scholarly journals Vitamin C-Assisted Fabrication of Aerogels from Industrial Graphene Oxide for Gaseous Hexamethyldisiloxane Adsorption

2021 ◽  
Vol 11 (18) ◽  
pp. 8486
Author(s):  
Yanhui Zheng ◽  
Xifeng Hou ◽  
Xiaolong Ma ◽  
Zelin Hao ◽  
Zichuan Ma
Keyword(s):  
Contact Angle ◽  
Graphene Oxide ◽  
Vitamin C ◽  
Energy Utilization ◽  
Raw Material ◽  
Raman Spectrometry ◽  
Water Contact ◽  
Industrial Grade ◽  
Bed Temperature ◽  
Hierarchical Porous

Volatile methyl siloxanes (VMSs) as a trace impurity in biogas decreases its energy utilization, and thus need to be removed. In this paper, a one-step hydrothermal reduction was performed to produce three-dimensional reduced graphene oxide aerogels (rGOAs) using industrial-grade graphene oxide (IGGO) as raw material and vitamin C (VC) as a reductant to facilitate the fabrication of rGOAs. The synthesis of rGOAs was a simple, green, and energy-efficient process. The developed rGOAs were characterized using the Brunauer–Emmett–Teller method, Raman spectrometry, scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction measurements and contact angle. The results obtained showed that rGOA-1 with a VC/IGGO ratio of 1/1 (m/m) exhibited a hierarchical porous structure and super-hydrophobicity, yielding a high specific surface area (137.9 m2 g−1) and superior water contact angle (143.8°). The breakthrough adsorption capacity of rGOA-1 for hexamethyldisiloxane (L2, a VMS model) was 11 times higher than that of IGGO. Low inlet concentration and bed temperature were considered beneficial for the L2 adsorption. Interestingly, rGOA-1 was less sensitive to water, and it was readily regenerated for reuse by annealing at 80 °C. The rGOAs have been demonstrated to have great potential for the removal of siloxanes from biogas.

scholarly journals The Effects of Hydrophobicity and Textural Properties on Hexamethyldisiloxane Adsorption in Reduced Graphene Oxide Aerogels

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1130
Author(s):  
Xifeng Hou ◽  
Yanhui Zheng ◽  
Xiaolong Ma ◽  
Yuheng Liu ◽  
Zichuan Ma
Keyword(s):  
Contact Angle ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Hydrothermal Treatment ◽  
Textural Properties ◽  
Treatment Temperature ◽  
Spectroscopic Techniques ◽  
Industrial Grade ◽  
Bed Temperature ◽  
Reduced Graphene

To expand the applications of graphene-based materials to biogas purification, a series of reduced graphene oxide aerogels (rGOAs) were prepared from industrial grade graphene oxide using a simple hydrothermal method. The influences of the hydrothermal preparation temperature on the textural properties, hydrophobicity and physisorption behavior of the rGOAs were investigated using a range of physical and spectroscopic techniques. The results showed that the rGOAs had a macro-porous three-dimensional network structure. Raising the hydrothermal treatment temperature reduced the number of oxygen-containing groups, whereas the specific surface area (SBET), micropore volume (Vmicro) and water contact angle values of the rGOAs all increased. The dynamic adsorption properties of the rGOAs towards hexamethyldisiloxane (L2) increased with increasing hydrothermal treatment temperature and the breakthrough adsorption capacity showed a significant linear association with SBET, Vmicro and contact angle. There was a significant negative association between the breakthrough time and inlet concentration of L2, and the relationship could be reliably predicted with a simple empirical formula. L2 adsorption also increased with decreasing bed temperature. Saturated rGOAs were readily regenerated by a brief heat-treatment at 100 °C. This study has demonstrated the potential of novel rGOA for applications using adsorbents to remove siloxanes from biogas.

Above 170° water contact angle and oleophobicity of fluorinated graphene oxide based transparent polymeric films

Carbon ◽  
2015 ◽  
Vol 84 ◽  
pp. 207-213 ◽  
Author(s):  
T. Bharathidasan ◽  
Tharangattu N. Narayanan ◽  
S. Sathyanaryanan ◽  
S.S. Sreejakumari
Keyword(s):  
Contact Angle ◽  
Graphene Oxide ◽  
Water Contact Angle ◽  
Polymeric Films ◽  
Water Contact ◽  
Fluorinated Graphene ◽  
Fluorinated Graphene Oxide

Top-Down Fabrication of Superhydrophilic Graphene Oxide Nanosheets

2016 ◽  
Vol 849 ◽  
pp. 738-742
Author(s):  
Xue Bing Hu ◽  
Yun Yu ◽  
Wen Xiou Ding ◽  
Zhou Hao Xiao ◽  
Yong Qing Wang ◽  
...  
Keyword(s):  
Contact Angle ◽  
Graphene Oxide ◽  
Chemical Oxidation ◽  
Monolayer Graphene ◽  
Graphene Oxide Nanosheets ◽  
Top Down ◽  
Laminar Structure ◽  
Water Contact ◽  
Hummers Method ◽  
Modified Hummers Method

As an oxidized form of graphene, graphene oxide has a variety of oxygen-containing groups together with a laminar structure, showing great potential in various engineering applications. In this work, on the basis of the top-down fabrication principle, superhydrophilic graphene oxide nanosheets with a uniform sheet size of ~50 nm diameter and 0.7 nm thickness were prepared by the modified Hummers method, and using microcrystalline graphite as the carbon source. After chemical oxidation, the obtained graphene oxide nanosheets had a great amount of C-O-C, C-OH and C=O groups and its water contact angle was ~3.9°. This result offers a facile strategy to fabricate superhydrophilic and monolayer graphene oxide nanosheets with well-defined morphology.

scholarly journals Optimization of Process Parameters for a Chemi-Absorbed Graphene Coating and Its Nano Tribological Investigation

Nanomaterials ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 55 ◽  
Author(s):  
Pengfei Li ◽  
Yuncheng Li ◽  
Hongyue Chen ◽  
Hui Liu ◽  
Xianhua Cheng
Keyword(s):  
Contact Angle ◽  
Graphene Oxide ◽  
Water Contact Angle ◽  
Coefficient Of Friction ◽  
Process Parameters ◽  
Self Assembly ◽  
Titanium Substrate ◽  
Oxide Coating ◽  
Water Contact ◽  
Hydrothermal Temperature

A reduced graphene oxide coating was deposited on a titanium substrate for potential anti-friction applications in nano- or micro-mechanical systems. A γ-aminopropyltriethoxysilane coating was self-assembled on the substrate as an adhesive interlayer beforehand. The process parameters of self-assembly and hydrothermal reduction of graphene oxide coating were explored via water contact angle and tribological tests. Insufficient self-assembly duration of graphene oxide layer can be detected by water contact angle results, and the corresponding coating displayed a higher coefficient of friction and shorter anti-wear lifetime than the optimized one. Proper hydrothermal temperature and duration were also confirmed by its water contact angle, coefficient of friction and anti-wear lifetime. Noticeably, excessive hydrothermal temperature or duration would reduce the coefficient of friction, but diminish the anti-wear resistance. The optimized process parameters were confirmed as assembly duration of graphene oxide coating for 12 h, hydrothermal reduction duration of 6–8 h at 135 °C. Nano tribological behaviors of the obtained hydrothermal reduced graphene oxide coating by AFM tester were then investigated under various testing circumstances. The results showed that the coating performed reliable and low adhesion and friction forces under all circumstances. The nanowear resistance of the titanium substrate was significantly strengthened by the prepared coating.

scholarly journals Preparation and Properties of Polyvinylidene Fluoride Nanocomposited Membranes based on Poly(N-Isopropylacrylamide) Modified Graphene Oxide Nanosheets

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 473 ◽  
Author(s):  
Xiangli Meng ◽  
Yuan Ji ◽  
Genhua Yu ◽  
Yujia Zhai
Keyword(s):  
Contact Angle ◽  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
Polyvinylidene Fluoride ◽  
Phase Inversion ◽  
Doping Amount ◽  
Water Contact ◽  
Modified Graphene Oxide ◽  
Modified Graphene ◽  
Scanning Electron

The nanomaterial of graphene oxide grafting poly (N-isopropylacrylamide) (GO-g-PNIPAAm) was synthesized and PVDF/GO-g-PNIPAAm blended membranes were fabricated by wet phase inversion. In this work, a hydrophilic nanomaterial GO-g-PNIPAAm with poly(N-isopropylacrylamide) (PNIPAAm) grafted on GO, was synthesized by the atom transfer radical polymerization (ATRP) method. The resulting nanomaterial was confirmed by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectrum, and X-ray photoelectron spectroscopy (XPS) analysis. The synthesized GO-g-PNIPAAm was incorporated with polyvinylidene fluoride (PVDF) via phase inversion, and investigated for its temperature sensitivity, porosity, contact angle, scanning electron microscopy, and permeate properties. The water contact angle measurements confirmed that GO-g-PNIPAAm nanomaterial-endowed PVDF membranes with better hydrophilicity and thermo-responsive properties compared with those of the pristine PVDF membranes. Bovine serum albumin (BSA) adsorption experiments suggested that excellent antifouling properties of membranes were acquired after adding GO-g-PNIPAAm. The modified membranes showed good performance when the doping amount of GO-g-PNIPAAm was 0.2 wt %.

scholarly journals Preparation and Characterization of a Hydrophilic Polysulfone Membrane Using Graphene Oxide

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Hoan Thi Vuong Nguyen ◽  
Thu Hong Anh Ngo ◽  
Khai Dinh Do ◽  
Minh Ngoc Nguyen ◽  
Nu Thi To Dang ◽  
...  
Keyword(s):  
Contact Angle ◽  
Graphene Oxide ◽  
Water Contact Angle ◽  
Water Flux ◽  
Feed Solution ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
Inversion Method ◽  
Water Contact ◽  
Polysulfone Membrane

In general, the polysulfone (PSf) membranes are popular choices for water treatment because they have high thermal stability and good chemical resistance. On the other hand, the filtration capacity of the polysulfone membrane is limited because of its low water flux and poor antifouling ability, which are caused by the low surface hydrophilicity of the membranes. In this research, blending of graphene oxide (GO) or graphene oxide-titanium dioxide (GO-TiO2) mixture into the polysulfone matrix had been carried out through the phase inversion method to enhance the hydrophilic and antifouling properties. Methods such as energy-dispersive X-ray spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and water contact angle measurement were used to examine the surface properties of the prepared membranes. Experimental results have led to a conclusion that graphene oxide can be stabilized into prepared membranes, and then, by reducing the water contact angle values, the surface of these membranes becomes hydrophilic, which increases the permeability and the water flux of methylene blue from the aqueous feed solution, improving the membrane’s antifouling resistance.

scholarly journals Durable Epoxy@ZnO Coating for Improvement of Hydrophobicity and Color Stability of Wood

Polymers ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1388 ◽  
Author(s):  
Vu Manh Tuong ◽  
Nguyen Van Huyen ◽  
Nguyen Trong Kien ◽  
Nguyen Van Dien
Keyword(s):  
Contact Angle ◽  
Water Contact Angle ◽  
Spray Coating ◽  
Color Stability ◽  
Xrd Analysis ◽  
Hexagonal Structure ◽  
Raw Material ◽  
Water Contact ◽  
Nanoscale Structures ◽  
Average Water

The hydrophobicity and color stability of wood are important properties that can be easily changed when wood is used as a raw material for outdoor products, reducing the service life of wood. Herein, an epoxy@ZnO coating was applied by a two-step simple spray coating method to improve the hydrophobicity and color stability of Styrax tonkinensis wood. The hydrophobicity, robustness of coating, as well as the color stability of uncoated wood samples and epoxy@ZnO coated wood samples were evaluated. The microstructure morphology and crystal structures of the coating were also characterized by a field-emission scanning electron microscope (FESEM) and X-ray diffraction (XRD) analysis, respectively. Results showed that the obtained epoxy@ZnO coating was not only superhydrophobic with an average water contact angle of 154.1°, but also maintained superhydrophobicity with an average water contact angle of 149.6° after five water jetting tests. The color stability of the coated wood samples was improved by around 50% compared to that of uncoated wood samples. Additionally, a continuous epoxy@ZnO coating with hierarchical micro/nanoscale structures constructed by the wurtzite hexagonal structure of ZnO micro/nanoparticles on wood surfaces was confirmed.

Ultra Fast Oil-Water Separation for Different Viscous Oil Using Flourine-Free, Reusable, Superhydrophobic Polyurethane Sponge

2020 ◽  
Vol 20 (3) ◽  
pp. 1540-1553 ◽  
Author(s):  
Jing Ma ◽  
Weihui Zhu ◽  
Patrick Osei Lartey ◽  
Wen Qin
Keyword(s):  
Contact Angle ◽  
Graphene Oxide ◽  
High Temperature ◽  
Reduced Graphene Oxide ◽  
Water Contact ◽  
Water Separation ◽  
Reduced Graphene ◽  
Oil Water Separation ◽  
Polyurethane Sponge ◽  
Oil Water

To exploit new adsorbents for oil-spill cleanup, a superhydrophobic material was fabricated by hightemperature reduced graphene oxide (HRGO) coated on commercial polyurethane (PU) sponge via facile dip-coating process. Compared with chemical reagent reduced graphene oxide, the graphene showed expanded sheets and vast surface area, which ensured the water contact angle of this synthesized sponge reached 150.0±2.5°. In order to break the boundary of poor adhesion of graphene on sponge skeleton, a simple approach of sealed thermal treatment was adopted in our work. And then the high-temperature reduced graphene oxide/polyurethane sponge treated with binary flourine-free organosilanes solution showed superhydrophobicity with high water contact angle (162.4±1.0°). Silanes addition also endowed the resultant sponge with enhanced interfacial adhesion on PU skeleton owing to interconnected structure. The as-prepared sponge displayed excellent adsorption capacity, which was 48–74 times of its own weight for different organic solvents and oils, and no decrease of the adsorption capacity was observed after 20 cycles. Besides, for the very sticky oil, the Joule-heat generated in the sponge by applied voltage could reduce the viscosity of oil. With the assistance of Joule-heat, the silane modified high-temperature reduced graphene oxide/polyurethane sponge achieved effective oil-water separation and greatly speeded up the separation efficiency. Additionally, whether in various temperature or corrosive conditions, the superhydrophobicity of the sponge almost remained stable, which was promising for oil/water treatment.

Recovering waste energy of the combined gas turbine system using paraffin melting

2020 ◽  
Vol 14 (4) ◽  
pp. 7481-7497
Author(s):  
Yousef Najjar ◽  
Abdelrahman Irbai
Keyword(s):  
Melting Process ◽  
Payback Period ◽  
Energy Utilization ◽  
Raw Material ◽  
Heat Transfer Fluid ◽  
Layered System ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Power Cycle ◽  
Waste Energy

This work covers waste energy utilization of the combined power cycle by using it in the candle raw material (paraffin) melting process and an economic study for this process. After a partial utilization of the burned fuel energy in a real bottoming steam power generation, the exhaust gas contains 0.033 of the initially burned energy. This tail energy with about 128 ºC is partly driven in the heat exchanger of the paraffin melting system. Ansys-Fluent Software was used to study the paraffin wax melting process by using a layered system that utilizes an increased interface area between the heat transfer fluid (HTF) and the phase change material (PCM) to improve the paraffin melting process. The results indicate that using 47.35 kg/s, which is 5% of the entire exhaust gas (881.33 kg/s) from the exit of the combined power cycle, would be enough for producing 1100 tons per month, which corresponds to the production quantity by real candle's factories. Also, 63% of the LPG cost will be saved, and the payback period of the melting system is 2.4 years. Moreover, as the exhaust gas temperature increases, the consumed power and the payback period will decrease.

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