Determination of the possibility of the synthesis of Zn-Al layered double hydroxides, intercalated with peroxyanions, as a perspective solid disinfectant

Layered double hydroxides (LDHs) have been widely investigated in a wide range of applications in health, in the pharmaceutical industry and in the material of biotechnology industries. This material can be considered as a group of promising materials in the development of new health applications. The combination of phosphonic acid with LDHs material create a new hybrid material with new properties.In this work the synthesis of Zn/Al double lay-ered hydroxides by chemical co-precipitation method (molar ration 2) and grafted with Diamino Dodecyl Phosphonic Acid (DDPA) via anion-exchange mechanism. The samples were characterized and confirmed by X-ray diffraction (XRD), and the presence of diamino dodecyl phosphonic acid (DDPA ) was verified by Elemental analysis, BET analysis, and infrared spec-troscopy. Both of the samples were found to be showing antibacterial activ-ity. The zone diameters of Zn-Al- LDH were 40 mm and 25 mm for Esche-richia coli(ATCC 25922) and Streptococcus (ATCC 25922)and 20 mm for bacillus (ATCC 25922) whereas the same for hybrid LDH (Zn-Al-DDPA)were43 mm , 32 mm and 25 mm for the same bacteria showing stronger antibacterial activity of the grafted material over the material itself. The experimental results confirm the application of Zn-Al-DDPA in the field of antibacterial activities and may offer a promising antibacterial elucidation to the society.

Laboratory synthesis of layered double hydroxides (LDH) often results in materials replete with stacking faults. Faults are known to affect several properties including sorption, electrochemical, and catalytic activity of this important class of materials. Understanding the occurrence of faults thus calls for a comprehensive analysis of formation and stability of ordered and faulted LDHs. High-temperature oxide melt solution calorimetric measurements made on an ordered and a faulted Mg-Al LDH with carbonate interlayer anion shows that ordered LDH is energetically more stable than the faulted one by ∼6 kJ/mol. The stacking faults are an intergrowth of 3R1 and 2H1 polytypes, and faults could thus mediate transformation of 3R1 to 2H1 polytypes. Several factors including pH and temperature of precipitation also affect layer stacking. The formation of stacking faults could therefore have its origin in kinetics. Water content in the interlayer also affects layer stacking, and hence it may affect properties of LDH. Improved understanding of the distribution of water molecules in LDH is also crucial in an environmental context, as LDH occur as minerals and are important for contaminant amelioration in the environment. Water adsorption calorimetry on dehydrated LDH shows a continuous decrease in the magnitude of adsorption enthalpy with increasing coverage, indicating the presence of energetically heterogeneous sites where the water molecules reside. The results also indicate that the energy of several sites where the water molecules may reside (whether in the interlayer or on the surface) overlaps, and hence it is hard to differentiate among them.

Layered double hydroxides (LDHs) are anionic clays important in disciplines such as environmental chemistry, geochemistry, and materials science. Developments in signal processing of extended X-ray absorption fine structure (EXAFS) data, such as wavelet transformation (WT), have been used to identify transition metals and Al present in the hydroxide sheets of LDHs. The WT plots of LDHs should be distinct from those of isostructural single metal hydroxides. However, no direct comparison of these minerals appears in the literature using WT. This work systematically analyzes a suite of Ni-rich mineral standards, including Ni-Al LDHs, single metal Ni hydroxides, and Ni-rich silicates using WT. The results illustrate that the WT plots for α-Ni(OH)2 and Ni-Al LDHs are often indistinguishable from each other, with similar two-component plots for the different mineral types. This demonstrates that the WT of the first metal shell often cannot be used to differentiate an LDH from a single metal hydroxide. Interlayer anions adsorbed to the hydroxide sheet of α-Ni(OH)2 affect the EXAFS spectra and are not visible in the FT but are clearly resolved and discrete in the WT.

Molten decane-1,10-dicarboxylic acid, sebacic acid, reacted with the layered double hydroxide (LDH) of initial composition Mg6Al3.4(OH)18.82(CO3)1.51(NO3)0.364.5H2O, at a temperature of 150 °C which is ca. 24 °C above the melting point of the acid. The reaction was not strongly exothermic and hence may be controlled by a suitable heating programme. X-Ray powder diffraction showed that the products were polyphasic and microcrystalline materials, the compositions of which were related to the original molar ratios of acid: LDH. Typically, the dominant phases were unintercalated LDH up to an acid : LDH ratio of 0.75 : 1; intercalated dianion (ratio ca. 1 : 1); salt, e.g. magnesium sebacate (for ratios 4 : 1 and higher). Fourier-transform infrared (FTIR) and 13C solid-state magic-angle spinning nuclear magnetic resonance (MAS NMR) spectroscopies of the reaction products confirmed the presence of the dianion –O2C(CH2)8CO2–. In no case was there evidence for undissociated guest acid molecules. The mechanism appears to involve the sorption of the acid, initially at the crystallite edges, followed by reaction of the molten acid with the basic solid host with evolution of CO2. The separated LDH layers then allow the acid to diffuse in. The product from the 1 : 1 mixture was similar to the intercalation compound obtained using a modified version of Drezdzon's method, which had previously been thought to be ineffective for sebacic acid.

In the article the process of Fe, Co, Ni and Cu hydroxides modified nanoparticles of layered double hydroxides (LDH) based on Zn and Al (Zn-Al LDH) was successfully presented. The precipitation method allowed to obtain nanoparticles of high crystallinity with lateral dimensions below 100 nm and thickness below 20 nm. The photocatalytic activity of the modified LDH in the degradation process of quinoline yellow was over 99%, while for the unmodified LDH the efficiency was only 30%. The study confirmed that modification of LDH with divalent ions had a significant effect on both photocatalytic and sorption properties. Furthermore, the study also investigated the effect of the nature of the type of light on the photodegradation efficiency.

The paper presents an overview of the thermal stabilizing behavior of Li-Al-X LDHs (layered double hydroxides) system when used in poly (vinyl chloride) as a stabilizer. Layered lithium aluminium double hydroxides having anions , , and Cl− have been synthesized by the hydrothermal method. The effects of the synthesis conditions on the structural and textural properties as well as on the thermal stability were investigated using different methods. The study suggests that, in contrast to the Mg-Al-X, Ca-Al-X LDH system where LDH having in interlayer is proven best, Li-Al-X LDH, the Cl− in the interlayer proves to be a better anion to impart thermal stabilization to PVC.

Re-use of Laundry Rinsing Water by low cost Adsorption Technology

Layered double hydroxides (LDH) can be classified as promising materials due to the ease of synthesis, as well as their wide scope of application. However, the process of LDH synthesis, depending on the LDH chemical composition, can take from tens of hours to several days. It was previously identified that ultrasound exposure during the LDH production significantly reduces the synthesis time, and LDHs produced in this way are interesting in relation to the study of their physicochemical properties and sorption capacity. In this work, the authors produced Mg/Fe LDHs in nitrate form by the traditional method and by the combined action of ultrasound and increased hydrostatic pressure. The resulting samples are characterized by a complex of physicochemical methods of analysis, including scanning electron microscopy (SEM), infrared spectroscopy (IR), X-ray phase analysis (XRD), and thermal gravimetric analysis (TGA) with differential scanning calorimetry (DSC). Experiments were carried out to study the sorption capacity of the obtained Fe/Mg LDH samples in relation to chromate ions under normal conditions and under the influence of ultrasound, including in combination with increased hydrostatic pressure. A photoelectric photometer was used to obtain and analyze data with quantitative values of the sorption process. Data of comprehensive analysis of the finished product indicate that the synthesized material is a Mg/Fe layered double hydroxide. X-ray phase analysis identified that the LDH synthesis using ultrasound and pressure increases the crystallinity degree of the finished product. It has been found that the sorption properties of LDHs produced by the conventional method and LDHs produced under the influence of ultrasound and pressure are different. In Mg/Fe LDHs synthesized by the conventional method, chromate sorption proceeds better than in samples synthesized using ultrasonic treatment in combination with increased hydrostatic pressure. The study shows that the sorption process of the examined LDH samples is described by different mathematical models.

La/Ce doped CoFe layered double hydroxides (LDH) highly enhanced oxygen evolution performance of water splitting

Sorption behavior of methyl orange from aqueous solution on organic matter and reduced graphene oxides modified Ni–Cr layered double hydroxides

Nitrogen removal via core-shell bio-ceramic/Zn-layer double hydroxides synthesized with different composites for domestic wastewater treatment

The use of pesticides adversely affects not only the environment, but also human health. A promising direction in solving this problem is to obtain hybrid materials capable of controlled release of pesticides. Layered double hydroxides (LDHs) can act as a matrix. Layered double hydroxides with intercalated glyphosate anions (MgAl-Gly-LDH) were synthesized by different methods: coprecipitation at constant pH (MgAl-Gly-LDH-c), synthesis under hydrothermal conditions (MgAl-Gly-LDH-ht), microwave method (MgAl-Gly-LDH-mw) and rehydration method (MgAl-Gly-LDH-re). All the synthesized samples were analyzed by X-ray phase analysis (XRD), energy dispersive X-ray spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. It is shown that the methods of co-precipitation and synthesis under hydrothermal conditions are most suitable for the synthesis of hybrid materials. Samples of MgAl-Gly-LDH-ht and MgAl-Gly-LDH-c have a well-crystallized structure, unlike the sample of MgAl-Gly-LDH-re, in which the LDH phase is practically absent.

Study on the adsorption of DNA on the layered double hydroxides (LDHs)

Nail polish, in particular gel polish, is the most commonly used cosmetic product. A component of the gel polish, which determines the consumer color characteristics of the gel polish. Layered double hydroxides (LDH) are promising pigments. To expand the range of colors and shades of pigments, the use of LDH with colored host and guest cations is promising. The parameters of synthesis and color characteristics of samples of Zn-Co and Cu-Co hydroxide pigments were studied. To obtain LDH with Co as a guest cation in the synthesis, the conversion of cobalt to the trivalent state was carried out at a temperature of 80 °C using oxidation with atmospheric oxygen or sodium hypochlorite. The oxidation efficiency was evaluated by X-ray phase analysis by the presence or absence of cobalt-containing phases. The color characteristics of the synthesized pigment samples were studied by spectroscopic measurement and calculation in RGB, CIELab, and LCH color models. The low efficiency of cobalt oxidation at the moment of Zn-Co LDH synthesis with atmospheric oxygen at an elevated synthesis temperature of 80 °C was shown, while cobalt was released as a separate Co3O4 phase. A higher efficiency of cobalt oxidation at the moment of synthesis using sodium hypochlorite with the formation of Zn-Co LDH was revealed. It is recommended to use the hypochlorite oxidation of Co2+ to Co3+ in the LDH synthesis with Co in the form of a guest cation. The formation of a separate phase of zinc oxide was found in both types of oxidation due to the thermal decomposition of zinc hydroxide. Comparative analysis of color characteristics showed that all samples have a brown color of different saturation. It was revealed that during the formation of Co-containing LDH, the lightness of the color decreases. Color saturation increases in the case of a colored host cation, such as Cu.

Layered double hydroxides with different divalent ions i.e. Mg/Fe and Ni/Fe were synthesized using coprecipitation method at basic condition. Materials were characterized using X-Ray diffraction and FTIR analyses. Furthermore, Mg/Fe and Ni/Fe layered double hydroxides were applied as adsorbent of Congo red dye in aqueous medium using batch system. Adsorption of Congo red on layered double hydroxides was investigated through kinetic and thermodynamic studies. X-ray diffraction analysis showed that unique diffraction of layered materials were identified at 2θ diffraction 11.33°, 29.55°, 59.66° (Mg/Fe) and 11.41°, 29.40°, 60.40° (Ni/Fe). Interlayer distance of Mg/Fe and Ni/Fe layered double hydroxides was 7.80 Å and 7.75 Å, respectively. IR spectrum of Mg/Fe and Ni/Fe layered double hydroxides showed that vibration of layered material was appeared at 1381 cm−1 (νN-O; nitrate), 347 cm−1 (νMg-O; layered double hydroxides), 586 cm−1 (νFe-O; layered double hydroxides) for Mg/Fe and 1381 cm−1 (νN-O; nitrate), 493 cm−1 (νNi-O; layered double hydroxides), 516 cm−1 (νFe-O; layered double hydroxides) for Ni/Fe. Kinetic pseudo second order was fitted than pseudo first order kinetic model for adsorption of Congo red with R ± 0.99 for both Mg/Fe and Ni/Fe. The rate of adsorption K2 for Mg/Fe and Ni/Fe layered double hydroxides was 0.008 g.mg−1min−1 and 0.0058 g.mg−1min−1. Adsorption of Congo red on Mg/Fe and Ni/Fe layered double hydroxides was well described and following Freundlich adsorption isotherm model shows physical adsorption process on layered double hydroxides.