1,720,970 research outputs found
Process intensification in metal recovery from solid waste: Challenges, opportunities and recent advances
Full text linkPhotocatalytic applications in wastewater and air treatment: A patent review (2010–2020)
Full text linkIn this work, we reviewed the most significant patents of the last decade (2010–2020) in the fields of water and air photocatalytic treatment. Patents were discussed by identifying the recurrent addressed issues and presenting the proposed solutions. Adoption of TiO2 and/or modified-TiO2-based material is still the most common choice of inventors, whereas many patents focus on the design of the plants/devices to improve efficiency of photocatalytic treatment by improving light utilization and contact between the phases. The review also highlights issues deriving from specific applications and outlines future trends in the field, such as the need for standardized testing and digitalization of monitoring and control
Recovery of palladium (II) from aqueous solution through photocatalytic deposition in presence of ZnO under UV/Visible-light radiation
No full textA shortage of market supplies is nowadays recorded for precious metals such as palladium, due to a wide range of applications in which they are used. The development of efficient and inexpensive recovery methodologies of precious metals from waste materials is thus necessary and urgent. In the present study a zinc oxide based photocatalytic system under UV/Visible-light radiation was chosen for palladium (II) deposition from solutions containing it. The effect of ethanol as sacrificial agent was investigated at varying catalyst load, irradiation conditions (UV+visible/visible/dark), metal starting concentration as well as the presence of cupric and chloride ions in solution. Moreover, ZnO dissolution at pH under 6.0 was proposed for the recovery of pure metallic palladium. A network of reactions and a kinetic model were proposed
Risk analysis of the sodium hypochlorite production process: Focus on the chlorine line
Full text linkMainly in the first part of COVID-19 pandemics, sodium hypochlorite was used as disinfectant, surprisingly also to spray over people. Several hazards may be associated to the production of this compound, such as chlorine gas toxicity and explosive hazards, due to the presence of hydrogen and chlorine, and corrosive hazards. Thus, loss prevention strategies must be ad-hoc developed to mitigate the risks. In the present work, the risk assessment of the first block of the process was performed, focusing the attention on chlorine risks. To this end, HAZOP analysis was first performed to identify the most critical top event, noticing the major issues in the quality of the final product and in the release of chlorine from pipes. Then, the fault tree analysis was built to calculate its failure rate. CFD simulations were used instead of empirical model to assess with a rigorous approach the chlorine dispersion, taking into account all the boundary conditions. In particular, by setting a hazardous chlorine concentration of 180 ppm corresponding to 50% fatalities for chlorine exposition for an exposure of 60 min, results without aspiration demonstrate the possibility for the cloud to impact workers at ground level also very far from the source point, while the chlorine cloud is moved upwards with a maximum length of 6.5 m when an aspiration is used, although the air ventilation speed is kept low
Risk analysis of sodium hypochlorite production process
Full text linkSodium hypochlorite poses explosive hazards associated with its complex reactive chemistry. The production process of sodium hypochlorite consists of a first block where the chlorine, caustic soda and hydrogen are produced in an electrolytic cell from brine and a second block where chlorination of caustic soda to form hypochlorite is carried out. This process is characterized by several hazards such as chlorine gas toxicity, explosive hazards due to the presence of hydrogen and chlorine and corrosive hazards. Loss of control of such substances has the potential to cause high-consequence low-probability events. Thus, specific safety measures have to be designed to mitigate risk. In the present work, the risk assessment of the first block of the process is performed, focusing on hydrogen risks. To this end, HAZOP analysis was performed to identify the top events. For each top event, based on properly developed fault trees, the frequency analysis was performed. Eventually, the consequence analysis was carried out by the simulation of phenomena leading to dispersion and consequent ignition of the cloud as function of the distance from the source. Simulations were performed by means of the software PHAST
Understanding the Wettability of Graphene Coatings: Insights, Measurements, and Implications for Diverse Applications
Full text linkGraphene’s (GR) wettability is a contentious subject marked by conflicting reports. Some studies claim superhydrophobicity with up to 150° contact angles indicating limited wettability. Conversely, other research suggests factors like surface roughness, contaminants, and lattice defects modify GR’s wettability, revealing moderate hydrophilicity in defect-free GR. Persistent disagreements center around the impact of GR production processes, substrate interactions, and environmental factors. This paper addresses the controversy by scrutinizing wetting measurement techniques and sample preparation. We present a comprehensive framework for sample preparation and characterization for a few GR layers. Key findings highlight the significance of sample preparation and the identification of Atomic Force Microscopy (AFM) and Vibrational Sum Frequency Generation (VSFG) spectroscopy as particularly valuable techniques for assessing GR wettability. These insights contribute to tailored GR-based applications, from surface coatings to catalysis and energy storage
Visible—Light Driven Systems: Effect of the Parameters Affecting Hydrogen Production through Photoreforming of Organics in Presence of Cu2O/TiO2 Nanocomposite Photocatalyst
Full text linkGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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