ABSTRACT
Forward osmosis (FO) has attracted special attention in water and wastewater treatment due to its role in addressing the challenges of water scarcity and contamination. The presence of emerging contaminants in water sources raises concerns regarding their environmental and public health impacts. Conventional wastewater treatment methods cannot effectively remove these contaminants; thus, innovative approaches are required. FO membranes offer a promising solution for wastewater treatment and removal of the contaminants in wastewater. Several factors influence the performance of FO processes, including concentration polarization, membrane fouling, draw solute selection, and reverse salt flux. Therefore, understanding and optimizing these factors are crucial aspects for improving the efficiency and sustainability of the FO process. This review stresses the need for research to explore the potential and challenges of FO membranes to meet municipal wastewater treatment requirements, to optimize the process, to reduce energy consumption, and to promote scalability for potential industrial applications. In conclusion, FO shows promising performance for wastewater treatment, dealing with emerging pollutants and contributing to sustainable practices. By improving the FO process and addressing its challenges, we could contribute to improve the availability of water resources amid the global water scarcity concerns, as well as contribute to the circular economy.
ABSTRACT
Currently, freshwater scarcity is one of the main issues that the world population has to face. To address this issue, new wastewater treatment technologies have been developed such as membrane processes. Among them, due to the energy disadvantages of pressure-driven membrane processes, Forward Osmosis (FO) and Low-Pressure Reverse Osmosis (LPRO) have been introduced as promising alternatives. In this study, the behavior of a 2.3 m2 tubular membrane TFO-D90 when working with municipal wastewater has been studied. Its performances have been evaluated and compared in two operating modes such as FO and LPRO. Parameters such as fouling, flow rates, water flux, draw solution concentration, organic matter concentration, as well as its recovery have been studied. In addition, the biogas production capacity has been evaluated with the concentrated municipal wastewater obtained from each process. The results of this study indicate that the membrane can work in both processes (FO and LPRO) but, from the energy and productivity point of view, FO is considered more appropriate mainly due to its lower fouling level. This research may offer a new point of view on low-energy and energy recovery wastewater treatment and the applicability of FO and LPRO for wastewater concentration.
ABSTRACT
In this work, we report a systematic study of the influence of film thickness on the structural and magnetic properties of epitaxial thin films of Pr2-δNi1-xMn1+xO6-y (PNMO) double perovskite grown on top of two different (001)-SrTiO3 and (001)-LaAlO3 substrates by RF magnetron sputtering. A strong dependence of the structural and magnetic properties on the film thickness is found. The ferromagnetic transition temperature (TC) and saturation magnetization (Ms) are found to decrease when reducing the film thickness. In our case, the thinnest films show a loss of ferromagnetism at the film-substrate interface. In addition, the electronic structure of some characteristic PNMO samples is deeply analyzed using X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) measurements and compared with theoretical simulations. Our results show that the oxidation states of Ni and Mn ions are stabilized as Ni2+ and Mn4+, thus the ferromagnetism is mainly due to Ni2+-O-Mn4+ superexchange interactions, even in samples with poor ferromagnetic properties. XMCD results also make evident large variations on the spin and orbital contributions to the magnetic moment as the film's thickness decreases.
ABSTRACT
Epitaxial thin films of Pr2-δNi1-xMn1+xO6-y (PNMO) double perovskite were grown on (001)-oriented SrTiO3 substrates by RF magnetron sputtering. The influence of the growth parameters (oxygen pressure, substrate temperature, and annealing treatments) on the structural, magnetic and transport properties, and stoichiometry of the films was thoroughly investigated. It is found that high-quality epitaxial, insulating, and ferromagnetic PNMO thin films can only be obtained in a narrow deposition parameter window. It is shown that a careful selection of the growth conditions allows for obtaining a high degree of Ni/Mn cation ordering, which is reflected in the values of the Curie temperature, TC, and saturation magnetization, MS, which are very close to those of bulk material.
ABSTRACT
Forward osmosis (FO) is a promising technology for the treatment of urban wastewater. FO can produce high-quality effluents and preconcentrate urban wastewater for subsequent anaerobic treatment. This membrane technology makes it possible to eliminate the pollutants present in urban wastewater, which can cause adverse effects in the ecosystem even at low concentrations. In this study, a 0.6 m2 hollow fiber aquaporin forward osmosis membrane was used for the treatment of urban wastewater from the Valladolid wastewater treatment plant (WWTP). A total of 51 Contaminants of Emerging Concern (CECs) were investigated, of which 18 were found in the target urban wastewater. They were quantified, and their ecotoxicological risk impact was evaluated. Different salts with different concentrations were tested as draw solutions to evaluate the membrane performances when working with pretreated urban wastewater. NaCl was found to be the most appropriate salt since it leads to higher permeate fluxes and lower reverse saline fluxes. The membrane can eliminate or significantly reduce the pollutants present in the studied urban wastewater, producing water without ecotoxicological risk or essentially free of pollutants. In all cases, good recovery was achieved, which increased with molecular weight, although chemical and electrostatic interactions also played a role.
ABSTRACT
The control of the spontaneous formation of nanostructures at the surface of thin films is of strong interest in many different fields, from catalysts to microelectronics, because surface and interfacial properties may be substantially enhanced. Here, we analyze the formation of nickel oxide nanocuboids on top of La2Ni1-xMn1+xO6 double perovskite ferromagnetic thin films, epitaxially grown on SrTiO3 (001) substrates by radio-frequency (RF) magnetron sputtering. We show that, by annealing the films at high temperature under high oxygen partial pressure, the spontaneous segregation of nanocuboids is enhanced. The evolution of the structural and magnetic properties of the films is studied as a function of the annealing treatments at different temperatures. It is shown that the formation of NiOx nanocuboids leads to a nanostructured film surface with regions of locally different electrical transport characteristics.
ABSTRACT
Cinco carbones de los departamentos de Cundinamarca, Boyacá y Norte de Santander (Colombia) se caracterizaron mediante análisis próximo, último, reológico, petrográfico, calorífico y termogravimétrico. Los parámetros analizados, especialmente aquellos que determinan las propiedades reológicas, muestran que los carbones estudiados y sus mezclas podrían producir un coque de buena calidad. Se observó la relación inversa entre el contenido de materia volátil y la reflectancia media aleatoria de la vitrinita, que se atribuye al aumento de la aromaticidad en la estructura molecular del carbón como una consecuencia del incremento en el rango. Los parámetros derivados del análisis termogravimétrico -máxima velocidad de desvolatilización y temperatura de máxima velocidad de desvolatilización- mostraron buenas correlaciones con la reflectancia media aleatoria de la vitrinita, igual que la máxima velocidad de desvolatilización con la fluidez máxima. Lo anterior indica que el análisis termogravimétrico podría ser una herramienta útil para caracterizar de manera rápida carbones usados en procesos de fabricación de coque metalúrgico.
Five types of coal from the states of Cundinamarca, Boyaca and Norte de Santander (Colombia) were characterized by proximate, ultimate, rheological, petrographic, calorific and thermogravimetric analysis. The parameters used, especially the ones which determine the rheological properties show that the studied coals and its blends could produce good quality coke. It was observed the inverse relationship between the volatile matter content and the mean vitrinite reflectance, relationship which is attributed to the increase of the aromaticity in the molecular structure of the coal as a consequence of the rank increase. The parameters derived from the thermogravimetric analysis, maximum velocity of de-volatilization and the temperature of maximum velocity of de-volatilization and the media reflectance of the vitrinite showed good correlations. Also was observed an interesting correlation between the velocity ofde-volatilization and maximum fluidity. This shows that the thermogravimetric analysis can be a useful tool to characterize in a quick way coals used for metallurgical coke production.
Cinco carvões dos departamentos de Cundinamarca, Boyacá e Norte de Santander (Colômbia) foram caracterizados por análise próxima, última, reológica, petrográfica e termogravimétrica. Os parâmetros analisados, em especial aqueles que determinam as propriedades reológicas mostram que os carvões estudados e suas misturas podem produzir coque de boa qualidade. Foi observada relação inversa entre o teor de matéria volátil e refletância média vitrinite, que é atribuído ao aumento da aromaticidade da estrutura molecular do carvão como um resultado do aumento no rango. Os parâmetros derivados da análise termogravimétrica, velocidade máxima de pirólise e temperatura de máxima velocidade de pirólise mostraram boas correlações com a refletância média vitrinite, tal como a velocidade máxima de pirólise e a fluidez máxima. Isto mostra que a análise termogravimétrica pode ser uma ferramenta útil para caracterizar rapidamente carvões utilizados nos processos de fabricação de coque metalúrgico.
