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Chemical Reviews Jul 2022Two-dimensional (2D) ultrathin silica films have the potential to reach technological importance in electronics and catalysis. Several well-defined 2D-silica structures... (Review)
Review
Two-dimensional (2D) ultrathin silica films have the potential to reach technological importance in electronics and catalysis. Several well-defined 2D-silica structures have been synthesized so far. The silica bilayer represents a 2D material with SiO stoichiometry. It consists of precisely two layers of tetrahedral [SiO] building blocks, corner connected via oxygen bridges, thus forming a self-saturated silicon dioxide sheet with a thickness of ∼0.5 nm. Inspired by recent successful preparations and characterizations of these 2D-silica model systems, scientists now can forge novel concepts for realistic systems, particularly by atomic-scale studies with the most powerful and advanced surface science techniques and density functional theory calculations. This Review provides a solid introduction to these recent developments, breakthroughs, and implications on ultrathin 2D-silica films, including their atomic/electronic structures, chemical modifications, atom/molecule adsorptions, and catalytic reactivity properties, which can help to stimulate further investigations and understandings of these fundamentally important 2D materials.
Topics: Adsorption; Catalysis; Electronics; Silicon Dioxide; Surface Properties
PubMed: 35731806
DOI: 10.1021/acs.chemrev.1c00995 -
Contributions To Nephrology 2023In this chapter, anticoagulation treatments for adsorption techniques in continuous renal replacement therapy (CKRT) will be reviewed. Anticoagulation used with... (Review)
Review
In this chapter, anticoagulation treatments for adsorption techniques in continuous renal replacement therapy (CKRT) will be reviewed. Anticoagulation used with adsorption techniques is quite different than anticoagulation in classical CKRT with nonadsorptive therapies. Regional citrate anticoagulation (RCA) and unfractionated heparin (UFH) are the most common anticoagulation modalities for both nonselective adsorptive membranes - such as surface-treated acrylonitrile 69 membranes (AN69ST) and polymethylmethacrylate membranes - and selective adsorptive membranes such as AN69-oXiris. For these techniques, the efficacy of RCA seems to be superior to UFH. Regardless of the lack of large comparative studies in comparison to ones conducted for adsorptive filter techniques in CKRT, RCA and UFH will also be discussed for nonselective adsorptive sorbents like CytoSorb and Jafron HA. For selective adsorptive sorbents, such as polymyxin-B hemoperfusion, UFH and RCA seems to be the appropriate techniques; however, randomized controlled trials confirming this are yet to be conducted. Lastly, anticoagulation prophylaxis for more specific techniques like coupled plasma filtration adsorption and double plasma molecular adsorption system will be discussed.
Topics: Humans; Heparin; Adsorption; Blood Coagulation; Citric Acid; Citrates; Anticoagulants
PubMed: 37263238
DOI: 10.1159/000527572 -
Water Science and Technology : a... Dec 2022Phosphate is considered the main cause of eutrophication and has received considerable attention recently. Several methods have been used for removal of phosphates in... (Review)
Review
Phosphate is considered the main cause of eutrophication and has received considerable attention recently. Several methods have been used for removal of phosphates in water and these include biological treatment, membrane filtration processes, chemical precipitation, and adsorption. Adsorption technology is highly effective in the removal of phosphate from wastewater even at low phosphate concentrations. Nanomaterials/nanoparticles, carbon-based materials (activated carbon and biochar), and their composites have been widely employed for the adsorptive removal and recovery of phosphate from wastewater due to their exceptional properties such as high surface area and high phosphate adsorption properties. This article is a review of the recently reported literature in the field of nanotechnology and activated carbon for the adsorption of phosphate from wastewater. Highlights of the adsorption mechanisms, adsorption behaviour, experimental parameters, effects of co-existing ions, and adsorbent modifications are also discussed.
Topics: Phosphates; Wastewater; Charcoal; Adsorption; Water Pollutants, Chemical; Kinetics
PubMed: 36579873
DOI: 10.2166/wst.2022.382 -
Chemosphere Sep 2022Various emerging organic micropollutants, such as pharmaceuticals, have attracted the interest of the water industry during the last two decades due to their... (Review)
Review
Various emerging organic micropollutants, such as pharmaceuticals, have attracted the interest of the water industry during the last two decades due to their insufficient removal during conventional water and wastewater treatment methods and increasing demand for pharmaceuticals projected to climate change-related impacts and COVID-19, nanosorbents such as carbon nanotubes (CNTs), graphene oxides (GOs), and metallic organic frameworks (MOFs) have recently been extensively explored regarding their potential environmental applications. Due to their unique physicochemical features, the use of these nanoadsorbents for organic micropollutans in water and wastewater treatment processes has been a rapidly growing topic of research in recent literature. Adsorptive membranes, which include these nanosorbents, combine the benefits of adsorption with membrane separation, allowing for high flow rates and faster adsorption/desorption rates, and have received a lot of publicity in recent years. The most recent advances in the fabrication of adsorptive membranes (including homogeneous membranes, mixed matrix membranes, and composite membranes), as well as their basic principles and applications in water and wastewater treatment, are discussed in this review. This paper covers ten years, from 2011 to 2021, and examines over 100 published studies, highlighting that micropollutans can pose a serious threat to surface water environments and that adsorptive membranes are promising, particularly in the adsorption of trace substances with fast kinetics. Membrane fouling, on the other hand, should be given more attention in future studies due to the high costs and restricted reusability.
Topics: Adsorption; COVID-19; Humans; Nanotubes, Carbon; Pharmaceutical Preparations; Water; Water Pollutants, Chemical; Water Purification
PubMed: 35537632
DOI: 10.1016/j.chemosphere.2022.134775 -
Journal of Hazardous Materials Jan 2022Developing a cost-effective, stable, and recyclable adsorbent with high adsorption capacity and rapid adsorption kinetics is highly demanded for water treatment but has...
Developing a cost-effective, stable, and recyclable adsorbent with high adsorption capacity and rapid adsorption kinetics is highly demanded for water treatment but has been proven challenging. Herein, we report a one-step strategy to synthesize tough porous nanocomposite hydrogel, by introducing biochar nanoparticles and interconnected pores into a polyacrylamide hydrogel matrix as an exemplary system. The polyacrylamide hydrogel provides the overall mechanical strength to carry loads and facilitate recycling, the biochar provides adsorptive locus for high adsorption capacity, and the interconnected pores expedite solvent transport for rapid adsorption kinetics. Mechanical characterizations manifest that the porous biochar hydrogel possesses a tensile strength of 128 kPa, a stretchability of 5.9, and a toughness of 538 J m. Porous structure analysis reveals that the hydrogel contains an increscent specific surface area by 441% and an augmented pore volume by 279% compared to pure polyacrylamide hydrogel. Experiments pertaining to adsorption isotherms and kinetics, with methylene blue as the model adsorbate, indicate enhanced adsorption performances. The tough hydrogel also allows facile recycling and maintains mechanical robustness after five regeneration cycles. Furthermore, biocompatibility is endorsed by cytotoxicity test. The proposed method could open an ample space for designing and synthesizing tough porous nanocomposite hydrogels for water treatment.
Topics: Adsorption; Hydrogels; Kinetics; Nanocomposites; Nanogels; Porosity; Water Pollutants, Chemical; Water Purification
PubMed: 34388914
DOI: 10.1016/j.jhazmat.2021.126754 -
Accounts of Chemical Research Oct 2022Chemical separations, mostly based on heat-driven techniques such as distillation, account for a large portion of the world's energy consumption. In principle,...
Chemical separations, mostly based on heat-driven techniques such as distillation, account for a large portion of the world's energy consumption. In principle, differential adsorption is a more energy-efficient separation method, but conventional adsorbent materials are still not effective for many industry-relevant mixtures. Porous coordination polymers (PCPs), or metal-organic frameworks (MOFs), are attractive for their well-defined, designable, modifiable, and flexible structures connecting to various potential applications. While the importance of the structural flexibility of MOFs in adsorption-based functions has been demonstrated, the understanding of this special feature is still in its infancy and mostly stays at the periodic structural transformation at the equilibrium state and the special shapes of single-component adsorption isotherms. There are many confusions about the categorization and roles of various types of flexibility. This Account discusses the role of flexibility of MOFs for adsorptive separation, mainly from the thermodynamic and kinetic points of view.As the classic type of framework flexibility, guest-driven structural transformations and the corresponding adsorption isotherms can be thermodynamically described by the energies of the host-guest system. The highly guest-specific pore-opening action showing contrasting single-component adsorption isotherms is regarded as a strategy for achieving molecular sieving without the need for aperture size control, but its effect and role for mixture separation are still controversial. Quantitative mixture adsorption/separation experiments showed that the common periodic (cooperative) pore-opening action leads to coadsorption of molecules smaller than the opened aperture, while the aperiodic (noncooperative) one can achieve inversed molecular sieving under a thermodynamic mechanism.The energy barrier and structure in the nonequilibrium state are also important for flexibility and adsorption/separation. With suitable energy barriers between metastable structures, new types of framework flexibility such as aperture gating can be realized. While kinetically controlled gating flexibility is usually ignored because of the difficulty of characterization or considered as disadvantageous for separation because of the variable aperture size, it plays a critical role in most kinetic separation systems, including adsorbents conventionally regarded as rigid. With the concept of gating flexibility, the meanings of aperture and guest sizes for judging molecular sieving need to be reconsidered. Gating flexibility depends on not only the host itself but also the guest, the host-guest interaction, and the external environment such as temperature, which can be rationally tuned to achieve special adsorption/separation behaviors such as inversed temperature dependence, molecular sieving, and even inversed thermodynamic selectivity. The comprehensive understanding of the thermodynamic and kinetic bases of flexibility will give a new horizon for next-generation separation materials beyond MOFs and adsorbents.
Topics: Adsorption; Metal-Organic Frameworks; Porosity; Temperature; Thermodynamics
PubMed: 36067359
DOI: 10.1021/acs.accounts.2c00418 -
Chemical Society Reviews Aug 2022Significant progress has been made in direct air capture (DAC) in recent years. Evidence suggests that the large-scale deployment of DAC by adsorption would be... (Review)
Review
Significant progress has been made in direct air capture (DAC) in recent years. Evidence suggests that the large-scale deployment of DAC by adsorption would be technically feasible for gigatons of CO capture annually. However, great efforts in adsorption-based DAC technologies are still required. This review provides an exhaustive description of materials development, adsorbent shaping, characterization, adsorption mechanism simulation, process design, system integration, and techno-economic analysis of adsorption-based DAC over the past five years; and in terms of adsorbent development, affordable DAC adsorbents such as amine-containing porous materials with large CO adsorption capacities, fast kinetics, high selectivity, and long-term stability under ultra-low CO concentration and humid conditions. It is also critically important to develop efficient DAC adsorptive processes. Research and development in structured adsorbents that operate at low-temperature with excellent CO adsorption capacities and kinetics, novel gas-solid contactors with low heat and mass transfer resistances, and energy-efficient regeneration methods using heat, vacuum, and steam purge is needed to commercialize adsorption-based DAC. The synergy between DAC and carbon capture technologies for point sources can help in mitigating climate change effects in the long-term. Further investigations into DAC applications in the aviation, agriculture, energy, and chemical industries are required as well. This work benefits researchers concerned about global energy and environmental issues, and delivers perspective views for further deployment of negative-emission technologies.
Topics: Adsorption; Amines; Carbon Dioxide; Kinetics; Porosity
PubMed: 35815699
DOI: 10.1039/d1cs00970b -
Chemosphere Nov 2023With the continuous development of society, industrialization, and human activities have been producing more and more pollutants. Fluoride discharge is one of the main... (Review)
Review
With the continuous development of society, industrialization, and human activities have been producing more and more pollutants. Fluoride discharge is one of the main causes of water pollution. This review summarizes various commonly used and effective fluoride removal technologies, including ion exchange technology, electrochemical technology, coagulation technology, membrane treatment, and adsorption technology, and points out the outstanding advantages of adsorption technology. Various commonly used fluoride removal techniques as well as typical adsorbent materials have been discussed in published papers, however, the relationship between different adsorbent materials and adsorption models has rarely been explored, therefore, this paper categorizes and summarizes the various models involved in static adsorption, dynamic adsorption, and electrosorption fluoride removal processes, such as pseudo-first-order and pseudo-second-order kinetic models, Langmuir and Freundlich isotherm models, Thomas and Clark dynamic adsorption models, including the mathematical equations of the corresponding models and the significance of the models are also comprehensively summarized. Furthermore, this comprehensive discussion delves into the fundamental adsorption mechanisms, quantification of maximum adsorption capacity, evaluation of resistance to anion interference, and assessment of adsorption regeneration performance exhibited by diverse adsorption materials. The selection of the best adsorption model not only predicts the adsorption performance of the adsorbent but also provides a better description and understanding of the details of each part of the adsorption process, which facilitates the adjustment of experimental conditions to optimize the adsorption process. This review may provide some guidance for the development of more cost-effective adsorbent materials and adsorption processes in the future.
Topics: Humans; Fluorides; Wastewater; Adsorption; Environmental Pollutants; Technology
PubMed: 37591373
DOI: 10.1016/j.chemosphere.2023.139808 -
Chemical Society Reviews Apr 2022Nuclear power will continue to provide energy for the foreseeable future, but it can pose significant challenges in terms of the disposal of waste and potential release... (Review)
Review
Nuclear power will continue to provide energy for the foreseeable future, but it can pose significant challenges in terms of the disposal of waste and potential release of untreated radioactive substances. Iodine is a volatile product from uranium fission and is particularly problematic due to its solubility. Different isotopes of iodine present different issues for people and the environment. I has an extremely long half-life of 1.57 × 10 years and poses a long-term environmental risk due to bioaccumulation. In contrast, I has a shorter half-life of 8.02 days and poses a significant risk to human health. There is, therefore, an urgent need to develop secure, efficient and economic stores to capture and sequester ionic and neutral iodine residues. Metal-organic framework (MOF) materials are a new generation of solid sorbents that have wide potential applicability for gas adsorption and substrate binding, and recently there is emerging research on their use for the selective adsorptive removal of iodine. Herein, we review the state-of-the-art performance of MOFs for iodine adsorption and their host-guest chemistry. Various aspects are discussed, including establishing structure-property relationships between the functionality of the MOF host and iodine binding. The techniques and methodologies used for the characterisation of iodine adsorption and of iodine-loaded MOFs are also discussed together with strategies for designing new MOFs that show improved performance for iodine adsorption.
Topics: Adsorption; Humans; Iodine; Ions; Metal-Organic Frameworks
PubMed: 35363235
DOI: 10.1039/d0cs01192d -
Environmental Science and Pollution... Dec 2022Adsorption is a promising technology for removing several contaminants from aqueous matrices. In the last years, researchers worldwide have been working on developing... (Review)
Review
Adsorption is a promising technology for removing several contaminants from aqueous matrices. In the last years, researchers worldwide have been working on developing composite adsorbents to overcome some limitations and drawbacks of conventional adsorbent materials, which depend on various factors, including the characteristics of the adsorbents. Therefore, it is essential to characterize the composite adsorbents to describe their properties and structure and elucidate the mechanisms, behavior, and phenomenons during the adsorption process. In this sense, this work aimed to review the main methods used for composite adsorbent characterization, providing valuable information on the importance of these techniques in developing new adsorbents. In this paper, we reviewed the following methods: X-Ray diffraction (XRD); spectroscopy; scanning electron microscopy (SEM); N adsorption/desorption isotherms (BET and BJH methods); thermogravimetry (TGA); point of zero charge (pH); elemental analysis; proximate analysis; swelling and water retention capacities; desorption and reuse.
Topics: Adsorption; Microscopy, Electron, Scanning; Technology; Thermogravimetry
PubMed: 36334205
DOI: 10.1007/s11356-022-23883-z