The adsorption of CO at polycrystalline copper surface was investigated spectroscopically. It was found that CO adsorbed as a linear adsorbed CO, Cu-COL and was a dominant species on copper surface at low CO concentration. A Cu-COL was electrochemically converted to a bridge bonded CO, Cu-COB at a high CO concentration condition. Increasing the CO surface coverage, qCO will increase the formation of adsorbed bridge bonded CO. A nitrogen gas purging treatment was used to examine the stability of an adsorbed CO through the evacuation process. The result showed that Cu-COB remained intact while Cu-COL was completely removed from the copper surface. It suggests that Cu-COL may involve in a weak bonding to a copper surface such as in a physisorbed interaction, while Cu-COB consists much stronger bonding such as a chemisorbed interaction. The N2 purging treatment also gave an additional prove that Cu-COB was partly converted to Cu(I)-CO at anodic potential regions.
Kajian pengoptimuman tindak balas pengepoksidaan minyak sawit olein (POo) dengan menggunakan mangkin asid performik (HCOOOH) telah dijalankan. Kesan tindak balas terhadap nisbah kepekatan HCOOH : H2O2 dan masa tindak balas telah dikaji pada suhu 45oC. Kandungan oksigen oksirana (OOC) optimum sebanyak 3.61% diperoleh dengan menggunakan nisbah mol 1 : 5 : 2 pada 150 min dan sebanyak 96.5% penukaran dapat dicapai. Hasil tindak balas adalah sebanyak 91.3%. Puncak kromatografi cecair berprestasi tinggi (HPLC) bagi minyak sawit olein terepoksida (EPOo) telah berubah sepenuhnya berbanding puncak HPLC POo. Spektrum transformasi Fourier infra-merah (FTIR) telah menunjukkan kehadiran puncak ikatan gelang oksirana pada 844 cm-1.
A study of the heavy metal bio-accumulation by fresh water fish, Tilapia nilotica around Lohan Dam was carried out in aquarium system. The study showed that the fish tissues cultured in contaminated water samples, (location S3 and 54) contain higher heavy metals concentration compared with the fish cultured in uncontaminated water samples (S1 and S2). The concentrations of Fe, Zn, Mn, Cu, Ni and Cr in fish tissues are higher compared with those of Co, Cd and Pb. The bio-accumulation rates of Zn, Mn, Cu, Ni and Co are 25 times higher than those of the base levels and 10 times higher than those of the controls. The heavy metal bio-accumulation order in T. nilotica is as follows: Mn> Cu> Cr> Ni> Co> Zn> Pb> Cd> Fe. The heavy metal intakes by fish during the experimental period did not exceed the level concentration levels.
Kajian bioakumulasi logam berat oleh ikan air tawar, Tilapia nilotica di perairan sekitar Empangan Lohan dilakukan dengan kaedah ternakan akuarium. Hasil kajian menunjukkan tisu ikan yang diternak dalam sampel air tercemar (lokasi S3 dan S4) mengandungi logam berat yang lebih tinggi dari tisu ikan yang diternak dalam sampel air tidak tercemar (lokasi S1 dan S2). Kepekatan logam berat seperti Fe, Zn, Mn, Cu, Ni dan Cr didapati tinggi dalam tisu ikan berbanding dengan kepekatan Co, Cd dan Pb. Kadar bioakumulasi logam berat daIam ikan didapati tinggi bagi Zn, Mn, Cu, Ni dan Co yang masing-masing melebihi 25 kali ganda dari paras asal dan lebih 10 kali ganda dari paras kawalan. Siri bioakumulasi logam berat yang dikaji dalam ikan T. nilotica menurut urutan; Mn> Cu> Cr> Ni> Co> Zn> Pb> Cd> Fe. Kepekatan logam berat yang dapat diambil oleh ikan dalam masa kajian tidak mencapai nilai yang dapat menyebabkan kematian kepada ikan.
Sebatian poliol minyak sawit olein (di-hidroksi-POo) (70% hasil) disintesis melalui pembukaan gelang oksirana minyak sawit olein terepoksida (EPOo) secara hidrolisis selanjar dan berkelompok. Hasil optimum pembukaan gelang oksirana (97.2%) bagi kedua-dua tindak balas selama 90 min (tindak balas selanjar) dan 75 min (tindak balas berkelompok) dengan menggunakan mangkin asid perklorik 3% v/wt. Spektrum transformasi Fourier inframerah (FTIR) di-hidroksi-POo menunjukkan kehadiran puncak lebar getaran regangan kumpulan hidroksil pada nombor gelombang 3429 cm-1, menunjukkan sebatian poliol telah berjaya dihasilkan. Spektrum resonan magnetik nukleus-karbon (13C-NMR) di-hidroksi-POo telah menunjukkan kehadiran puncak karbon yang terikat dengan kumpulan hidroksil (74.5 ppm). Spektrum resonan magnetik nukleus-proton (1H-NMR) di-hidroksi-POo telah menunjukkan kehadiran puncak proton yang terikat pada karbon poliol (3.4 ppm) dan proton pada kumpulan hidroksil (4.6 ppm). Kelikatan kinematik produk poliol (nilai hidroksil sebanyak 110.7 mgKOH/g minyak) adalah 1435.2 cSt (40oC) dan 55.2 cSt (100oC) dengan indeks kelikatan 78.
Sebatian hidroksi-eter-POo
(80% hasil) disintesis melalui pembukaan gelang oksirana minyak sawit olein terepoksida
(EPOo
) secara alkoholisis. Hasil optimum pembukaan gelang oksirana (99.2%) dicapai dengan menggunakan asid
sulfurik 3% v/bt pada suhu tindak balas yang tinggi (80o
C) selama 30 minit masa tindak balas. Spektrum resonan
magnetik nukleus-proton (1
H-NMR) hidroksi-eter-POo
telah menunjukkan kehadiran puncak proton pada karbon eter
(3.2, 3.5 ppm) dan proton pada kumpulan hidroksil (4.8 ppm). Spektrum resonan magnetik nukleus-karbon (13C-NMR)
hidroksi-eter-POo
telah menunjukkan kehadiran puncak karbon yang terikat dengan kumpulan hidroksil (75 ppm) dan
karbon pada karbonil kumpulan eter (72 ppm). Kelikatan kinematik hidroksi-eter-POo
adalah 234.4 cSt (40o
C) dan 28.1
cSt (100o
C) dengan indeks kelikatan 156.
Jatropha curcas oil was extracted using n-hexane as solvent in the Soxhlet extraction method. The physicochemical properties of Malaysian Jatropha curcas oil were evaluated. The result showed that the Jatropha seeds consist of 60% (dry w/w) crude oil. The physicochemical properties showed that the seed oil contained low moisture level of 0.02±0.01%, acid value (1.50±0.07%), iodine value (91.70 ± 1.44 mg/g), peroxide value (0.66±0.04 miliequivalence/kg) and saponification value of 208.5±0.47 mg/g respectively. Gas chromatography analysis showed that oleic acid (46.00±0.19%) appears as dominant fatty acid in seed oil followed by linoleic acid (31.96±0.19%) and palmitic acid (13.89±0.06%). High performance liquid chromatography (HPLC) results showed that the dominant triacylglycerols present were PLL (22.00%), POP(16.48%), 000(16.48%), 00L(16.23%) and OLL(13.00%).
Crude fat and fatty acids composition were examined in 16 different species of Malaysian freshwater fishes. Nine species of farmed and seven species of wild fishes lipids were extracted using chloroform: methanol sohxlet extraction. The results showed that the crude lipids in muscle of farmed fishes were higher than the wild fishes, ranging from 20 - 50 % (wt/wt) and 4 – 15 % (wt/wt) respectively. Asian red-tail catfish showed highest total lipid among other fishes which was of 51.64 % (wt/wt), followed by red pomfret and yellow-tail catfish which were of 46.2% and 43.2% respectively. Eicosapentaenoic acid, EPA and docosahexaenoic acid, DHA in wild fishes were found higher compared to captive fish. Among the fishes studied, grey feather back contain high in EPA (2.9%) and DHA (12.1%) as well as snakeskin gouramy (EPA; 3.0% and DHA; 12.8%) and tengalan (EPA; 1.1% and DHA; 7.2%). Other fishes, on the other hand contain less percentage in w-3 fatty acids. The diet and the environment where the fishes were found are the main reason for the differences in fish fatty acids content.
A series of ester compounds derived from ricinoleic acid to be used as biolubricants base stock have been synthesized. The resulting products were confirmed by FTIR and NMR analyses. The synthesis was carried out in three stages: epoxidation of ricinoleic acid; synthesis of 10,12-dihydroxy-9-acyloxystearic acid from epoxidized ricinoleic acid with various fatty acids and esterification of the acyloxystearic acid products with octanol to yield octyl-10,12-dihydroxy-9-acyloxystearate. The viscosities, flash points and pour points (PP) behavior of the products were measured. The resulting esters had an increased in molar weight and viscosity and decreased in pour points as compared to ricinoleic acid.
Urea complexation is a method favoured by researchers to separate fatty acids based on molecular structure. In this study, effects of urea amount, crystallisation temperature and crystallisation time on the final products of urea complexation were examined. Box-Behnken Design (BBD) was employed to study the significance of these factors and the optimum conditions for the technique were predicted and verified. Results showed that urea-to-polyunsaturated fatty acid (PUFA) mole ratio and crystallisation temperature were two significant variables for enrichment of PUFA in non-urea complexing fraction (NUCF). In a 17-point experimental design, percentage of saturated fatty acid (SFA) was reduced almost entirely from initial 4.49%, monounsaturated fatty acid (MUFA) reduced from 57.02% to 41.32%, while PUFA increased from 33.49% to 53.87% in NUCF. Optimum condition for maximum PUFA and minimum SFA and MUFA contents was predicted at urea-to-PUFA mole ratio of 20, crystallisation temperature of –20°C and crystallisation time of 29.67 h.
Fats and oils in human diets are the main sources of essential fatty acids for the body. However, there is a mounting concern about the intake of foods containing trans fatty acids (TFAs) due to their deleterious effects on human. Thus, the accurate detection of fatty acids (FAs) and TFAs is needed to control and correct nutrition labeling in dietary fat samples. Accordingly, a method for the identification and quantification of FAs and TFAs in food fats by gas chromatography (GC) based on the extraction of lipids and derivatization using base catalyzed followed by trimethylsilyl-diazomethane (TMS-DM) was developed. The proposed method was evaluated to standard mixture of oleic acid (OA) (C18:1cis 9) and Elaidic acid (EA) (C18:1 trans 9) and its application to three samples of commercial margarines was demonstrated. Based on the results obtained, recovery values (R) from all the samples were close to 100%. Repeatability (RSD) values ranged between 0.78 and 2.47%, while Reproducibility (RSD) values ranged between 1.14 and 3.65%. Consequently, the proposed method is sensitive, accurate and suitable for FAs and TFAs analysis of food fats and oils and can be applied to nutritional, medicine and food studies.
1-(5-Mercapto-1,3,4-oxadiazol-2-yl)-2-(pyridine-2-ylamino)ethanone (3), has been synthesized from 2-(pyridine-2-ylamino)acetohydrazide (2). A yellow colored compound (2) was reacted with carbon disulfide and potassium hydroxide in absolute ethanol to obtain the 1-(5-mercapto-1,3,4-oxadiazol-2-yl)-2-(pyridine-2-ylamino)ethanone. Structures of the synthesized compounds were supported by means of IR, NMR, MS spectroscopic and elemental analysis. The synthesized compounds were evaluated for their antimicrobial activity and were expressed as the corresponding minimum inhibitory concentration (MIC). A brown colored compound (3) with 90% yield has been successfully synthesized. This compound was found to have significant antimicrobial activity with MIC value ranging from 30.2 - 43.2 μg cm-3. The findings of the present study indicate that cyclization of hydrazide acid group of 2-(pyridine-2-ylamino)acetohydrazide (2) into 1,3,4-oxadiazole nucleus resulted in increased antimicrobial activity.
Elektrod platinum-polivinilklorida (Pt-PVC) untuk pengoksidaan elektrokimia etanol dalam larutan alkali telah direkabentuk. Elektrod Pt-PVC dibina dengan mencampurkan serbuk-serbuk logam platinum dengan PVC (95:5 w/w), diaduk untuk mendapatkan campuran yang homogen, ditambahkan dengan tetrahidrofuran (THF) untuk melarutkan PVC, dikeringkan, dimasukkan ke dalam acuan berdiameter 1 cm dan ditekan pada tekanan kira-kira 10 tan/cm2. Kajian elektrokimia dilakukan menggunakan voltammetri kitaran (CV) dan kronokoulometri (CC). CV untuk etanol yang menggunakan elektrod-elektrod kepingan logam Pt dan Pt-PVC masing-masing memberikan ketumpatan arus 0.25 mA/cm2 dan 85 mA/cm2 untuk puncak penjerapan hidroksida. Ini menunjukkan bahawa elektrod Pt-PVC mempunyai nilai konduktiviti dan perilaku elektrokimia yang lebih baik untuk pengoksidaan etanol dalam KOH berbanding elektrod kepingan logam Pt. Hasil kajian mendapati bahawa terdapat peningkatan peratus hasil elektrolisis dari 3.64% kepada 23.64% asid asetik apabila elektrod Pt-PVC digunakan untuk pengoksidaan elektrokimia 0.25 M etanol dalam larutan elektrolit 1.0 M KOH menggantikan elektrod kepingan logam Pt.
Potassium hydroxide (KOH)-catalyzed reactions were utilized to hydrolyze Jatropha curcas seed oil. In this study, the effect of ethanolic KOH concentration, reaction temperature and reaction time to the free fatty acid (FFA) produced were investigated. D-Optimal Design was employed to study the significance of these factors and optimum conditions for the technique was predicted. The results showed that ethanolic KOH concentration was a significant variable for hydrolysis of J. curcas seed oil. In 18 experimental designs, FFA percentage of hydrolyzed J. curcas seed oil increased from 1.89% to 102.2%. The optimal conditions of response were found at 1.75M of ethanolic KOH, 65 °C and at 2 h reaction time. Fourier Transforms Infrared Spectroscopy (FTIR) spectrum analysis confirmed the concentration of ethanolic KOH i.e. at 1.00, 1.50 dan 1.75 M affect the percentage yields of J. curcas seed oil hydrolysis process.
The epoxidation process of RBD palm oil was carried out using in situ generated performic acid. The effect of various
process variables such as the formic acid towards hydrogen peroxide mole ratio, the reaction temperature and the
reaction time were optimized by using response surface methodology (RSM). The D-optimal design was used to evaluate
the influence of process variables and their interaction in order to obtain the process optimum conditions. The results
showed that the optimum conditions of the epoxidation process were at 5.91 mole ratio of formic acid towards 3.60 mole
of hydrogen peroxide, reaction temperature of 40ºC and reaction time of 2.55 h. At the optimum condition, the epoxidised
RBD palm oil (EPO) yield was 86% with oxirane oxygen content (OOC) of 3.46%. The results showed in good agreement
with the predicted values from the RSM model.
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%.
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.
The crude oil of Malaysian castor bean Ricinus communis L. seed was extracted by Soxhlet method using hexane. The physicochemical characteristics of castor bean oil were evaluated. The results showed that Malaysian castor seeds contain a relatively high percentage of total lipids content; 43.3% (per dry weight), high iodine value (84.5 mg/g) and saponification value (182.96 mg/g). The seed oil moisture content, acid value and free fatty acid percentage (% FFA) were 0.2%, 4.88 mg/g and 3.4%, respectively. The unsaturated fatty acids (UFA) content were 97.5% of the total fatty acids composition. Ricinoleic acid comprises over 84% while other fatty acids present were linoleic (7.3%), oleic (5.5%), palmitic (1.3%), stearic (1.2%) and linolenic (0.5%), respectively. Five types of castor bean seed oil triacylglycerols were identified as triricinolein, RRR (84.1%), diricinoleoylstearoylglycerol, RRS (8.2%), diricinoleoyloleoyl-glycerol, RRO (5.6%), diricinoleoyllinoleoylglycerol, RRL (1.2%) and diricinoleoylpalmitoyl-glycerol, RRP (0.9%) respectively.
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%.