The application of homogenous and heterogeneous catalysts for ethoxylation of lauric acid (LAc) with ethylene oxide (EO) was conducted in this study. Ethoxylation reaction of LAc with EO with the mole ratio 1:3 (LAc:EO) have been done at reaction temperature 130-135°C under 1.8 bar pressure to produce Ethoxylated Lauric Acid (LAc:3EO), a type of nonionic surfactant. This experiment showed that potassium tert-butoxide (tBuOK) as a base homogenous catalyst gave good selectivity and activity compared with potassium methoxide, potassium ethoxide and potassium butoxide. Studies on intercalation of hydrotalcite (HT) with tBuO- to form HTtBuO as solid base catalyst was conducted. Ethoxylation reaction using heterogenous catalyst based on intercalated of HT-tBuO gave lower activity compared with tBuOK as homogenous catalyst. This might be due to diffusion which occurred significantly in heterogenous catalyst compared with homogenous catalyst. Analysis of nonionic surfactant LAc:3EO using HTtBuO as a catalyst gave no undesired side product. Detail analysis of the reaction products using GC-Tof technique gave a mixture of ester of LAc:3EO and polyethylene glycol (PEG).
A modified controlled chemical co-precipitation of alkaline aqueous ferrous and ferric salt solution at pH 8 with continuous addition of ammonia solution 25% under a degassed atmosphere was performed to synthesis magnetite (Fe3O4) nanoparticles. Formation of magnetite nanoparticles was conducted by adjusting the ferric to ferrous ions in the ratio of 1:1, 1:2 and 2:1. Further investigation on the surfactant-coated magnetite nanoparticles by using 8% surfactant sodium dodecyl sulphate (SDS) was also studied. The synthesized magnetite nanoparticles were characterized by Transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray diffractometer (XRD). TEM results shows that magnetite nanoparticles which were synthesized with ferric/ferrous ratio 2:1 are in sphere shape and have the smallest particle size distribution range which is about 12-17 nm. The particles size distribution range of coated magnetite was decreased to 11-15 nm after coated with 8% surfactant SDS. XPS results indicated that the produced magnetite nanoparticles consisted of elemental iron and oxygen at 72.76% and 22.27% respectively. The phase and face-centered cubic structure of magnetite nanoparticle was also confirmed by XRD. Magnetite nanoparticle synthesized with ferric to ferrous ratio of 2:1 and coated with 8% surfactant SDS shows the best crystallinity among all samples with particle distribution size range from 11-15 nm.
The scarcity of land based oil reserves has necessitated the exploration of off shore oil. This exploration is often carried out in pristine waters and the use of green chemicals is essential to reduce environmental degradation. In the recovery of oil and gas from rocky formations, well bore fluids such as packer fluids, fracturing fluids, conformance and permeability control fluids are extensively employed. Potassium oleate as viscoelastic surfactants gives a low partition coefficient when in contact with hydrocarbon. Bromination of the oleate chain has been shown in this work to increase the partition coefficient and still maintaining its viscoelasticity. The partition coefficient increased to ca 8% compared to negligible for potassium oleate. A gel was formed when a 20% solution of potasssium 9-bromo stearate was mixed with 8% KCl. Contacting this gel with hydrocarbon resulted in a loss of viscosity due to the improved solubility of the brominated compound in hydrocarbon. This facilitates the removal of the surfactants after its use as a fracturing fluid. The viscoelastic properties were demonstrated using a Bohlin rheometer. The graph of viscosity vs shear rate shows at first a shear rate independence up to a shear rate of 0.2 s-1 and then falling with shear rate typical of a viscoelastic fluid. The zero shear viscosity η0 varied from 18 Pa s to 220 Pa s whilst the shear viscosity at 100 s-1 ranged from 0.16 Pa s to 1.5 Pa s for surfactant concentration from 5 to 20%.
An efficient analytical technique capable of analyzing three most common phosphodiesterase-5 (PDE5) inhibitors (vardenafil, sildenafil and tadalafil) simultaneously in premix coffee was developed. Sample extractions using either acetonitrile or methanol with two different extraction techniques (with and without evaporation steps) were evaluated. Identification and quantitation was conducted by high performance liquid chromatography with photo-diode-array (HPLC-DAD) at different wavelengths; 230 nm, 245 nm and 290 nm; and by time of flight mass spectrometry (LC-MS-TOF). Extraction with acetonitrile (without evaporation with nitrogen) showed recovery ranging from 105% to 113% (± <10%) for HPLC-DAD at 245 nm and 93% to 102% (± <2.5%) for LC-MS-TOF. Chromatogram separation was best achieved with mobile phase consisted of water (0.1% formic acid) and acetonitrile (0.1% formic acid) with gradient elution within 20 min. Thus, the results indicated that extraction using acetonitrile without evaporation step was the most efficient technique for determination of PDE5 inhibitors in premix coffee.
Rheological properties of highly concentrated oil-in-water (O/W) emulsions (HCEs), formed by mixing palm-based nonionic surfactant, C12E6 (HLB = 11.7, CMC = 25μM), water and olive oil volume fraction ≥78vol% were investigated. Samples with lower oil volume fraction (<85%) and surfactant concentration (<8%) exhibited polydispersity of broader droplet size distribution (DSD). In contrast, samples with higher oil volume fraction (>85%) and surfactant concentration (>8%) displayed monodispersity of narrower DSD. The average droplet size decreased with increasing oil volume fraction and surfactant concentration. All frequency sweep experiments exhibited higher G’ than G”, representing the predominantly elastic nature of HCEs. The crossover of the ascendant and descendant flow curves of HCEs with higher oil volume fraction (>85%) and surfactant concentration (>8%) implied a structural build-up that could give rise to very high stability. The high stability was confirmed through accelerated stability test at 40oC for three months.
This paper reports on structural, optical transmittance and electrical properties of fluorine-doped tin oxide (FTO) thin films deposited using an inkjet printer. The FTO ink was synthesized from a mixture of tin chloride pentahydrate (SnCl4.5H2O) and ammonium fluoride (NH4F) solutions. The thin films were deposited on glass substrates at ambient temperature or heated at 40oC and 60oC. The surface electronic state and the elemental composition of the thin films were analyzed using XPS spectroscopy. The spectra of the FTO thin films revealed that tin, oxygen, fluoride and carbon were present in the samples. The signals corresponding to Sn 3d5/2, O1s, and F1s were found at 486.6 eV, 530.5 eV and 684.5 eV, respectively. XRD analysis showed that the FTO films were in the form of crystalline with cassiterite shape. The optical and electrical properties of the films were affected by the deposition temperatures. It was observed the film deposited at 40oC has the optimum optical transmittance and sheet resistivity which were 91%T and 16 Ω/, respectively.
Synthesis of new lubricants nowadays is increasing to improve the lubricity properties and the quality of lubricant. In
the current study, eight diesters with different chemical structures were tested in terms of their suitability as lubricants.
The esterification reaction was carried out using Dean-Stark distillation method with some modification. Fourier
transformation infra-red (FTIR), proton and carbon nuclear magnetic resonance (1
H-NMR and 13C-NMR), were used to
verify the chemical structure of the diesters. The results showed that the dioleyl pimelate (DOlP), dioleyl adipate (DOlA),
dioleyl glutarate (DOlG), and dioleyl succinate (DOlSuc) showed good low temperature properties with pour point values
at -10, -12, -16 and -20°C, respectively. The dioleyl dodecanedioate (DOlD) indicated remarkable flash point value at
305°C and had slightly high oxidative stability temperature (OT) at 183°C. The flash point increased with the number of
carbons for dicarboxylic acid used, while oxidative stability was affected by the unsaturated of oleyl alcohol. Tribological
study showed that the diesters were non-Newtonian except DOlD, which was Newtonian fluid. All the diesters were found
to be boundary lubricants with low coefficients of friction (COF). Overall, the results indicated that all the diesters studied
can be used as lubricating base oils.
A qualitative analysis of the individual compounds in Litsea fulva (locally known as ‘Medang’) essential oils was performed by comprehensive two-dimensional gas chromatography (GC × GC) coupled with time-of-flight mass spectrometer (TOF/MS) for the identification of the resolved peaks. Litsea fulva essential oil was found to contain 98 identifiable peaks with 32 compounds were identified with good matches. These compounds identified included 30 hydrocarbons, 22 alcohols, five acids, 16 ketones, five aldehydes, 12 esters, six ethers and two other compounds. The L. fulva leaf oil contained alcohols and ethers, with 34.09% and 24.38%, respectively. The major components of these oils were cis-Z-α-bisabolene epoxide (9.51%), trans-Z-α-bisabolene epoxide (8.36%), C13H20O2 (7.39%), longipinocarvone (5.68%), τ-Cadinol (4.24%), C15H24O (4.98%) and α-cadinol (3.95%). The study also showed that the comprehensive two-dimensional gas chromatography (GC × GC) is a better and more powerful separation tool in GC and an identification tool for analyzing complex volatile oils compared with the one-dimensional GC.
Nano sized copper sulfide, iron sulfide and molybdenum sulfide were successfully synthesised via a simple hydrothermal method. Sodium thiosulfate pentahydrate (Na2S2O3×5H2O) and hydroxylamine sulfate ((H3NO)2×H2SO4) were used as the starting materials and reacted with the transition metal source at 200oC for 90 min. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and Fourier transform infrared spectroscopy (FTIR). Spherical shape CuS and FeS2 nanoparticles with high crystallinity were successfully produced. The transmission electron micrographs revealed the well-dispersibility of the produced nanoparticles. Scanning electron micrograph showed the MoS2 nanoparticles possessed a spherical shape with sheet-like structure covering on the outer surface of the particles.
Chemical structure of treated and untreated Aciplex membrane has been studied by X-ray Photoelectron Spectroscopy (XPS). Survey spectra showed that both membrane surfaces consist of Fluorine, Carbon, Oxygen, Sulphur and trace of Titanium. Binding energies for the elements are (C1s at 290.6 eV, F1s at 687.5 eV, O1s at 531.3 eV, S2P at 168.1 eV and Ti2P at 454.4 eV). Analysis of narrow scan XPS-spectra of each element demonstrate the presence of (-CF, -CF2, CF3, C-O-C and SO-3) groups, which are in agreement with the structural formula as disclosed by the manufacturer. There is no significant change in chemical states of untreated and treated membrane, which reflect its stability to treatment conditions.
Struktur kimia Aciplex membran yang sudah dibersihkan dan yang belum dibersihkan telah dikaji menggunakan Spektroskopi Fotoelektron Sinaran-X (XPS). Spektra yang telah ditinjau menunjukkan bahawa kedua-dua permukaan membran mengandungi Florin, Karbon, Oksigen, Sulfur dan sedikit Titanium. Tenaga ikatan bagi unsur-unsur tersebut adalah (C1s pada 290.6 eV, F1s pada 687.5 eV. O1s pada 531.3 eV, S2P pada 168.2 eV dan Ti2P pada 454.4 eV). Analisis imbasan kecil spektra-xps bagi setiap unsur menunjukkan kehadiran kilmpulan (-CF, - CF2, CF3, C-O-C dan SO-3) yang bertepatan dengan formula struktur dari pihak pembekal. Tiada terdapat perubahan nyata berhubung dengan keadaan kimia membran yang sudah dibersihkan dan yang belum dibersihkan yang menggambarkan kestabilannya terhadap keadaan pembersihan.
Kajian mengenai penghasilan estolida berasaskan kepada asid risinoleik dan asid oleik telah dilakukan. Asid polihetero, asid 12-fosfotungstik dan asid silikotungstik telah digunakan sebagai mangkin dan tindak balas dilakukan pada suhu 60 atau 90ºC, selama 10 atau 24 jam. Nisbah mol antara asid risinoleik dan asid oleik ialah 2:1 dan peratus berat mangkin terhadap reaktan adalah 5%. Spektrum FTIR produk estolida telah dibandingkan dengan produk tindak balas yang menggunakan mangkin homogen asid perklorik. Pembentukan estolida ditunjukkan dengan kehadiran tiga puncak baru pada 1733 cm-1 untuk kumpulan berfungsi C=O ester, 967 cm-1 untuk -CH=CH- trans dan 1177 cm-1 untuk C-O-C. Spektrum FTIR yang serupa juga telah diperoleh untuk produk menggunakan mangkin homogen asid perklorik. Analisis LC-MS menunjukkan terbentuk tiga puncak baru monoestolida pada masa penahanan (Rt) 8.6 (m/z 577), 10.2 (m/z 559) dan 12.1 minit (m/z 561). Hasil kajian menunjukkan tindak balas kondensasi antara oleik-risinoleik dengan menggunakan asid perklorik, pepejal asid silikotungstik dan asid fosfotungstik sebagai mangkin berjaya menghasilkan estolida masing-masing dengan peratus hasil 70.2, 70.0 dan 60.8%.
Struktur-nano TiO2 dengan pelbagai saiz dan bentuk telah disintesis melalui kaedah hidrotermal menggunakan serbuk nanozarah TiO2 sebagai prekursor. Sistem hidrotermal yang mudah, murah dan bebas templet pada suhu rawatan 180ºC, pengaruh medium alkali dengan penambahan NaOH dan KOH ke atas saiz, morfologi dan sifat fotovoltaik struktur-nano TiO2 telah dikaji. Sampel telah diperincikan oleh mikroskopi elektron transmisi (TEM), analisis penyebaran tenaga sinar-x (EDAX) manakala keupayaan fotovoltaik sel suria sensitif pewarna (DSSC) diukur menggunakan Gamry Potentiostat Series G-300. Hasil kajian dengan menggunakan agen alkali yang berlainan (NaOH dan KOH) jelas mempengaruhi morfologi TiO2 dan sel suria sensitif pewarna yang terdiri daripada struktur nanorod TiO2 menunjukkan keupayaan terbaik dengan voltan litar terbuka (Voc) sebanyak 416.8 mV, ketumpatan arus litar terbuka (Jsc) sebanyak 0.169 mA/cm2 dan kecekapan penukaran (η) sebanyak 0.0232% di bawah iluminasi lampu xenon AM 1.5.