Electrochemical regeneration of Granular Activated Carbon is an emerging treatment option to restore adsorption capacity in systems designed to remove organic contaminants from aqueous solutions. The ...electro-Fenton process is one such electrochemical process and it is reviewed along with other members of its family including Photoelectro-Fenton and Heterogeneous electro-Fenton and electro-Fenton like reactions, for its ability to regenerate Granular Activated Carbons contaminated with organics. The behaviour of critical operating parameter such as pH, current, catalyst concentration and initial contaminant concentration are reviewed to find optimal operating conditions. The relationship between electro-Fenton regeneration and the chemical and physical surface of the carbon is also explored. Understanding regeneration mechanisms and the optimal operating conditions enables these technologies to be used commercially and to be scaled-up and treat contaminated waters more efficiently.
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•Electro-Fenton regeneration can range from 28% to 100% efficient.•Elevated catalyst concentration can reduce regeneration efficiency.•Regeneration increased carbon hydrophilicity and increases pore diameter.
•Overview of research conducted surrounding the electrochemical regeneration of GAC.•Discusses the regenerative mechanism and theory behind electrochemical regeneration.•Varying reactor configuration ...and operating conditions affect regeneration outcomes.•Specifies industrial applications for which this technology may be used.
The electrochemical treatment of exhausted granular activated carbon (GAC) has been identified as an effective alternative to traditional adsorbent regeneration methods (e.g. thermal, chemical, and microbial). However, despite its proven potential and initial investigation over two decades ago, the development of this technology has been progressing slowly, hindering its deployment in industrial applications. Thus, a review has been conducted that aims to present the fundamentals of GAC electrochemical regenerative methods, what research has been conducted to develop the technology to the present day, and lastly, identify limitations and future prospects associated with electrochemical methods. The regenerative mechanism is firstly discussed, followed by a presentation of the varying reactor configurations and operating parameters utilized during the electrochemical treatment of GAC materials exhausted with a broad range of wastewater contaminants. Finally, emerging electrochemical technologies used for the commercial treatment of exhausted adsorbent materials and contaminated soils are discussed.
Abstract
Catalytic solvent regeneration has attracted broad interest owing to its potential to reduce energy consumption in CO
2
separation, enabling industry to achieve emission reduction targets of ...the Paris Climate Accord. Despite recent advances, the development of engineered acidic nanocatalysts with unique characteristics remains a challenge. Herein, we establish a strategy to tailor the physicochemical properties of metal-organic frameworks (MOFs) for the synthesis of water-dispersible core-shell nanocatalysts with ease of use. We demonstrate that functionalized nanoclusters (Fe
3
O
4
-COOH) effectively induce missing-linker deficiencies and fabricate mesoporosity during the self-assembly of MOFs. Superacid sites are created by introducing chelating sulfates on the uncoordinated metal clusters, providing high proton donation capability. The obtained nanomaterials drastically reduce the energy consumption of CO
2
capture by 44.7% using only 0.1 wt.% nanocatalyst, which is a ∽10-fold improvement in efficiency compared to heterogeneous catalysts. This research represents a new avenue for the next generation of advanced nanomaterials in catalytic solvent regeneration.
The use of microfluidic devices in solvent extraction Ciceri, Davide; Perera, Jilska M.; Stevens, Geoffrey W.
Journal of chemical technology and biotechnology (1986),
June 2014, Letnik:
89, Številka:
6
Journal Article
Water and soil contamination due to potentially toxic elements (PTEs) represents a critical threat to the global ecosystem and human health. Naturally abundant resources have significant advantages ...as adsorbent materials for environmental remediation over manufactured materials such as nanostructured materials and activated carbons. These advantages include cost-effectiveness, eco-friendliness, sustainability, and nontoxicity. In this review, we firstly compare the characteristics of representative adsorbent materials including bentonite, zeolite, biochar, biomass, and effective modification methods that are frequently used to enhance their adsorption capacity and kinetics. Following this, the adsorption pathways and sites are outlined at an atomic level, and an in-depth understanding of the structure-property relationships are provided based on surface functional groups. Finally, the challenges and perspectives of some emerging naturally abundant resources such as lignite are examined. Although both unamended and modified naturally abundant resources face challenges associated with their adsorption performance, cost performance, energy consumption, and secondary pollution, these can be tackled by using advanced techniques such as tailored modification, formulated mixing and reorganization of these materials. Recent studies on adsorbent materials provide a strong foundation for the remediation of PTEs in soil and water. We speculate that the pursuit of effective modification strategies will generate remediation processes of PTEs better suited to a wider variety of practical application conditions.
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•Naturally abundant materials are promising for PTEs remediation.•Modification methods to enhance adsorption capacity are compared.•The adsorption pathways of PTEs are summarized.•Adsorption sites of PTEs based on functional groups are identified.•Utilization of lignite as an emerging naturally abundant resource is discussed.
Currently, a large proportion of global fossil fuel emissions originate from large point sources such as power generation or industrial processes. This trend is expected to continue until the year ...2030 and beyond. Carbon capture and storage (CCS), a straightforward and effective carbon reduction approach, will play a significant role in reducing emissions from these sources into the future if atmospheric carbon dioxide (CO
2
) emissions are to be stabilized and global warming limited below a threshold of 2 °C. This review provides an update on the status of large scale integrated CCS technologies using solvent absorption for CO
2
capture and provides an insight into the development of new solvents, including advanced amine solvents, amino acid salts, carbonate systems, aqueous ammonia, immiscible liquids and ionic liquids. These proposed new solvents aim to reduce the overall cost CO
2
capture by improving the CO
2
absorption rate, CO
2
capture capacity, thereby reducing equipment size and decreasing the energy required for solvent regeneration.
CO2 emissions from industrial processes and their adverse implications on the climate is of major concern. Carbon capture and storage (CCS), especially using chemical-absorption-based processes, has ...been regarded as one of the most realistic pathways to curtail global warming and climate change. However, the energy-intensive nature of CO2 capture and therefore its expensive cost of operation has been regarded as the main barrier halting its widespread implementation among the portfolio of low-carbon energy technologies currently available. Recently, catalytic solvent regeneration has drawn significant attention as a new class of technology for energy-efficient CO2 capture with great potential for large-scale implementation. In this review, recent progress and developments associated with catalyst-aided solvent regeneration for low-temperature energy-efficient CO2 desorption is presented. A detailed discussion of heterogeneous acid–base catalyst is undertaken and the specific privileges, drawbacks, and challenges of each catalyst identified and commented upon. In keeping with the latest investigations, the promotion mechanism of catalytic CO2 desorption and the role of Lewis acids, Brønsted acids, and basic active sites are scrutinized. The performance of solid acid–base catalysts in different primary and blended amine solutions associated with their physicochemical properties is also reviewed. Finally, the status of catalytic solvent regeneration for post-combustion CO2 capture is comprehensively analyzed and a clear pathway for future research investigations is provided.
Replacement of volatile organic compounds （VOCs） by greener or more environmentally sustainable solvents is becoming increasingly important due to the increasing health and environmental concerns as ...well as economic pressures associated with VOCs. Solvents that are derived from biomass, namely bio-derived solvents, are a type of green solvent that have attracted intensive investigations in recent years because of their advantages over con- ventional VOCs, such as low toxicity, biodegradability and renewability. This review aims to summarize the use of bio-derived solvents in solvent extraction applications, with special emphasis given to utilization of biodiesels and terpenes. Compared with the conventional VOCs, the overall performance of these bio-derived solvents is comparable in terms of extraction yields and selectivity for natural product extraction and no difference was found for metal extraction. To date most researchers have focused on laboratory scale thermodynamics studies. Future work is required to develop and test new bio-derived solvents and understand the kinetic performance as well as solvent extraction nilnt nlant studies.
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•A series of novel GlyK/DMF/H2O solvents was successfully developed for CO2 capture.•NMR spectroscopy was used to identify the species at different phases.•The upper liquid phase of ...developed solvent was free from CO2-containing species.•The heat duty of solvent was reduced by 59.1% compared to the aqueous solvent.
The energy penalty is a primary limitation for the implementation of the aqueous solvents for large-scale post-combustion CO2 capture processes. In this study, a novel aqueous-based phase change solvent, composed of potassium glycinate (GlyK, reactive species), water (H2O, solvent) and dimethylformamide (DMF, antisolvent) was developed to improve the energy efficiency of CO2 capture. To examine the role of the antisolvent, a series of aqueous-based amino acid solvents (GlyK-X) with different DMF:H2O (X) volume ratios was prepared, fully characterized and assessed. It was observed that a CO2-free phase appeared at the top of the aqueous-based amino acid GlyK-X solvents after CO2 absorption which can be easily separated and recycled to the absorption column and save energy. The results showed that the GlyK-60 solvent with DMF:H2O volume ratio of 60:40 had a very high CO2-free phase volume (63%). Moreover, the GlyK-60 solvent exhibited 26.1% (0.433–0.546 mol CO2/mol GlyK) enhancement in CO2 absorption capacity, 38.5% (130–80 min) decrease in regeneration time and 59.1% reduction in relative heat duty compared to the conventional aqueous GlyK solvent. Overall, the outcomes confirmed that the aqueous-based phase change GlyK-60 solvent is a viable solvent option for large-scale CO2 capture with extra-low energy consumption and a key to the success of Paris Climate Accord.
