Development of a dispersive solid phase microextraction method based on the application of MgAl, NiAl, and CoAl-layered double hydroxides for the efficient removal of α- and ß-naphthol isomers from water samples by capillary electrophoresis.

The present work describes a quick, simple, and efficient method based on the use of layered double hydroxides (LDH) coupled to dispersive solid phase micro-extraction (DSPME) to remove α-naphthol (α-NAP) and ß-naphthol (ß-NAP) isomers from water samples. Three different LDHs (MgAl-LDH, NiAl-LDH, and CoAl-LDH) were used to study how the interlayer anion and molar ratio affected the removal performance. The critical factors in the DSPME procedure (pH, LDH amount, contact time) were optimized by the univariate method under the optimal conditions: pH, 4-8; LDH amount, 5 mg; and contact time, 2.5 min. The method can be successfully applied in real sample waters, removing NAP isomers even in ultra-trace concentrations. The large volume sample stacking (LVSS-CE) technique provides limits of detections (LODs) of 5.52 µg/L and 6.36 µg/L for α-naphthol and ß-naphthol, respectively. The methodology's precision was evaluated on intra- and inter-day repeatability, with %RSD less than 10% in all cases. The MgAl/Cl--LDH selectivity was tested in the presence of phenol and bisphenol A, with a removal rate of >92.80%. The elution tests suggest that the LDH MgAl/Cl--LDH could be suitable for pre-concentration of α-naphthol and ß-naphthol in future works.

LDH-Indomethacin Nanoparticles Antitumoral Action: A Possible Coadjuvant Drug for Cancer Therapy.

Indomethacin (INDO) has a mechanism of action based on inhibiting fatty acids cyclooxygenase activity within the inflammation process. The action mechanism could be correlated with possible anticancer activity, but its high toxicity in normal tissues has made therapy difficult. By the coprecipitation method, the drug carried in a layered double hydroxides (LDH) hybrid matrix would reduce its undesired effects by promoting chemotherapeutic redirection. Therefore, different samples containing INDO intercalated in LDH were synthesized at temperatures of 50, 70, and 90 °C and synthesis times of 8, 16, 24, and 48 h, seeking the best structural organization. X-ray diffraction (XRD), vibrational Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), spectrophotometric analysis in UV-VIS, and differential thermogravimetric analysis (TGA/DTA) were used for characterization. Our results indicate that higher temperatures and longer synthesis time through coprecipitation reduce the possibility of INDO intercalation. However, it was possible to establish a time of 16 h and a temperature of 50 °C as the best conditions for intercalation. In vitro results confirmed the cell viability potential and anticancer activity in the LDH-INDO sample (16 h and 50 °C) for gastric cancer (AGP01, ACP02, and ACP03), breast cancer (MDA-MB-231 and MCF-7), melanoma (SK-MEL-19), lung fibroblast (MRC-5), and non-neoplastic gastric tissue (MN01) by MTT assay. Cell proliferation was inhibited, demonstrating higher and lower toxicity against MDA-MB-231 and SK-MEL-19. Thus, a clinical redirection of INDO is suggested as an integral and adjunctive anticancer medication in chemotherapy treatment.

Development, synthesis, and application of magnetic layered double hydroxides (Fe3O4@SiO-LDH/DS-) as an efficient adsorbent for the removal of tetracyclines from milk samples.

This work presents the development, synthesis, and application of a layered double hydroxide (LDH) coupled to magnetic particles for the removal of antibiotics as tetracyclines (TC´s): tetracycline (TC), chlortetracycline (CT), oxytetracycline (OT), and doxycycline (DT) from milk samples. The LDH synthesis conditions, reaction time (30-90 min), molar ratios Mg2+/Al3+ (7:1-1:7), interlayer anion (NO3-, Cl-, CO32-, and dodecyl sulphate (DS-)) were evaluated. Under synthesis conditions (reaction time of 30 min, Mg2+/Al3+ molar ratio of 7:1, and DS- as interlayer anion), the LDH was coupled in a magnetic solid phase microextraction (MSPµE) methodology. At the optimal extraction conditions (pH 6, 5 min of contact time, 10 mg of adsorbent), a removal percentage of 99.0 % was obtained for each tetracycline. FTIR, TGA, SEM, and adsorption isotherms were employed to characterize the optimal adsorbent. Each experiment was corroborated by large-volume sample stacking capillary electrophoresis (LVSS-CE). The adsorbent was applied directly to positive milk samples (previously tested) for TC´s removal.

Ecotoxicology Evaluation of a Fenton-Type Process Catalyzed with Lamellar Structures Impregnated with Fe or Cu for the Removal of Amoxicillin and Glyphosate.

Antibiotics and pesticides, as well as various emerging contaminants that are present in surface waters, raise significant environmental concerns. Advanced oxidation processes, which are employed to eliminate these substances, have demonstrated remarkable effectiveness. However, during the degradation process, by-products that are not completely mineralized are generated, posing a substantial risk to aquatic ecosystem organisms; therefore, it is crucial to assess effluent ecotoxicity following treatment. This study aimed to assess the toxicity of effluents produced during the removal of amoxicillin and glyphosate with a Fenton-type process using a laminar structure catalyzed with iron (Fe) and copper (Cu). The evaluation included the use of Daphnia magna, Selenastrum capricornutum, and Lactuca sativa, and mutagenicity testing was performed using strains TA98 and TA100 of Salmonella typhimurium. Both treated and untreated effluents exhibited inhibitory effects on root growth in L. sativa, even at low concentrations ranging from 1% to 10% v/v. Similarly, negative impacts on the growth of algal cells of S. capricornutum were observed at concentrations as low as 0.025% v/v, particularly in cases involving amoxicillin-copper (Cu) and glyphosate with copper (Cu) and iron (Fe). Notably, in the case of D. magna, mortality was noticeable even at concentrations of 10% v/v. Additionally, the treatment of amoxicillin with double-layer hydroxides of Fe and Cu resulted in mutagenicity (IM ≥ 2.0), highlighting the necessity to treat the effluent further from the advanced oxidation process to reduce ecological risks.

Development of Y-TZP/MWCNT-SiO2 nanocomposite for dental protheses.

Y-TZP/MWCNT-SiO2 nanocomposite was synthesized by co-precipitation and hydrothermal treatment methods. After the characterization of the MWCNT-SiO2 powder, specimens were obtained from the synthesized material Y-TZP/MWCNT-SiO2 by uniaxial pressing for a second characterization and later comparison of its optical and mechanical properties with the conventional Y-TZP. The MWCNT-SiO2 was presented in bundles of carbon nanotubes coated by silica (mean length: 5.10 ± 1.34 µm /D90: 6.9 µm). The composite manufactured was opaque (contrast ratio: 0.9929 ± 0.0012) and had a white color with a slightly difference from the conventional Y-TZP (ΔE00: 4.4 ± 2.2) color. The mechanical properties of Y-TZP/MWCNT-SiO2: vickers hardness (10.14 ± 1.27 GPa; p = 0.25) and fracture toughness (4.98 ± 0.30 MPa m1/2; p = 0.39), showed no significant difference from the conventional Y-TZP (hardness: 8.87 ± 0.89; fracture toughness: 4.98 ± 0.30 MPa m1/2). However, for flexural strength (p = 0.003), a lower value was obtained for Y-TZP/MWCNT-SiO2 (299.4 ± 30.5 MPa) when compared to the control Y-TZP (623.7 ± 108.8 MPa). The manufactured Y-TZP/MWCNT-SiO2 composite presented satisfactory optical properties, however the co-precipitation and hydrothermal treatment methods need to be optimized to avoid the formation of porosities and strong agglomerates, both from Y-TZP particles and MWCNT-SiO2 bundles, which lead to a significant decrease in the material flexural strength.

Development of Dipeptide N-acetyl-L-cysteine Loaded Nanostructured Carriers Based on Inorganic Layered Hydroxides.

N-acetyl-L-cysteine (NAC), a derivative of the L-cysteine amino acid, presents antioxidant and mucolytic properties of pharmaceutical interest. This work reports the preparation of organic-inorganic nanophases aiming for the development of drug delivery systems based on NAC intercalation into layered double hydroxides (LDH) of zinc-aluminum (Zn2Al-NAC) and magnesium-aluminum (Mg2Al-NAC) compositions. A detailed characterization of the synthesized hybrid materials was performed, including X-ray diffraction (XRD) and pair distribution function (PDF) analysis, infrared and Raman spectroscopies, solid-state 13carbon and 27aluminum nuclear magnetic resonance (NMR), simultaneous thermogravimetric and differential scanning calorimetry coupled to mass spectrometry (TG/DSC-MS), scanning electron microscopy (SEM), and elemental chemical analysis to assess both chemical composition and structure of the samples. The experimental conditions allowed to isolate Zn2Al-NAC nanomaterial with good crystallinity and a loading capacity of 27.3 (m/m)%. On the other hand, NAC intercalation was not successful into Mg2Al-LDH, being oxidized instead. In vitro drug delivery kinetic studies were performed using cylindrical tablets of Zn2Al-NAC in a simulated physiological solution (extracellular matrix) to investigate the release profile. After 96 h, the tablet was analyzed by micro-Raman spectroscopy. NAC was replaced by anions such as hydrogen phosphate by a slow diffusion-controlled ion exchange process. Zn2Al-NAC fulfil basic requirements to be employed as a drug delivery system with a defined microscopic structure, appreciable loading capacity, and allowing a controlled release of NAC.

Biomaterials Based on Organic Polymers and Layered Double Hydroxides Nanocomposites: Drug Delivery and Tissue Engineering.

The development of biomaterials has a substantial role in pharmaceutical and medical strategies for the enhancement of life quality. This review work focused on versatile biomaterials based on nanocomposites comprising organic polymers and a class of layered inorganic nanoparticles, aiming for drug delivery (oral, transdermal, and ocular delivery) and tissue engineering (skin and bone therapies). Layered double hydroxides (LDHs) are 2D nanomaterials that can intercalate anionic bioactive species between the layers. The layers can hold metal cations that confer intrinsic biological activity to LDHs as well as biocompatibility. The intercalation of bioactive species between the layers allows the formation of drug delivery systems with elevated loading capacity and modified release profiles promoted by ion exchange and/or solubilization. The capacity of tissue integration, antigenicity, and stimulation of collagen formation, among other beneficial characteristics of LDH, have been observed by in vivo assays. The association between the properties of biocompatible polymers and LDH-drug nanohybrids produces multifunctional nanocomposites compatible with living matter. Such nanocomposites are stimuli-responsive, show appropriate mechanical properties, and can be prepared by creative methods that allow a fine-tuning of drug release. They are processed in the end form of films, beads, gels, monoliths etc., to reach orientated therapeutic applications. Several studies attest to the higher performance of polymer/LDH-drug nanocomposite compared to the LDH-drug hybrid or the free drug.

Nickel removing by electrocoagulation of Ni(II)-NH3-CO2-SO2-H2O system. Kinetics, isothermal, mechanism and estimated cost of operation.

This study reports nickel removing by electrocoagulation of Ni(II)-NH3-CO2-SO2-H2O system at laboratory scale. Experiments were done using Al/Al pair electrodes at initial nickel concentration between 293 and 1356 mg·L-1 and under operation parameters of pH 8.6, current density 9.8 mA·cm-2, electrolysis time 30 min, and temperature 60 ºC. The obtained results show removal efficiencies between 97.7 and 99.7 %. Kinetics modeling suggested combined effects of external diffusion and nucleation, and as controlling step the chemical reaction and a possible autocatalytic contribution. The process followed the Langmuir´s isotherm with a maximum adsorption capacity of 7519 mg·g-1. ICP-OES, XRD and FTIR characterization of the precipitates indicated a typical Ni-Al layered double hydroxide structures with 33.4-40.7 % nickel and 6.3-7.0 % aluminum depending on initial nickel concentration. The operation costs of energy and electrode consumption were 320 - 537 $·t-1 of removed nickel.

Nanoclays: Promising Materials for Vaccinology.

Clay materials and nanoclays have gained recent popularity in the vaccinology field, with biocompatibility, simple functionalization, low toxicity, and low-cost as their main attributes. As elements of nanovaccines, halloysite nanotubes (natural), layered double hydroxides and hectorite (synthetic) are the nanoclays that have advanced into the vaccinology field. Until now, only physisorption has been used to modify the surface of nanoclays with antigens, adjuvants, and/or ligands to create nanovaccines. Protocols to covalently attach these molecules have not been developed with nanoclays, only procedures to develop adsorbents based on nanoclays that could be extended to develop nanovaccine conjugates. In this review, we describe the approaches evaluated on different nanovaccine candidates reported in articles, the immunological results obtained with them and the most advanced approaches in the preclinical field, while describing the nanomaterial itself. In addition, complex systems that use nanoclays were included and described. The safety of nanoclays as carriers is an important key fact to determine their true potential as nanovaccine candidates in humans. Here, we present the evaluations reported in this field. Finally, we point out the perspectives in the development of vaccine prototypes using nanoclays as antigen carriers.

Layered Double Hydroxides as Rising-Star Adsorbents for Water Purification: A Brief Discussion.

Within the frame of this article, briefly but comprehensively, we present the existing knowledge, perspectives, and challenges for the utilization of Layered Double Hydroxides (LDHs) as adsorbents against a plethora of pollutants in aquatic matrixes. The use of LDHs as adsorbents was established by considering their significant physicochemical features, including their textural, structural, morphological, and chemical composition, as well as their method of synthesis, followed by their advantages and disadvantages as remediation media. The utilization of LDHs towards the adsorptive removal of dyes, metals, oxyanions, and emerging pollutants is critically reviewed, while all the reported kinds of interactions that gather the removal are collectively presented. Finally, future perspectives on the topic are discussed. It is expected that this discussion will encourage researchers in the area to seek new ideas for the design, development, and applications of novel LDHs-based nanomaterials as selective adsorbents, and hence to further explore the potential of their utilization also for analytic approaches to detect and monitor various pollutants.

LTA and FAU-X Iron-Enriched Zeolites: Use for Phosphate Removal from Aqueous Medium.

Hydrothermally synthesized Linde type A (LTA) and faujasite X (FAU-X) zeolites are low-cost and environmentally benign inorganic carriers for environmental applications. In this study, (oxy)hydroxides were incorporated onto LTA and FAU-X zeolites to promote the phosphate adsorption. The performance of LTA-Fe and FAU-X-Fe was evaluated through batch adsorption assays. A complete evaluation was performed to recover phosphate from synthetic wastewater. The effect of pH, concentration, equilibrium, and kinetic parameters on phosphate adsorption and its further reuse in sorption-desorption cycles were evaluated. LTA-Fe and FAU-X-Fe are effective for adsorption of phosphate at neutral (e.g., pH 7.0 ± 0.2) and in a broad range of phosphate concentrations. Higher ratios of adsorption capacities were obtained by synthetic zeolites enriched with iron in comparison to their parent forms. The phosphate adsorption occurred through hydrogen bonding and complexation reactions between protonated iron hydroxyl groups and phosphate anions. The phosphate monolayer adsorption was followed by diffusion through the internal pores and 80% of the equilibrium adsorption was reached within 50 min. The LTA-Fe and FAU-X-Fe can be used for phosphate recovery from wastewater treatment plants. The use of LTA-Fe and FAU-X-Fe in a tertiary wastewater treatment stage could allow to reduce the phosphate-phosphorous content, reaching the regulatory levels (equal 1 mg L-1 total phosphorous). The phosphate adsorption using LTA-Fe and FAU-X-Fe does not require pH adjustment, and it is endothermic. The reusability of both iron zeolites is limited, and they can be finally disposed for soil amendment applications.

Novel bio-fertilizer based on nitrogen-fixing bacterium immobilized in a hydrotalcite/alginate composite material.

The bacterium Streptomyces sp. is a common genus of the actinomycetes class found in soils and rhizospheres. This bacterium can produce substances with bio-stimulant capacity through the fixation of nitrogen from the air. In this work, the Streptomyces sp. bacterium was immobilized on a ZnMgAl-hydrotalcite clay and embedded in calcium alginate beads to generate a novel bio-composite that functions as a bacterial reservoir and as a controlled release material for bacteria to be used as a bio-fertilizer.The results showed that the novel bacterium-hydrotalcite/alginate bio-composite was very efficient as a bio-fertilizer showing a plant length of 64 mm in only 14 days of growing, which corresponds to an increase of ca. 760% in the lettuce plant growth in comparison with the materials without bacteria. In short, the present results demonstrate that the hydrotalcite and alginate served as an excellent container to keep the bacteria alive, providing nutrients to them and controlling their delivery.

Can the toxicity of polyethylene microplastics and engineered nanoclays on flatfish (Solea senegalensis) be influenced by the presence of each other?

Microplastics and nanomaterials are applied in a myriad of commercial and industrial applications. When leaked to natural environments, such small particles might threaten living organisms' health, particularly when considering their potential combination that remains poorly investigated. This study investigated the physiological and biochemical effects of polyethylene (PE; 64-125 µm in size, 0.1, 1.0, and 10.0 mg·L-1) single and combined with an engineered nanomaterial applied in antifouling coatings, the copper-aluminium layered double hydroxides (Cu-Al LDH; 0.33, 1.0, and 3.33 mg·L-1) in the flatfish Solea senegalensis larvae (8 dph) after 3 h exposure, in a full factorial design. Particles ingestion, histopathology, and biochemical biomarkers were assessed. Fish larvae presented <1 PE particles in their gut, independently of their concentration in the medium. The histological health index showed minimal pathological alterations at PE combined exposure, with a higher value observed at 1 mg LDH·L-1 × 0.1 mg PE·L-1. Gut deformity and increased antioxidant defences (catalase), neurotransmission (acetylcholinesterase), and aerobic energy production (electron transport system) were observed at PE ≥ 1.0 mg·L-1. No oxidative damage (lipid peroxidation) or alterations in the detoxification capacity (glutathione-S-transferase) was observed on single and combined exposures. PE, combined or not with Cu-Al LDH, does not seem to compromise larvae's homeostasis considering levels reported so far in the marine and aquaculture environments. However, harsh effects are expected with MP contamination rise, as projections suggest.

Zn(ferulate)-LSH Systems as Multifunctional Filters.

Excessive UV solar radiation exposure causes human health risks; therefore, the study of multifunctional filters is important to skin UV protective ability and also to other beneficial activities to the human organism, such as reduction of reactive oxygen species (ROS) responsible for cellular damages. Potential multifunctional filters were obtained by intercalating of ferulate anions into layered simple metal hydroxides (LSH) through anion exchange and precipitation at constant pH methods. Ultrasound treatment was used in order to investigate the structural changes in LSH-ferulate materials. Structural and spectroscopic analyses show the formation of layered materials composed by a mixture of LSH intercalated with ferulate anions, where carboxylate groups of ferulate species interact with LSH layers. UV-VIS absorption spectra and in vitro SPF measurements indicate that LSH-ferulate systems have UV shielding capacity, mainly UVB protection. The results of reactive species assays show the ability of layered compounds in capture DPPH•, ABTS•+, ROO•, and HOCl/OCl- reactive species. LSH-ferulate materials exhibit antioxidant activity and singular optical properties that enable their use as multifunctional filters.

Phosphate removal from industrial wastewaters using layered double hydroxides.

In the present study, Mg-Al and Zn-Al layered double hydroxides (LDH) were synthesized by the co-precipitation method and employed to remove phosphate from synthetic aqueous solutions and industrial wastewaters. LDH were characterized by X-ray diffraction (XRD), N2 adsorption/desorption isotherms (BET method), thermal analyses (TG-DTA) and Fourier transform infrared spectroscopy (FTIR). XRD and TG-DTA analysis showed that Mg-Al and Zn-Al formed the LDH structure. Experimental adsorption data indicated that pseudo-second order model best described phosphate adsorption kinetics. Data of equilibrium experiments fitted well to Sips and Freundlich models for Mg-Al and Zn-Al, respectively. The effect of co-existing anions on the phosphate adsorption capacity was analyzed by utilizing industrial wastewater. The results showed that the phosphate removal decreases in the presence of other anions. Mg-Al adsorbent exhibited 74% removal of phosphate with a dosage of 5 g/L in industrial wastewater.

Remediation by means of EDTA of an agricultural calcareous soil polluted with Pb.

The dispersion of mine tailings affects ecosystems due to their high content of potentially toxic elements. Environmental risk increases when the soil impacted by tailings is used for agriculture; this use may result in health impacts. This study analyzes the feasibility of remediating a calcareous soil (used for maize cultivation) polluted with lead in the semiarid zone of Zimapán, México, by using EDTA as an extractant. Total geoavailable and bioaccessible concentrations in the gastric and intestinal phases were determined to evaluate lead availability and health risk. The soil was then washed with EDTA, and the geochemical fractionation (interchangeable, carbonates, Fe/Mn oxy-hydroxides, organic matter-sulfides, and residual) and impact on the mesophile bacteria and fungi/yeast populations were analyzed. The results showed total Pb concentrations up to 647 ± 3.50 mg/kg, a 46% bioaccessible fraction (297 ± 9.90 mg/kg) in the gastric phase and a 12.2% (80 ± 5 mg/kg) bioaccessible fraction in the intestinal phase, indicating a health and environmental risk. Meanwhile, the geochemical fractionation before washing showed a Pb fraction mainly consisting of Fe/Mn oxy-hydroxides (69.6%); this reducible fraction may progressively increase its bioaccessibility. Geochemical fractionation performed in the washed soil showed differences from that determined before the treatment; however, the iron and manganese fraction, at 42.4%, accounted for most of the Pb. The soil microbiology was also modified by EDTA, with an increase in aerobic bacteria and a decrease in fungi/yeast populations. Although 44% total lead removal was achieved, corresponding to a final concentration of 363.50 ± 43.50 mg/kg (below national and USEPA standards), washing with EDTA increased the soluble and interchangeable lead concentrations. Statistical analysis indicated a significant effect (p < 0.05) of EDTA on the soil's geochemical fractionation of lead.

Polymer/Iron-Based Layered Double Hydroxides as Multifunctional Wound Dressings.

This work presents the development of multifunctional therapeutic membranes based on a high-performance block copolymer scaffold formed by polyether (PE) and polyamide (PA) units (known as PEBA) and layered double hydroxide (LDH) biomaterials, with the aim to study their uses as wound dressings. Two LDH layer compositions were employed containing Mg2+ or Zn2+, Fe3+ and Al3+ cations, intercalated with chloride anions, abbreviated as Mg-Cl or Zn-Cl, or intercalated with naproxenate (NAP) anions, abbreviated as Mg-NAP or Zn-NAP. Membranes were structurally and physically characterized, and the in vitro drug release kinetics and cytotoxicity assessed. PEBA-loading NaNAP salt particles were also prepared for comparison. Intercalated NAP anions improved LDH-polymer interaction, resulting in membranes with greater mechanical performance compared to the polymer only or to the membranes containing the Cl-LDHs. Drug release (in saline solution) was sustained for at least 8 h for all samples and release kinetics could be modulated: a slower, an intermediate and a faster NAP release were observed from membranes containing Zn-NAP, NaNAP and Mg-NAP particles, respectively. In general, cell viability was higher in the presence of Mg-LDH and the membranes presented improved performance in comparison with the powdered samples. PEBA containing Mg-NAP sample stood out among all membranes in all the evaluated aspects, thus being considered a great candidate for application as multifunctional therapeutic dressings.

Plant growth regulation by seed coating with films of alginate and auxin-intercalated layered double hydroxides.

Auxins are a class of organic substances known as plant-growth regulators, which act on plant physiology, promoting its full development. However, due to the great instability of these substances among the diversity of crops and cultivation environments, it is necessary to seek more efficient modes of application, which lead to a homogeneous distribution and promote a sustained release according to the plants demand. Seed coating, using films containing a biodegradable polymer and auxins intercalated into layered compounds, emerges as a very promising approach to a new form of growth regulator application. Thus, the presented work had three aims: (i) the synthesis and characterization of an organic-inorganic hybrid material containing a layered double hydroxide (LDH) of zinc and aluminum and the synthetic auxin 1-naphthalenoacetic acid (ZnAl-NAA-LDH), (ii) the coating of bean seeds (Phaseolus vulgaris L.) with composite films produced from mixtures of alginate polymer and ZnAl-NAA-LDH, and (iii) the evaluation of the plant response by bioassays. The hybrid ZnAl-NAA-LDH was characterized by a set of analytical techniques, including powder X-ray diffraction, thermogravimetric analysis coupled to differential scanning calorimetry and mass spectrometry, specific surface area measurement, and scanning electron microscopy. Bioassays were performed with the seeds coated with the composite film to assess the germination rate and germination speed index of the seeds, as well as biometric analyses including measurements of root area, root fresh matter, and shoot length of the plants. The bioassay performed in soil pots showed that the alginate film containing ZnAl-NAA-LDH yields an enhancement regarding root area, fresh root matter and shoot length of plants. Thus, films produced from a mixture of alginate and the hybrid material containing the growth regulator intercalated into LDH can be a viable alternative to enhance plant development, which can be included in seed management.

Unveiling the Occurrence of Co(III) in NiCo Layered Electroactive Hydroxides: The Role of Distorted Environments.

Co- and Ni-based layered hydroxides constitute a unique class of two-dimensional inorganic materials with exceptional chemical diversity, physicochemical properties and outstanding performance as supercapacitors and overall water splitting catalysts. Recently, the occurrence of Co(III) in these phases has been proposed as a key factor that enhance their electrochemical performance. However, the origin of this centers and control over its contents remains as an open question. We employed the Epoxide Route to synthesize a whole set of α-NiCo layered hydroxides. The PXRD and XAS characterization alert about the occurrence of Co(III) as a consequence of the increment in the Ni content. DFT+U simulation suggest that the shortening of the Co-O distance promotes a structural distortion in the Co environments, resulting in a double degeneration in the octahedral Co 3d orbitals. Hence, a strong modification of the electronic properties leaves the system prone to oxidation, by the appearance of Co localized electronic states on the Fermi level. This work combines a microscopic interpretation supported by a multiscale crystallochemical analysis, regarding the so-called synergistic redox behavior of Co and Ni, offering fundamental tools for the controllable design of highly efficient electroactive materials. To the best of our knowledge, this is the first computational-experimental investigation of the electronic and structural details of α-NiCo hydroxides, laying the foundation for the fine tuning of electronic properties in layered hydroxides.

Preparation and evaluation of hydrocalumite-iron oxide magnetic intercalated with dodecyl sulfate for removal of agrichemicals.

The magnetic adsorbent prepared with hydrocalumite-iron oxide (HC/Fe) modified with dodecyl sulfate (DS) was examined for the removal of the agrichemicals atrazine (ATZ) and chlorpyrifos (CPF) from aqueous solution. The adsorbent HC-DS/Fe was characterized by infrared spectroscopy (IR), Raman spectroscopy, X-ray diffractometry (XRD) and atomic absorption spectrometry. The effects of adsorbent dosage, contact time, pH and initial concentration of ATZ and CPF were evaluated. HC-DS/Fe presented a maximum adsorption capacity for ATZ of 4.5 mg g-1 (30 min) and for CPF of 72.9 mg g-1 (210 min) at 25 °C. HC-DS/Fe can be readily removed from the aqueous solution by magnetization because of its magnetic properties. The free energy variation for HC-DS/Fe during the adsorption of the ATZ was -48.78 to -53.91 kJ mol-1 and for the CPF of -55.79 to -59.28 kJ mol-1, suggesting the spontaneity of the adsorption process. The positive value of △H suggests an endothermic process for the interaction of ATZ and CPF by HC-DS/Fe. This adsorbent showed satisfactory results when used in the treatment of a sample of river water, fortified with the agrichemicals chlorpyrifos, atrazine, thiamethoxam and acetamiprid.