with contact angle and FT-IR measurements and successfully applied as model systems for real paper samples. Regarding the interactions of the cellulose films with the model compounds, the two inherently different methods, HS-SPME-GC/FID and TPD, provide very comparable results. While the nonpolar n-decane was readily released from the cellulose films, the polar model compound deuterated methanol showed a strong interaction with the polar cellulose surface.

Effect of the essential oils addition on the rate of bacterial cellulose surface overgrowth by mold fungi

Effect of the essential oils addition on the rate of bacterial cellulose surface overgrowth by mold fungi. The aim of this study was to determine the effectiveness of protecting films made of bacterial cellulose with essential oils against overgrowth by mold fungi. The cellulose film produced by microorganisms forming a pellicle called SCOBY was modified by introducing into the cellulose pulp essential oils: cinnamon and manuka. Samples of the protected film were treated with mold fungi: Chaetomium globosum, Aspergillus niger and Trichoderma viride. On the basis of the tests conducted, the rate of film overgrowth by mold fungi and the effectiveness criteria of cellulose film protection with essential oils were determined. The addition of cinnamon oil protected the film against the growth of Aspergillus niger and Chaetomium globosum fungi. Manuka oil slowed down the growth of Chaetomium globosum microorganisms on the surface of the bacterial cellulose film sample, but did not protect the samples from overgrowth. The essential oils tested were ineffective against the fungus Trichoderma viride.

Effects of Amino Acid Side-Chain Length and Chemical Structure on Anionic Polyglutamic and Polyaspartic Acid Cellulose-Based Polyelectrolyte Brushes

We used atomistic molecular dynamics (MD) simulations to study polyelectrolyte brushes based on anionic α,L-glutamic acid and α,L-aspartic acid grafted on cellulose in the presence of divalent CaCl2 salt at different concentrations. The motivation is to search for ways to control properties such as sorption capacity and the structural response of the brush to multivalent salts. For this detailed understanding of the role of side-chain length, the chemical structure and their interplay are required. It was found that in the case of glutamic acid oligomers, the longer side chains facilitate attractive interactions with the cellulose surface, which forces the grafted chains to lie down on the surface. The additional methylene group in the side chain enables side-chain rotation, enhancing this effect. On the other hand, the shorter and more restricted side chains of aspartic acid oligomers prevent attractive interactions to a large degree and push the grafted chains away from the surface. The difference in side-chain length also leads to differences in other properties of the brush in divalent salt solutions. At a low grafting density, the longer side chains of glutamic acid allow the adsorbed cations to be spatially distributed inside the brush resulting in a charge inversion. With an increase in grafting density, the difference in the total charge of the aspartic and glutamine brushes disappears, but new structural features appear. The longer sides allow for ion bridging between the grafted chains and the cellulose surface without a significant change in main-chain conformation. This leads to the brush structure being less sensitive to changes in salt concentration.

Effects of Amino Acid Side Chain Length and Chemical Structure on Anionic Polyglutamic and Polyaspartic Acid Cellulose-Based Polyelectrolyte Brushes

We used atomistic molecular dynamics (MD) simulations to study polyelectrolyte brushes based on anionic α-L-glutamic acid and α-L-aspartic acid grafted on cellulose in the presence of divalent CaCl2 salt at different concentrations. The motivation is the search of the ways to control properties such as sorption capacity and the structural response of the brush to multivalent salts. For this detailed understanding of the role of side chain length, chemical structure and their interplay is required. It was found that in the case of glutamic acid oligomers, the longer side chains facilitate attractive interactions with the cellulose surface, which forces the grafted chains to lie down on the surface. The additional methylene group in the side chain enables side chain rotation enhancing this effect. On the other hand, the shorter and more restricted side chains of aspartic acid oligomers prevent attractive interactions to a large degree and push the grafted chains away from the surface. The difference in side chain length also leads to differences in other properties of the brush in divalent salt solutions. At a low grafting density, the longer side chains of glutamic acid allow the adsorbed cations to be spatially distributed inside the brush resulting in a charge inversion. With an increase in grafting density, the difference in the total charge of the aspartic and glutamine brushes disappears, but new structural features appear. The longer sides allow for ion bridging between the grafted chains and the cellulose surface without a significant change in main chain conformation. This leads to the brush structure being less sensitive to changes in salt concentration.

Investigating the effects of substrate morphology and experimental conditions on the enzymatic hydrolysis of lignocellulosic biomass through modeling

Background Understanding how the digestibility of lignocellulosic biomass is affected by its morphology is essential to design efficient processes for biomass deconstruction. In this study, we used a model based on a set of partial differential equations describing the evolution of the substrate morphology to investigate the interplay between experimental conditions and the physical characteristics of biomass particles as the reaction proceeds. Our model carefully considers the overall quantity of cellulase present in the hydrolysis mixture and explores its interplay with the available accessible cellulose surface. Results Exploring the effect of various experimental and structural parameters highlighted the significant role of internal mass transfer as the substrate size increases and/or the enzyme loading decreases. In such cases, diffusion of cellulases to the available cellulose surface limits the rate of glucose release. We notably see that increasing biomass loading, while keeping enzyme loading constant should be favored for both small- (R < 300 $$\mu m$$ μ m ) and middle-ranged (300 < R < 1000 $$\mu m$$ μ m ) substrates to enhance enzyme diffusion while minimizing the use of enzymes. In such cases, working at enzyme loadings exceeding the full coverage of the cellulose surface (i.e. eI>1) does not bring a significant benefit. For larger particles (R > 1000 $$\mu m$$ μ m ), increases in biomass loading do not offset the significant internal mass transfer limitations, but high enzyme loadings improve enzyme penetration by maintaining a high concentration gradient within the particle. We also confirm the well-known importance of cellulose accessibility, which increases with pretreatment. Conclusions Based on the developed model, we are able to propose several design criteria for deconstruction process. Importantly, we highlight the crucial role of adjusting the enzyme and biomass loading to the wood particle size and accessible cellulose surface to maintain a strong concentration gradient, while avoiding unnecessary excess in cellulase loading. Theory-based approaches that explicitly consider the entire lignocellulose particle structure can be used to clearly identify the relative importance of bottlenecks during the biomass deconstruction process, and serve as a framework to build on more detailed cellulase mechanisms.

Bioprocessing of Waste Sago Pulp Fiber Based on Chloride Solution for Cellulose Isolation

The utilization of chloride solution in the bioprocessing of sago pulp fiber waste (SPFW) aims to obtain high purity cellulose before its use in making bioethanol. Before the bioprocessing, SPFW with a powder size of 149 μm was immersed in 15% (v/v) NH4OH and 5% (v/v) H2O2 solution. Bioprocessing parameters reported in this study included bioprocessing time, chloride solution concentration, and bioprocessing temperature. Based on the optimization results, the SPFW bioprocessing for 5 hours using 4% hydrochloric acid and a temperature of 95oC was the optimum condition with the acquisition of cellulose content of 67%. SPFW cellulose was confirmed by the presence of specific IR absorption peaks at wave numbers 1429.4 cm-1, 1322.4 cm-1, 1157.3 cm-1, 1110 cm-1, and 897 cm-1. Scanning Electron Microscopy (SEM) analysis shows that bioprocessing using chloride solutions produces a porous, rough, and fibrous cellulose surface. Also, the fiber length is irregular with the irregular location. Based on XRD analysis, SPFW bioprocessing produced single-phase cellulose with a crystal size of 15 nm. Physically, the bioprocessing causes the discoloration of the sago pulp fiber to turn dark brown.

Preparation and Characterization of a New Polymeric Multi-Layered Material Based K-Carrageenan and Alginate for Efficient Bio-Sorption of Methylene Blue Dye

The current study highlights a novel bio-sorbent design based on polyelectrolyte multi-layers (PEM) biopolymeric material. First layer was composed of sodium alginate and the second was constituted of citric acid and k-carrageenan. The PEM system was crosslinked to non-woven cellulosic textile material. Resulting materials were characterized using FT-IR, SEM, and thermal analysis (TGA and DTA). FT-IR analysis confirmed chemical interconnection of PEM bio-sorbent system. SEM features indicated that the microspaces between fibers were filled with layers of functionalizing polymers. PEM exhibited higher surface roughness compared to virgin sample. This modification of the surface morphology confirmed the stability and the effectiveness of the grafting method. Virgin cellulosic sample decomposed at 370 °C. However, PEM samples decomposed at 250 °C and 370 °C, which were attributed to the thermal decomposition of crosslinked sodium alginate and k-carrageenan and cellulose, respectively. The bio-sorbent performances were evaluated under different experimental conditions including pH, time, temperature, and initial dye concentration. The maximum adsorbed amounts of methylene blue are 124.4 mg/g and 522.4 mg/g for the untreated and grafted materials, respectively. The improvement in dye sorption evidenced the grafting of carboxylate and sulfonate groups onto cellulose surface. Adsorption process complied well with pseudo-first-order and Langmuir equations.