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Nitrogen stress condition is believed to increase the production of lipid in microalgae, but the synthesis of both lipid and carbohydrate is less known. Therefore, the effect of nitrogen stress condition on the synthesis of lipid and carbohydrate of Tetradesmus obliquus UPSI-JRM02 was studied in a 2 L bioreactor system. The highest lipid and carbohydrate yields achieved under nitrogen stress condition were 37% and 23%, respectively. Nitrogen stress condition induced the accumulation of carbohydrate at early stage but started to reduce on day 4 when the carbon shifted towards lipid production. The fatty acid profile produced under nitrogen stress condition was composed of 54% polyunsaturated fatty acid (PUFA), 43% saturated fatty acid (SFA) and 3% monounsaturated fatty acid (MUFA). The biofuel properties of T. obliquus obtained under the nitrogen stress condition was within the range of biodiesel standard and is most suitable for the usage in cold country.

The proliferation of mosquito-borne diseases is a major health concern worldwide. An effective strategy to prevent the transmission of mosquito-borne diseases is using larvae control. Cinnamaldehyde, a substance from the cinnamon tree, is widely used in larvicide formulations, yet applications are limited due to the poor water solubility of cinnamaldehyde. Therefore, we prepared a sodium alginate–chitosan nanocomposite as a nanocarrier of cinnamaldehyde, and we tested the effect of this encapsulated cinnamaldehyde on Aedes aegypti larvae. The nanocomposites/cinnamaldehyde formulations were characterised by Fourier transform infrared spectroscopy and nuclear magnetic resonance, which evidenced encapsulation. A ratio of 150:1 w/w nanocomposite/cinnamaldehyde induced the highest encapsulation efficiency of 95.25%, a loading capacity of 81.42%. This extended the cinnamaldehyde release by 28 h and controlled mosquito larvae.

Photocatalyst of hydroxyapatite–nano TiO2 (HAp-nTiO2) was prepared from phosphatation of calcined cockle (Anadara granosa) shells followed by dispersion of nano TiO2 powder into HAp precipitate and calcination at 400 °C for 2 h. The prepared material was characterized using X-ray diffraction, scanning electron microscope–energy dispersive X-ray spectrophotometry, gas sorption analysis, and UV-Vis diffuse reflectance spectrophotometry. The photocatalytic activity of the material was evaluated for methyl violet degradation over photocatalysis and photooxidation mechanism. The results showed that the homogeneous dispersion of TiO2 in the HAp-nTiO2 composite was achieved, as seen in the X-ray diffraction analysis, diffuse reflectance UV-Vis, and gas sorption analyses. The physicochemical and photocatalytic character of the composite exhibited the positive role of HAp as TiO2 support in enhancing the photocatalytic activity with a higher turnover number and reusability property than that of pure TiO2. It was also noted that the HAp-nTiO2 composite demonstrated rapid methyl violet degradation over photooxidation rather than by photocatalytic mechanism.

Andrographis paniculata Ness is one of the plants that is under explored and could contain potentially active substances to serve as an antimalarial. Structure investigation of major compounds that have responsibility for the antimalarial activity of Andrographis paniculata Ness’s n-hexane extract is very important so that it is known whether the antimalarial activity is synergistic or from the major compounds. Menthol and dioctyladipate as major component from n-hexane extract of Andrographis paniculata Ness have been succesfully isolated using simple and inexpensive methods. The solvent system used are n-hexane : ethyl acetate (10:1) and n-hexane: chloroform (10:3) consecutively either for column or preparative thin layer chromatography. FT-IR, 1H-NMR and GC-MS were used to determine the structure of compounds. The activity of n-hexane extract, menthol and dioctyladipate related to the inhibition of heme polymerization have been done comprehensively. The inhibition of heme polymerization activity of isolate compounds and n-hexane extract are classified to a good level (dioctyl adipate IC50 = 1.15 ± 0.41 mg/mL, menthol IC50 = 0.31 ± 0,01 mg/mL, and n-hexane extract IC50 = 0.07 ± 0.03 mg/mL) and potentially as antimalarial. From the IC50, the antimalarial activity of Andrographis paniculata Ness’s n-hexane extract is working synergistically, not by the major compounds.

This study investigates the potential of N-octyl chitosan derivatives, namely N-octyl-O-sulfate chitosan (NOOSC), N-octyl-N-succinyl chitosan (NONSC) and N-octyl-O-glycol chitosan (NOOGC) as amphiphilic carrier agents for atrazine in water-insoluble herbicide formulations. The N-octyl chitosan derivatives were characterised using several analytical instruments such as Fourier Transform Infrared (FTIR) Spectrometer, CHNS-O Elemental Analyser (CHNS-O), Transmission Electron Microscope (TEM), Thermogravimetric Analyser (TGA), Differential Scanning Calorimeter (DSC) and Fluorescence Spectrometer. The encapsulation of atrazine by N-octyl chitosan derivatives was studied using a High Performance Liquid Chromatography (HPLC). The FTIR spectra of N-octyl chitosan derivatives confirmed the presence of hydrophobic and hydrophilic groups on chitosan backbone. TEM images revealed that N-octyl chitosan derivatives have formed self-aggregates with a spherical shape. The CMC values for N-octyl chitosan derivatives were between 0.06 and 0.09 mg/mL. The encapsulation efficiency (EE) values for amphiphilic chitosan were greater than 90%. The release profiles showed different release behaviour of pure herbicide in solution as compared to atrazine-loaded N-octyl chitosan derivatives. Results suggest that the chitosan derivatives offer promising characteristics that enable them to act as effective carrier agents for atrazine. In conclusion, the application of N-octyl chitosan derivatives could reduce the use of organic solvents in herbicide formulations by 37.5%.

In the present study, gelatin–carboxymethyl cellulose blend film was synthesized, characterized and applied for the first time to preserve cherry tomatoes (Solanum lycopersicum var. cerasiforme) and grapes (Vitis vinifera). Gelatin (Gel) film forming solution was incorporated with carboxymethyl cellulose (CMC) at three volume per volume (Gel:CMC) ratios, namely 75:25, 50:50 and 25:75. CMC treatment has improved the transparency, tensile strength (TS), elongation at break (EAB), water vapor permeability and oxygen permeability of gelatin films. A pronounced effect was obtained for 25Gel:75CMC film. The TS and EAB values were increased from 25.98 MPa and 2.34% (100Gel:0CMC) to 37.54 MPa and 4.41% (25Gel:75CMC), respectively. A significant improvement in antimicrobial property of gelatin films against two food pathogens, namely Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was obtained in the presence of CMC. The effectiveness of gelatin–CMC blend films to extend the shelf life of agricultural products was evaluated in a 14-day preservation study. The gelatin–CMC films were successfully controlled the weight loss and browning index of the fruits up to 50.41% and 31.34%, respectively. Overall, gelatin–CMC film is an environmental friendly film for food preservation. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s13197-019-03809-3) contains supplementary material, which is available to authorized users.

In this study, the synthesis of ZnO/SiO2 nanocomposites using bamboo leaf ash (BLA) and tested their photocatalytic activity for rhodamine B decolorization have been conducted. The nanocomposites were prepared by the sol–gel reaction of zinc acetate dihydrate, which was used as a zinc oxide precursor, with silica gel obtained from the caustic extraction of BLA. The effect of the Zn content (5, 10, and 20 wt%) on the physicochemical characteristics and photocatalytic activity of the nanocomposites was investigated. The results of X-ray diffraction, scanning electron microscopy, gas sorption, and transmission electron microscopy characterization confirmed the mesoporous structure of the composites containing nanoflower-like ZnO (wurtzite) nanoparticles of 10–30 nm in size dispersed on the silica support. Further, the nanocomposites were confirmed to be composed of ZnO/SiO2 by X-ray photoelectron spectroscopy analysis. Meanwhile, diffuse-reflectance UV–visible spectrophotometry analysis of the nanocomposites revealed band gap energies of 3.38–3.39 eV. Of the tested nanocomposites, that containing 10 wt% Zn exhibited the highest decolorization efficiency (99%) and fastest decolorization rate. In addition, the degradation efficiencies were not reduced significantly after five repeated runs, demonstrating the reusability of the nanocomposite catalysts. Therefore, the ZnO/SiO2 nanocomposite obtained from BLA is a promising reusable photocatalyst for the degradation of dye-polluted water.

Rotenone is a hydrophobic organic compound with the excellent insecticidal property. However, its hydrophobicity and the short period of efficacy due to rapid degradation in the presence of UV light and air have limited its application as an insecticide. This study studied the effects of hydrophobic alkyl groups on encapsulation and controlled release of rotenone by amphiphilic chitosan derivatives namely, octyl glycol chitosan (OGC) and lauryl glycol chitosan (LGC) were assessed. The physical and chemical properties of OGC and LGC were characterized using Fourier Transform Infrared (FTIR) Spectrometer, CHNO Elemental Analyzer, UV-Visible Spectrophotometer, Fluorescence Spectrofluorometer, and Differential Scanning Calorimetry (DSC). The efficiency of OGC and LGC to encapsulate for rotenone in its micelles was determined by using a High-Performance Liquid Chromatography (HPLC). FTIR and CHNO elemental analyses confirmed the amphiphilic chitosan derivatives were successfully synthesized using the reverse micelles method. The finding from the solubility study shows that the addition of the glycol group to the chitosan backbone has enhanced chitosan’s solubility properties in neutral and basic media. OGC and LGC exhibited good affinity towards rotenone with an encapsulation efficiency of more than 90%. The in vitro release study showed that the OGC and LGC could control the release of rotenone from its micelles. This study demonstrates that OGC and LGC showed beneficial properties to be further developed as a potential carrier in the pesticide formulation.

Development of low-cost, sustainable and environmentally friendly biodiesel is a key focus in the energy industry worldwide. It is known that selecting suitable raw feedstock materials and optimising an efficient transesterification process are crucial in biodiesel production. Effective and realistic strategies are imperative in order to boost the quantity and quality of biodiesel production. In fact, scientists and researchers have put great effort to improve the market value of their biodiesel products. In recent years, the feasibilities of several raw materials as feedstocks to produce biodiesel have been assessed by researchers. These materials were reported able to produce biodiesel that met international standards, namely the American Society for Test and Materials D6751 and European Standard 14214. Although these biodiesel products have met the quality criteria, their fatty acid methyl ester (FAME) contents differ. This review focuses on optimum conditions (methanol/oil molar ratio, amount of catalyst, reaction temperature and reaction time) of transesterification process for biodiesel production from various feedstocks. The influence of these factors on FAME composition is also discussed. This review is beneficial to scientists working on biodiesel production particularly for the evolution of eco-friendly and low-cost biodiesel.

In this study, the effectiveness of lala clam (Orbicularia orbiculata) shell, a fishery waste, as an adsorbent for removal of Cd(II), Cu(II) and Pb(II) ions from contaminated water was evaluated by characterization and adsorption studies. The characterization study was performed using Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray (EDX) Spectroscopy and Fourier Transform Infrared (FTIR) Spectroscopy techniques. The effects of solution pH (pH 1.0 to 6.0), adsorbent dosage (0.125 to 0.750 g) and initial adsorbate concentration (10 to 200 mg/L) on adsorption capacity of lala clam shell were studied. The capability of lala clam shell to remove metal ions from aqueous solution was assessed in both single- and mix-metal systems. The adsorption equilibrium data were fitted to Freundlich and Langmuir isotherm models. At an optimum solution pH of 6.0 and initial metal ion concentration of 200 mg/L, the maximum adsorption capacity (Qmax) values of Cd(II), Cu(II) and Pb(II) ions were determined as 66.66, 64.94 and 100.00 mg/g, respectively. The removal performance of lala clam shell (63.80 to 93.79%) for metal ions from battery manufacturing wastewater was comparable to that of three commercial activated carbons derived from olive tree wood (73.01 to 94.83%), coconut shell (68.10 to 95.17%) and bamboo (69.33 to 94.48%), which are commonly used for water treatment in Libya, Malaysia and Indonesia, respectively. The results obtained from this study suggest that lala clam shell exhibits a great potential to be used as an effective alternative to expensive adsorbents for water treatment.

Biodiesel from insect larvae is an alternative to plant biodiesel, which have issues of using edible plants. On the contrary, insects can grow on waste. Although the conversion of larval lipids to biodiesel is known, characterisation of larval biodiesel is rarely reported. Here, black soldier fly larvae were cultivated for 20 days on kitchen waste. Larval lipids were extracted and converted to biodiesel by two-step transesterification. Analysis by optical polarisation microscopy from − 5 to + 15 °C showed tiny needle-like shaped crystals. Fourier transform infrared spectra of black soldier fly biodiesel revealed absorption bands at 1459 and 1435 cm−1 corresponding to methyl ester, the main functional group of biodiesel. Nuclear magnetic resonance (NMR) analysis confirmed the presence of methyl ester by showing peaks at 3.6 and 2.3 ppm by 1H NMR, and at 176 and 51.56 ppm by 13C NMR. Overall, our results confirm the successful conversion of black soldier fly larval lipid to biodiesel. This biodiesel met the American Society for Test and Materials D6751 and European Standard 14214.

In this study, an amphiphilic chitosan derivative namely N,N-dimethylhexadecyl carboxymethyl chitosan (DCMC) was synthesised and applied for the first time as a carrier agent for rotenone. The physical and chemical properties of DCMC were characterised by using Fourier Transform Infrared Spectrometer (FTIR), Proton Nuclear Magnetic Resonance Spectrometer ((1)H NMR), CHN-O Elemental Analyser, Thermogravimetric Analyser (TGA) and Differential Scanning Calorimeter (DSC). DCMC was soluble in acidic (except pH 4), neutral and basic media with percent of transmittance (%T) values ranged from 67.2 to 99.4%. The critical micelle concentration (CMC) was determined as 0.095mg/mL. Transmission Electron Microscopy (TEM) analysis confirmed that DCMC has formed self-aggregates and exhibited spherical shape with the size of 65.5-137.0nm. The encapsulation efficiency (EE) and loading capacity (LC) of DCMC micelles with different weight ratios (DCMC:rotenone; 5:1, 50:1 and 100:1) were determined by using High Performance Liquid Chromatography (HPLC). The weight ratio of 100:1 gave the best EE with the value of more than 95.0%. DCMC micelles performed an excellent ability to control the release of rotenone, of which 99.0% of rotenone was released within 48h. Overall, DCMC has several key features to be an effective carrier agent for pesticide formulations.

Layered double hydroxides and layered hydroxide salts have generated enormous excitement in the inorganic field due to their potential to act as versatile host materials in fabricating novel host–guest layered materials. The ability of the layered hydroxide anion exchanger to be incorporated with a wide range of guest ions enable them to be exploited in various applications related to pesticides. This review sums up the different methods of preparing layered hydroxide anion exchanger, summarises the types of anion intercalated into these layered hydroxide anion exchanger based on their respective systems, and elucidates their potential applications in pesticide-related fields.

Magnesium layered hydroxide (MLH) intercalated with anionic 3-(4-methoxyphenyl)propionic acid (MPP) was synthesised by a direct reaction method using magnesium oxide and MPP as precursors. A further coating of chitosan was applied on the external surface of MLH–MPP nanocomposite to form a new material, named MLH–MPP/chitosan nanocomposite. The XRD pattern showed an intense and sharp peak at basal spacing 18.9 A, proving that MPP anions were successfully intercalated into the interlayer gallery of MLH in a monolayer arrangement. The XRD pattern of the MLH–MPP/chitosan nanocomposite shows similar peaks with the MLH–MPP nanocomposite. The result was also supported by FTIR spectra and elemental analysis. TGA/DTG spectra showed that the thermal stabilities of the guest anion in the both nanocomposites were markedly enhanced. A controlled-release study of the MPP ion from the MLH–MPP/chitosan nanocomposite showed a slower release compared to MLH–MPP nanocomposite with an initial rapid release and slow r...

In this study, a two-step transesterification process was applied to convert crude BSF larval oil into biodiesel. The effects of methanol:oil (molar ratio), catalyst amount (weight %), reaction time (minutes) and temperature (°C) on biodiesel production were investigated. Central Composite Design (CCD) of Response Surface Methodology (RSM) was used to optimise experimental data obtained from these four variables. The prediction of biodiesel yield was made by employing a quadratic model, whereby the R2 values were greater than 0.99. Based on optimisation studies, a combination of an application of petroleum ether and reaction time of 6 hours was the best to extract crude larval oil with 47% of lipid yield. Meanwhile, methanol:oil molar ratio of 12:1, catalyst (NaOH) concentration of 1.0 weight %, a reaction time of 32 minutes and temperature of 60°C were required to obtain biodiesel with 96% of production yield from BSF crude larval oil. Both BSF crude larval oil and biodiesel were characterised using several analytical instruments such as Fourier Transform Infrared (FTIR) spectrometer and Gas Chromatography – Flame Ionisation Detector (GC-FID). Overall, findings from this study highlight the potential to produce eco-friendly biodiesel from BSF larvae reared on soya residue.

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.

The study on the removal of rhodamine B under ultrasonic-assisted oxidation or called as sonocatalytic oxidation using tin oxide-immobilized onto montmorillonite (SnO2/MMT) has been investigated. A hydrothermal synthesis was used for preparing the immobilized SnO2 nanoparticles into montmorillonite structure, and the as-synthesized material was characterized using X-ray diffraction, gas sorption analysis, UV–vis diffuse reflection spectroscopy (UV–vis diffuse reflectance spectroscopy), scanning electron microscopy, and transmission electron microscopy techniques. The kinetics study of the sonocatalytic-assisted oxidation was performed by the comparison with SnO2 and MMT, and in order to discover the kinetic characteristics of the sonocatalytic oxidation, varied condition such as the effect of initial concentration of rhodamine B, pH, the addition of H2O2 were examined. The proposed kinetic model revealed that the degradation obeys the apparent first-order rate kinetics. Refer to the dependence of the kinetics reaction to the initial concentration rhodamine B and H2O2 concentration, it is noted that the reaction fit with the Langmuir and Okitsu model suggesting that the sonocatalytic mechanism is influenced by active interface interaction for the cavitation and radical formation as the main operational parameters. pH of the solution directly influences the initial rate of the reaction as the effect of zeta potential of the surface. Reusability study revealed that the catalyst maintains the stability until 3 cycles utilization with the maximum degradation efficiency of ∼100 % under the condition of ultrasound frequency of 40 W, 68 kHz, catalyst dose of 0.5 g/L, and reaction time of 2 h.

This study involves the preparation of hematite/biochar (HBC) nanocomposite and its photocatalytic evaluation for methylene blue degradation. HBC material was synthesized based on carbonization of iron oxide precursor-treated Salacca skin powder. Characterization studies of the material were carried out using x-ray diffraction, scanning electron microscope-energy dispersive x-ray, transmission electron microscope, and gas sorption analysis. Dispersed Fe2O3 with sizes ranging from 20 to 50 nm in the nanocomposite were identified, showing a band gap energy of 2.21 eV. Results show that the material demonstrates suitable physicochemical performance for photocatalytic application. By varying the initial concentration of methylene blue, it is noted that the decolorization obeys pseudo-first-order kinetics and fits the Langmuir-Hinshelwood mechanism. The decolorization kinetics was observed to be at optimum level at pH 7, reaching this state with a catalyst dosage of 0.5 g/L. The performance of the photocatalyst was observed to be better with H2O2 addition, in which the decolorization efficiencies reach 99.9% for all varied initial concentrations with 1 h treatment.

In this work, chitosan, gelatin and methylcellulose films incorporated with tannic acid (TA) were synthesised, characterised and applied for the first time to preserve cherry tomatoes (Solanum lycopersicum var. cerasiforme) and grapes (Vitis vinifera). The addition of TA at 15% (w/w) increased the transparency value of biopolymer films. The highest increment of transparency value was obtained for MC-TA film, increased from 0.572 to 4.73 A/mm. Based on antimicrobial study, the addition of TA improved the antibacterial properties of biopolymers against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The ability of films to preserve both fruits was evaluated in a 14-day preservation study. The application of biopolymer films treated with TA has decreased the weight loss and browning index of fruits, as compared to control films. A significant reduction in the weight loss of cherry tomatoes wrapped with chitosan (from 21.3 to 19.6%), gelatin (from 22.1 to 15.5%) and methylcellulose (26.2 to 20.5%) films were obtained following TA treatment. Overall, results obtained from this study highlight the effects of TA on physiochemical properties of biopolymer films and their ability to preserve fruits.

The article reports on a MWCNT paste electrode modified with the fenchone diazine tetracarbonylmolybdenum(0) complex, and on its application to sensitive determination of Cu(II) by using square wave anodic stripping voltammetry. Under optimal conditions and at a typical working voltage of 33 mV (vs. Ag/AgCl), response is linearly related to the concentration of Cu(II) in the 0.1 nM to 1.0 μM range, and the limit of detection is 80 pM. The relative standard deviation [for n = 5 and at a 1.0 μM concentration of Cu(II)] is 3.6 %. Unlike Pb(II), the ions Ni(II), Mg(II), Cd(II), Co(II), Hg(II), and Zn(II) do not strongly interfere. Electrochemical impedance spectroscopy reveals a fast charge transfer at the electrode-solution interface. The method was applied to the analysis of Cu(II) in water samples, and the results agreed well with those obtained by ICP-OES.

Rotenone is an active ingredient that has been widely used as pesticide. However, rotenone is poorly soluble in water. Therefore, a water-soluble carrier is needed. Here, we synthesised, characterised and applied oleoyl-carboxymethyl chitosan for the first time as a carrier agent for rotenone. Oleoyl-carboxymethyl chitosan is soluble in acidic, neutral and basic media. The critical micelle concentration of oleoyl-carboxymethyl chitosan is 0.096 mg/mL. Oleoyl-carboxymethyl chitosan formed self-aggregates and exhibited spherical shape with the values of 35.5–66.4 nm. We studied the encapsulation efficiency and loading capacity of oleoyl-carboxymethyl chitosan micelles with different weight ratios of oleoyl-carboxymethyl chitosan to rotenone. We found an encapsulation efficiency of 97 % and a loading capacity of 0.97 % for oleoyl-carboxymethyl chitosan/rotenone 100:1 w/w. Oleoyl-carboxymethyl chitosan released 96.00 % of the rotenone loaded within 50 h. Overall, our findings show the feasibility of oleoyl-carboxymethyl chitosan as a novel water-solubilising agent for pesticide formulations.

For the first time, amorphous aluminium–copper (Al–Cu) alloy nanowires decorated with carbon spheres (CS) were synthesised from waste engine oil (WEO) as a starting material. The synthesis process was carried out in two-stage thermal chemical vapour deposition system under typical synthesis condition of 5.33 wt% ferrocene as catalyst, precursor and synthesis temperature of 450 and 700 °C, respectively. Metal contaminants of Al and Cu in WEO promote the growth of amorphous Al–Cu alloy nanowires and high carbon content in WEO undeniable promotes the growth of CS. Field emission scanning electron microscopy analysis showed that the amorphous Al–Cu alloy nanowires dimension was about 120 nm in diameter and a few micrometres in length, while the diameter of CS were a few hundred nanometre to micrometre-sized. X-ray diffraction pattern of amorphous Al–Cu alloy nanowires revealed the formation of different Al–Cu phases. This study offers a new and simple technique to synthesise amorphous Al–Cu alloy nanowires decorated with CS from waste material namely WEO. The newly produced nanomaterials open up potential application in energy storage devices.

In this study, electrochemical exfoliation method was adopted in the production of graphene oxide (GO). The electrolyte used was sodium dodecyl sulphate (SDS) aqueous solution at various concentrations from 0.001 to 1.0 M. The effect of SDS concentrations on the morphology of GO samples were characterized using field emission scanning electron microscopy (FESEM), energy dispersive X-ray, micro-Raman and UV-Vis spectroscopy. As evident by the FESEM analysis, the concentration of SDS does give effect to the GO obtained in this study. The lowest GO production is given by the lowest concentration of SDS used which is 0.001 M. However, in term of ID/IGratio, the sample prepared at 0.001 M has the lowest value (0.33) as compared to the sample prepared with highest SDS concentration of 1.0 M (ID/IG~1.12). Meanwhile, the presence of absorbance peaks in the range of 224-237 nm from UV-Vis spectra analysis were seen for the whole samples and this indicate the formation of GO.

For the first time, zinc oxide (ZnO) nanoflowers on ZnO nanorods were produced on carbon nanotubes (CNTs) synthesised from waste cooking palm oil precursor. First, CNTs were grown using a thermal chemical vapour deposition method. Next, ZnO nanostructures were deposited using the sonicated sol–gel immersion method and the prepared samples were characterised using electron microscopy, micro-Raman spectroscopy and X-ray diffraction. The field electron emission properties of the samples indicated that the ZnO nanoflowers grown on the CNTs had better emission performances than the pristine aligned ZnO nanorods. The resulting CNTs/ZnO nanocomposite had reasonable turn-on and threshold fields of 4.6 and 6.7 V/µm, which corresponded with the electric fields required to create current densities of 1.0 µA/cm 2 and 0.1 mA/cm 2 , respectively. This study shows the important roles of CNTs in ZnO nanoflowers growth and the abilities of CNTs to enhance ZnO emission properties.

Carbon nanotubes (CNTs) were successfully synthesized using waste cooking palm oil (WCPO) as precursor by modified double-stages thermal chemical vapor deposition set-up. The total amount of 30 ml WCPO precursor was consumed during the experiment with 5.33 wt% ferrocene as catalyst. Precursor volume of 2 ml was injected continuously for different time intervals of 5, 8, 10 and 12 minutes respectively. The effect of time interval between injections on the production of CNTs were systematically studied using field emission scanning electron microscopy, micro-Raman spectroscopy and current-voltage (I-V) measurement system. It was detected that the differences in time interval of injections resulted in different quality and diameter of CNTs produced. Sample produced at 10 minutes of time interval of injection gave the smallest tubes diameter in the range of 39.45-49.01 nm and good crystallinity of 0.69 ID/IG ratio. This sample also gave the best I-V characteristic with conductivity of 6.06 x 10-1 S/cm.

Zinc oxide/carbon nanotubes (ZnO/CNTs) nanocomposite has been widely studied in the last few years due to their remarkable properties and versatile applications. Various methods have been presented in order to enhance the excellent properties of ZnO/CNTs nanocomposite. Here we reviewed several synthesis methods including single- and multiple steps to fabricate the ZnO/CNTs nanocomposite and the potential application of the nanocomposite in field emission and solar cell devices.

Quasi-aligned carbon nanotubes (CNTs) were successfully synthesised for the first time using waste engine oil (WEO) as the carbon source via thermal chemical vapour deposition (TCVD). The high carbon content of WEO was believed to promote the growth of the quasi-aligned CNTs. The synthesis process was performed at precursor and synthesis temperatures of 500 and 750 °C, respectively, with a ferrocene catalyst concentration of 17.99 wt%. Typical characterisation methods were employed to examine the CNTs: electron microscopy, energy dispersive X-Ray, X-ray diffraction and micro-Raman spectroscopy. The ability of CNT samples to emit electrons was also investigated by field electron emission (FEE) analysis. Electron microscopy and micro-Raman analysis revealed a dense mixture of quasi-aligned single- and multi-walled CNTs with a moderate I D /I G ratio of 0.90. The overall diameters of the CNTs ranged from 18.0 to 29.8 nm, with the diameters of the single-walled CNTs estimated to be between 0.6 and 1.1 nm. The FEE results showed that the quasi-aligned CNTs synthesised from WEO exhibited reasonable turn-on and threshold fields of 4.1 and 7.2 V μm −1 , which corresponded to current densities of 0.1 and 1.0 μA cm −2 , respectively. This study highlights WEO as a new, cheap, abundant and easily available carbon source for quasi-aligned CNTs production with a potential application in electron emission devices.

Zn/Al layered double hydroxide (LDH) intercalated by an anionic phenoxyherbicide guest, 3-(4-methoxypheny) propionate (MPP) were prepared by ion-exchange method. Power XRD and FTIR shows that the MPP phenoxyherbicide were successfully intercalated into the LDH interlayer. The basal spacing for Zn/Al layered double hydroxide-3-(4-methoxyphenyl) propionate nanocomposite (LDH-MPP) was 18.7 Å - 20.5 Å for 0.015 M, 0.025 M, and 0.050 M of MPP, respectively. Thermal analysis shows that the thermal stability of MPP was improved by the intercalation into the LDH interlayer. The results were also supported by elemental analysis and the surface morphology of this nanocomposite.

A B S T R A C T The efficacy of coconut dregs residue, a by-product from coconut milk production factory, to adsorb Cu(II), Ni(II) and Pb(II) ions from aqueous solutions was investigated. The effects of experimental parameters such as solution pH, contact time and initial metal concentration on adsorption process were examined in batch experiments. The equilibrium data were best described by the Langmuir isotherm model, while the dynamical data followed the pseudo-second order kinetic model. The Freundlich constant (n) and separation factor (RL) values suggest that the metal ions were favourably adsorbed onto biosorbent. The affinity of the biosorbent for metal ion was in the order of Pb(II) > Cu(II) > Ni(II), both in single- and multi-metal systems. The characterisation studies were carried out using scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDX) and Fourier transform infrared spectrometer (FTIR). Complexation between metal ions and binding sites of the biosorbents was the main adsorption mechanism. Coconut dregs residue removed Cu(II) better than bamboo derived activated carbon, a commercial activated carbon, from electroplating effluent.

The performance of single-, double- and triple-chain anionic sulphosuccinate surfactants for dispersing multiwall carbon nanotubes (MWNCTs) in natural rubber latex (NR-latex) was studied using a range of techniques, including field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and Raman spectroscopy. The conductivities of the nanocomposites were also investigated using four-point probe measurements. Here, MWCNTs were efficiently dispersed in NR-latex with the aid of hyperbranched tri-chain sulphosuccinate anionic surfactants, specifically sodium 1,4-bis(neopentyloxy)-3-(neopentyloxycarbonyl)-1,4-dioxobutane-2-sulphonate (TC14). This paper highlights that TC14 performs much better than that of the commercially available surfactant sodium dodecyl sulphate (SDS), demonstrating how careful consideration of surfactant architecture leads to improved dispersibility of MWCNTs in NR-latex. The results should be of significant interest for improving nanowiring applications suitable for aerospace-based technology.

Thymol is a hydrophobic active ingredient and widely used as an alternative pesticide for pest control. However, due its low solubility in water, a water-soluble carrier is required in its formulation. Therefore in this study, the potential of an amphiphilic chitosan, namely lauryl glycol chitosan (LGC) as a carrier to encapsulate and release thymol was evaluated. The physical and chemical properties of LGC were characterized using Fourier Transform Infrared (FTIR) Spectrometer, Proton Nuclear Magnetic Resonance (1H NMR) Spectrometer, UV-Visible Spectrophotometer, Thermogravimetric Analyser (TGA) and Transmission Electron Microscope (TEM). A Fluorescence Spectrometer was used to determine the critical micelle concentration (CMC) value of LGC in aqueous solution. The encapsulation efficiency of LGC for thymol was determined by using a High Performance Liquid Chromatography (HPLC). The FTIR and 1H NMR analyses confirmed the structure of the synthesized LGC. It was noted that the addition of lauryl and glycol groups to the chitosan backbone has enhanced the solubility properties of chitosan in neutral and basic media. TEM observation confirmed that LGC could form self-aggregates in the solution with a spherical shape. The CMC value determined for LGC was 0.008 mg/mL. LGC exhibited good affinity towards thymol with an encapsulation efficiency of 58%. The findings from in vitro release study showed that the LGC could prolong the release of thymol from its micelles. Results from this study highlight that LGC possesses great characteristics to be further developed as a promising carrier in the pesticide formulation.

Dyes are stable organic pollutants that have been used in many industries and become one of the toxic contaminants for the environment. This research aimed at preparing a magnetic chitosan nanocomposite (MCN) as an effective adsorbent for cationic and anionic dye removal from aqueous solution. The MCN was synthesized using a coprecipitation method. The physical properties of MCN were characterized using elemental analysis (CHNO), vibrating sample magnetometry (VSM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and X-ray diffractometry (XRD). The results confirm that chitosan has been embedded on the surface of magnetic material and shows superparamagnetic properties behavior. A series of adsorption were conducted to investigate dosage of adsorbent, contact time and initial dye concentration to obtain the optimum condition of adsorption for both methylene blue (MB) and congo red (CR) dyes. The experimental equilibrium adsorption were then analyzed by the Langmuir and Freundlich isotherm models. Based on the correlation coefficient (R 2) values, the equilibrium adsorption data were fitted to the Langmuir isotherm model. The maximum adsorption capacity (q m) obtained from the Langmuir isotherm model for MB and CR onto MCN was 0.1308 and 1.8257 mg/g, respectively. Results highlight the potential of MCN application as an adsorbent for water contaminated by dyes.

The overall objective of present work was to prepare and use chitosan-titanium dioxide (CS-TiO2) nanocomposite as an adsorbent to remove two toxic dyes, namely Methyl Orange (MO) and Rhodamine B (RhB) from the aqueous solution. This work consists of two main parts, namely adsorption and characterization studies. For adsorption studies, several experimental parameters were studied such as the effect of initial concentration, solution pH and adsorbent dosage. Meanwile, Scanning Electron Microscope (SEM), Thermogravimetric Analyser (TGA), and X-ray Diffractometer (XRD) were used for characterization studies. The outcomes have shown that the equilibrium data correlated well to Freundlich isotherm model with adsorption capacity at equilibrium (K F) was determined as 1.608 mg/g for MO and 7.646 mg/g for RhB, respectively. Based on SEM analysis, the rod- and needle-like deposits on the surface of CS-TiO2 nanocomposite were disappeared following interaction with MO and RhB. There were cube-like deposits observed on the surface of CS-TiO2 nanocomposite after adsorption of MO, while a dense and uneven surface texture were observed after adsorption of RhB. From TGA analysis, CS had two degradation stages, while CS-TiO2 nanocomposite had three steps of decomposition. Furthermore, XRD results observed diffraction peaks for CSTiO2 at 2θ = 34.075°, 29.235°, 25.47° and 20.26°.

Two phenoxyherbicide nanocomposites, namely cloprop-layered double hydroxide and cloprop-zinc- layered hydroxide nanocomposites, have been synthesized by using co-precipitation and direct reaction method. PXRD pattern showed an expansion of interlayer spacing with the value of 21.0 A and 22.7 A for cloprop-layered double hydroxide and cloprop-zinc-layered hydroxide nanocomposite, respectively. It is evident from FTIR and elemental analyses that both nanocomposites were successfully intercalated between the interlayers of layered metal hydroxide. Controlled release of cloprop anion from interlayer of nanocomposites for both cloprop-layered double hydroxide and cloprop-zinc-layered hydroxide nanocomposite into phosphate solution was rapid initially and slow thereafter. The percentage of accumulated release of cloprop anion from cloprop-zinc-layered hydroxide nanocomposite was slightly higher than that from cloprop-layered double hydroxide nanocomposite. Kinetic behavior of cloprop release was governed by pseudo-second-order for cloprop-layered double hydroxide nanocomposite while parabolic diffusion for cloprop-zinc-layered hydroxide nanocomposite. Results from this study highlight the potential of both nanocomposites as capsulated material for controlled release of cloprop phenoxyherbicides anion.

The feasibility of durian tree sawdust (DTS), coconut coir (CC) and oil palm empty fruit bunch (EFB) as low-cost biosorbents for the removal of Cu(II), Pb(II) and Zn(II) ions from aqueous solutions was investigated. The effects of solution pH and initial metal concentration on adsorption capacity were examined in batch experiments. The affinity and the adsorption capacity of DTS, CC and EFB were evaluated. The adsorption behaviour of Cu(II), Pb(II) and Zn(II) ions onto DTS, CC and EFB was described using Freundlich and Langmuir isotherm models. The separation factor (RL) analysis suggests that the removal of metal ions onto three agricultural wastes studied was favourable. The maximum adsorption capacities (Q) estimated from the Langmuir isotherm model for Cu(II), Pb(II) and Zn(II) were 18.42, 20.37 and 22.78 mg/g for DTS, 18.38, 37.04 and 24.39 mg/g for CC, and 26.95, 37.59 and 21.19 mg/g for EFB, respectively. The characterisation studies were carried out using Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectrometer (EDX) and Fourier Transform Infrared Spectrometer (FTIR). The surface morphology of the biosorbents changed significantly following interaction with metal ions. The primary adsorption mechanism was complexation between metal ions and binding sites of biosorbents. Both hydroxyl and amine groups are the main binding sites in DTS, CC and EFB.

A pot experiment was conducted to evaluate the growth and metal accumulation in water spinach (Ipomoea aquatica) established on a 30-year old active firing range soil amended with chicken manure (CM) and coconut tree sawdust (CTS) at application rates of 0%, 1% and 3% (w/w). Both amendments increased biomass yield and reduced plant metal uptake. The bioconcentration factor (BCF) and transportation factor (TF) values of the metals were in the order of Zn > Cu > Pb. The ammonium acetate extractable metals in soil decreased significantly (p < 0.05) following CM and CTS treatments. It was estimated that the off-take value of Zn could be reduced from 10.01 kg/ha (zero treatment) to 6.60 kg/ha (CM 3% w/w) and 3.17 kg/ha (CTS 3% w/w). No toxicity symptoms were observed in water spinach over the pot experiment. Therefore, chicken manure and coconut tree sawdust are two promising agents for immobilizing heavy metals in contaminated land.

In the present study, the feasibility of amphiphilic chitosan derivatives, namely oleoyl carboxymethyl chitosan (OCMCs), N,N-dimethylhexadecyl carboxymethyl chitosan (DCMCs) and deoxycholic acid carboxymethyl chitosan (DACMCs) as carrier agents for rotenone in water-insoluble pesticide formulations was investigated. Fourier Transform Infrared (FTIR) Spectrometer, CHN-O Elemental Analyser (CHN-O) and Transmission Electron Microscope (TEM) were used to characterise amphiphilic chitosan derivatives. The critical micelle concentration (CMC) of amphiphilic chitosan derivatives was determined using a Fluorescence Spectrometer. A High Performance Liquid Chromatography (HPLC) was used to determine the ability of OCMCs, DCMCs and DACMCs to load and release rotenone in an in vitro system. Based on TEM analysis, results have shown that amphiphilic chitosan derivatives formed self-assembly and exhibited spherical shape. The CMC values determined for OCMCs, DCMCs and DACMCs were 0.093, 0.098 and 0.468 mg/mL, respectively. The encapsulation efficiency (EE) values for the materials were more than 97.0%, meanwhile the loading capacity (LC) values were greater than 0.90%. OCMCs, DCMCs and DACMCs micelles exhibited an excellent ability to control the release of rotenone, of which 90.0% of rotenone was released within 40 to 52 h. In conclusion, OCMCs, DCMCs and DACMCs possess several key features to act as effective carrier agents for rotenone. Overall, amphiphilic chitosan derivatives produced in this study were successfully increased the solubility of rotenone by 49.0 times higher than free rotenone.In the present study, the feasibility of amphiphilic chitosan derivatives, namely oleoyl carboxymethyl chitosan (OCMCs), N,N-dimethylhexadecyl carboxymethyl chitosan (DCMCs) and deoxycholic acid carboxymethyl chitosan (DACMCs) as carrier agents for rotenone in water-insoluble pesticide formulations was investigated. Fourier Transform Infrared (FTIR) Spectrometer, CHN-O Elemental Analyser (CHN-O) and Transmission Electron Microscope (TEM) were used to characterise amphiphilic chitosan derivatives. The critical micelle concentration (CMC) of amphiphilic chitosan derivatives was determined using a Fluorescence Spectrometer. A High Performance Liquid Chromatography (HPLC) was used to determine the ability of OCMCs, DCMCs and DACMCs to load and release rotenone in an in vitro system. Based on TEM analysis, results have shown that amphiphilic chitosan derivatives formed self-assembly and exhibited spherical shape. The CMC values determined for OCMCs, DCMCs and DACMCs were 0.093, 0.098 and 0.468 mg/mL, respectiv...

Wastewater originating from industrial effluents contains many types of pollutants including dyes. Anionic and cationic dyes are very toxic and they can cause several problems to aquatic system. In present study, razor clam shell was used as a potential adsorbent to remove two classes of dyes, namely anionic (Congo red, CR) and cationic (Rhodamine B, RB) dyes from aqueous solution. Batch adsorption experiments were performed to study the effects of three experimental parameters, namely solution pH, adsorbent dosage and initial dye concentration, on adsorption capacity of CR and RB onto razor clam shell. Results indicated that pH 2.0 was optimum pH for adsorbent to adsorb both CR and RB. At an initial concentration of 20 mg/L, the removal percentages of CR and RB were 97% and 38%, respectively. The Freundlich and Langmuir isotherm models were used to describe adsorption behaviour of CR and RB, as well as the relationship between adsorbent and adsorbate. The adsorption equilibrium data were well fitted to F...

Textile effluents are considered as potential sources of water pollution because they contain toxic dyes. In the present study, lala clam shell was used as an alternative low-cost adsorbent for the removal of two harmful dyes, namely methyl orange (MO) and methylene blue (MB) from aqueous solution. Batch adsorption studies were carried out by varying experimental parameters such as solution pH, initial concentration and adsorbent dosage. The optimum pH values for MO and MB removal were pH 2.0 and pH 8.0, respectively. At an initial MO and MB concentration of 20 mg/L, the maximum removal percentage of MO and MB were 18.9 % and 81.3 %, respectively. The adsorption equilibrium data were correlated with both Langmuir and Freundlich isotherm models. The biomass adsorbent was characterised using Field Emission Scanning Electron Microscope (FESEM) and Fourier Transform Infrared Spectrometer (FTIR). Results from this study suggest that lala clam shell, a fishery waste, can be beneficial for water treatment.

The effects of chitosan, a fishery waste-based material, and its derivative glutaraldehyde cross-linked chitosan (chitosan-GLA) on metal uptake by Lolium perenne (perennial ryegrass) and Brassica napus (rapeseed) were studied in a greenhouse pot experiment. Metal uptake by perennial ryegrass was highly dependent on the rate of addition of the chitosans. Low application rate (1% w/w) enhanced metal uptake, whereas 10% (w/w) addition decreased metal uptake. It was estimated that chitosan 1% (w/w) treatment could assist perennial ryegrass to remove approximately 3.2 kg Zn/ha and 0.29 kg Pb/ha. For rapeseed, metal uptake was decreased at all rates of application of chitosans. The ammonium acetate extractable metals in soil decreased following application of chitosans and plant growth.

The binding efficiency of chitosan samples for Ag(+), Cd(2+), Cu(2+), Pb(2+) and Zn(2+) has been evaluated in order to consider their application to remediate metal contaminated soil and water. The sorption behaviour of metal ions was assessed using a batch technique at different contact time and initial metal concentration with different background electrolytes. The kinetics followed a pseudo-second-order model, while the equilibrium data correlated well with the Freundlich and Langmuir isotherm models. For example, the maximum sorption capacity (Q) for chitosan was estimated as 1.93 mmol/g for Ag(+), 1.61 mmol/g for Cu(2+), 0.94 mmol/g for Zn(2+), 0.72 mmol/g for Cd(2+) and 0.64 mmol/g for Pb(2+). Covalent interaction between metal ions and functional groups (amino and hydroxyl) of the chitosans was the main binding mechanism. Ion exchange is not an important process. Chitosan and cross-linked chitosans were able to bind metal ions in the presence of K(+), Cl(-) and NO(3)(-). The nature of Cl(-) and NO(3)(-) ions did not affect Zn(2+) binding by the chitosans. Even at 11x dilution, the chitosans were able to retain metal ions on their surfaces.

In this study, [Ir(2,4-F2ppy)2(2-(1,2,4-triazol-1-yl)pyridine>)]PF6 (C1), [Ir(2,4-F2ppy)2(2-(2-(4-dimethylbenzyl)-1,2,4-triazol-1-yl)pyridine)]PF6 (C2) and [Ir(2,4-F2ppy)2(2(2-hexyl-1,2,4-triazol-1-yl)pyridine)]PF6 (C3) complexes were successfully synthesised by refluxing the mixture of dichloro-bridged iridium(III) dimer, [Ir(2,4-F2ppy)2(μ-Cl)]2 and corresponding triazolium salt containing N-heterocyclic carbene (NHC) as ancillary ligands. 1H NMR of all complexes display well-resolved signals between 10.00-5.00 ppm assign to proton at the aromatic region for penylpyridine and pyridyltriazole. Spectra of C2 and C3 also display signals at aliphatic region (singlets) between 0.80-1.50 ppm that proved the presence of methylbenzyl and hexyl substituent on the pyridyltriazole ring. In addition, IR analysis reported the presence of C=C and C=N stretching of pyridine at range 1570-1470cm−1 and C-H stretching of aromatic pyridine at 2990-3080cm−1. Besides, UV-Vis absorption data showed that the low-energy metal-to-ligand charge-transfer (MLCT) band in C2 (364 nm) is significantly blue-shifted compared to C1 (375 nm) and C3 (381 nm). Overall, this study reported the synthesis and spectroscopic study of phenylpyridine Ir(III) complexes with various types of pyridyltriazole (NHC ancillary ligands).

Lipid enhancement is important to reduce production cost thus increasing the commercial values of microalgal biofuel production. Physical stress such as temperature and light intensity are known to increase lipid productivity because these factors might affect the phase transition of lipid, macromolecule formation and physiochemical reactions of microalgae. In this study, the effect of light intensity and temperature on lipid productivity of Tetradesmus obliquus was studied. T.obliquus UPSI-JRM02 was cultured in BG11 media at different temperature range (25–40°C) and light intensity (4000–30000 lux), respectively, within 14 days of growth period. The highest lipid productivity was obtained at temperature and light intensity of 36°C and 23500 lux. At this condition, 27 mg/L/day of lipid productivity and 23% of total lipid was successfully produced. The result shows the possibility of increasing T.obliquus lipid productivity by giving physical stress to the cell.