Swift Reduction of Nitroaromatics By Gold Nanoparticles Anchored On Steam-Activated Carbon Black Via Simple Preparation

Gold (Au) nanoparticles supported on certain platforms display highly efficient activity on nitroaromatics reduction. In this study, steam-activated carbon black (SCB) was used as a platform to fabricate Au/SCB catalysts via a green and simple method for 4-nitrophenol (4-NP) reduction. The obtained Au/SCB catalysts exhibit efficient catalytic performance in reduction of 4-NP (rate constant kapp = 2.1925 min-1). The effects of SCB activated under different steam temperature, Au loading amount, pH and reaction temperature were studied. The structural advantages of SCB as a platform were analyzed by various characterizations. Especially, the result of N2 adsorption-desorption method showed that steam activating process could bring higher surface area (from 185.9689 m²/g to 249.0053 m²/g), larger pore volume (from 0.073268 cm³/g to 0.165246 cm³/g) and more micropore for SCB when compared with initial CB, demonstrating the suitable of SCB for Au NPs anchoring, thus promoting the catalytic activity. This work contributes to the fabrication of other supported metal nanoparticle catalysts for preparing different functional nanocomposites for different applications.

Mechanistic insights into the adsorption of methylene blue by particulate durian peel waste in water

This study aims to investigate the adsorption of methylene blue (MB) over particulate durian peel waste, which is chemically-activated with hydrogen peroxide. The equilibrium data is well-described by the Freundlich isotherm model, which outlines where the MB adsorption takes place predominantly on multilayers and heterogeneous surfaces of the biosorbent. The Freundlich adsorption constants, KF and n, are 11.06 L/g and 2.94, respectively. Thermodynamic data suggests that the MB adsorption occurs spontaneously and exothermically. The enthalpy and entropy for the MB adsorption are obtained as 10.26 kJ/mol and 0.058 kJ/mol K, respectively, in the temperature range of 303–323 K. Based on the stepwise desorption method, the adsorption of MB is dominated by physical interactions, particularly hydrogen bonding.

Overview of sorption analysis capabilities for meso- and microporous zeolites nanomaterials

In this paper we consider the main application features of the thermal desorption method of inert gases, implemented on the Sorbi MS (Meta, Russia) device, for the analysis of meso- and microporous materials. Recommendations on the choice of measurement modes for stable operation of the Sorbi MS device are offered (including recommendations on mass, sample preparation mode). The article presents the results of the micropores analysis by the t-plot and Sing method.

Unexpectedly efficient ion desorption of graphene–based materials

Ion desorption is extensive and extremely challenging for adsorbents with superior performance, for which conventional desorption methods involving high acid or base concentrations and large consumption of reagents are widely used. Here we experimentally demonstrated the unexpectedly rapid and efficient desorption of ions on magnetite–graphene oxide (M–GO) by adding trace amounts of Al3+. The corresponding concentration of Al3+ used was reduced by a factor of at least 250 compared with the conventional desorption method. The desorption rate reached up to ~ 97.0% for the typical radioactive and bivalent ions of Co2+, Mn2+, and Sr2+ within ~ 1 min. Importantly, we achieved the effective enrichment of radioactive 60Co, with the volume of the concentrated 60Co solution reduced by approximately 10 times compared with the initial solution. Density functional theory calculations revealed that the interaction of graphene with Al3+ was much stronger than that with divalent ions, yielding the adsorption probability of Al3+ superior to Co2+, Mn2+, and Sr2+ ions, suggesting that the proposed method could be used to enrich a wider range of ions in the fields of energy, biology, environment, and materials science.

Anomalous effect of Cu2O and CuO deposit on the porosity of a macroreticular anion exchanger

When synthesizing copper compounds containing polymeric adsorbents, it was found that the two copper oxides, Cu2O and CuO, deposited in the skeleton of a strongly basic macroreticular anion exchanger (An) radically diminished the porosity of the obtained composites in relation to the host material. In order to investigate this phenomenon more closely, An/Cu2O and An/CuO (both based on the commercial anion exchanger Amberlite IRA900Cl), containing 8.6 and 8.2 wt% Cu, respectively, were subjected to scrutiny. The porous characteristics of the thermally dried and freeze-dried samples were determined using the N2 adsorption–desorption method and mercury intrusion porosimetry. The thermally dried samples lost their porosity and increased their bulk density in relation to the pure resin indicated a significant reduction in their volume. It was found that during drying, the grains shrank as much as the pores collapsed. The decay of the porous structure resulted from the surface morphology of the Cu2O and CuO particles and their tendency to agglomerate. Both freeze-dried samples retained the porous characteristics typical for macroporous anion exchangers. In contrast to the most popular hybrid ion exchangers containing hydrated polyvalent metal oxides (such FeOOH), An/Cu2O and An/CuO showed markedly strong volume contraction effect in relation to moisture content. Graphical abstract

An Ecofriendly Synthesis of 2-oxazolidinone From 2-aminoethanol and Urea Under Solvent-free Condition Using CeO2 Nanoparticles

Cerium dioxide nanoparticles were prepared by the sol-gel method using cellulose as a template and used in the synthesis of 2-oxazolidinone from urea and 2-aminoethanol under solvent-free conditions. All the reaction parameters were optimized to obtain the best selectivity and conversion. The selectivity of 100 % to 2-oxazolidinone with a pretty complete conversion of about 98.4 % was achieved. The prepared catalyst was characterized by Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and volumetric isothermal nitrogen gas adsorption-desorption method (BET).

REMOÇÃO DE H2S EM ÁGUA SUBTERRÂNEA PELO MÉTODO DE DESSORÇÃO GASOSA

<p class="Default">Dos recursos que a natureza proporciona, a água é essencial à sobrevivência do meio biótico. Não só está disponível na superfície terrestre como também pode ser captada em aquíferos subterrâneos. Entretanto, para ser consumida, a água deve estar apta para tal, obedecendo aos critérios de potabilidade, contendo as concentrações permitidas de agentes contaminantes e poluentes ou estando livre dessas substâncias, que podem atribuir cor, gosto e/ou odor. Dentre os contaminantes comuns em águas subterrâneas, encontra-se o sulfeto de hidrogênio que confere um odor característico, idêntico ao de ovo podre. O presente estudo analisou a qualidade da água do poço construído no Instituto Federal de Educação Ciência e Tecnologia da Bahia (IFBA), <em>campus</em> Porto Seguro, cuja concentração de H₂S foi determinada por titulação iodométrica. A partir do método de dessorção gasosa, o objetivo foi remover o sulfeto contido na água. A pesquisa exigiu construção de uma torre de dessorção de bancada, operando em batelada, com vazão de entrada do ar constante de 13,59 m³ h^-1. A vazão de alimentação de água foi 0,0030 m³ h^-1 e 0,0015 m³ h^-1 e o rendimento do sistema para a remoção do sulfeto obtido para essas vazões foi de 60,842 ± 1,859% e 68,326 ± 2,352%, respectivamente. Os resultados atenderam às expectativas acerca da remoção do teor de sulfeto de hidrogênio dissolvido na água bem como mostraram que o protótipo da torre de dessorção pode ser utilizado em grande escala. </p><p><strong>Palavras-chave</strong>: Águas Subterrâneas; Odor e Gosto; Sulfeto de Hidrogênio; Dessorção; Poço Profundo</p><p> </p><p align="center">REMOVAL OF H₂S IN GROUNDWATER BY THE GAS DESORPTION METHOD</p><p class="Default"><strong>Abstract</strong></p><p>The resources that nature provides, water is essential to the culture of the biotic environment. It is not only available in the Earth's surface, but also can be captured in underground aquifers. However, to be consumed, the water must be able to do so, according to the potability criteria, containing the allowable concentrations of contaminants and pollutants or being free of these substances that give color, taste and odor. Among the common contaminants in groundwater, hydrogen sulfide gives characteristic odor similar to rotten eggs. The present study analyzed the water quality of the artesian well built at the Federal Institute of Education, Science and Technology of Bahia (IFBA), campus Porto Seguro, whose H₂S concentration was determined by iodometric. Using the gas desorption method, the objective was removed sulfide contained in the water. The research required the construction of a bench-top desorption tower, operating in batches, with a constant air intake flow of 13.59 m³ h^-1. The water supply flow was 0.0030 m³ h^-1and 0.0015 m³ h^-1and the system yield for removing the sulfide obtained for these flows was 60.842 ± 1.859% and 68.326 ± 2.352%, respectively. The expectations met expectations regarding the removal of the hydrogen sulfide content dissolved in the water as well as determining that the desorption tower prototype can be used on a large scale.</p><p><strong>Keywords</strong>: Groundwater; Odor and Taste; Hydrogen Sulfide; Desorption; Artesian Well</p>

Characterization of Commercial TiO2 P90 Modified with ZnO by the Impregnation Method

This article is devoted to TiO2/ZnO nanocomposites’ creation by modifying with the commercial TiO2/P90 product using the impregnation method and identifying the effect of the ZnO modifier on its adsorption, structural, photocatalytic, and electrical properties. The synthesized TiO2/ZnO nanocomposites were characterized by XRD, XRF, XPS, and low-temperature nitrogen adsorption-desorption methods. As a result, nanostructured TiO2/ZnO composites with the ZnO content of 2, 5, 10, and 15% were obtained. It was shown that the phase composition of TiO2/P90 does not change during the nanocomposite synthesis. XPS studies of TiO2/ZnO nanocomposites indicated the presence of Ti4+, Zn2+, O2−, and OH states on their surface, which is associated with TiO2, ZnO, and hydroxide ions. The nitrogen adsorption-desorption method showed that the commercial TiO2/P90 sample is nonporous, and all TiO2/ZnO nanocomposites are characterized by almost the same homogeneous mesoporous structure. Experimentally established sorption and photocatalytic properties depend on the specific surface area and electrostatic interaction with dyes. The effect of the ZnO modifier on I-V characteristics of the TiO2/P90 sample was revealed. The obtained experimental data showed that the TiO2/P90 sample contains one type of current carriers, and TiO2/2ZnO and TiO2/5ZnO nanocomposites are characterized by two types of current carriers.