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41.
Rosana A. Gonalves Rosimara P. Toledo Nirav Joshi Olivia M. Berengue 《Molecules (Basel, Switzerland)》2021,26(8)
Over the last two decades, oxide nanostructures have been continuously evaluated and used in many technological applications. The advancement of the controlled synthesis approach to design desired morphology is a fundamental key to the discipline of material science and nanotechnology. These nanostructures can be prepared via different physical and chemical methods; however, a green and ecofriendly synthesis approach is a promising way to produce these nanostructures with desired properties with less risk of hazardous chemicals. In this regard, ZnO and TiO2 nanostructures are prominent candidates for various applications. Moreover, they are more efficient, non-toxic, and cost-effective. This review mainly focuses on the recent state-of-the-art advancements in the green synthesis approach for ZnO and TiO2 nanostructures and their applications. The first section summarizes the green synthesis approach to synthesize ZnO and TiO2 nanostructures via different routes such as solvothermal, hydrothermal, co-precipitation, and sol-gel using biological systems that are based on the principles of green chemistry. The second section demonstrates the application of ZnO and TiO2 nanostructures. The review also discusses the problems and future perspectives of green synthesis methods and the related issues posed and overlooked by the scientific community on the green approach to nanostructure oxides. 相似文献
42.
Konstantinos Petrotos Ioannis Giavasis Konstantinos Gerasopoulos Chrysanthi Mitsagga Chryssoula Papaioannou Paschalis Gkoutsidis 《Molecules (Basel, Switzerland)》2021,26(1)
Orange pomace (OP) is a solid waste produced in bulk as a byproduct of the orange juice industry and accounts for approximately 50% of the quantity of the fruits processed into juice. In numerous literature references there is information about diverse uses of orange pomace for the production of high-added-value products including production of natural antioxidant and antimicrobial extracts rich in polyphenols and flavonoids which can substitute the hazardous chemical antioxidants/antimicrobials used in agro-food and cosmetics sectors. In this work and for the first time, according to our knowledge, the eco-friendly aqueous vacuum microwave assisted extraction of orange pomace was investigated and optimized at real industrial scale in order to produce aqueous antioxidant/antimicrobial extracts. A Response Surface Optimization methodology with a multipoint historical data experimental design was employed to obtain the optimal values of the process parameters in order to achieve the maximum rates of extraction of OP total polyphenols and/or total flavonoids for economically optimum production at industrial scale. The three factors used for the optimization were: (a) microwave power (b) water to raw pomace ratio and (c) extraction time. Moreover, the effectiveness and statistical soundness of the derived cubic polynomial predictive models were verified by ANOVA. 相似文献
43.
Peng Liu Hui Ruan Tiantian Li Jiaqi Chen Fuqiu Ma Duoqiang Pan Wangsuo Wu 《Molecules (Basel, Switzerland)》2021,26(4)
The low cost β-zeolite and ethylenediamine modified β-zeolite (EDA@β-zeolite) were prepared by self-assembly method and used for Cu(II) removal from contaminated aqueous solution. Removal ability of β-zeolite toward Cu(II) was greatly improved after ethylenediamine (EDA) modification, the removal performance was greatly affected by environmental conditions. XPS results illustrated that the amide group played important role in the removal process by forming complexes with Cu(II). The EDA@β-zeolite showed desirable recycling ability. The finding herein suggested that the proposed composite is a promising and suitable candidate for the removal of Cu(II) from contaminated natural wastewater and aquifer. 相似文献
44.
针对某钢厂转炉煤气加压站大风机电机采用工频加变频的恒压闭环运行方式,变频风机极易发生喘振的现象,为了确保大风机稳定、安全的运行,在风机喘振的预防和控制方法上进行改进。采用两台风机同步变频调速与最小极值流量法的模糊PID控制相结合的防喘振控制方法,同步变频调速控制策略有效地预防喘振的发生,最小极值流量法的模糊PID控制策略最大限度的扩大了风机的运行区间,通过MATLAB软件仿真,证明模糊PID的动态响应速度和鲁棒性较常规PID有较大的改良。控制系统通过工业网络完成现场设备和远程的通讯,使控制系统达到高水平的智能自动化。 相似文献
45.
M. Sc. Moritz C. Baier Dr. Martin A. Zuideveld Prof. Dr. Stefan Mecking 《Angewandte Chemie (International ed. in English)》2014,53(37):9722-9744
Research on “post‐metallocene” polymerization catalysis ranges methodologically from fundamental mechanistic studies of polymerization reactions over catalyst design to material properties of the polyolefins prepared. A common goal of these studies is the creation of practically useful new polyolefin materials or polymerization processes. This Review gives a comprehensive overview of post‐metallocene polymerization catalysts that have been put into practice. The decisive properties for this success of a given catalyst structure are delineated. 相似文献
46.
介绍了一个开放性环境化学实验。该实验以被重金属污染的土壤为研究对象,分别使用稀盐酸、乙二胺四乙酸、氯化钙为淋洗剂,对其进行化学淋洗修复。通过电感耦合等离子体光谱仪分析比较修复前后土壤中铅、镉的含量,用以帮助学生加深理解配合/螯合作用、酸-碱反应、离子交换反应、胶体的性质、土壤重金属形态、土壤性质与组成等相关环境化学知识。实验所用的土壤样品由学生自选,不同类型土壤的理化性质影响淋洗效果,从而增加了实验结果的不确定性。本实验贴近学科前沿且联系工程实际,可激发学生独立思考和探索精神,提高学生的科研能力与解决复杂问题的能力。 相似文献
47.
《Arabian Journal of Chemistry》2020,13(11):7609-7625
The presence and fate of polyaromatic hydrocarbons (PAHs) in the environment are receiving a great concern. In this study, three oil-contaminated soils (industrial area, Dukhan city, and artificial soils) were utilized to examine the effect of microwave (MW) heating and UV-C irradiation on the PAHs degradation. A rapid assessment of the impact was evaluated using Fourier transform infrared (FTIR) and multivariate analysis. The total organic matter values for the maximum PAHs reduction were evaluated based on the FTIR spectra of the contaminated soils followed with the principal component analysis (PCA). The results showed that the highest total organic carbon reduction was achieved for the industrial soil sample that required a high MW power and long MW exposure time. On the other hand, the Dukhan city soil sample, which has the lowest total organic carbon, required a high MW power and short MW exposure time followed by UV-C treatment for 20 min to reach the maximal FTIR transmittance reduction. The cluster analysis was also used to evaluate the impact of MW heating, and MW heating followed by UV-C irradiation on the degradation of PAHs. The PCA results of the industrial city sample showed that neither MW treatment (100% MW, 15 min exposure time) followed by UV-C treatment for 20 min nor 10 min is significantly different from the MW treatment (100% MW, 15 min exposure time). However, for the Dukhan sample, the UV-C treatment at 10 min after high MW power and long exposure time (100% MW, 15 min exposure time) was the most efficient treatment. 相似文献
48.
Today, analyzing of sound pressure level and frequency is considered as an important index in human society. Sound experts believe that analyzing of these parameters can help us to better understanding of work environments. Sound measurements and frequency analysis did to fix the harmful frequency in all sections in Shiraz gas power plant with sound analyzer model BSWA 308. The sound pressure levels (LP) and the one and one-third octave band were continuously measured in A and C weighting networks and slow mode for time response. Excel 2013 and Minitab 18.1 software used for statistical calculations. Results analyzed by Minitab 18.1 software. The highest harmful frequency in Shiraz Gas Power Plant (SGPP) was 50 Hz with 115 dB. The sound pressure level (SPL) ranged from 45 dB to 120 dB in one-third octave band and weighting network C. The maximum sound pressure level was in Craft electricity generator with 105.3 dB and 67 Hz. Sound pressure level in surrounded environment was 120 dB. According to the results, in this industry the sound pressure level exceeded the Occupational Exposure Level of Iran (OEL). The value of sound pressure level were higher than the Standard of occupational health. SGPP consumes 47000 cubic meters of natural gas per hour to produce 100 MW (Mega Watt) of electricity. It is very high and it is not economical and cost effective. These numbers indicate that the power plant’s efficiency is low. It could be concluded that the noise pollution is an important issue in these industries. Moreover, SGPP produce noise with loss energy. Frequencies rotation at high sound pressure levels toward low frequencies were happened. 相似文献
49.
Samar Beaino Peter El Hage Rodolphe Sonnier Sylvain Seif Roland El Hage 《Molecules (Basel, Switzerland)》2022,27(2)
This study highlights the synthesis of a new thermal insulating geopolymer based on the alkaline activation of fly ashes. A porous geopolymer material can be prepared without the addition of a foaming agent, using high ratio solution/ashes (activating solutions used are water, sodium or potassium hydroxide). In order to increase the porosity of the material and to make it more ecological, rice husks are incorporated into the formulation. The geopolymer materials were prepared at room temperature and dried at moderate temperature (105 °C) by a simple procedure. The microstructural characteristics of these new porous geopolymers were assessed by optical microscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA) and X-ray fluorescence (XRF). Infrared spectroscopy (FTIR) was used to confirm the geopolymerisation. The effect of the ratio solution/ashes and the percentage of the rice husk addition on thermal and mechanical analysis was evaluated. An insulating material for a solution/ashes ratio of 0.9 and a rice husk content of 15% having a λ value of 0.087 W/(m·K), a porosity of 61.4% and an Rc value of 0.1 MPa was successfully prepared. 相似文献
50.
J. C. Raines J. P. Schmidt J. P. Burelbach H. K. Fauske 《Journal of Thermal Analysis and Calorimetry》2006,85(1):53-55
Hydrogen
peroxide is a very versatile oxidizing agent, and it is also environmentally
compatible considering that the products of its exothermic decomposition are
oxygen and water.When kept in a clean temperature-controlled environment,
the self-reaction (decomposition) rate is extremely low. However, it is well
known that even a small amount of contamination will dramatically increase
the reaction rate. This paper describes the use of the fast thermal activity
interpreter (FTAI) instrument to examine the chemical reactivity of commercially
available 50% hydrogen peroxide at two different temperatures (30 and 40°C)
both with and without contamination. The results show that at 30°C a small
amount of rust (330 ppm) increases the reaction rate of 50% hydrogen peroxide
by a factor of 50. When the temperature is increased to 40°C, the reaction
rate is further increased by almost a factor of four. The implication for
reactivity management is that at this contamination level most practical vessel
sizes would require emergency venting capability.
An evaluation
was then performed to determine the emergency venting requirement for the
safe transportation or storage of the contaminated hydrogen peroxide. It was
determined that for quantities of the material less than 5 gallons, conventional
breather vents would be sufficient to accommodate the gas evolved. However,
for larger quantities, a safety relief device would be needed. For example,
for a 400-gallon tote bin at 40°C the required minimum vent area is estimated
to be 4.3 in2, corresponding to a minimum vent
diameter of 2.3 inches. 相似文献