Journal of Energy Storage
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2020
·
IF 3.762
Xian Wan,Cong Chen,Songyun Tian,Baohua Guo
A novel phase change materials (PCMs) composite was fabricated by sol-gel method for cold energy storage. Methyl laurate (ML) as cold energy medium was preferred due to its appropriate phase change temperature (3.96 ℃) and high latent heat (210.1 J/g), and silica provided a complete external protection for the ML. Various techniques were used to characterize the as-prepared ML/SiO 2 PCMs composite so as to investigate its structure and thermal properties, including scanning electron microscopy (SEM), fourier transforms infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA). During the PCMs composite forming process, hydrogen bonds generated by the interaction of carboxyl group of ML, the silicon hydroxyl group of silica, and the hydroxyl groups of emulsifier PVA promoted the morphology change of the PCMs composite from sphere-like to net-like structure. The DSC results showed that the net-like PCMs melted at 6.71 ℃ with a latent heat of 151.3 J/g and solidified at -5.43 ℃ with a latent heat of 148.9 J/g. Besides, the PCMs composite exhibited outstanding chemical compatibility, thermal reliability and complete micromorphology. Thus, the prepared ML/SiO 2 PCMs composite with novel net-like structure had great potential for cold energy storage.
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FOOD CHEMISTRY
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2020
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IF 6.306
Li Wang,Shuang Shao,Million Paulos Madebo,Yuanyuan Hou,Yonghua Zheng,Peng Jin
Effect of nano-SiO 2 packing on postharvest quality and antioxidant capacity of two different loquat cultivars (white-flesh ‘Qingzhong’ and red-flesh ‘Dawuxing’) were determined. Results showed that nano-SiO 2 packing significantly inhibited internal browning, retarded the decline of total soluble solids, titratable acidity, ascorbic acid content and extractable juice in both cultivars. Decay index of nano-SiO 2 packing in ‘Dawuxing’ and ‘Qingzhong’ was 53.25% and 42.84% lower than control after the day 12, respectively. Meanwhile, nano-SiO 2 packing enhanced the contents of individual phenolic compounds and soluble sugar compounds, induced higher superoxide dismutase and catalase activities, which contributed to improving 1,1-diphenyl-2-picrylhydrazyl and hydroxyl radical scavenging capacity. Furthermore, the contents of total soluble solids, ascorbic acid and soluble sugar were higher in ‘Qingzhong’ than those in ‘Dawuxing’, which dedicated to better quality. These results indicated that nano-SiO 2 packing was a promising approach in inhibiting decay, maintaining quality and expanding shelf life of loquats.
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Alexandria Engineering Journal
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2020
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IF 2.46
Saifeldin M. Siddeeg,Abdelfattah Amari,Mohamed A. Tahoon,Norah Salem Alsaiari,Faouzi Ben Rebah
For the simultaneous removal of water contaminants, a novel nanocomposite has been produced. The iron oxide core with silica shell was used to prepare functional magnetic polymer Fe 3 O 4 /SiO 2 /glycidyl methacrylate (GMA)-S-SH nanocomposite. The sulfur functional nanocomposite is suitable for the immobilization of laccase enzyme. The synthesized nanocomposite was characterized using FT-IR spectroscopy, SEM, TEM, XRD, and magnetometer. The effect of pH, temperature, and storage time over free and immobilized enzyme was studied that indicating the higher stability of immobilized enzyme than that free one. The prepared novel nanocomposite showed high adsorption capacity toward Cd +2 ions in addition to the degradation of meloxicam and piroxicam anti-inflammatory drugs. The removal efficiency reached up to 94% ± 2%, 92% ± 2%, and 95% ± 2% for Cd +2 ions, meloxicam, and piroxicam, respectively at optimum pH and temperature. Also, the results show that this nanocomposite is recyclable. The efficient removal of Cd +2 ions and pharmaceuticals can be reached up to four cycles. We conclude that the prepared nanocomposite is promising for water treatment.
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OPTICAL MATERIALS
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2020
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IF 2.779
Xiaoyu Sun,Xiaozhuang Xu,Guanyu Song,Jielei Tu,Lei Li,Pinyuan Yan,Weinan Zhang,Kai Hu
The broadband antireflective coatings (ARCs) can effectively reduce the optical loss in the transmittance process and improve energy efficiency in solar cells. MgF 2 /SiO 2 bilayer films were prepared on the surface of soda–lime substrates via sol – gel spin-coating combined with electron beam (e-beam) evaporation. The bottom layer was the MgF 2 film obtained from e-beam evaporation, whereas the top layer was the nanoporous SiO 2 film via sol–gel spin-coating method. The refractive indices of MgF 2 and SiO 2 layers at 550 nm are 1.38 and 1.12, respectively. The structural, morphological, and optical properties of the films were characterized. The effects of annealing temperature, Triton X-100 concentration, and spin-coating speed on the properties of the film were investigated. The transmittance spectra of the coatings were investigated, and the broadband antireflective performance of the bilayer structure was examined. A bilayer coating with optical properties close to the theoretical design results was obtained by optimizing the refractive index and the thickness of the double coatings. The solar transmittances of the soda–lime glass coated with the MgF 2 /SiO 2 bilayer antireflective film increased by 8.89% at 400–800 nm. The multilayer antireflective film exhibits promising applications in photoelectric devices, high power laser systems, and antidazzle glasses.
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LUMINESCENCE
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2020
·Vol. 35
·期 6
·835-844
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IF 1.855
Zheng Chang,Jing Feng,Xingwang Zheng
In this paper, a convenient reverse-phase microemulsion method for the synthesis of SiO 2 nanoparticles (NPs) by simply introducing the chitosan and fluorescent dye of lucigenin during the formation reaction of SiO 2 NPs was proposed. Addition of chitosan can make the SiO 2 NPs porous, and increases lucigenin molecule incorporation into chitosan/SiO 2 NPs nanopores based on electrostatic interaction and supermolecular forces. Therefore, fluorescence quantum yield of the lucigenin/chitosan/SiO 2 composite nanoparticles was increased by introduction of chitosan and compared with lucigenin/SiO 2 NPs without chitosan. Because the number of negative charges carried when using single-stranded DNA (ssDNA) was different from that of double-stranded DNA (dsDNA), the numbers of lucigenin/chitosan/SiO 2 composite nanoparticles with positive charge adsorbed using ssDNA or dsDNA were different. Consequently, fluorescence intensity caused using ssDNA or dsDNA/miRNA was clearly discriminative. With increase in target DNA/miRNA concentration, the difference in fluorescence intensity also increased, resulting in a good linear relationship between fluorescence intensity sensitizing value and target miRNA concentrations. Therefore, a new fluorescence analysis method for direct detection of let-7a in human gastric cancer cell samples without enzyme, label free and no immobilization was established using lucigenin/chitosan/SiO 2 composite nanoparticles as a DNA hybrid indicator. The proposed method had high sensitivity and selectivity, low cost and the detection limit was 10 fM (S/ N = 3).
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ChemCatChem
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2020
·Vol. 12
·期 14
·3670-3678
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IF 4.853
Mengjiao Zhang,Youwei Yang,Antai Li,Dawei Yao,Yueqi Gao,Busha Assaba Fayisa,Mei-Yan Wang,Shouying Huang,Jing Lv,Yue Wang,Xinbin Ma
Graphical Cu-based catalyst : In the hydrogenation of ethylene carbonate (EC), nanoflower-like catalysts with high fiber density exhibited nearly 98 % EC conversion when the H 2 /EC ratio was decreased to 60, while the catalyst with solid sphere structure required at least a H 2 /EC ratio of 140. This is attributed to the H 2 -enrichment effect of nanoflower-like morphology with dense fibers, which accelerated the reaction rate and achieved excellent activity at a low H 2 /EC ratio. The hydrogenation of ethylene carbonate (EC) to produce methanol and ethylene glycol (EG) is one of the key steps in the promising route for CO 2 utilization on a large scale. However, the high H 2 /EC ratio in feed (usually as 200∼300) is generally required to achieve favorable catalytic activity, inducing the high cost for H 2 circulation in the industrial application. Here, we report a series of nanoflower-like catalysts with curved fibers and open ends, among which the catalyst with the highest fiber density exhibited nearly 98 % EC conversion, 75 % methanol selectivity and over 99 % EG selectivity when the H 2 /EC ratio was decreased to 60. Combining the characterizations of active species distribution and high-pressure H 2 adsorption, it is demonstrated that the nanoflower-like morphology with dense fibers could remarkably enrich the hydrogen adsorption, consequently, accelerate the reaction rate and present an excellent performance at a low H 2 /EC ratio. These insights may provide instructive suggestions for further design of catalysts for the hydrogenation reactions.
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SEPARATION AND PURIFICATION TECHNOLOGY
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2020
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IF 5.774
Heng-Chen Liu,Hui-Xian Wang,Yu Yang,Zhao-Yong Ye,Keisuke Kuroda,Li-an Hou
A non-toxic and applicable surface-modified polyvinylidene fluoride (PVDF) membrane consisting of Prussian blue (PB) and aminating silica (A-SiO 2 ) nanoparticles was fabricated for the selective removal of trace radionuclide cesium (Cs) from water. The modified membrane denoted as PB/A-SiO 2 /PVDF exhibited high selective removal of cesium with a high permeate flux of more than 800 L/h∙bar∙m 2 in a wide pH range from 3 to 9. The adsorption experiments showed that the Langmuir isotherm model and the pseudo-second order model fitted well with the experimental results. The maximum adsorption capacity was 10.95 mg-Cs/g-membrane (i.e. 78.21 mg-Cs/g-PB sorbent on membrane) for the membrane at an initial Cs concentration of 50 mg/L. Based on the high Cs adsorption capacity of PB, the membrane could remove more than 97.5% Cs in the presence of the coexisting ions and organic matter for more than 10 h. The filtrated membrane could be effectively regenerated by NH 4 Cl, H 2 O 2 and HNO 3 solution with negligible decrease in removal efficiency after repeated use. With the high membrane flux and selective removal efficiency, the fabricated membrane can be potentially applied in Cs contaminated water treatment.
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SOLAR ENERGY MATERIALS AND SOLAR CELLS
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2020
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IF 6.984
Zilu Liu,Bingtao Tang,Shufen Zhang
Polyethylene glycol (PEG)/poly Acrylic acid (PAA)/silica (SiO 2 ) composite phase change materials (PCMs) with strong shape stability were successfully synthesized by a simultaneous sol-gel reaction, and in situ free radical polymerization . The network structure, shape stability, phase change enthalpy , and thermostability of the prepared materials were characterized through FT-IR, DSC , TGA , and XRD . The synthesized PEG/PAA/SiO 2 composite PCMs with a semi-interpenetrating network (semi-IPN) exhibited a high phase change enthalpy of 172.9 J/g and strong shape stability under 355 °C. The interaction between PEG and PAA/SiO 2 network was also discussed in this paper, as well as the relationship between the interaction, energy density , and shape stability. The prepared PEG/PAA/SiO 2 composite PCMs provided a novel method in preparing shape stable phase change materials.
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CHINESE JOURNAL OF CHEMICAL ENGINEERING
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2020
·
IF 2.627
Ruilong Zhang,Zhiping Zhou,Wenna Ge,Yi Lu,Tianshu Liu,Wenming Yang,Jiangdong Dai
Massive oily wastewater discharged from industrial production and human daily life have been an urgent environmental and ecological challenge. Superhydrophobic materials have attracted tremendous attention due to their unique properties and potential applications in the treatment of wastewater. In this study, a novel superhydrophobic/superoleophilic composite melamine sponge modified with dual silanized SiO 2 microspheres was fabricated simply by a two-step sol–gel method using vinyltriethoxysilane and hexadecyltrimethoxysilane as functional agent, which exhibited a water contact angle of 153.2° and a water sliding contact angle of 4.8°. Furthermore, the composite sponge showed the excellent oil adsorption performance and the compressive elasticity reaching up to 130 g·g −1 of dichloromethane and 33.1 kPa of compressive stress. It was worth noting that the composite sponge presented the excellent separation efficiency (up to 99.5%) in the processes of continuous oil/water separation. The robust superhydrophobic composite melamine sponge provided the possibility with the practical application for oil–water separation.
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WATER RESEARCH
·
2020
·
IF 9.13
Dingyuan Liang,Xiangrui Wang,Ying Wang,Zhaomin Dong,Xiaoli Zhao,Wenhong Fan
Dissolved organic matter (DOM) in aquatic ecosystems reshapes the surface of nanoparticles (NPs) greatly. Understanding how these changes influence the bioavailability of NPs is critical for accurately predicting the ecological risks of NPs. A quantitative model based on the two-step internalization process enabled the differentiation between the adhesion ability of NPs to membranes and the internalization capacity. Using protozoa Tetrahymena thermophila as the test organism, fluorescein isothiocyanate-modified silica NPs (FITC-SiO 2 ) and silica-coated gold NPs (Au@SiO 2 ) were prepared to validate the model and study the influence of DOM on uptake. DOM reduced the ability of Au@SiO 2 to adhere onto cell membranes and the inhibitory effect of bovine serum albumin (BSA) and β-lactoglobulin was higher due to their higher molecular weights and the weaker interaction. Moreover, DOM increased the internalization capacity. 80% Au@SiO 2 was internalized in the presence of humic acid (HA), over 90% Au@SiO 2 was internalized in the presence of the two proteins, whereas only 60% were internalized by the control group. Next, the specific recognition of the cell internalization in the presence of DOM was confirmed. We concluded that the traditional “accumulation” may misestimate the true biological effect caused by NPs coated with DOM. NPs coated with highly bioavailable DOM pose a greater risk to aquatic ecosystems because they are more likely to be internalized by living organisms.
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Nanomaterials
·
2020
·Vol. 10
·期 5
·883
·
IF 4.324
Bonan Zhao,Zhipeng Dong,Qiyan Wang,Yisong Xu,Nanxia Zhang,Weixing Liu,Fangning Lou,Yue Wang
The size-uniformed mesoporous Ag@SiO2nanospheres’ catalysts were prepared in one-pot step via reducing AgNO3by different types of aldehyde, which could control the size of Ag@SiO2NPs and exhibit excellent catalytic activity for the hydrogenation of nitrobenzene. The results showed that the Ag core size, monitored by different aldehydes with different reducing abilities, together with the ideal monodisperse core-shell mesoporous structure, was quite important to affect its superior catalytic performances. Moreover, the stability of Ag fixed in the core during reaction for 6 h under 2.0 MPa, 140 °C made this type of Ag@SiO2catalyst separable and environmentally friendly compared with those conventional homogeneous catalysts and metal NPs catalysts. The best catalyst with smaller Ag cores was prepared by strong reducing agents such as CH2O. The conversion of nitrobenzene can reach 99.9%, the selectivity was 100% and the catalyst maintained its activity after several cycles, and thus, it is a useful novel candidate for the production of aniline.Keywords:mesoporous;Ag@SiO2;catalyst;hydrogenation;nitrobenzene
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JOURNAL OF RARE EARTHS
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2020
·
IF 3.104
Shuo Wang,Zhenke Chen,Ying Zhao,Chenlu Sun,Jianye Li
In this work, the unique starlike La-doped ZnO–SiO 2 photocatalysts were constructed by an evaporation and calcination method and characterized in detail. UV–vis reflectance and DFT calculation confirm that the doping with La allows to obtain a decrease of band gap of ZnO/SiO 2 , which enhances visible light absorbance and oxidizing ability. The photoluminescence intensity reduces greatly, indicating more effective separation of the photogenerated carriers of La-doped ZnO-SiO 2 . Photocatalytic activities of La-doped ZnO-SiO 2 with different doping ratios under simulated visible light irradiation were evaluated with malachite green (MG) as a model pollutant. Under optimized conditions including solution pH of 8, 15 mg/L of MG solution and 15 mg of catalyst dosage, 0.2% La-ZnO-SiO 2 exhibits the best catalytic activity in photodegradations of MG in water. The removal and mineralization efficiency of MG can reach 96.1% and 70.9% in 140 min, respectively. The as-prepared catalysts present superior stability and recyclability after four times reuse. Moreover, selective quenching experiments indicate that hydroxyl radical (·OH), hole (h + ) and superoxide radical (·O 2 - ) are the main reactive species responsible for MG degradation. Possible mechanism for photocatalytic elimination of MG over La-doped ZnO/SiO 2 photocatalyst is finally proposed.
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