Azlan Kamari

Preparation of multiwall carbon nanotubes (MWCNTs) stabilised by highly branched hydrocarbon surfactants and dispersed in natural rubber latex nanocomposites

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.

A review of materials used as carrier agents in pesticide formulations

Development of environmentally-friendly pesticides for sustainable agriculture is a key focus in the agrochemical industry. Identifying novel active ingredients and improving the delivery system of a pesticide are the main challenges in developing new pesticides. Strategies for the control of delivery systems for slow and sustained release of agrochemicals are of great interest to environmental scientists. In this context, the selection of materials to be used as carrier agents in pesticide formulations is crucial. In recent years, the efficacy of several materials for agrochemical formulations has been evaluated by researchers. These materials have unique properties, such as being biodegradable and biocompatible, and having low toxicity and involving a simple preparation process. This review summarises recent applications of various materials in pesticide formulations. The application of the materials can effectively encapsulate or bind the pesticide’s active ingredients in the material’s matrix with a sustained release profile and slow mobility in soil. This review also discusses some issues and concerns that are faced in formulating pesticide products.

N,N-dimethylhexadecyl carboxymethyl chitosan as a potential carrier agent for rotenone

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.

Synthesis and Characterization of Layered Double Hydroxide-3-(4-Methoxyphenyl) Propionate Nanocomposite

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.

Layered hydroxide anion exchanger and their applications related to pesticides: a brief review

Abstract 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.

Assessment of heavy metals in water, sediment, Anabas testudineus and Eichhornia crassipes in a former mining pond in Perak, Malaysia

ABSTRACT The concentrations of Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sn and Zn were analysed in water, sediment, muscle of climbing perch fish (Anabas testudineus), and tissue of water hyacinth plants (Eichhornia crassipes) collected from a former tin-mining pond in Perak, Malaysia. The monitoring was performed during the minimum and maximum rainfall periods. The concentrations of As, Cr, Fe, Ni, Pb and Zn in water exceeded the permissible limits set by the Interim National Water Quality Standards for Malaysia (INWQS). The risk index (RI) values determined for As, Cd, Cr, Cu, Hg, Pb and Zn in sediment presented a low degree of ecological risk. The order of the top three heavy metals measured in fish muscle was Zn > Fe > Al. The estimated daily intake (EDI) of As and Cr exceeded the allowable limits in both rainfall periods. The bioconcentration factor (BCF) and translocation factor (TF) values of Zn in water hyacinth were 24.865 and 3.214, respectively. The concentrations of Cu and Zn in the plant tissue were significantly correlated (p < .05) with the concentrations of heavy metals in water. Overall, climbing perch and water hyacinth are excellent bioindicators of environmental impacts on water bodies.

Combination Effect of Temperature and Light Intensity on Lipid Productivity of Tetradesmus obliquus

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.

Chitosan, gelatin and methylcellulose films incorporated with tannic acid for food packaging

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.

Active biopolymer film based on carboxymethyl cellulose and ascorbic acid for food preservation

In the present study, an active biopolymer film based on carboxymethyl cellulose (CMC) and ascorbic acid (AA) was synthesised at an incorporation rate of 15% (w/w). Several analytical instruments such as Fourier Transform Infrared Spectrometer (FTIR), Thermogravimetry Analyser (TGA), UV-Visible Spectrophotometer (UV-Vis), Scanning Electron Microscope (SEM) and Universal Testing Machine were used to characterise the physical and chemical properties of CMC-AA film. The addition of AA significantly reduced elongation at break (322%) and tensile strength (10 MPa) of CMC-AA film. However, CMC-AA film shows a better antimicrobial property against two bacteria, namely Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) as compared to CMC film. The CMC-AA film was able to preserve cherry tomato with low weight loss and browning index. Overall, results from this study highlight the feasibility of CSAA film for food preservation.In the present study, an active biopolymer film based on carboxymethyl cellulose (CMC) and ascorbic acid (AA) was synthesised at an incorporation rate of 15% (w/w). Several analytical instruments such as Fourier Transform Infrared Spectrometer (FTIR), Thermogravimetry Analyser (TGA), UV-Visible Spectrophotometer (UV-Vis), Scanning Electron Microscope (SEM) and Universal Testing Machine were used to characterise the physical and chemical properties of CMC-AA film. The addition of AA significantly reduced elongation at break (322%) and tensile strength (10 MPa) of CMC-AA film. However, CMC-AA film shows a better antimicrobial property against two bacteria, namely Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) as compared to CMC film. The CMC-AA film was able to preserve cherry tomato with low weight loss and browning index. Overall, results from this study highlight the feasibility of CSAA film for food preservation.

HEAVY METALS AND GAMMA RADIOACTIVITY BIOACCUMULATIONIN Artemisia absinthium L. GROWN ON A WASTE DUMP

In the current context of industrialization, chemical and radioactive pollution is a concern for environmental protection and interference with human health. Care for environmental protection also includes vegetation that grows spontaneously in potentially contaminated places, thus avoiding illness among the population if consumed. The study area is located at 4.5km SSE from downtown Bacău City, Romania and is the result of the manufacture of H3PO4 through the wet method. In this study, the concentrations of cadmium (Cd), lead (Pb), and copper (Cu) in soil, and in Artemisia absinthium L. (root and aerial part) medicinal plant that grows spontaneously in a polluted area, respectively the phosphogypsum landfill from Bacău, were evaluated for two consecutive years, 2014 and 2015. The main purpose of this paper is to investigate the level of bioaccumulation in plants and soil concentrations immediately after definitive ending of the commercial activity of Amurco SA Bacău located in the southern industrial area of the city and 10 years after ending of the dumping of the phosphogypsum storage. The obtained results were compared with the reference values according to the legislation on environmental pollution assessment. The average values obtained for soil Cd concentration are close to the normal values for samples taken from the phosphogypsum landfill, respectively 1 mg/kg in both studied years. However, some values for Cd in the soil were above the normal value, respectively 1.227 mg/kg in 2014 and 2.665 mg/kg in 2015. We note that in 2015, unlike in 2014, thus evidencing the effect of accumulation over time, the presence of values above the normal value also in the case of Cd in the soil (33.034 mg/kg) and in the case of Pb in the soil (34.117 mg/kg). The concentration of heavy metals (Cu, Pb and Cd) in the plant material harvested in 2014 and 2015 has exceeded the maximum concentration recommended by the Codex Alimentarius Commission (CAC) for most samples. Also, the values for γ radioactivity bioaccumulation factors are up to four times higher in the roots than in the aerial parts. In terms of biometric parameters, there was observed a strong direct correlation between the length of the aerial parts and level of gamma radioactivity in soil samples at both depths. The results registered for the plants grown on the top of the landfill show that the high values of heavy metals bioaccumulation degree from the aerial parts can be caused by adsorption of particles from the air. Thus, it can be concluded that even if the influence of the phosphogypsum landfill is only local, a monitoring program of aerial transport is needed.