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91.
《Journal of Saudi Chemical Society》2022,26(2):101441
Marine fishery wastes such as bivalve shells, crab shells and cuttlebone are rich in calcium. Calcium carbonate derived from these materials can be transformed into calcium oxide by calcination, which is used in a wide variety of applications (e.g., biomaterials for bone and teeth implants and drugs). In this study we analyze the effects of calcination temperatures (550 °C, 700 °C and 900 °C) on characteristics and elemental composition of calcium oxide derived from shells of four marine species collected in Thailand: oyster (Saccostrea cucullata), green mussel (Perna viridis), blue swimming crab (Portunus pelagicus), and cuttlefish (Sepia brevimana). The XRD patterns indicated the complete transformation of calcium carbonate into calcium oxide, observed by the changes of diffraction angles at 900 °C for all calcined samples, except cuttlebone, which was calcined successfully at 700 °C. Likewise, the FT-IR results revealed changes of functional groups at the same calcination temperatures. In addition, ICP-OES showed the effects of calcination temperature on elemental contents: major elements (Ca, P and K) increased in all samples, and some minor elements increased in blue swimming crab shell (Zn and Cu) and oyster shell (Fe) as a result of increasing the calcination temperature. This study demonstrates the optimum calcination temperature of calcium oxide production from four types of marine wastes that might be benefit for the chemical compound production industry. 相似文献
92.
In the present work, the synthesis and characterization of the Bis(4-acetylanilinium) tetrachlorocuprate(II) compound are presented. The structure of this compound is analyzed by X-ray diffraction which confirms the formation of single phase and is in good agreement the literature. Indeed, the Thermo gravimetric Analysis (TGA) shows that the decomposition of the compound is observed in the range of 420–520 K. However, the differential thermal analysis (DTA) indicates the presence of a phase transition at T=363 k. Furthermore, the dielectric properties and AC conductivity were studied over a temperature range (338–413 K) and frequency range (200 Hz–5 MHz) using complex impedance spectroscopy. Dielectric measurements confirmed such thermal analyses by exhibiting the presence of an anomaly in the temperature range of 358–373 K. The complex impedance plots are analyzed by an electrical equivalent circuit consisting of resistance, constant phase element (CPE) and capacitance. The activation energy values of two distinct regions are obtained from log σT vs 1000/T plot and are found to be E=1.27 eV (T<363 K) and E=1.09 eV (363 K<T).The frequency dependence of ac conductivity, σac, has been analyzed by Jonscher's universal power law σ(ω)=σdc+Aωs. The value of s is to be temperature-dependent, which has a tendency to increase with temperature and the non-overlapping small polaron tunneling (NSPT) model is the most applicable conduction mechanism in the title compound. 相似文献
93.
Titanium-based metal composites (TMCs) are showing great potential to replace existing traditional materials in aerospace, automotive, and other high temperature engineering applications. This is due to their excellent mechanical, thermal, and physical properties and improved strength to weight ratio. Weight savings in the aerospace industry results in higher efficiency. Carbon nanotubes (CNTs), because of their low density and high Young's modulus, are considered to be an excellent reinforcement for metal matrix composites (MMCs). In the last 20 years extensive research has been carried out to investigate the combination of carbon nanotubes with aluminum, nickel, copper, magnesium, and other metal matrices. The production techniques such as mechanical alloying through powder metallurgy routes and their effects on the mechanical properties of CNT reinforced TMCs are reviewed in this article. The role of the volume fraction of carbon nanotubes and their dispersion into the metal matrix are highlighted. Governing equations to predict the mechanical and tribological properties of CNT reinforced titanium matrix composites are deduced. With the help of this initial prediction of properties, the optimal processing parameters can be optimized. Successful development of CNT reinforced TMCs would result in better wear and mechanical behavior and enhance their ability to withstand high temperature and structural loading environments. 相似文献
94.
本文较为系统地研究了铜粉催化剂加入方式对C.I.颜料红177中间体4,4'-二氨基-1,1'-二蒽醌-3,3'-二磺酸(DAS)合成过程中的乌尔曼偶联反应速率的影响规律。 研究结果表明,在55 ℃较佳反应温度下,先加入与溴氨酸钠质量比为2:5的铜粉,反应一段时间后再加入与溴氨酸钠的质量比为1:5的铜粉,与一次性加入与溴氨酸钠的质量比为3:5的铜粉相比较,综合反应时间可节省2~3 h。 另外,对于DAS中混有的铜盐,采取在制备过程中加入柠檬酸的方法予以去除,此举可提高DAS的纯度。 当铜粉与柠檬酸的质量比为6:1时,可使DAS中铜盐的含量小于0.001%。 此外还探究了蒸馏后滤液的剩余量对DAS收率的影响,结果表明,滤液的剩余量在20 mL时,DAS的收率在95%以上。 基于本文的研究结果提出,欲进一步提高该反应的收率,需要寻找更高效的催化剂。 相似文献
95.
96.
Ganesan Karuppiah Kailasanathan Chidambara Kuttalam Murugesan Palaniappan Carlo Santulli Sivasubramanian Palanisamy 《Molecules (Basel, Switzerland)》2020,25(23)
In the present study, a model is presented to optimize the fabrication parameters of natural fiber reinforced polyester matrix composites with dual fillers. In particular, jute fiber mat was chosen as reinforcement and eggshell powder (ESP) and montmorillonite nanoclay (NC) were selected as fillers. The weight per square meter (GSM) of the fiber, the weight percentage of ESP and NC have been chosen as independent variables and the influence of these variables on tensile, flexural and impact strength of the composite has been inspected. The permutations of the different combinations of factors are intended to accomplish higher interfacial strength with the lowest possible number of tested specimens. The experiments were designed by the Taguchi strategy and a novel multi-objective optimization technique named COPRAS (COmplex PRoportional ASsessment of alternatives) was used to determine the optimal parameter combinations. Affirmation tests were performed with the optimal parameter settings and the mechanical properties were evaluated and compared. Experimental results show that fiber GSM and eggshell powder content are significant variables that improve mechanical strength, while the nanoclay appears less important. 相似文献
97.
用HNO3-HCl溶解试样,在几个相同量的试液中,分别加入质量浓度依次递增的5种元素的标准溶液,用火焰原子吸收法连续测定了Fe、Pb、Sb、Zn和Ni的含量,建立了优化的仪器测定条件,并对可能存在的元素进行了干扰试验。结果表明,Fe、Pb、Sb等5种元素的回收率为98.0%~102.3%,相对标准偏差为1.4%~2.5%。 相似文献
98.
99.
通过改变灰化温度,灰化时间及盐酸浓度三因素设计正交试验,对样品牦牛奶粉及市售奶粉进行干法消化。用火焰原子吸收光谱法对样品中的Ca, Mg, Fe, Cu, Zn, Mn, K和Na等八种元素进行测定。实验表明,最佳消化条件为:灰化温度510 ℃,灰化时间4 h,盐酸体积比为1∶5。在最佳实验条件下,对牦牛奶粉各元素的含量做了回收实验,回收率范围在95.2%~107.3%,相对标准偏差0.38%~3.86%(n=6)。实验结果表明:牦牛奶粉营养元素含量丰富, 是营养价值极高的食品。 相似文献
100.