Layered double hydroxides — multifunctional nanomaterials (original) (raw)
Related papers
Inorganics
Layered double hydroxides (LDHs), a type of synthetic clay with assorted potential applications, are deliberated upon in view of their specific properties, such as adsorbent-specific behavior, biocompatibility, fire-retardant capacity, and catalytic and anion exchange properties, among others. LDHs are materials with two-dimensional morphology, high porosity, and exceptionally tunable and exchangeable anionic particles with sensible interlayer spaces. The remarkable feature of LDHs is their flexibility in maintaining the interlayer spaces endowing them with the capacity to accommodate a variety of ionic species, suitable for many applications. Herein, some synthetic methodologies, general characterizations, and applications of LDHs are summarized, encompassing their broader appliances as a remarkable material to serve society and address several problems viz. removal of pollutants and fabrication of sensors and materials with multifaceted useful applications in the medical, electroc...
Layered double hydroxides: a gleam on their synthetic routes with biomedical applications
Layered double hydroxides: a gleam on their synthetic routes with biomedical applications, 2023
sustainability perspective. The reduction of waste and utilization or recyclization of waste with the exploration of sustainable and cost-effective materials and treatment methods are becoming the fascinating aspect of science and technology [1, 2]. Sustainable research is generally based on the green chemistry concept which requires the need for environmental, economic and social aspects to be assimilated. It involves the use of various materials that are facile synthesized from easily available and low-cost precursors with no hazardous effluents. These materials have been widely used for the energy-saving, waste reduction, recycling of plastics, water treatment, etc. Catalysis and adsorption are important tools for the processing and production of various chemicals or fuels through environmental sustainability and remediation [3-5]. Recently, the pertinence of layered double hydroxide (LDHs) or Hydrotalcite-type anionic clays (HTs) in various fields has gained considerable attention into their environmental remediation and sustainable development. These clays have been studied and recently investigated in catalysis and adsorption processes. Furthermore, these clay materials can also be produced by the facile and ease of synthesis pathways from easily available chemicals with less hazardous effluents. These materials are quite stable, cost-effective
Layered Double Hydroxides (LDHs): Versatile and Powerful Hosts for Different Applications
Layered double hydroxides are an emerging and intriguing class of materials having unique structural properties that allow their application in very different fields, such as catalysis, pollution control, agriculture, electronic, nanomedicine and drugs delivery. They are constituted by a sheets structure with formula [M2+1-x M3+x (OH)2](An-)x/n yH2O (M2+= Zn, Mg, Fe, Ni, Co..; M3+=Al, Ga, Fe…; An- = nitrates, carbonates, chloride). The exchange of these counterions with others inorganic/organic species, producing hybrid nanocomposites, makes these systems ideal candidates for many application. The goal is to find the right cationic ratio and the proper experimental conditions (pH, temperature, time, concentrations) to make the exchange process rapid and with high yield. A large number of synthetic processes for the nanocomposites production are theoretically disposable: coprecipitation, ionic exchange, reconstruction, hydrothermal or sol-gel synthesis. We will briefly describe the structural features of LDHs and the most widespread synthetic procedures.
Layered double hydroxides: A review
Combination of two-dimensional layered materials and intercalation technique offers a new area for developing nanohybrids with desired functionality. Layered double hydroxides (LDHs) are mineral and synthetic materials with positively charged brucite type layers of mixed metal hydroxides. Exchangeable anions located in interlayer spaces compensate for positive charge of brucite type layer. Since most biomolecules are negatively charged, can be incorporated between LDHs. A number of cardiovascular, anti-inflammatory agents are either carboxylic acids or carboxylic derivatives and could be ion exchanged with LDHs to have controlled release. LDHs have technological importance in catalysis, separation technology, medical science and nanocomposite material engineering.
Chemistry of Materials, 2009
A simple, economical, and environmentally friendly method for the production of layered double hydroxides (LDHs) is presented. The synthesis procedure is based on dispersing insoluble metal oxides, adjusting the pH by adding an optimum amount of metal nitrates, and dispersing and aging the product for a short time (6-8 h). The final product does not require washing, opposite to the traditional coprecipitation synthesis procedure. A dissolution-precipitation-recrystallization mechanism is proposed for the formation of LDHs, based on particle size measurements, XRD analyses, radial distribution functions, and 27 Al MAS NMR studies. Solids were characterized by XRD, N 2 physisorption, TGA-DTA, SEM, and TEM, revealing that both LDHs and their calcination products have very similar properties to those prepared by conventional procedures. Pure LDH phase is obtained after 6-8 h; a large, uniform particle size that would usually require prolonged hydrothermal treatments is attained. Surface areas ranged from 32 to 93 m 2 g -1 and from 140 to 230 m 2 g -1 for fresh and calcined samples, respectively. This new method is intended to satisfy the growing demand of LDHs in large-scale applications as catalysts, SO x adsorbents, PVC additives, etc.
A B S T R A C T This work is the first report that critically reviews the properties of layered double hydroxides (LDHs) on the level of speciation in the context of water treatment application and dynamic adsorption conditions, as well as the first report to associate these properties with the synthetic methods used for LDH preparation. Increasingly stronger maximum allowable concentrations (MAC) of various contaminants in drinking water and liquid foodstuffs require regular upgrades of purification technologies, which might also be useful in the extraction of valuable substances for reuse in accordance with modern sustainability strategies. Adsorption is the main separation technology that allows the selective extraction of target substances from multicomponent solutions. Inorganic anion exchangers arrived in the water business relatively recently to achieve the newly approved standards for arsenic levels in drinking water. LDHs (or hydrotalcites, HTs) are theoretically the best anion exchangers due to their potential to host anions in their interlayer space, which increases their anion removal capacity considerably. This potential of the interlayer space to host additional amounts of target aqueous anions makes the LDHs superior to bulk anion exchanger. The other unique advantage of these layered materials is the flexibility of the chemical composition of the metal oxide-based layers and the interlayer anions. However, until now, this group of " classical " anion exchangers has not found its industrial application in adsorption and cat-alysis at the industrial scale. To accelerate application of LDHs in water treatment on the industrial scale, the authors critically reviewed recent scientific and technological knowledge on the properties and adsorptive removal of LDHs from water on the fundamental science level. This also includes review of the research tools useful to reveal the adsorption mechanism and the material properties beyond the nanoscale. Further, these properties are considered in association with the synthetic methods by which the LDHs were produced. Special attention is paid to the LDH properties that are particularly relevant to water treatment, such as exchangeability ease of the interlayer anions and the LDH stability at the solid-water interface. Notably, the LDH properties (e.g., rich speciation, hydration, and the exchangeability ease of the interlayer anions with aqueous anions) are considered in the synthetic strategy context applied to the material preparation. One such promising synthetic method has been developed by the authors who supported their opinions by the unpublished data in addition to reviewing the literature. The reviewing approach allowed for establishing regularities between the parameters: the LDH synthetic method―structure/surface/interlayer―removal―suitability for water treatment. Specifically, this approach allowed for a conclusion about either the unsuitability or promising potential of some synthetic methods (or the removal approaches) used for the preparation of LDHs for water purification at larger scales. The overall reviewing approach undertaken by the authors in this work mainly complements the other reviews on LDHs (published over the past seven to eight years) and for the first time compares the properties of these materials beyond the nanoscale.
Clay minerals and layered double hydroxides for novel biological applications
Applied Clay Science, 2007
This review is focused on the pharmaceutical and biological applications of clays, clay minerals and layered double hydroxides (LDHs). Novel nanohybrids of clay mineral-/ or LDH-biomaterials, including vitamins, drugs, and DNA strands are discussed for possible future developments in cosmetics, pharmaceutics, medicine as well as information storage.
Layered Double Hydroxides Nanomaterials in Biomedicine and (bio) Sensing Design
Biomedical Journal of Scientific & Technical Research, 2018
Layered double hydroxides are known for over 150 years. The first discovered natural mineral with this structure was hydrotalcite [5], reported by Hochstetter in 1842, synthesized 100 years later by Feitknecht [6]. The structure of this compound is related to that of brucite in which part of Mg 2+ cations are replaced by Al3+. Carbonate anions are intercalated between the layers to maintain the electroneutrality of material. The presence of hydrotalcite in nature is reduced. For this reason, the synthesis of LDHs was
Preparation of Layered Double Hydroxides toward Precisely Designed Hierarchical Organization
ChemEngineering
Layered double hydroxides (LDHs) are a class of materials with useful properties associated with their anion exchange abilities for a wide range of materials’ applications including adsorbent, catalyst and its support, ceramic precursor, and drug carrier. In order to satisfy the requirements for the detailed characterization and the practical application, the preparation of LDHs with varied composition and particle morphology has been examined extensively. The versatility of the preparation methods led LDHs with varied composition and micro/macroscopic morphology, which makes the application of LDHs more realistic. In the present review article, synthetic methods of LDHs are overviewed in order to highlight the present status of the LDHs for practical application.