Vol 5, No 2 (Published)
Table of Contents
Open AccessOriginal Research Article
by Lilia Fernández-Sánchez, Mirella Gutiérrez-Arzaluz
2022,5(2);
498 Views
Abstract
This work aims to present two syntheses according to the green chemistry principles of Cu 2 (OH)PO 4 . The first one is a mechanochemical synthesis which was carried out with Cu 3 (PO 4 ) 2 and NaOH at room temperature and without solvent (principles five and six), the second one employed an aqueous suspension of copper phosphate (principle six). The products were characterized by X-ray diffraction, scanning electron microscopy, infrared spectroscopy and elemental analysis. Using an analysis and evaluation scale based on green principles, the synthesis method reported in this study was compared with the traditional hydrothermal synthesis method, which was found to be a polluting process, while the synthesis method reported in this study was a clean process. It was concluded that clean processes lead to time savings, low energy costs and environmental care.
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Open AccessOriginal Research Article
by Marcelo Rodríguez Valdivia, Rivalino Guzmán Ale, Martha Huamán Gutiérrez
2022,5(2);
511 Views
Abstract
This article reports the results of an investigation carried out in order to obtain zeolitic material of the GIS-NaP type with high cation exchange capacity using brick waste. The hydrothermal synthesis was carried out in a stainless-steel reactor using NaOH activating solutions at concentrations of 2.0, 2.5 and 3.0 M, activation temperatures of 100, 120 and 140 ℃ and activation times of 7, 8 and 9 hours. The product obtained was characterized by X-ray Fluorescence, Scanning Electron Microscopy (SEM), X-ray Diffraction, and Cation Exchange Capacity (CEC). The results obtained showed that for the hydrothermal conversion test at 140 ℃/2 M/7 hours, GIS-NaP synthetic zeolite with a cation exchange capacity equal to 163.5 meq/100 g was obtained. The statistical analysis, applying a factorial experimental design, indicated that the main factors with a great effect on the cation exchange capacity (CEC) are the activation temperature and the interaction between it and the concentration of the activating solution, with a degree of significance of 0.049250 and 0.056631 for a confidence level of 90.82%. An empirical mathematical model was developed and validated by applying ANOVA analysis that considers the interaction effects of all factors and was optimized by applying the response surface methodology.
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Open AccessOriginal Research Article
by Huifang Zhao, Huayu Zhao, Siwen Yi, Ruiping Zhang
2022,5(2);
457 Views
Abstract
using the synthesized nickel particle/graphene (Ni/Gr) composite as a new matrix and adsorbent, a matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) platform was constructed for the efficient analysis of various drugs, amino acids and other small biological molecules. Compared with the traditional matrix of 2, 5-dihydroxyphenyl acid (DHB) and a series of comparison materials (Gr, Ni-1/gr and Ni-5/gr), Ni-2/gr as MALDI matrix has the advantages of low background noise, high ionic strength, high signal-to-noise ratio and wide linear range (0.01 ~ 50 μmol/L, 0.2 ~ 50 μmol/l and 0.05 ~ 60 μmol/l) when analyzing the molecules of resveratrol, 6-gingerol and rutin in the positive ion mode. The detection limits (LODs) of resveratrol, 6-gingerol and rutin were respectively 0.0038, 0.09 and 0.02 μmol/L. Ni-2/gr complex has the characteristics of high specific surface area, rich mesoporous structure, a large number of sp 2 structures, strong UV absorption and high saturation magnetization value (MS). It can be used as an adsorbent to magnetically enrich phenylalanine, tryptophan and tyrosine, and can also be used to magnetically enrich low concentration tryptophan in mouse serum samples.
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Open AccessOriginal Research Article
by Marcelo Rodríguez Valdivia, Gladys Ocharán Velásquez, Karen Calderón Soncco, Víctor Benavides Paredes
2022,5(2);
379 Views
Abstract
This paper reports the results of the synthesis of zeolitic material with adsorbent capacity from a rock of volcanic origin from sillar, Arequipa, Peru. The experimentation was carried out in a stainless steel reactor using solutions with different concentrations of KOH (2.0, 2.5 and 3.0 M), at a constant temperature of 150 ℃ and with a contact time between the volcanic material and the solution of 24, 48 and 72 h. The product obtained was characterized by means of scanning microscopic analysis (SEM) and cation exchange capacity (CIC). The results showed that synthetic zeolite was produced as a function of KOH concentration as the most influential independent variable. The highest cation exchange capacity (CEC) observed was 27.91 meq/100 g and corresponded to the formation of Linde F zeolite obtained with a 3.0 M KOH solution and for a time of 72 hours using a material whose particle size was 4 mm. Adsorption tests were performed using solutions containing Cu 2+ cations in order to evaluate their adsorption capacity and kinetics.
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Open AccessOriginal Research Article
by Xuqiang Ren, Donglin Li, Zhenzhen Zhao, Guangqi Chen, Kun Zhao, Xiangze Kong, Tongxin Li
2022,5(2);
543 Views
Abstract
Al doped lithium-rich manganese-based Li 1.2 Mn 0.54− x Al x Ni 0.13 Co 0.13 O 2 ( x = 0, 0.03) cathode materials for lithium-ion batteries were synthesized with sol-gel method, and then Li 2 WO 4 coating was prepared by one-step liquid phase method. The effects of Al doping and Li 2 WO 4 coating on the electrochemical properties of lithium-rich manganese-based cathode materials were systematically studied. The results show that Al doping significantly improves the cycle stability of lithium-rich manganese-based cathode material, and the coating Li 2 WO 4 significantly improves its magnification performance and the voltage attenuation of discharge plateau. The coating amount of Li 2 WO 4 is 5%, and the specific capacity of Li 1.2 Mn 0.51 Al 0.03 Ni 0.13 Co 0.13 O 2 cathode material is still up to about 110 mAh·g −1 in the charge and discharge voltage range of 2.0-4.8 V and the current density of 1,000 mA·g −1 . At the same time, the capacity retention rate of 300 cycles at the current density of 100 mA·g −1 is 78%, and the voltage attenuation of the discharge plateau during the cycle is also significantly reduced. This work provides a new idea for solving the cycle stability and platform voltage attenuation of lithium-ion battery lithium-rich manganese-based cathode materials.
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Open AccessOriginal Research Article
by Jingnan Guo, Yanlin Wang, Baihe Guo, Xiaolei Qiao, Xiaofei Wang, Jinrong Guo, Yan Jin
2022,5(2);
258 Views
Abstract
In this paper, the preparation of potassium carbonate modified SiO 2 -Al 2 O 3 composite aerogel, the carbonation characteristics of K 2 CO 3 and the decarburization characteristics of regeneration cycle were studied. The influence of loading rate on CO 2 adsorption was studied by using a fixed bed reactor, and the microstructure of the samples was analyzed by combining SEM and BET. The results show that during the alkali fusion sintering of Na 2 CO 3 , the Si-O-Si and Si-O-Al bonds break, the crystal structure is destr oyed, and the covalent bond of mullite is transformed into the ionic bond of nepheline. Through orthogonal test, taking the specific surface area of aerogel as the measurement index, the optimal calcination conditions are determined as follows: 900 ℃ , reac tion for 60 min, Na 2 CO 3 addition ratio of 0.5. The more K 2 CO 3 is loaded, the less the corresponding active sites on the surface of the carrier. When the loading is 30%, the maximum CO 2 adsorption capacity is 2.86 mmol·g –1 . Excess K 2 CO 3 will plug the pore structure, destroy the diffusion of CO 2 , and reduce the diffusion and utilization efficiency. The percentage of mesoporous pore volume decreased from 94.21% to 89.32%, indicating that the active component K 2 CO 3 was mainly filled in the mesoporous. After 10 cycle regeneration tests, the CO 2 adsorption capacity of the adsorbent decreased by 10.49%. The pore structure of the adsorbent was stable and the decarburization performance was excellent.
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Open AccessOriginal Research Article
Cu/CuO/ZnO/PPy heterojunction material was prepared for Hg2+ anti-interference detection in seawater
by Ming Li, Zhengming Li, Xiaotong Dong, Liangbin Jia, Meiyan Zhu, Ye Ma, Minggang Zhao, Hongzhi Cui
2022,5(2);
226 Views
Abstract
Hg 2+ pollution poses a major threat to human health and the ecological environment, but there is still a lack of direct and sensitive Hg 2+ detection technology. In this study, C u/ C u O / Z n O wires were prepared by alkaline oxidation and hydrothermal methods. Polypyrrole (PPy) was covered on the surface of the material by electrochemical polymerization. Using the principle of electrochemical signal response driven by p-n junction barrier, the material was used for the direct electrochemical detection of Hg 2+ and was tested by differential pulse voltammetry. The composite has a good linear relationship in the Hg 2+ concentration range of 200–1600 nmol/L, and has ultra-high sensitivity (1,010.82 μA∙L/(nmol∙cm 2 )) and ultra-low detection limit (2.1 pmol/L). The new sensing mode based on the interface barrier eliminates the interference of other ions. The recovery rate of Hg 2+ in tap water, river water and sea water is 97.3%–105.0%, and the RSD is 1.8%–5.6%. This method using p-n junction barrier can be extended to the development and research of other sensors for detecting heavy metal ions.
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Open AccessCase Report
by Camila Pedreros Calvo, Kelly Viviana Valderrama López, Rafael Nikolay Agudelo Valencia, Karina Pérez Cortés, Carlos Enrique Campo
2022,5(2);
221 Views
Abstract
This work was carried out to improve the performance of an ozonation system used for wastewater treatment in a pharmaceutical industry. In order to improve the mineralization of organic matter, ferrous sulfate was applied as a catalyst to the reaction system. After this, the pH of the water was adjusted to 8.5–10, so that the process is carried out under alkaline conditions. Finally, O 3 was injected through a Venturi tube in order to improve the mass exchange between gas and water. Preliminary operating data indicate that the treatment system achieves chemical oxygen demand (COD) removals of less than 10%. The tests were conducted at full scale and the water quality variables were analyzed at different reaction times. It was determined that for an ozone dose equal to 10 g/h and 10 mg/L Fe 2+ and an initial water pH equal to 9, 4.5 hours were required to achieve a reduction of 30.73% COD and 36.85% total organic carbon (TOC). The results obtained with an initial pH higher than 9.5 indicate that the effectiveness of the process is reduced, a fact that may be caused by the rapid formation of insoluble Fe(OH) 3 , which decreases the availability of the catalyst for the formation of OH * radicals in the water.
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