M. Radzi Bin Abas

Composition of extractable organic matter of air particles from Malaysia : Initial study

The solvent extractable compounds of airborne particulate samples, which were collected on two occasions in a suburb of Kuala Lumpur, Malaysia, with a standard high-volume air sampler, were investigated to determine the distributions of homologous and biomarker compounds. These preliminary results show that both samples contain n-alkanes, n-alkanoic acids and n-alkanols as the dominant solvent-extractable components, with minor amounts of n-alkanedioic acids, n-alkanones, terpenoids, sterols, and phthalate contaminants, derived from biogenic sources (vascular plant wax) and from anthropogenic utilization of fossil fuel products (lubricating oil, vehicle fuels, etc.). Some compositional differences are observed in the two samples and greater atmospheric concentrations were found for almost all organic components in the sample collected under hazy conditions. This is interpreted to be due to the local build-up of organic contaminants as a result of atmospheric stability during the haze episode, to atmospheric photochemical reactions, and to some unidentified anthropogenic activities which are peculiar to the city. Some of the organic components are also suspected to be brought in from areas outside the region.

On-line preconcentration and determination of trace metals using a flow injection system coupled to ion chromatography

A flow injection (FI) method with on-line preconcentration using a mini-column loaded with 8-hydroxyquinoline immobilized on controlled pore glass (CPG-8HQ) is described for the determination of trace metals by ion chromatography (IC) with pyridine-2-6-dicarboxylic acid (PDCA) as the eluent. Copper, cadmium, lead, zinc, nickel and iron were determined at ppb level after post-column derivatization with 4-(2-pyridylazo)-resorcinol (PAR). The detection limits (3sigma) for the FI/IC system were 8.27, 0.89, 0.09, 0.06, 0.09 and 0.07 g l(-1) for Pb(2+), Cd(2+), Cu(2+) Ni(2+), Zn(2+) and Fe(3+), respectively, using 5 ml sample volume. The method was applied to the analysis of Malaysian natural waters.

Fluxes of ions in precipitation, throughfall and stemflow in an urban forest in Kuala Lumpur, Malaysia

A study was carried out to determine the chemical composition of bulk precipitation, throughfall and stemflow in an urban forest in Kuala Lumpur, Malaysia. The mean weekly rainfall recorded during the period of study was 63.2 mm. Throughfall, stemflow and canopy interception of incident precipitation were 77.1%, 1.2% and 21.7% respectively. Bulk precipitation, througfall and stemflow were acidic, the pH recorded being 4.37, 4.71 and 4.15 respectively. In all cases the dominant ions were NO3, SO4, Cl, NH4, K, Ca and Na. Of the ions studied Ca, K, Cl, SO4, Mg and Mn showed net increases in passing through the forest canopy, while NH4, Na, NO3, Zn, H and Fe showed net retention. This study shows that the urban environment of Kuala Lumpur contributes considerable amounts of materials to the atmosphere, as reflected by the high ionic contents in bulk precipitation, throughfall and stemflow.

Adsorption of methylene blue on activated carbon fiber prepared from coconut husk: isotherm, kinetics and thermodynamics studies

AbstractThe adsorption of methylene blue (MB) on activated carbon fiber (ACF) and granular activated carbon (ACG) was studied in a batch system. The effects of initial concentration, agitation time, solution pH, and temperature were examined. Adsorption isotherms were described using both the Langmuir and Freundlich models. It was found that the Langmuir model fits well with the experimental data. The pseudo-first-order, pseudo-second-order, and intra-particle diffusion models were used to examine the kinetics data. The results obtained showed that empirical kinetics data of both ACF and ACG were only well described by the second-order model. It was observed that the ACF has adsorption performance higher than that of ACG. Adsorption thermodynamics parameters were estimated and their values indicated that the adsorption of MB on ACF and ACG were endothermic and spontaneous processes. Thermodynamic results also indicate that the adsorption of MB on both adsorbents is by chemical interaction.

Adsorption of 4-nitrophenol on palm oil fuel ash activated by amino silane coupling agent

Abstract Adsorption of 4-nitrophenol on palm oil fuel ash activated by amino silane coupling agent was investigated. Experiments were carried out at 30°C as function of contact time, initial concentration (2500–4500 mgl−1) and pH (1–7.4). The equilibrium adsorption data of 4-nitrophenol on activated palm ash were analyzed by Langmuir Freundlich and Temkin models. The results indicated that the Langmuir model provides the best correlation of the experimental data. The maximum adsorption capacity of the activated palm oil fuel ash was determined with the Langmuir equation and found to be 1000 mg g−1 adsorbent at 30oC. Adsorption kinetics data were modeled using the pseudo-first-order, pseudo-second-order and intra-particle diffusion equations. It was shown that pseudo-second-order kinetic equation could best describe the adsorption kinetics. The results obtained in this work indicate that activated palm oil fuel ash is suitable as adsorbent material for adsorption of 4-nitrophenol from aqueous solutions.

Optimization of Conditions for Preparation of Activated Carbon from Coconut Husk Fiber Using Responses from Measurements of Surface Area and Adsorption

Coconut husk fiber-based activated carbon was synthesized using ZnCl2. Analytical technique such as SEM was used for the characterization of the developed activated carbon obtained from the carbon husk. Effects of various influential parameters are optimized using the Taguchi experimental design. The optimization of SBET with the percentage removal of 4-nitrophenol, methylene blue and acid red-27 dye were applied as standard responses, the optimized parameters for SBET were activation temperature of 800 °C, concentration of ZnCl2 of 50 % w/v, nitrogen flow rate of 100 cm3/min, activation time of 2 h and carbonization temperature of 300 °C. 4-Nitrophenol optimized conditions were: carbonization at 400 °C, impregnation with 5 % w/v ZnCl2 solution and activation at 700 °C for 2 h with nitrogen flow rate of 200 cm3/min. Except for the impregnation ratio, nitrogen flow rate and activation time in the case of methylene blue, the ideal conditions of the percentage removals of methylene blue and acid red-27 are almost equal to that of the SBET. The surface characteristics of the samples produced under optimal conditions were examined. There are no pores available in the surface of the coconut fiber compared to the surface of the other two samples prepared under ideal conditions. Moreover, the activated carbons prepared under these optimized conditions contain small amounts of oxygen and have neutral surfaces.

Heavy metal accessions to the forest floor of an urban forest reserve in Kuala Lumpur city, Malaysia

Abstract A study was carried out to determine the total accessions of Cd, Cu, Pb and Zn in bulk precipitation, throughfall, stemflow, and litterfall at a secondary forest in Kuala Lumpur, Malaysia. This study shows that the urban environment of Kuala Lumpur contributes a considerable amount of heavy metals to the atmosphere and forest floor as reflected by the high metal contents in bulk precipitation, throughfall and stemflow. The forest canopy filters and retains the metals, which are subsequently transferred to the soil. The concentrations of the metals in precipitation, throughfall and litterfall were in the order ZnPb > Cu > Cd. As a result of interaction between the atmosphere and the forest canopy, the net fluxes of heavy metals to the forest floor were 156.4, 121.7, 28.2 and 10.4 g · ha −1 · week −1 for Zn, Pb, Cu and Cd, respectively. All the metals studied showed net retention at the canopy with Pb as the most retained metal followed by Zn, Cu and Cd. The aqueous pathways contributed more to the net flux of heavy metals (except for Zn) than litterfall.