Current Issue : April-June Volume : 2023 Issue Number : 2 Articles : 5 Articles
From sucrose aqueous solution of high viscosity, sucrose was crystallized by seeded cooling in a batch crystallizer. At low seed loadings, the product crystal size distribution (CSD) was wide-spread because of enormous secondary and primary nucleation. However, at high seed loadings, it became uni-modal, where the crystallization was dominated by seed growth with practically no secondary nucleation. Enough seeding was thus effective in suppressing nucleation even during batch crystallization with high viscosity solution. The volume mean size of the product crystals obtained at high seed loadings agreed with that calculated by a simple mass balance assuming growth-dominated crystallization with no change in the number of crystals....
Microwave irradiation has been used to enhance the reaction yields and selectivities for organic transformation. In this paper, microwave irradiation (MW) was investigated for the environmentally benign synthesis of benzoxazoles through the cyclization of 2-aminophenols and benzaldehydes using deep eutectic solvent (DES) as a catalyst. The [CholineCl][oxalic acid] was easily synthesized from choline chloride with oxalic acid and used without further purification. [CholineCl][oxalic acid] catalyzed the synthesis of benzoxazoles to produce the desired product in a good to excellent conversion and selectivity underMWirradiation. The presence of [CholineCl][oxalic acid] helps to promote the rapid heating transfer from microwave irradiation into the reaction mixture. The [CholineCl][oxalic acid] can be recovered and reused several times without a considerable degradation in catalytic activity....
Despite having detrimental impacts on the environment and human health, used engine oil is not properly disposed of in Ghana. However, used engine oil can be a valuable resource when recycled. This study investigates the recovery of base oils from used engine oils collected in one Ghanaian municipality. The used engine oils are re-refined either through acid-clay treatment or solvent extraction. Pour point, density, viscosity index, and total acid number of used engine oil and re-refined oils were measured in order to evaluate the two re-refining processes used and assess whether it is appropriate to reuse the re-refined oils as base oils. The pour point, total acid number, and viscosity index of the re-refined oils were significantly different from those of the used engine oils. The density of the re-refined oils varied little from that of the used engine oils (by 0.83% to 6.65%). These changes indicate the separation of some components, primarily impurities, from used engine oil as a result of re-refining. Compared to solvent extraction, acid-clay treatment was found to be less selective. When nitric acid or sulphuric acid was used, acid-clay treatment often produced group I and II base oils, whereas hydrochloric acid typically produced group III base oils. Also, the solvent extraction process frequently yielded oils with very high viscosity indices comparable to group III base oils. It is recommended that the type of base oil preferred for the production of new lubricants should be taken into account when deciding on a specific method for re-refining used engine oil....
Black phosphorus (BP) is a unique two-dimensional material with excellent conductivity, and a widely tunable bandgap. In recent years, its application in the field of energy has attracted extensive attention, in terms of energy storage, due to its high theoretical specific capacity and excellent conductivity, black phosphorus is widely used as electrode material in battery and supercapacitors, while for energy generating, it has been also used as photocatalyst and electrocatalysts to split water and produce hydrogen. Black phosphorus demonstrates even better stability and catalytic performance through further construction, doping, or heterojunction. This review briefly summarizes the latest research progress of black phosphorus and its composites in energy preparation and storage, as well as ammonia nitrogen fixation, and also looks into the possible development directions in the future....
Research and development of efficient, economical and resource-based flue gas desulfurization technology has always been a hot spot in the field of air pollution control. Molecular sieve materials have been paid attention to by SO2 adsorbent researchers due to their huge specific surface area. In this paper, 13X zeolite was modified with Cu(NO3)2·3H2O to obtain 13x-Xwt %CuO (calculated by the amount of CuO loaded). The adsorption time and capacity of SO2 penetration sorbent and the isothermal curve of N2 adsorptiondesorption were studied. The results are as follows: 13X-3wt%CuO has the best adsorption effect, the penetration adsorption time is 110 min, the penetration adsorption capacity is 43.41 mg·g−1, the saturation adsorption capacity is 49.27 mg·g−1; The amount of CuO loading has a great influence on the adsorption effect of modified 13X molecular sieve on SO2. SEM and BET characterization showed that CuO modification did not change the external morphology of 13X molecular sieve, changed the pore size, but did not block the original channel of the molecular sieve, before and after modification belong to the type I adsorption isothermal curve. The pore size distribution and type of molecular sieve, as well as the content and type of alkali metal cations jointly control the adsorption process of SO2 by 13X-xwt %CuO. XPS characterization showed that Cu(NO3)2 decomposed into CuO and Cu2O during roasting at 450˚C, CuO/Cu2O ≈ 1.5. The R2 values of the quasi-second-order kinetic models obtained from the 13X-Xwt %CuO particle diffusion kinetic models were all above 0.99, indicating that the quasi-second-order kinetic equations were more relevant. Particle diffusion dynamics model in fitting results show that the adsorption process can be divided into two stages, the first phase of surface adsorption and diffusion rate in the granules common control process, more accurate dynamics model of the secondary in the second phase particle diffusion rate control stage, mainly for the micropore adsorption or chemical adsorption, quasi level 2 dynamic model conformity of variation; C is a constant not equal to 0, indicating that the adsorption of SO2 is not completely through the form of intra-particle diffusion, and a small amount of chemisorption exists. And it is the compound effect of multiple adsorption mechanisms....
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