Search

The efficiency of Azadirachta indica (neem leaves) to be used in medicine and consumer products is proven due to the bioactive compounds contains in the plant. The most effective solvent needs to explore to optimize the extract yield. In this study, two methods of extraction were applied, Soxhlet, and immersion techniques to study which method gives higher neem extract. Different solvents were used as an extraction medium, methanol, ethanol, ethyl acetate, and hexane. The physical properties and stability tests were observed after week 4 and week 8. The yield percentages collected from both methods were recorded. All crude oil of extract gave brown color and smelly with high viscosity of the solution. The sedimentation collected was less than 2 w/w% after 1500 rpm of centrifuging speed and 5 w/w% after 3000 rpm of speed. The pH study showed all extracts gave low acidic after week 4 (5.6–5.9) and became neutral after week 8 (7.0–7.2) to determine the stability of the extract. The maximum percentage of yield, 22.0% obtained from ethanol extraction in the immersion method and 21.5% from Soxhlet extraction, suggested ethanol enhanced the extract production. Distilled water was used in the immersion method to study the potential of the solvent since it is cost-effective and environmentally friendly. The extracted amount was lower than obtained from other solvents and the maximum yield attained from extraction at 90 °C. As conclusion, ethanol gave maximum yield at 90 °C of extraction.

Direct Ethanol Fuel Cells (DEFCs) structures compose membrane that separate anode and cathode. Membrane is vital structure, that play an essential role in facilitating electrochemical reaction. The crucial characteristics of an excellent membrane to be applied in DEFCs should posses high ionic conductivity. However, current membrane in DEFCS relatively has lower ionic conductivity with a high price. Membrane conductivity is obtained from the measurement of resistivity of the proton-conductive membrane against the flow of current. Ionic conductivity measured by electrochemical impedance spectroscopy (EIS) using electrochemical system. In this study, the Anion Exchange Membrane (AEM) using Methyllcellulose as host was fabricated using simple casting solution technique with KOH as doping salt and Polyetylene glycol as plasticizer. The effects of weight variations of KOH and Polyethylene glycol (PEG) were investigated on conductivity measurements of membrane. The optimal ratio of AEM using MC, KOH and PEG was performed via Central Composite Design (CCD) experiment. Based on the hierarchical agglomerative cluster analysis (HACA) approach, the results are grouped into their own clusters which shows the most reliable results. The optimum weight of plasticizers recorded is 1.5 g, 0.55 g, and 1.0 g for MC, KOH and PEG respectively yield the maximum conductivity which is 0.00025305 S/m. In summary, the findings of proper ratio weight of each compound are crucial to enhance the conductivity value.

Direct ethanol fuel cell (DEFC) are promising for portable power source due to ethanol non toxic, renewable and high energy density. DEFC is grouped according to the type of membrane used either acidic and alkaline. In this review, the development of acidic membrane and alkaline membrane of previous literature is presented including the commercial membranes. In addition to that, different types of polymeric and filler including organic and inorganic membrane is discussed. Membrane performance and behavior is determined from it's characterization covering variables such as water uptake, ion exchange capacity, ethanol permeability, conductivity and membrane morphology. Future membrane development is discussed towards to maximized the DEFC performance ,that will enable the technology entering the commercial market.

Nanocomposite films of PVA (polyvinyl alcohol) with GF(graphene flakes), GO (graphene oxide) and G(Graphite) as nanofillers have been synthesized. Nanocomposites were prepared to contain various weight amounts of nanofiller (0.3, 1, 1.5, 2 and 3%) within PVA matrix. The film is cast on a clean glass plate through the solution casting method and dried in the oven. Here a report of a simple and practical approach to synthesizing graphene-reinforced poly (vinyl alcohol) (PVA) composite films by incorporating other filler into PVA aqueous solution. Further, the investigation of thermal properties was used using thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). Thermal stability shows the best stability with the nanofillers content of 1% for G, GO and GF. Nanocomposites with an additional of 1% GF gives the highest thermal stability compared to 1% of G and GO.

Nowadays, the application of portable electronics devices such as smartphone, notebook and tablet playing important role in daily life. This portable electronic devices required portable powering sources such as battery. However, the current battery technology containing liquid electrolyte which is hazardous and harmful when leaking. Therefore, the major purpose of this study was to propose a new biodegradable, safe and low cost solid polymer electrolyte (SPEs) mainly from Methylcellulose (MC) doped Ammonium Nitrate (AN). The study was conducted by using casting method as it is the most appropriate technique due to its simplicity and low cost. Methylcellulose (MC) as the host was doped with different weight percentage (wt%)of Ammonium Nitrate (AN) to fabricate SPEs. The result shows the adding of AN onto MC was significantly enhanced the physical properties of SPEs. The loading of 2g MC with 25% AN (MC2_25AN) yield the highest conductivity at 3.5 × 10−7 Sm−1 at room temperature. Furthermore, the MC2_25AN poses a good stability with the lowest swelling rate. Therefore, the use of low cost and biodegradable MC and AN have a great potential to replace the hazardous electrolyte in electrochemical powering sources.

Azido-Terminated Poly(2-isopropyl-2-oxazoline)(N3-PIPOZ) was prepared and it was then functionalized onto reduced graphene oxide (rGO). rGO was prepared from the reduction of graphene oxide (GO) by using hydrazine. The exfoliation of GO was measured using UV-Vis Spectroscopy. As a result, covalent functionalized reduced graphene (rGO-PIPOZ) with good solubility was successfully produced using grafting-on technique. Fourier transform infrared (FTIR) and thermogavimetric analysis(TGA) results proved the attachment of PIPOZ macromolecules onto rGO. rGO-PIPOZ showed best solubility in methanol (MeOH). The production of rGO- PIPOZ can be facilitated to a broad range application of graphene such as in polymer nanocomposites and lithium ion batteries.

Heavy metals have become a serious pollutant in water as a result of its non-biodegradable and toxicity properties. In this research, banana peel was synthesized as bioadsorbent to remove heavy metals from contaminated water. The major problem associated with banana peel bioadsorbent is that the activated carbon produces from biomass materials possess insignificant adsorption capability compared to its commercial counterpart. Besides that, large quantity of banana peel wastes contributes to its significant disposal problem. Thus, the present work is expected to solve the problems of banana peel disposal by converting it into bioadsorbent. The objectives of this research are to synthesize banana peel bioadsorbent and to evaluate heavy metals adsorption performance of the banana peel bioadsorbent. The bioadsorbent were treated using KOH in its preparation. The materials then undergo characterization using FTIR and AAS. The carboxylic and hydroxyl functional groups were confirmed by FTIR. The maximum removal efficiency for Pb and Fe ions were 100% and 64% respectively. The comprehensive utilization of low-cost raw material as bioadsorbent in wastewater activities are highly suggested due to its facile processing, abundantly available and environmental friendly.

Polymer nanocomposites based on polylactic acid (PLA) and graphene (Gr) were blended via melt blending and solution mixing. The properties of hardness and melt flow index (MFI) were investigated with variables of Gr loading from 0.5–2.0 wt.% and the effect of poly(ethylene glycol) (PEG) as plasticizer. The PLA/Gr nanocomposites exhibited higher hardness compared with neat PLA for both methods of nanocomposites preparation which were due to stiffness effect from nanofiller. The loading of PEG in the PLA nanocomposites resulted in the slightly decreasing of hardness. The hardness of PLA and PLA nanocomposites obtained from melt blending were higher than hardness from solution mixing where 2.0 wt.% Gr loading in PLA exhibited maximum value which was 83.1 Shore D. The significant improvement on the MFI could be seen with plasticizer loading compared to unfillled PEG in PLA blends obtained from both methods. Again, the MFI values of PLA/Gr showed from melt blending were higher than exhibited from solution blending method. The highest MFI was 70.6 g/10 min, obtained from 0.5 wt.% Gr loading in PLA/PEG/Gr nanocomposite. The morphology study from Field Emission Scanning Electron Microscopy (FESEM) analysis confirmed the interfacial interaction and homogeneity of Gr in PLA in order to enhance the hardness and MFI properties as discussed above.

Nanocomposites are currently being used in a number of fields, and new applications are continuously being developed including mechanical and biomaterial devices, as well as various in solar and fuel cells applications. Generally, the synthesis of polymer nanocomposites are done using solution chemistry, and this may raise serious concerns regarding air and water pollutions. Immediately, the ‘green’ method using supercritical carbon dioxide (scCO2) has grabbed the attention of researchers who are responsible to synthesize polymer composites by non-hazardous routes. Extrusion processes would benefit from the use of scCO2 since the rationale of the extrusion process is to formulate, provide texture and shape molten polymers by forcing them through a die. ScCO2 has been used in several studies as a medium of clay dispersion in polymer matrix by providing a solvent-free fabrication route for nanocomposites. Furthermore, it has more favorable interactions with polymers compared to other inert gases and has the ability to be dissolve in large quantities. It acts as a plasticizer, which modifies viscosity and interfacial properties of the polymer drastically. In this paper, experimental and theoretical studies of solubility and viscosity of several polymer melts in clay are discussed in detail. The assistance of scCO2 in clay dispersion and as a foaming agent has been reviewed extensively.