Molecular Dynamics Simulation of Wetting Behavior: Contact Angle Dependency on Water Potential Models

The underlying principle of surface wettability has obtained great attentions for the development of novel functional surfaces. Molecular dynamics simulations has been widely utilized to obtain molecular-level details of surface wettability that is commonly quantified in term of contact angle of a liquid droplet on the surface. In this work, the sensitivity of contact angle calculation at various degrees of surface hydrophilicity to the adopted potential models of water: SPC/E, TIP4P, and TIP5P, is investigated. The simulation cell consists of a water droplet on a structureless surface whose hydrophilicity is modified by introducing a scaling factor to the water-surface interaction parameter. The simulation shows that the differences in contact angle described by the potential models are systematic and become more visible with the increase of the surface hydrophilicity. An alternative method to compute a contact angle based on the height of center-of-mass of the droplet is also evaluated, and the resulting contact angles are generally larger than those determined from the liquid-gas interfacial line.

Preparation and Characterization of Curcumin Nanoemulsion in Olive Oil-Tween 80 System using Wet Ball Milling Method

Nanoemulsion has been developed as a drug delivery system which increases bioavailability and effectiveness of curcumin. Many methods and formulations have been applied in order to fabricate the most efficient nanoemulsion system to deliver curcumin. Wet ball milling is a simple technique to grind solids like powder to produce nano emulsion. On the other hand, a combination of olive oil and curcumin in Mediterranian Diet shows a promising anticancer activity. This research aims to elaborate the preparation and characterization of curcumin nanoemulsion in olive oil-Tween 80 system with wet ball milling method. It is expected that the procedure yields a combination of curcumin and olive oil in nanoemulsion system with simple preparation. This research uses curcumin as active compound, olive oil as solvent for curcumin, Tween 80 as stabilizer, and water as dispersing agent. Particle size and polydispersity index are determined using Dynamic Light Scattering technique. The results show that the best milling time is 8 hours to produce nanoemulsion that has diameter of 303 nm and polidispersity index of 0.29. Nanoemulsion system is stable for 60 days storage at 4 oC and 25 oC. The maximum curcumin mass that can be loaded in the system while maintaining particle size in nanoemulsion range is 300 mg.

Effects of Montmorillonite and Cane Sugar Composition on The Properties of Montmorillonite-Carbon Sulfonate Catalyst

The influence of montmorillonite and cane sugar mixture with composition of 1:3, 1:2, 1:1, 2:1, and 3:1 to the characteristics of the synthesized montmorillonite-carbon sulfonate composite catalyst had been investigated. The mixture of montmorillonite and cane sugar was carbonized at 400 oC for 15 hours and then sulfonated using sulfuric acid at 175 oC for 15 hours. The presence of sulfonate group was detected using FT-IR and the surface topology of the catalyst was characterized using SEM-EDX. FT-IR spectra showed the existence of sulfonate group at wave number of 1095 cm-1. SEM-EDX analysis showed that the catalyst with the montmorillonite and cane sugar ratio of 1:2 consisted of 1.06% sulfur. The catalyst activity was examined using an esterification reaction between acetic acid and ethanol, and the reaction products were characterized using GC-MS. The chromatogram peak at m/z = 88 confirmed that the product was ethyl acetate. Catalyst with the montmorillonite and cane sugar ratio of 1:2 was shown to have the highest acidity and gave the highest esterification product with 76.97% conversion.

Synthesis and Application of Na2O/ZrO2 Nanocomposite for Microwave-assisted Transesterification of Castor Oil

Transesterification reaction of castor oil catalyzed by Na2O/ZrO2 to produce biodiesel has been investigated. The catalyst was made by activating the ZrO2 with 98\% NaOH 5 M, dried in oven for 24 hours, and followed by calcination in a muffle furnace at 500 oC for 5 hours. XRD analysis shows that the catalyst has typical peaks at 2? = 38.32o, 33.19o, and 54.97o. The activation of the catalyst led to an increase of wt% of O and Na, but reduce the wt% of Zr. Transesterification of castor oil was carried out by varying the catalyst composition(w/w%) to determine its optimum conversion into product. The products were analyzed by GC-MS to determine the content and composition of the compounds, IR Spectroscopy to identify the functional group of the product, and ASTM analysis method to compare the quality of the product to the standard. The transesterification of castor oil was found to be optimum at 4% catalyst with biodiesel yield of 57.02%. However, the highest yield of methyl ester of ricinoleic acid, at 89.72%, was obtained using 2% catalyst (w/w%).

Synthesis and Application of Nanolayered and Nanoporous Materials

Nanoscale materials are currently an attractive research subject because their properties are in contrast to their macroscopic counterparts. An inert material, such as bulk platinum metal for example, is known to exhibit a catalytic properties when its size is reduced into nanoscale. A stable material can become flammable or combustible, such as aluminum, and isolator material can become a conductor. Many attractive quantum phenomena also arise from reducing a material size into nanoscale dimensions. This review article discusses the concept, synthesis, and characterization of organic and inorganic nanolayered and nanoporous materials; and their application to catalysis and adsorption processes. Past achievements and future perspectives in the field of nanomaterial researches will be discussed as well. Furthermore, in the era of green chemistry, nanomaterials with all their derivatives are also required to have sustainable characteristics, such as biodegradable and renewable; which emphasizes that the development of nanomaterials in the framework of green chemistry should always be a priority. Through the synthesis of novel and functional nanomaterials using natural and local-based materials around us that are environmentally friendly and relatively easy to be obtained, our goal toward the inheritance of a greener world for the future generations is not an impossible dream.