1,721,016 research outputs found
Recovery of rare earths and base metals from spent nickel-metal hydride batteries by sequential sulphuric acid leaching and selective precipitations
No full textAdvanced wastewater oxidation processes and their role in water reuse for a circular economy
No full textCombined Hydrodynamic Cavitation-based Processes as an Efficient Treatment Approach for Real Textile Industrial Wastewater
Full text linkAs industrialization and globalization have advanced in recent years, an expanding volume of textile dye effluent and pharmaceutical wastewater has been discharged into the environment. Hydrodynamic cavitation (HC) and its combination with other advanced processes such as hydrogen peroxide (H2O2), were studied in this work for the removal of textile dye effluent from aqueous media. The effect of different molar ratio of H2O2 dose was examined. The experimental tests were carried out at pH_ value= 2 and input pressure p_in=4.5 bar, with a mix of three types of textile wastewater sampled at different treatment times. The concentration of H2O2 was varied from 0.1 M to 0.9 M. The evaluation of the efficiency of the combined process, in the removal of color and COD from textile wastewater, was investigated. The results showed that the degradation of textile wastewater using HC and HC in combination with other advanced oxidation process (AOP’s) followed a pseudo-first-order reaction kinetic. Under the following operative conditions of pH_ value= 2 and input pressure p_in=4.5 bar, the HC + H2O2 process demonstrated a greater efficiency of 88%, 37%, and 65% the chemical oxygen demand (COD) reduction in 60 minutes for (0.3, 0.7 and 0.9 mol/L,) of H2O2, respectively. combined process could be a useful technology for treating textile wastewater
Effect of the hydrodynamic cavitation for the treatment of industrial wastewater
No full textIn the present work, the degradation of tetramethyl ammonium hydroxide (TMAH) from synthetic liquid waste of electronic industry was investigated by using hydrodynamic cavitation process. The core of the experimenal apparatus was a Venturi tube having a diameter of 12 mm and a convergent of 2 mm. The experiments were performed using synthetic solutions with an initial TMAH concentration of 2 g/L. A factorial plant with 2 factors and 2 levels was planned to prove that the hydrodinamic cavitation was an effective methodf to degrade TMAH. The investigated factors were: solution pH (3 - 20) and time (5 -20 min). The experiments have been carried out at a fixed temperature of 20°C and a pressure of 4 bar. The inlet pressure of 4 bar was chosen as a result of preliminary experiments that showed as at this value the degradation yields were higher than those obtained at other pressure values. The experiments showed that pH solution was significant with a negative effect. The optimal performance (around 44%) of process for degradation of tetramethyl ammonium hydroxide was achieved at pH=3 after 20 minutes
Oil refining spent catalysts: A review of possible recycling technologies
No full textThe aim of this review paper is to analyse the current management of spent fluid catalytic cracking catalysts (FCCCs) and the relevant possible reuse and recycling methods in order to avoid landfilling. FCCCs are used in refining processes for conversion of vacuum gas oil into more valuable gasoline blend components and other products. Every year the worldwide supply is estimated at about 840,000 t (Letzsch, 2014). The main recycling technique found in literature for spent FCCCs entails their use as raw material for concrete and mortar production as partial replacement of sand and cement powder. Other minor applications include their use as catalysts for plastic and biomass pyrolysis and gasification or for production of synthetic fuels. Despite their importance, these processes have not been widely developed at industrial scale. Disposal to landfill or use for concrete blend is still the main choice for the handling of spent catalysts, despite the content of rare earths elements and sometimes other interesting metals like vanadium and nickel that could be recovered. Nevertheless, in the future these catalysts will represent an interesting source for secondary raw materials, considering the scarcity of rare earth elements and shortage of supply, due to the fact that production is concentrated only in few countries. In this perspectives, the recovery of rare earth elements will be of great interest to countries that do not own primary ores. Future research work is expected to lead to economical processes that reach a complete recycling in order to avoid landfilling. This action could be helped by the adoption of new environmental regulations which will heavily charge landfilling as final disposal
Application of hybrid oxidative processes based on cavitation for the treatment of methyl blue solutions
No full textOver the past few decades, the scientific community has developed an increasing interest in high-performance water treatment systems based on cavitational processes. Hydrodynamic cavitation (HC) is one of the promising technologies for wastewater treatment, especially for dyeing solutions, since it shows high efficiency in treating dyes, even at low concentrations. Both strategies have been shown to be efficient ways to get rid of pathogenic bacteria by disinfecting waters and achieving the mineralization of numerous organic pollutants. This makes cavitation-based techniques an attractive choice for use in water treatment facilities' post-treatment stages. Modern techniques have been presented that combine advanced oxidation processes (AOPs) with cavitation for increased oxidation capacity. When used together, cavitation and AOPs (such as O3, H2O2, and Fenton's process) can cause materials to decay much more quickly. This work aims to investigate the degradation of Methyl Blue (MB) with HC and evaluate the effectiveness of a hybrid process (O3 + HC). The experimental tests were conducted to determine the optimal operating conditions (pressure, pH, O3 dosage). Furthermore, the feasibility of MB mineralization at a high concentration range (10-100 mg/l) was performed. Cost estimation and energetic analysis were discussed. As a result, the optimal conditions were: P = 4.5 bar, pH 2, O3 = 7.5 mg/L. For the initial concentration of 10 mg/L, the MB decolorization yield of HC, O3, and HC + O3 were 10%, 99%, and 100%, respectively, after 30 min of treatment. The addition of O3 promoted the degradation efficiency above 95%, decreasing the treatment time. Increasing the O3 feed rate can reduce the treatment time. A flow rate of 8 L/min of ozone was adopted in the optimal flow value. The hybrid process has an important effect in improving the performance of wastewater treatment by reducing treatment time, causing saving in energy consumption and process cost
Environmental sustainability assessment of different strategies for the treatment of wastewater from textile industry
Full text linkSevere water consumption and highly polluted wastewater are the main issues of textile industries, which can affect environmental safety. Advanced oxidation processes (AOP) emerged as innovative strategies to enhance conventional wastewater treatments, for their strong ability to reduce chemical oxygen demand (COD) and pollutants. Among these, hydrodynamic cavitation (HC) stands out as a promising technique to minimize the chemical additive uses, thereby improving the process sustainability. A life cycle assessment (LCA) was conducted to compare four scenarios, traditional biological treatment, membrane treatment combined with AOP and HC used either as pre- or post-treatment to the biological process. The results showed that biological process followed by HC offers the lowest environmental impact. This is attributed to a configuration change (compared to HC as pre-treatment) that reduces energy consumption without compromising water quality. In the climate change category, one of the most relevant, HC as a post-treatment (scenario 4) reduces the impact by 94%, compared to HC pre-treatment (scenario 3). It also achieves around 30% impact reduction relative to biological treatment, while ensuring the highest water quality, with a 98% reduction in COD. This quality supports the potential for water recirculation within textile manufacturing. Furthermore, the possibility of water reuse offsets the environmental cost of producing high-quality water, with an average environmental credit between 440 (scenario 3) and 600 (scenario 1) m3-world eq, in the water use category. The superiority of the HC post-treatment setup was also confirmed from a performance standpoint, as it reduces the complexity of process management
Treatment of fluid catalytic cracking spent catalysts to recover lanthanum and cerium: Comparison between selective precipitation and solvent extraction
No full textOptimizing dismantling approaches for recycling of li-ion batteries: Strategies, challenges and economic analysis
Full text linkLithium-ion batteries (LIBs) are widely used in electric vehicles, consumer electronics, and energy storage systems due to their high energy density and long operational life. As demand for these batteries rises globally, their end-of-life management has become a growing concern due to environmental risks, material scarcity, and recycling inefficiencies. This review addresses the urgent need for safe, sustainable, and cost-effective dismantling practices, recognized as the most critical and preparatory step in LIB recycling, by evaluating current methods and proposing future directions. The review examines manual, mechanical and automated dismantling approaches, highlighting their respective advantages and limitations. Manual method offers straightforward material recovery but face safety, labour, and efficiency challenges. Emerging automated solutions using robotics, AI, and machine learning promise improvements in safety, scalability, and disassembly precision. In addition to dismantling strategies, the review discusses regulatory frameworks, environmental implications, and the importance of standardizing battery design for easier disassembly. It also provides future perspectives emphasizing automation, eco-friendly chemical processes, and public participation in battery collection. By organizing scattered knowledge and offering critical insights and recommendations, this review serves as a comprehensive resource for researchers, policymakers, and industry stakeholders. It aims to guide sustainable innovation and foster circular economy practices in LIB end-of-life management
Rare earths from secondary sources: profitability study
No full textThe paper is focused on the economic analysis of two hydrometallurgical processes for recovery of yttrium and other rare earth elements (REEs) from fluorescent phosphors of spent lamps. The first process includes leaching with sulphuric acid and precipitation of a mixture of oxalates by oxalic acid, the second one includes leaching with sulphuric acid, solvent extraction with D2EHPA, stripping by acid and recovery of yttrium and traces of other rare earths (REs) by precipitation with oxalic acid. In both cases the REEs were recovered as oxides by calcination of the oxalate salts. The economic analysis was estimated considering the real capacity of the HydroWEEE mobile's plant (420 kg batch(-1)). For the first flow-sheet the cost of recycling comes to 4.0 (sic) kg(-1), while the revenue from the end-product is around 5.40 (sic) kg(-1). The second process is not profitable, as well as the first one, taking into account the composition of the final oxides: the cost of recycling comes to 5.2 (sic) kg(-1), while the revenue from the end- product is around 3.56 (sic) kg(-1). The process becomes profitable if the final RE oxide mixture is sold for nearly 50 (sic) kg(-1), a value rather far from the current market prices but not so unlikely since could be achieved in the incoming years, considering the significant fluctuations of the Res' market
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