Synthesis and Physico-Chemical Properties of Zinc Aluminium-Layered Double Hydroxide and Its Nanocomposites

In this study, zinc-aluminium-nitrate-LDH (ZANO) at different Zn/Al molar ratios of 1, 2, 3 and 4 were successfully synthesised via co-precipitation method. Studies on intercalation of various anions namely dodecylsulphate (DS), acetate (AC), anthranilate (AN), salicylate (SAL) acetylsalicylate (ASAL), 2,4-dichlorophenoxy acetate (24D), naphthalene acetate (NAA) and anthraquinone-2-sulfonate (AQ2) for the formation of the nanocomposites had been carried out. The anions of DS (having 12 C) and AC (having 2 C) were chosen to study the effect of the alkyl length on the formation of the nanocomposites and it was revealed that the basal spacing values were varied depending on the size of the anion. The nanocomposites of AN, SAL and ASAL with different ortho benzoate substitution groups were prepared via co-precipitation method. The basal spacing expansions of the nanocomposites: ZAA (ca. 1.3 nm), ZAS (ca. 1.6 nm) and ZAAS (1.6 nm) compared to that of the LDH (0.9 nm) are evidence of the successful intercalation process. Anion exchange study of various anions having different number of benzene rings (24D, NAA, AQ2) and different ortho benzoate substitution groups (AN, SAL, ASAL) were carried out. ZADS was chosen as a starting material where DS (interlayer anion), was expected to exchange with the newly introduced anions. Only AQ2 and AN were successfully exchanged with DS in between the layers. Thermal decomposition of the nanocomposites (ZAA, ZAS, ZAAS) at the heating temperature of 100-1000 ºC showed that the nanocomposites were thermally stable up to 300 ºC. The release profile of the ASAL anion from ZAAS in different solutions (pH 2, 6.5, 10) revealed that the ASAL anion was rapidly released into the medium at pH 2. The interlayer spacing of ZAAS slightly reduced at pH 6.5 and at pH 10 the basal spacing shrinks due to the replacing the ASAL anion by the carbonate anion. Kinetic models of pseudo-second order could be used to describe the release of the ASAL from ZAAS

Characterization of cucumber mosaic virus (CMV) causing mosaic symptom on Catharanthus roseus (L.) G. don in Malaysia

A cucumber mosaic virus (CMV) isolate, causing leaf mosaic and distortion, malformed flowers or colourbreaking on the petals of Catharanthus roseus in Serdang, Selangor, Malaysia, was identified and designated as Malaysian periwinkle isolate (CMV-MP). The virus was spherical in shape with the size of 28.6 ± 0.48 nm in diameter with a central core. It was mechanically transmitted to various test plants which produced typical symptoms of CMV infection. The coat protein (CP) gene of the virus was amplified using reverse transcriptasepolymerase chain reaction (RT-PCR) and cloned in Escherichia coli using TOPO-TA vector. A single open reading frame of 657 nucleotides, potentially encoding for 218 amino acids was sequenced. A comparison with the CP genes of other CMV isolates indicated that CMV-MP shared 100% sequence homology to the CP gene sequence of C. roseus isolate of CMV in India. This is the first aetiology report on C. roseus in Malaysia showing natural mosaic disease symptoms supported with the nucleotide sequence analysis of the causal virus

Ultrastructural features of Catharanthus roseus leaves infected with cucumber mosaic virus

Catharanthus roseus var. rosea, infected with Malaysian isolate of cucumber mosaic virus (CMV-MP), exhibited leaf mosaic, leaf deformation and malformed flowers. Electron microscopic examination of the infected leaf cells revealed significant alteration of the chloroplasts in the mesophyll cells. Large starch grains in necrotic zones and disorganized thylakoid system were the most prominent modifications observed within the chloroplasts of the infected tissues. Meanwhile, membrane-bound vesicles were detected in the vacuoles of the CMV-MP-infected leaf cells. A crystalline array of phytoferritin macromolecules was detected in the chloroplast at 40 days post-inoculation. However, neither single nor aggregate of CMV-MP particles was detected in the cytoplasm due to difficulties in differentiating them from the ribosomes. Nonetheless, structure resembling the inclusion bodies, commonly produced after virus infection, could not be found in the infected leaf cells. Similarly, structure abnormality in the nucleus or mitochondria was also not observed

Removal of methyl orange dye by manganese/aluminium- layered double hydroxide

As textile production flourishes nowadays, the amount of dyed wastewater entering the water body has also increased. Dyes could have serious negative impacts to the environment and also the human health, hence, they need to be removed from the water body. In this study, layered double hydroxide (LDH) of manganese/aluminium (MnAl) was synthesised to be used as a potential adsorbent to remove methyl orange (MO) dye due to its unique lamellar structure which provides LDH with high anion adsorption and exchange ability. MnAl was synthesized by using co-precipitation method and characterized by powder X-ray diffraction (PXRD), Fourier-Transform Infrared Spectroscopy (FTIR), Inductively coupled plasma atomic emission spectroscopy (ICP-AES) and Carbon, Hydrogen, Nitrogen, Sulphur (CHNS) elemental analysers, and Accelerated Surface Area and Porosity Analyzer (ASAP). Adsorption studies were conducted at different contact times and dosages of MnAl to evaluate the performance of MnAl in removing MO from water. Kinetic and isotherm models were tested using pseudo-first order, pseudo-second order, Langmuir isotherm and Freundlich isotherm. MnAl LDH was found to be perfectly fitted into pseudo-second order and Langmuir isotherm

Intercalation of Anthranilate Ion Into Zinc-Aluminium-Layered Double Hydroxide

Nanocomposites of zinc-aluminium-anthranilate (ZAAN) have been synthesized at different concentrations of anthranilic acid by co-precipitation method. These materials have been examined in detail by powder X-ray powder diffraction (PXRD) which showed the expansion of the basal spacing from 0.89 to ca. 1.33 nm and the shifting of the 003 peak towards the lower 2q angle. This indicates that the anthranilate anion was successfully intercalated into the interlayer gallery. However, FTIR analysis showed nitrate anion was also co-intercalated in the interlayer. The resulting nanocomposites show Type IV adsorption-desorption isotherms indicated the mesoporous structure of the material. BET surface area was found to be slightly different compared to zinc-aluminium-nitrate-layered double hydroxide (ZANO) after the intercalation process took place. Both ZANO and ZAAN have similar surface morphology, namely a flaky-like structure, but they are of different sizes

Preparation of Layered Double Hydroxides with Different Divalent Metals for the Adsorption of Methyl Orange Dye from Aqueous Solutions

In this study, layered double hydroxides (LDHs) with different divalent metal cations were prepared and then utilized as adsorbent for the removal of dye from aqueous solutions. LDHs are positively charged lamellar solids consisting of divalent and trivalent metallic cations and exchangeable interlayer anions. The potential combinatorial series of M/aluminum (M=Ca, Mn and Zn) LDHs for the removal of methyl orange (MO) dye from aqueous solutions were investigated.  LDHs were synthesized via a co-precipitation method and characterized using powder X-Ray diffraction (PXRD) and Fourier-transform infrared spectrophotometer (FTIR). The LDHs were then used as adsorbent for the removal of MO dye at different LDH dosages. As the LDH dosage increased, the removal percentage of MO dye also increased. CaAl, MnAl and ZnAl LDHs were able to adsorb up to 96.6%, 97.9% and 99.8% of MO dye, respectively, after being put in contact with the LDHs for 24h. Their adsorption ability was further analyzed by using Langmuir and Freundlich isotherm models in which the adsorption mechanism was determined. Adsorption of MO by CaAl, and ZnAl LDHs was governed by the Langmuir isotherm model while the adsorption data for MnAl LDH was found to fit well with the Freundlich isotherm model

Controlled release formulation of an anti-depression drug based on a L-phenylalanate-zinc layered hydroxide intercalation compound

The intercalation of L-phenylalanate (LP) into the interlayer gallery of zinc layered hydroxide (ZLH) has been successfully executed using a simple direct reaction method. The synthesised intercalation compound, zinc layered hydroxide-L-phenylalanate (ZLH-LP), was characterised using PXRD, FTIR, CHNS, ICP-OES, TGA/DTG, FESEM and TEM. The PXRD patterns of the intercalation compound demonstrate an intense and symmetrical peak, indicating a well-ordered crystalline layered structure. The appearance of an intercalation peak at a low angle of 2θ with a basal spacing of 16.3 Å, signifies the successful intercalation of the L-phenylalanate anion into the interlayer gallery of the host. The intercalation is also validated by FTIR spectroscopy and CHNS elemental analysis. Thermogravimetric analysis confirms that the ZLH-LP intercalation compound has higher thermal stability than the pristine L-phenylalanine. The observed percentage of L-phenylalanate accumulated release varies in each release media, with 84.5%, 79.8%, 63.8% and 61.8% release in phosphate buffer saline (PBS) solution at pH 4.8, deionised water, PBS solution at pH 7.4 and NaCl solution, respectively. The release behaviour of LP from its intercalation compounds in deionised water and PBS solution at pH 4.8 follows pseudo second order, whereas in NaCl solution and PBS solution at pH 7.4, it follows the parabolic diffusion model. This study shows that the synthesised ZLH-LP intercalation compound can be used for the formation of a new generation of materials for targeted drug release with controlled release properties

A brief review on recent graphene oxide-based material nanocomposites: synthesis and applications

In a past few years, more focus has been given to graphene, especially for its facile synthesis, novel hybrids materials and applications. Recently, researchers' attention has also focused on graphene oxide (GO) and reduced graphene oxide (rGO) nanocomposites, which lead to the development of various applications. Their superb and impressive characteristic makes them suitable candidates to be hybridized with polymer, metal oxide, and biomaterials. In this brief review, we will run through the accomplishments of effective approaches for synthesizing graphene oxide-based material nanocomposites together with their recently developed applications

Synthesis and properties of zinc-aluminium-acetylsalicylate-nanocomposite

Intercalation of acetylsalicylate anion into zinc-aluminium-layered double hydroxide has been successfully accomplished via co-precipitation method. Good crystallinity of both the zinc-aluminium-layered double hydroxide (ZANO) and the zinc-aluminium-acetylsalicylate-nanocomposite (ZAAS) were obtained when the Zn/Al ratio used was 3. Expansion of the basal spacing of the layered double hydroxide (LDH) after intercalation process from 8.9 Å to 16.3 Å was observed. However, FTIR analysis showed that nitrate anion was co-intercalated into the interlayer of the nanocomposite and the result was in agreement with the elemental analysis. TGA-DTG results showed that the encapsulation of the acetylsalicylate anion into the interlayer increased its thermal stability. The nitrogen adsorption-desorption isotherms showed that the resulting materials were of Type IV with H3 hysteresis loop. SEM micrograph of ZANO showed its flaky-like structure; while that of ZAAS showed a compact structure

Synthesis and characterization of mesoporous zinc layered hydroxide-isoprocarb nanocomposite

The ion exchange method was used to intercalate a poor water-soluble insecticide, isoprocarb into zinc layered hydroxide (ZLH). PXRD analysis indicated the successful intercalation with good crystallinity for the resulting nanocomposite, with a basal spacing of 33.1 Å. FTIR analyses showing the resemblance of an absorption peak of the nanocomposite with the host and the guest anion. The thermal analysis confirmed that the nanocomposite had better thermal stability compared to the pristine isoprocarb. The nanocomposite also characterized by elemental and surface morphology analysis. The surface analyses of the host and nanocomposite showed mesoporous-type material characteristics. On the whole, the intercalation process decreased the pore size of the nanocomposite compared to the pristine host, layered zinc layered hydroxide-sodium dodecyl sulphate (ZLH-SDS). The obtained material is believed has a great potential as an environmentally friendly insecticide. Keywords: Intercalation, Characterization, Zinc layered hydroxide, Isoprocarb, Mesoporou