Fotodegradasi fenol dan 4-klorofenol dalam air menggunakan titanium dioksida

Pencemaran sumber air merupakan masalah utama kepada keperluan air minuman dan kehidupan akuatik pada masa kini. Pelbagai teknologi digunakan untuk merawat sumber air. Salah satu kaedah tersebut ialah dengan menggunakan semikonduktor TiO₂ sebagai fotomangkin dalam fotodegradasi sebatian organik. Dalam kajian ini fotodegradasi fenol dan 4-klorofenol menggunakan serbuk mangkin TiO₂ dan TiO₂ (sol-gel) yang dipegunkan di atas kaca (TiO₂/kaca) digunakan. Pemegunan Ti02/kaca dilakukan dengan dua kaedah; iaitu berdasarkan bilangan celupan TiO₂/kaca dan berdasarkan amaun TiO₂. Didapati dengan menggunakan serbuk mangkin TiO₂ kadar fotodegradsi 20 ppm fenol mencapai 73.0% dan 4-klorofenol ialah 97.4%. Kadar fotodegradasi fenol mencapai 30.5% dengan menggunakan kaedah bilangan celupan TiO₂/kaca dimana pencelupan kaca dilakukan sebanyak 8x. Manakala dengan menggunakan kaedah berdasarkan amaun TiO₂/kaca didapati kadar fotodegradasi fenol mencapai 43.4% apabila jisim TiO₂ yang dipegunkan di atas kaca mencapai jisim maksimum iaitu 0.077 ± 0.003 g. Apabila amaun TiO₂/kaca meningkat kadar fotodegradasi fenol juga meningkat. Peningkatan suhu pengkalsinan TiO₂/kaca memberikan keputusan perkadaran songsang dim ana peningkatan suhu pengkalsinan mengurangkan kadar fotodegradasi fenol. Pada suhu pengkalsinan yang tinggi didapati berlakunya penanggalan TiO₂ yang dipegunkan ke atas kaca. Namun kesan kenaikan suhu larutan fenol dan 4-klorofenol menunjukkan perkadaran terus, dim ana kenaikan suhu 30°C hingga 50°C masing-masing dapat meningkatkan kadar fotodegradasi fenol sebanyak 15.8% dan 12.2% bagi 4-klorofenol. Kesan penambahan ion-ion K⁺, Na⁺, Ca²⁺ dan Zn²⁺ kepada larutan fenol terhadap kadar fotodegradasi juga dikaji. Didapati dengan menggunakan serbuk TiO₂ kadar fotodegradasi meningkat apabila ion K⁺ dan Ca²⁺ dengan kepekatan 0.01 M dan ion Zn²⁺ dengan kepekatan 0.001 M ditambahkan. Tetapi dengan penambahan ion Na+ ianya didapati merencatkan kadar fotodegradasi fenol. Manakala dengan menggunakan amaun TiO₂/kaca pula, penambahan ion Ca 2⁺ merencatkan kadar fotodegradasi fenol dan 4-klorofenol. Sementara penambahan ion K⁺ pada kepekatan 0.01 M pula dapat meningkatkan kadar fotodegradasi 4-klorofenol

Distribution of trace elements in core marine sediments of coastal East Malaysia by instrumental neutron activation analysis

A study was carried out on the distribution and enrichment of trace elements in the core marine sediments of East Malaysia from three stations at South China Sea and one station each at Sulu Sea and Sulawesi Sea. Five stations of sediment cores were recovered and the vertical concentration profiles of six elements namely Br, Cs, Hf, Rb, Ta, and V were determined using the instrumental neutron activation analysis. The enrichment factor, geoaccumulation index and the modified degree of contamination were used to calculate the anthropogenic and pollution status of the elements in the samples. Except for Cs and Hf, which by the enrichment factor are categorized from minimum enrichment to moderate enrichment in all stations and for V and Rb in Sulu Sea and Sulawesi Sea, which are categorized minimum enrichment, other elements are found to be no enrichment at all stations. The geoaccumulation index of Hf in one station shows moderately polluted and for other elements are unpolluted. However, the modified degree values of all samples are less than 1, suggesting very low contamination of elements found in all the stations

Distribution of heavy metals in core marine sediments of coastal East Malaysia by instrumental neutron activation analysis and inductively coupled plasma spectroscopy

Fifty-five core marine sediments from three locations at South China Sea and one location each at Sulu Sea and Sulawesi Sea of coastal East Malaysia were analyzed for heavy metals by instrumental neutron activation analysis and inductively coupled plasma mass spectroscopy. The enrichment factor and the modified degree of contamination were used to calculate the anthropogenic and pollution status of the elements in the samples. The enrichment factor of As, Cd, Cr, Cu, Ni, Pb, and Zn varied from 0.42-4.26, 0.50–2.34, 0.31–0.82, 0.20–0.61, 0.91–1.92, 0.23–1.52, and 0.90–1.28, respectively, with the modified degree of contamination values below 0.6. Comparative data showed that coastal East Malaysia has low levels of contamination

k0-Instrumental Neutron Activation Analysis Method Validation for Trace Element Determination using Environmental Reference Materials

Presently, the k0-standardization method of instrumental neutron activation analysis (k0-INAA) technique has become the preferred method for multi-elemental analysis due to its high metrological value. The reactor neutron parameters (α and f) for rotary rack as well as the detector efficiency were determined and used for ko-INAA. The information is then used to compute the elemental concentration of certified reference materials (CRMs) using k0-INAA software developed in Vietnam. This results of the CRMs analysis showed the average z-score were below the threshold value of 2 with precision of about 10% for most of the element concentrations analyzed. The result has been very promising and at present stage, the laboratory is focusing on testing this method and capacity building for our staff. In future, the k0-INAA technique will be used to analyze air particulate, marine environmental samples, geological samples and archeological artifacts as well as to provide analytical services to clients from industries in particular

Instrumental neutron activation analysis of marine sediment in-house reference material

Reference materials play an important role in demonstrating the quality and reliability of analytical data. The advantage of using in-house reference materials is that they provide a relatively cheap option as compared to using commercially available certified reference material (CRM) and can closely resemble the routine test sample. A marine sediment sample was designed as an in-house reference material, in the framework of quality assurance and control (QA/QC) program of the Neutron Activation Analysis (NAA) Laboratory at Nuclear Malaysia. The NAA technique was solely used for the homogeneity test of the marine sediment sample. The CRM of IAEA- Soil 7 and IAEA- SL1 (Lake Sediment) were applied in the analysis as compatible matrixbased reference materials for QA purposes

Assessment of Elemental Pollution in Marine Sediment from Talang-Satang and Bako National Park of Sarawak, Malaysia (Special Issue> Malaysian Nuclear Agency)

The assessments ofelemental polluti oinn sediment collected from national park ofSarawak were done based on their distribution pattern ,geoaccumulation index and enrichment factor ,The enrichment factor s(EF )were determined by the elemental rationing method, whilst the geoaccumulati oinndex (Ig .by. )comparing of current concentration to background concentration of metals, The elements were analyzed by using Instmmenta1 Neutron Activatio nAnalysis (INAA) .The results of enrichment facto rshow tha tTalang-Satang and Bako National Park have significant contaminated by toxic elements such as As, Cr, Sb, Ti and U. Base on the classification system proposed for sediment qualit ywith referring to Ig. ,the sediment quali tyof the Talang-Satang and Bako National Park for Arsenic (As) contamination can be categorized as moderate to extremely contaminated. Contamination of element such as Cr, Sb and Ti can be categorized as uncontaminated to moderate contaminated, and U can be categorized as uncontaminated to moderate and strong contaminated, The average concentration of As in sediment of Bako shown surpassed sediment qualit yguidelin eCprobable effect concentration - PEC) value, whilst Cr concentration in sediment of Talang-Satang shown above midpoint effect concentration (MEC) .This indicatin gt,he sediment ofBako and Talang-Satang could have a potentia lfor producing chronic effect to the marine biot aor benthi ocrganism

Polycyclic aromatic hydrocarbon (PAH) contamination in the sediments of East Coast Peninsular Malaysia

The polycyclic aromatic hydrocarbons (PAHs) are pollutants of concern due to their persistent in the marine ecosystem, thus its can cause long-term adverse effect to the marine life. In this study the concentrations of PAHs in east coast Peninsular Malaysia sediments were determined. About ten stations along the east coast of the coastal area were selected to collect sediment samples using grab sampler. The PAHs from the sediment samples were soxhlet extracted using mixture of hexane and dichloromethane (DCM). Fractionation was done using the silica-alumina column. About 17 compounds of the PAHs were determined using the Gas Chromatography-Mass Spectrometer (GCMS model QP5050A). The Σ PAHs was found in range between 0.26μg/g to 0.59μg/g dry weight. The data from the study signified that the main source of PAHs in the sediment of the east coast peninsular Malaysia is originated from the pyrolytic source

Testing the applicability of the k(o)-NAA method at the MINT's TRIGA MARK II reactor

The Analytical Chemistry Laboratory at MINT is using the NAA technique since 1980s and is the only laboratory in Malaysia equipped with a research reactor, namely the TRIGA MARK II. Throughout the years the development of NAA technique has been very encouraging and was made applicable to a wide range of samples. At present, the k0 method has become the preferred standardization method of NAA (k0-NAA) due to its multi-elemental analysis capability without using standards. Additionally, the k0 method describes NAA in physically and mathematically understandable definitions and is very suitable for computer evaluation. Eventually, the k0-NAA method has been adopted by MINT in 2003, in collaboration with the Nuclear Research Institute (NRI), Vietnam. The reactor neutron parameters (a and f) for the pneumatic transfer system and for the rotary rack at various locations, as well as the detector efficiencies were determined. After calibration of the reactor and the detectors, the implemented k0 method was validated by analyzing some certified reference materials (including IAEA Soil 7, NIST 1633a, NIST 1632c, NIST 1646a and IAEA 140/TM). The analysis results of the CRMs showed an average u score well below the threshold value of 2 with a precision of better than 710% for most of the elemental concentrations obtained, validating herewith the introduction of the k0-NAA method at the MINT

A Long Term Study on Characterization and Source Apportionment of Particulate Pollution in Klang Valley, Kuala Lumpur

Samples of airborne particulate matter, PM2.5 and PM10–2.5 were collected using a Gent stacked filter sampler at an urban site, Klang Valley, Kuala Lumpur between January 2002–December 2011. The samples were analyzed for their elemental composition and black carbon content by Particle Induced X-ray Emission (PIXE) and light absorption, respectively. The annual average for PM2.5, PM10–2.5 and PM10 ranged from 21 to 35, 18 to 26 and 44 to 56 μg m–3, respectively. Factor analysis method and the Positive Matrix Factorisation (EPA PMF3) technique were also applied to the fine fraction data set in order to identify the possible sources of particulate matter and their contributions to the ambient particulate matter concentrations in the Klang Valley. A five factor PMF solution was found for PM2.5 particulate matter. The sources identified were; motor vehicles, industry, smoke/biomass burning, secondary sulphate and soil. It was found that the primary source of haze air particulate matter was locally generated mostly from vehicular emissions which contribute about 35% of the PM2.5 mass. The Hybrid Single Particle Lagrangian Intergrated Trajectory (HYSPLT) model was also used to explore possible long range transport of pollution. Smoke trans-boundary events were identified based on fine potassium from the data base in 2004, 2006 and 2008

Rare earth elements in core marine sediments of coastal East Malaysia by instrumental neutron activation analysis

A study was carried out on the concentration of REEs (Dy, Sm, Eu,Yb, Lu, La and Ce) that are present in the core marine sediments of East Malaysia from three locations at South China Sea and one location each at Sulu Sea and Sulawesi Sea. The sediment samples were collected at a depth of between 49 and 109 m, dried, and crushed to powdery form. The entire core sediments prepared for Instrumental Neutron Activation Analysis (INAA) were weighted approximately 0.0500 g to 0.1000 g for short irradiation and 0.1500 g to 0.2000 g for long irradiation. The samples were irradiated with a thermal neutron flux of 4.0×1012 cm−2 s−1 in a TRIGA Mark II research reactor operated at 750 kW. Blank samples and standard reference materials SL-1 were also irradiated for calibration and quality control purposes. It was found that the concentration of REEs varies in the range from 0.11 to 36.84 mg/kg. The chondrite-normalized REEs for different stations suggest that all the REEs are from similar origins. There was no significant REEs contamination as the enrichment factors normalized for Fe fall in the range of 0.42–2.82