| 1. |
- Anusuyadevi, Prasaanth Ravi, et al.
(författare)
-
Floating Photocatalysts for Effluent Refinement Based on Stable Pickering Cellulose Foams and Graphitic Carbon Nitride (g-C3N4)
- 2020
-
Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 5:35, s. 22411-22419
-
Tidskriftsartikel (refereegranskat)abstract
- The transfer of heterogeneous photocatalysis applications from the laboratory to real-life aqueous systems is challenging due to the higher density of photocatalysts compared to water, light attenuation effects in water, complicated recovery protocols, and metal pollution from metal-based photocatalysts. In this work, we overcome these obstacles by developing a buoyant Pickering photocatalyst carrier based on green cellulose nanofibers (CNFs) derived from wood. The air bubbles in the carrier were stable because the particle surfactants provided thermodynamic stability and the derived photocatalytic foams floated on water throughout the test period (4 weeks). A metal-free semiconductor photocatalyst, g-C3N4, was facilely embedded inside the foam by mixing the photocatalyst with the air-bubble suspension followed by casting and drying to produce solid foams. When tested under mild irradiation conditions (visible light, low energy LEDs) and no agitation, almost three times more dye was removed after 6 h for the floating g-C3N4-CNF nanocomposite foam, compared to the pure g-C3N4 powder residing on the bottom of a ca. 2 cm-high water pillar. The buoyancy and physicochemical properties of the carrier material were imperative to render escalated oxygenation, high photon utilization, and faster dye degradation. The reported assembly protocol is facile, general, and provides a new strategy for assembling green floating foams that can potentially carry a number of different photocatalysts.
|
|
| 2. |
- Anusuyadevi, Prasaanth Ravi, et al.
(författare)
-
Photoresponsive and Polarization-Sensitive Structural Colors from Cellulose/Liquid Crystal Nanophotonic Structures
- 2021
-
Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 33:36, s. 2101519-
-
Tidskriftsartikel (refereegranskat)abstract
- Cellulose nanocrystals (CNCs) possess the ability to form helical periodic structures that generate structural colors. Due to the helicity, such self-assembled cellulose structures preferentially reflect left-handed circularly polarized light of certain colors, while they remain transparent to right-handed circularly polarized light. This study shows that combination with a liquid crystal enables modulation of the optical response to obtain light reflection of both handedness but with reversed spectral profiles. As a result, the nanophotonic systems provide vibrant structural colors that are tunable via the incident light polarization. The results are attributed to the liquid crystal aligning on the CNC/glucose film, to form a birefringent layer that twists the incident light polarization before interaction with the chiral cellulose nanocomposite. Using a photoresponsive liquid crystal, this effect can further be turned off by exposure to UV light, which switches the nematic liquid crystal into a nonbirefringent isotropic phase. The study highlights the potential of hybrid cellulose systems to create self-assembled yet advanced photoresponsive and polarization-tunable nanophotonics.
|
|
| 3. |
- Anusuyadevi, Prasaanth Ravi, et al.
(författare)
-
Role of cellular solids in heterogeneous photocatalytic applications
- 2021
-
Ingår i: Nanostructured Photocatalysts: From Fundamental to Practical Applications. - : Elsevier BV. ; , s. 305-330
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Heterogeneous photocatalysis exhibits the potential for the complete degradation of pollutants present in water or gas phase. The effective realization of heterogeneous photocatalysis, at both large-scale industrial setups for water treatment and in situ application for solar remediation of ecological units, can be achieved by the concurrent development of photocatalytic supports along with solid semiconductor materials targeted for implementation as photocatalysts. This chapter provides an update of such developments in the field of photocatalytic supports, very specifically, on cellular solid-based carriers (foams). In the first part, a brief introduction to the fundamentals of cellular solids is presented. Subsequently, the role of cellular solids, as structured photocatalytic supports, for implementation in large-scale, continuously processed photoreactors for high-throughput water treatment, are discussed. The second part of this chapter reports all the materials used, up-to-date, in the fabrication of cellular solid-based photocatalyst carriers for the real-time solar remediation of the natural system. Finally, this chapter ends up in the discussion of novel cellulose nanofiber-based nanofoams as buoyant photocatalytic supports for the realization of bio-based, nonmetallic, nontoxic floating photocatalysts.
|
|
| 4. |
- Anusuyadevi, Prasaanth Ravi, et al.
(författare)
-
Synthetic Plant Cuticle Coating as a Biomimetic Moisture Barrier Membrane for Structurally Colored Cellulose Films
- 2023
-
Ingår i: Advanced Materials Interfaces. - : Wiley. - 2196-7350. ; 10:7
-
Tidskriftsartikel (refereegranskat)abstract
- Photonic films based on cellulose nanocrystals (CNCs) are sustainable candidates for sensors, structurally colored radiative cooling, and iridescent coatings. Such CNC-based films possess a helicoidal nanoarchitecture, which gives selective reflection with the polarization of the incident light. However, due to the hygroscopic nature of CNCs, the structural colored material changes and may be irreversibly damaged at high relative humidity. Thus, moisture protection is essential in such settings. In this work, hygroscopic CNC-based films are protected with a bioinspired synthetic plant cuticle; a strategy already adopted by real plants. The protective cuticle layers altered the reflected colors to some extent, but more importantly, they significantly reduced the water vapor permeance by more than two orders of magnitude, from 2.1 × 107 (pristine CNC/GLU film) to 12.3 × 104 g µm m−2 day−1 atm−1 (protected CNC/GLU film). This expands significantly the time window of operation for CNC/GLU films at high relative humidity.
|
|
| 5. |
- Cui, Yuxiao, et al.
(författare)
-
Achieving carbonized minitablet-shaped structures from lignin : The importance of heating rate on shape
- 2023
-
Ingår i: Journal of Analytical and Applied Pyrolysis. - : Elsevier BV. - 0165-2370 .- 1873-250X. ; 176, s. 106260-
-
Tidskriftsartikel (refereegranskat)abstract
- Shape-anisotropic building blocks are vital in the creation of hierarchical materials in nature, as it enables directional alignment, property anisotropy and overall functionality improvement in biological materials. Likewise, the performance of carbonized superstructures could potentially be more precisely designed by using anisotropic building blocks. Lignin represents an important and sustainable alternative in the production of carbonized materials, which is due to its abundance and high carbon content (∼60%). However, to expand its utility, for producing carbonized shape-anisotropic materials, adequate synthesis and pyrolysis-protocols are essential. Here, a fractionated and acetylated Kraft lignin was used to successfully self-assemble shape-anisotropic microcapsules. Then a carbonization procedure (slow heating at 0.6 °C min−1), that retained the original shape-anisotropy after carbonization, was developed. The formation mechanism was discussed as a function of the heating rate. The overall strategy was template-free and the attained shape-anisotropies were well-defined and narrow in size distribution. This is a scalable route for achieving shape-anisotropic carbonized building blocks from lignin.
|
|
| 6. |
- Cui, Yuxiao, et al.
(författare)
-
Hierarchical soot nanoparticle self-assemblies for enhanced performance as sodium-ion battery anodes
- 2022
-
Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 10:16, s. 9059-9066
-
Tidskriftsartikel (refereegranskat)abstract
- The drawbacks of amorphous hard carbon are its low conductivity and structural instability, due to its large volume change and the occurrence of side reactions with the electrolyte during cycling. Here, we propose a simple and rapid method to address these disadvantages; we used an emulsion solvent-evaporation method to create hierarchically structured microparticles of hard carbon nanoparticles, derived from soot, and multi-walled-carbon-nanotubes at a very low threshold of 2.8 wt%. These shrub-ball like microparticles have well-defined void spaces between different nanostructures of carbon, leading to an increased surface area, lower charge-resistance and side reactions, and higher electronic conductivity for Na+ insertion and de-insertion. They can be slurry cast to assemble Na+ anodes, exhibiting an initial discharge capacity of 713.3 mA h g(-1) and showing long-term stability with 120.8 mA h g(-1) at 500 mA g(-1) after 500 cycles, thus outperforming neat hard carbon nanoparticles by an order of magnitude. Our work shows that hierarchical self-assembly is attractive for increasing the performance of microparticles used for battery production.
|
|
| 7. |
- Cui, Yuxiao, et al.
(författare)
-
High Value Use of Technical Lignin. Fractionated Lignin Enables Facile Synthesis of Microcapsules with Various Shapes : Hemisphere, Bowl, Mini-tablets, or Spheres with Single Holes
- 2020
-
Ingår i: ACS Sustainable Chemistry and Engineering. - : AMER CHEMICAL SOC. - 2168-0485. ; 8:35, s. 13282-13291
-
Tidskriftsartikel (refereegranskat)abstract
- Anisotropic carbon-rich microcapsule morphologies are of great value in many applications including catalysis, energy storage, biomedicine, and osmosis-triggered drug delivery, due to an observed shape effect. However, high-precision synthesis, to generate large yields of well-defined anisotropic shapes, is generally challenging. Here, we show for the first time that a modified carbon-rich waste-material, a fractionated and acetylated Kraft lignin, enables facile production of large amounts of well-defined "acorn-like" microcapsules with heterogeneous shell thicknesses. This is due to the inherent physicochemical properties of the fractionated lignin at the oil/water (O/W) interface. The acorn-shape is strongly related to two distinct lignin-molecule populations, that phase separate during microcapsule formation. Fine-tuning the post-treatment conditions (pressure or hydrothermal temperature) results in a number of different microcapsule shapes; hemisphere, bowl, mini-tablets, or spheres with single holes. Further chemical modification to their surfaces is also demonstrated. The present study provides a new library of shape-anisotropic carbon-rich building blocks that open new avenues for assembling hierarchical material with a high level of complexity.
|
|
| 8. |
- Cui, Yuxiao, et al.
(författare)
-
Self-assembled carbon spheres prepared from abundant lignin and urea for photocatalytic and self-propelling applications
- 2021
-
Ingår i: Carbon Trends. - : Elsevier BV. - 2667-0569. ; 3, s. 100040-
-
Tidskriftsartikel (refereegranskat)abstract
- Lignin is a valuable bio-resource in the manufacturing of carbon-based functional materials, because of its large carbon content (~60%), various phenolic structural units, abundancy and sustainability. Here, we explored its use in photocatalytic and self-propelling applications. First, hydroxyl-abundant lignin-based carbon precursor particles, HCLSs, were produced by hydrothermal carbonization of lignin-based microcapsules (LCs). Then, by heating urea coated HCLSs, carbon spheres with a layer of graphitic carbon nitride (g-C3N4) were produced. The presence of surface available -OH groups on the HCLSs, were critical in the formation mechanism. Under visible-light irradiation, the photocatalytic spheres exhibited enhanced activity (49% of the model pollutant remained after 60 min, at 100 mW cm−2) and possessed a three times higher average removal rate constant compared to that of g-C3N4 powder. The g-C3N4 powder was obtained when heating urea only. Additionally, by introducing a Pt/Pd coating on only one side of the composite spheres, the spheres were made self-propelling in the presence of a fuel (H2O2). This work provides new insights into the preparation principles of lignin-based photocatalytic spheres for effective solar photocatalysis applications.
|
|
| 9. |
- Ghorbani, Morteza, et al.
(författare)
-
Acoustic Response of a Novel Class of Pickering Stabilized Perfluorodroplets
- 2019
-
Konferensbidrag (refereegranskat)abstract
- IntroductionAcoustic Droplet Vaporization (ADV) is a phase change phenomenon in which the liquid state, in the form of droplets, is converted to gas as a result of bursts in the excited ultrasound field. Having a wide range of medical applications, ADV has drawn considerable attention in imaging [1], diagnosis and critical medical treatment [2]. Therefore, benefitting from its broad potentials, with the consideration of its capability in localized noninvasive energy exposure, it is possible to utilize its effect in different medical applications from targeted drug delivery [3] to embolotherapy [4].Apart from the droplet characterization and ADV effectiveness on the applied region, the physics of ADV and particularly the ultrasound analysis is an essential parameter in the initiation of the vaporization. This part, which is related to acoustic wave physics, implies that ADV is mostly dependent on ultrasound pressure, frequency and temperature. In this sense, Miles et al. [5] tried to find incident negative pressure - called as ADV threshold- which is necessary for the induction of nucleation. It was successfully shown that the negative pressure required for the nucleation prior to collapse can be determined via perturbation analysis of a compressible inviscid flow around a droplet for various frequencies and diameters. In addition, the fluid medium which constitutes the droplet emulsion and the surrounding fluid constructs a significant field within ADV. In this regard, there are many studies which illustrated that the diameter of the droplets subjected to the acoustic waves undergoes a significant expansion of 5 to 6 times of their regular sizes [6-8].In this study, a new type of pickering stabilized perfluorodroplets (PFC) was examined under the effect of the different acoustic parameters to evaluate its potential in the acoustic droplet vaporization process. To assess the pressure effects on the stabilized droplets, the acoustic power within the ultrasound tests was varied and the phase trasnition was characterized according to the experimental conditions. Opticell® was utilized as the transparent device to visualize the droplets, which were exposed to the acoustic waves with the aid of the microscope and multi-well microplate.MethodsMaterials and emulsion preparationPerfluoropentane (PFC5) was purchased from Apollo Scientific (City, U.K.). Bleached sulfite pulp (from Nordic Paper Seffle AB, Sweden) was used in the production of the cationic cellulose nanofibers (CNFs). The CNF suspension (1.32 wt%) were prepared as described previously [9]. The CNFs had a dimension of 3.9 ± 0.8 nm in width and a length in the micrometer range. The amount of cationic groups was 0.13 mmol per g fiber, obtained from conductometric titration [9]. A suspension of CNF (0.28 wt%) was prepared by diluting the stock CNF with MilliQ-water (pH of diluted CNF suspension was 9.5). The suspension was treated with ultra-sonication at amplitude of 90% for 180 s (Sonics, Vibracell W750). The suspension was brought to room temperature. An amount of 36 g of the 0.28 wt% CNF suspension was mixed with 1 g of PFC5. The mixture was sonicated for 60s at an amplitude of 80% (under ice-cooling) to obtain the CNF-stabilized PFC5 droplets.The protocol for the acoustic tests100 μL of CNF-stabilized PFC5 droplets were added to 1900 μL of deionized water in order to prepare the solution which were exposed to the ultrasound waves. The droplet sample, diluted 1:19 in distilled water was introduced to the Opticell® and the acoustic waves at a fixed frequency and different powers were applied to the trageted area inside the Opticell® which is located inside a water bath. The ultrasound triggered sample then was placed under a 20X magnification objective of upright transmitted light microscope (ECLIPSE Ci-S, Nikon, Tokyo, Japan). The acoustic tests were performed using high-power tone burst pulser-receiver (SNAP Mark IV, Ritec, Inc., Warwick, RI, USA) equipped with a transducer (V382-SU Olympus NDT, Waltham, MA ) operating at the frequency of 3.5 MHz. The emulsion of CNF-stabilized PFC5 droplets were exposed to the power range which has the acsending trend from -30 to 0 dB at the given frequency. To investigate the droplet size variations at each power between, the droplets were collected inside the Opticell® and the droplet diameter was measured with the aid of the ImageJ software (version 1.50b, National institutes of health, USA) to determine the concentration and size distribution. The Gaussian distribution is ploted with mean value and standad deviation recover from the experimental data. An in-house image edge detection MATLAB™ script (MathWorks Inc., Natick, MA) were applied to analyze the images obtained from the microscope and provides the size and volume distributions.ResultsThe size of PFP droplets is an important parameter to controll in the therapeutic applications. Here, a new type of Pickering stabilized perfluorodroplets were prepared where the PFP/water interface was stabilized with cellulose nanofibers (CNF) and the size of the droplets could easily be controlled by varying the amount of CNF added. The resulting droplets were investigated using a single crystal transducer. Apart from the medical applications, controlling the droplet size is important from droplet dynamics point of view, becausethe interfacial energy is crucial in the assumption of the critical nucleus radius. Therefore, it is possible to estimate the negative peak pressure required for the phase transition once the droplet is controlled and interfacial energy deposited inside and on the surface of the droplet are balanced.According to the results in Figure 1, there is an appreciable rise of the size of the droplets after ultrasound waves exposure, particularly at -8 dB power. The experiments were performed for 30 seconds at different powers ranging from -30 to 0 dB, while the frequency was kept constant at 3.5 MHz, burst width in cycles was selected as 12 and repetition rate was set to 100. Images included in Figure 1 demonstrate major transitions in the intervals at -16, -8 and 0 dB. As shown in this figure, the droplet size increased with the power rise and more bubbles with bigger sizes appears at higher powers. This outcome implies the significant role of the applied frequency and power on the phase shift and subsequent mechanisms as a result of the acoustic wave exposure on the new nontoxic and incompatible droplet type.Figure 2 shows the average number of droplets and volume distribution at the corresponding powers to the Figure 1. It is shown that while the average diameter of the droplets is around 3.5 µm, the generated bubbles, as a result of the ADV, reaches up to 15 µm at the highest possible power. For each set of experiment (corresponding to a given power) 32 images were taken, thus, to reduce the errors and obtain the standard deviation (approximately 0.8 for all the cases), the presented diagrams for the droplet distributions exhibits the mean value for all of the acquired images. Therefore, it is shown that the droplet emulsion exhibited in NO US in Figure 2, which shows the regular view and distribution range of the CNF-stabilized PFC5 droplets at the room temperature, experiences ADV process with the diameter rise of about 5 times at the highest power when the frequency is fixed at 3.5 MHz.ConclusionsThe results show that there is appreciable rise on the size of the droplets after ultrasound waves exposure at a fixed frequency. Acoustic droplet vaporization (ADV) was illustrated at different powers for CNF-stabilized PFC5 droplets as a new class of pickering stabilized perfluorodroplets with the increase in the size of the droplets and following phase trasition to bubbles. Diameter increase of 5 times were obtained after the ultrasound exposure indicating the efficiency of the suggested droplets for the ADV process and therapeutic applications. References[1] Arena CB, Novell A, Sheeran PS, Puett C, Moyer LC, Dayton PA, Dual-Frequency Acoustic Droplet Vaporization Detection for Medical Imaging 2015, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 62: 9.[2] Kripfgans OD, Fowlkes JB, Miller DL, Eldevik OP, Carson PL, Acoustic droplet vaporization for therapeutic and diagnostic applications 2000, Ultrasound Med. Biol, 26:1177–1189.[3] Kang ST, Yeh CK, Intracellular Acoustic Droplet Vaporization in a Single Peritoneal Macrophage for Drug Delivery Applications 2011, Langmuir, 27:13183–13188.[4] Zhu M, Jiang L, Fabiilli ML, Zhang A, Fowlkes JB, Xu LX, Treatment of murine tumors using acoustic droplet vaporization-enhanced high intensity focused 2013, Ultrasound Phys. Med. Biol, 58:6179–6191.[5] Miles CJ, Doering CR, Kripfgans OD, Nucleation pressure threshold in acoustic droplet vaporization 2016, Journal of Applied Physics, 120:034903.[6] Sheeran PS, Wong VP, Luois S, McFarland RJ, Ross WD, Feingold S, Matsunaga TO, Dayton PA, Decafluorobutane as a phase-change contrast agent for low-energy extravascular ultrasonic imaging 2011, Ultrasound Med. Biol, 37:1518–1530.[7] Kripfgans OD, Fowlkes JB, Miller DL, Eldevik OP, Carson PL, Acoustic droplet vaporization for therapeutic and diagnostic applications 2000, Ultrasound Med. Biol, 26:1177–1189.[8] Kang S, Huang Y, Yeh C, Characterization of acoustic droplet vaporization for control of bubble generation under flow conditions 2014, Ultrasound Med. Biol, 40:551–561.[9] Svagan AJ, Benjamins JW, Al-Ansari Z, Shalom DB, Müllertz A, Wågberg L, Löbmann K, Solid cellulose nanofiber based foams–towards facile design of sustained drug delivery systems 2016, J. Control Release, 244:74–82 (Part A).
|
|
| 10. |
- Ghorbani, Morteza, et al.
(författare)
-
Facile Hydrodynamic Cavitation ON CHIP via Cellulose Nanofibers Stabilized Perfluorodroplets inside Layer-by-Layer Assembled SLIPS Surfaces
- 2019
-
Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212.
-
Tidskriftsartikel (refereegranskat)abstract
- The tremendous potential of “hydrodynamic cavitation on microchips” has been highlighted during recent years in various applications. Cavitating flow patterns, substantially depending upon thermophysical and geometrical characteristics, promote diverse industrial and engineering applications, including food and biomedical treatment. Highly vaporous and fully developed patterns in microfluidic devices are of particular interest. In this study, the potential of a new approach, which includes cellulose nanofiber (CNF)- stabilized perfluorodroplets (PFC5s), was assessed inside microfluidic devices. The surfaces of these devices were modified by assembling various sizes of silica nanoparticles, which facilitated in the generation of cavitation bubbles. To examine the pressure effects on the stabilized droplets in the microfluidic devices, the upstream pressure was varied, and the cavitation phenomenon was characterized under different experimental conditions. The results illustrate generation of interesting, fully developed, cavitating flows at low pressures for the stabilized droplets, which has not been previously observed in the literature. Supercavitation flow pattern, filling the entire microchannel, were recorded at the upstream pressure of 1.7 MPa for the case of CNF-stabilized PFC5s, which hardly corresponds to cavitation inception for pure water in the same microfluidic device.
|
|
