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Carboxymethylcellulose (CMC) acts as a coating material for a magnesium-layered hydroxide-3-(4-methoxyphenyl)propionate (MLH-MPP) nanocomposite via spontaneous self-assembly. The resulting product is called a magnesium-layered hydroxide-3-(4-methoxyphenyl)propionate/carboxymethylcellulose (MLH-MPP/CMC) nanocomposite. The XRD pattern of the MLH-MPP/CMC nanocomposite showed that MPP was maintained in the interlayers of the MLH, thus confirming that CMC is only deposited on the surface of the MLH-MPP nanocomposite. These findings were also supported by FTIR spectra, SEM and TEM. TGA data showed that the thermal stability of the intercalated MPP was significantly enhanced compared to pure MPP and uncoated nanocomposite. The release of MPP from the interlayers of MLH-MPP/CMC nanocomposite showed slower release than did uncoated nanocomposite and followed pseudo–second-order kinetics. Since the herbicide, MPP was released from the synthesised nanocomposite in a sustained manner, thus, it has excellent potential to be used as a controlled-release herbicide formulation. Keywords: Magnesium-layered hydroxide, 3-(4-Methoxyphenyl)propionic acid, Carboxymethylcellulose, Direct reaction method, Controlled release

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, Mesoporous

A facile electrochemical exfoliation method was established to efficiently prepare conductive paper containing reduced graphene oxide (RGO) with the help of single chain anionic surfactant ionic liquids (SAILs). The surfactant ionic liquids are synthesized from conventional organic surfactant anions and a 1-butyl-3-methyl-imidazolium cation. For the first time the combination of SAILs and cellulose was used to directly exfoliate graphite. The ionic liquid 1-butyl-3-methyl-imidazolium dodecylbenzenesulfonate (BMIM-DBS) was shown to have notable affinity for graphene, demonstrating improved electrical properties of the conductive cellulose paper. The presence of BMIM-DBS in the system promotes five orders of magnitude enhancement of the paper electrical conductivity (2.71 × 10−5 S cm−1) compared to the native cellulose (1.97 × 10−10 S cm−1). A thorough investigation using electron microscopy and Raman spectroscopy highlights the presence of uniform graphene incorporated inside the matrices. Studies into aqueous aggregation behavior using small-angle neutron scattering (SANS) point to the ability of this compound to act as a bridge between graphene and cellulose, and is responsible for the enhanced exfoliation level and stabilization of the resulting dispersion. The simple and feasible process for producing conductive paper described here is attractive for the possibility of scaling-up this technique for mass production of conductive composites containing graphene or other layered materials.

Hydrothermal method has been proven to be an effective method to synthesise the nanostructured titanium dioxide (TiO2) with good morphology and uniform distribution at low temperature. Despite of employing a well-known and commonly used glass substrate as the support to hydrothermally synthesise the nanostructured TiO2, this study emphasised on the application of kaolin hollow fibre membrane as the support for the fabrication of kaolin/TiO2 nanorods (TNR) membrane. By varying the hydrothermal reaction times (2 h, 6 h, and 10 h), the different morphology, distribution, and properties of TiO2 nanorods on kaolin support were observed by field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscope (AFM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). It was found that the well-dispersed of TiO2 nanorods have improved the surface affinity of kaolin/TNR membrane towards water, allowing kaolin/TNR membrane prepared from 10 h of hydrothermal reaction to exhibit the highest water permeation of 165 L/h.m2.bar. In addition, this prepared membrane also showed the highest photocatalytic activity of 80.3% in the decolourisation of reactive black 5 (RB5) under UV irradiation. On top of that, the kaolin/TNR membrane prepared from 10 h of hydrothermal reaction also exhibited a good resistance towards photocorrosion, enabling the reuse of this membrane for three consecutive cycles of photocatalytic degradation of RB5 without showing significant reduction in photocatalytic efficiency towards the decolourisation of RB5.

In this study, we report a novel and efficient way to produce large-area graphene and syngas simultaneously from CH4 and CO2 via CVD. The successful synthesis of syngas was confirmed by online gas chromatography characterization whereas the graphene produced within the same process was verified using Raman spectroscopy, Raman mapping and HRTEM. This work helps to better understand graphene growth from CH4 and CO2 and improve the CVD method by providing a novel pathway for the synthesis of large-area graphene with a valued by-product. With our derived CVD approach, graphene was grown while producing syngas and consuming green-house gases which is of great importance in this current climate change phenomenon.

Graphene oxide (GO) has been used as a promising material for antimicrobial surface due to its contact-based antimicrobial activity. The antimicrobial activity of GO was thought to be mediated by physical and chemical interactions when sheets come in direct contact with bacterial cells. Antimicrobial surfaces have important applications in the biomedical field for preventing microbial contamination of medical devices, or in environmental systems where bio-fouling is a major cause of increased operation costs in marine transport, membrane-based water treatment, and heat exchangers. It has been reported that, the antimicrobial activity depends up on the size of GO sheets. Herein, In order to know the accurate assessment of the antimicrobial activity of GO through the suspension assays and surface coatings, we used ultrasonic irradiations to tune the size of GO synthesized through an electrochemical exfoliation method assisted by a surfactant, SDS, in a concentration of 0.01 M to study the antimicrobial activity towards a gram-positive bacteria, Enterococcusfaecalis (cocci) and, a gram - negative bacteria, Escherichia coli (rod-shaped). It has been found that, the ultrasonication time has an effect on the introduction of edge-plane sites on the GO sheets, and their effect on the antimicrobial activity.

The adverse effects of ammonia found in wastewater streams lead to the development of advanced water treatment technology, i.e. membrane contactor (MC). In this study, single layer hollow fibre membrane (SLZK) and dual layer hollow fibre membrane (DLZK) were prepared from zirconia and kaolin and modified into hydrophobic membrane through simple grafting process via fluoroalkylsilane (FAS) agent. The properties of membranes such as morphology, surface roughness, mechanical strength, wettability and liquid entry pressure were analysed through scanning electron microscopy (SEM), atomic force microscopy (AFM), 3-point bending strength, contact angle and LEPw setup. Finally, the performance of the membranes was also investigated towards ammonia removal via membrane contactor system. Our findings showed that hydrophobicity properties significantly improved for both SLZK and DLZK membranes after grafting modification process as indicated by the increase of contact angle value from 5° and 1° to 132.7° and ~180.0° respectively. Based on the morphological analysis, the surface of DLZK showed more porous structure as compared to the SLZK. In addition, DLZK also displayed the highest mechanical strength and contact angle reading of 125 MPa and ~180° respectively. This suggests that the DLZK showed an excellent membrane contactor performance with highest value of mass transfer coefficient (3.77 x 10-5 ms-1) and almost complete removal of ammonia removal (91%). Overall, these results implied that dual layer ceramic membrane developed from kaolin and zirconia could provide the basis for the development of alternative ceramic membrane with excellent properties for membrane contactor system.

A modelling and optimization approach was implemented for the succinate recovery, a high-value organic acid, from concentrated feeds using polyimide (PI)/graphene oxide (GO) mixed matrix membrane (MMM) cross-linked with ethylenediamine (EDA). The effects of parameters, including i) time for crosslinking, ii) time for solvent evaporation, and iii) feed concentration, on succinate rejection and separation factor (SF) were investigated. The optimization of the dominant factors, namely, crosslinking time and succinate concentration, greatly enhanced the succinate rejection and SF, where 73% initial drop in succinate rejection was improved, and a membrane rejection performance of above 80% was sustained, even when the succinate concentration rose to 50 g/L. This improvement was attributed to the formation of covalent bonds and a reduction in the d-spacing of the cross-linked MMM. The optimization study with a desirability of 0.81 also demonstrated the applicability of the model to an actual broth. The optimized membrane prepared at 1.61 h crosslinking time, 30 s evaporation time and 30 g/L succinate concentration demonstrated 86% succinate recovery from the actual broth, 0.15-0.33 SF, and 96% flux recovery ratio. Thus, this optimization study could be a way forward in exploring, simultaneously expanding cross-linked membrane applications especially in product recoveries from concentrated feed(s).

The chemically modified multiwalled carbon nanotubes (MWCNTs) paste electrode with chloroplatinum(II) complex for the determination of mercury is presented. The chloroplatinum(II) complex was characterized by nuclear magnetic resonance spectroscopy (NMR), Fourier transforms infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM). The capability of the electron transfer rate on the surface of modified electrode evaluated is by electrochemical impedance spectroscopy (EIS). The square wave stripping voltammetry (SWSV) technique was employed to investigate the performance of chloroplatinum(II) complex-MWCNTs paste electrode for determination of mercury. Several operational parameters such as the composition ratios of the electrode, type of supporting electrolyte, pH of the solution, and the SWSV parameters were thoroughly investigated. Under optimal conditions, the linear range obtained was from 5.0 μM to 0.1 mM with limit detection of 3.7 μM. The interference from other heavy metals such as Ca2+, Mg2+, Ni2+, Zn2+, Cd2+, Co2+, Ba2+, Mn2+, and Ce3+ did not influence the electrochemical response. The chloroplatinum(II) complex-MWCNTs paste electrode was successfully applied to determine mercury in skin lightening cosmetics with a good recovery (98.9%–101.1%).

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 A, 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.

The environmental pollution that results from the excessive usage of pesticides has been threatening the communities for decades. In this study, carboxymethyl cellulose (CMC) is proposed as a coating agent to encapsulate zinc hydroxide nitrate–sodium dodecylsulphate–imidacloprid (ZHN–SDS–IC) for the implementation of controlled release formulation (CRF) in pesticide. The physicochemical properties of the ZHN–SDS–IC–CMC were characterised so that their crystallinity, thermal behaviour and surface morphology could be examined. The findings from the release study revealed the potential for CMC to prolong the release of imidacloprid (IC). A strong hygroscopic and adequate swelling characteristic enabled the CMC to develop an external gel layer on the surface of the ZHN–SDS–IC–CMC that acted as an additional barrier and slowed the release of the intercalated IC. The ZHN–SDS–IC–CMC that was synthesised can contribute to overcoming the environmental issues due to excessive usage of pesticides and can create a better future for the community.

A technology for converting waste materials to high quality large-area monolayer graphene film can be significant and thereby obtaining high value-added product. Here, we revealed the transformation of waste chicken fat into uniform monolayer graphene film on re-solidified Cu by a low pressure chemical vapor deposition (LPCVD) technique. The evolve gas analyzer-gas chromatography⿿mass spectrometry (EGA-GC⿿MS) analysis of chicken fat oil showed that the free fatty acid in chicken oil decomposed into a short hydrocarbon chains which makes it favorable to use as a carbon precursor for graphene synthesis. Growth of uniform monolayer graphene film on the re-solidified Cu was confirmed by Raman mapping, where 2D to G peak intensity ratio (I2D/IG) is 3.0 at most of the area. Thus, the use of waste from poultry industry as a carbon source instead of commonly used hydrocarbon gas sources for graphene synthesis can be an approach for green nanotechnology.

In the present work, the feasibility of chitosan-graphene oxide (CS-GO) nanocomposites, namely CS-GO 1% (w/w), CS-GO 2% (w/w) and CS-GO 3% (w/w) as water-solubilising agents for rotenone pesticide was evaluated for the first time. The CS-GO nanocomposites were characterised by using FTIR, SEM, TEM and XRD analyses. The interaction of nanocomposites with rotenone was investigated through adsorption study involving several experimental parameters such as solution pH, initial concentration and contact time. Additionally, the desorption study was carried out using HCl and NaOH as desorption agents. Based on correlation coefficient (R2), the adsorption kinetic data were best described by the pseudo-first order equation while the adsorption equilibrium data were correlated well with the Langmuir isotherm model. The GO nanoparticle aggregates have a spherical shape with size ranged from 1.40 to 34.7 nm. The crystallinity of CS was increased following interaction with GO, whereby the intensity of diffractive peak at 2θ = 20.42° was increased to more than 4000 counts. Based on Langmuir isotherm model, CS-GO 3% (w/w) exhibited the highest adsorption capacity for rotenone with Q value of 92.59 mg/g. The main mechanism for interaction of CS-GO nanocomposites with rotenone was through formation of hydrogen bond. The presence of -OH, -COOH and -NH functional groups on CS-GO nanocomposites significantly contributed to water-solubilising mechanism. The CS-GO 1% (w/w), CS-GO 2% (w/w) and CS-GO 3% (w/w) nanocomposites were able to increase the solubility of rotenone in water by 34.40%, 38.80% and 46.30%, respectively.

Controlled release formulations of herbicides have been recognised to have potential in reducing the adverse effects of conventional herbicides on our environment. In this work, the controlled release behaviour of quinclorac (QC) from zinc/aluminium-layered double hydroxide-quinclorac (Zn/Al-LDH-QC) and its chitosan-coated composite Zn/Al-LDH-QC-Chi into aqueous solutions of Na3PO4, Na2SO4 and NaCl were studied. The physicochemical properties of both composites were studied initially, using powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR), thermogravimetric and derivative thermogravimetric analysis (TGA/DTG) and field emission scanning electron microscopy (FESEM) instruments, so that the effect of chitosan coating on their functional groups, thermal stabilities and surface morphology could be observed thoroughly. The results from the release studies showed that the presence of chitosan as a coating enhances the electrostatic attraction between the positively charged amino groups on the backbone of chitosan and the negatively charged QC anions, thus assisting in prolonging the time of release of QC. The kinetic studies revealed that both Zn/Al-LDH-QC and Zn/Al-LDH-QC-Chi composites obey second-order mechanisms, thus signifying that the release of QC into the release media by both composites took place via dissolution and ion exchange. These results therefore indicate the promising potential of Zn/Al-LDH-QC and Zn/Al-LDH-QC-Chi to overcome the drawbacks of the over-use of herbicides in paddy cultivation areas.