C. E. Seng

University of Science Malaysia, Penang, Penang, Malaysia

Are you C. E. Seng?

Claim your profile

Publications (23)47.57 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Bioregeneration of mono-amine modified silica gel (MAMS) adsorbent loaded with Acid Orange 7 (AO7), Acid Yellow 9 (AY9) and Acid Red 14 (AR14), respectively, was investigated under two different operational conditions, namely absence/presence of sucrose/bacto-peptone as the co-substrate and different biomass acclimation concentrations. The results revealed that the AY9- and AR14-loaded MAMS adsorbents could almost be completely bioregenerated but only in the presence of co-substrate whereas the bioregeneration of AO7-loaded MAMS could achieve up to 71% in the absence of the co-substrate. These differences could be related to the structural properties of the investigated azo dyes. In addition, the results showed that the bioregeneration duration of AO7-loaded MAMS could be progressively shortened by using biomass acclimated to increasingly higher AO7 concentration. However, the bioregeneration efficiencies were found to be relatively unchanged under different biomass acclimation concentrations.
    Bioresource Technology 06/2013; 143C:584-591. DOI:10.1016/j.biortech.2013.06.055 · 5.04 Impact Factor
  • S M Khor, S L Ng, P E Lim, C E Seng
    [Show abstract] [Hide abstract]
    ABSTRACT: The objective of this study was to evaluate the effects ofNi(II) and Cr(VI) individually and in combination on the simultaneous removal of chemical oxygen demand (COD), nitrogen and metals under a sequencing batch reactor (SBR) operation. Three identical laboratory-scale SBRs were operated with FILL, REACT, SETTLE, DRAW and IDLE periods in a ratio of 1:12:1:2:8 for a cycle time of 24 h until the steady state was achieved. Nickel(II) at increasing concentrations up to 35 mg/L was added to one of the reactors; Cr(VI) at increasing concentrations up to 25 mg/L was added to a second reactor; while a combination of Ni(II) and Cr(VI) in equal concentrations up to 10 mg/L was added to a third reactor. The results demonstrate that both Ni(II) and Cr(VI) exerted a more pronounced inhibitory effect on the removal of ammonia nitrogen (AN) than on COD removal. Synergistic and antagonistic inhibitory effects on the rates of COD and AN removal, respectively, were observed for the 50% Ni(II) and 50% Cr(VI) (w/w) mixture in the concentration range between 10 and 20 mg/L. The simultaneous presence of 50% Ni(II) and 50% Cr(VI) at a concentration of 20 mg/L resulted in system failure.
    Environmental Technology 12/2011; 33(15-16):1903-14. DOI:10.1080/09593330.2011.568008 · 1.20 Impact Factor
  • Y M Loo, P E Lim, C E Seng
    [Show abstract] [Hide abstract]
    ABSTRACT: The objective of this research was to evaluate the treatment ofp-nitrophenol (PNP) as a sole organic carbon source using a sequencing batch reactor (SBR) with the addition of adsorbent. Two types of adsorbents, namely powdered activated carbon (PAC) and pyrolysed rice husk (PRH) were used in this study. Two identical SBRs, each with a working volume of 10 L, were operated with fill, react, settle, draw and idle periods in the ratio of 2:8:1:0.75:0.25 for a cycle time of 12 h. The results showed that, without the addition of adsorbent, increasing the influent PNP concentration to 200 mg/L resulted in the deterioration of chemical oxygen demand (COD) removal efficiency and PNP removal efficiency in the SBRs. Improvement in the performance of the SBR was observed with the addition of PAC. When the dosage of 1.0 g PAC/cycle was applied, COD removal of 95% and almost complete removal of PNP were achieved at the influent PNP concentration of 300 mg/L. The kinetic study showed that the rates of COD and PNP removal can be described by the first-order kinetics. The enhancement of performance in the PAC-supplemented SBR was postulated to be due to the initial adsorption of PNP by the freshly added and the bioregenerated PAC, thus reducing the inhibition on the microorganisms. The PRH was found to be ineffective because of its relatively low adsorption capacity for PNP, compared with that of PAC.
    Environmental Technology 04/2010; 31(5):479-87. DOI:10.1080/09593330903514482 · 1.20 Impact Factor
  • S L Ng, C E Seng, P E Lim
    [Show abstract] [Hide abstract]
    ABSTRACT: A kinetic model consisting of first-order desorption and biodegradation processes was developed to describe the bioregeneration of phenol- and p-nitrophenol-loaded powdered activated carbon (PAC) and pyrolyzed rice husk (PRH), respectively. Different dosages of PAC and PRH were loaded with phenol or p-nitrophenol by contacting with the respective phenolic compound at various concentrations. The kinetic model was used to fit the phenol or p-nitrophenol concentration data in the bulk solution during the bioregeneration process to determine the rate constants of desorption, k(d), and biodegradation, k. The results showed that the kinetic model fitted relatively well (R(2)>0.9) to the experimental data for the phenol- and p-nitrophenol-loaded PAC as well as p-nitrophenol-loaded PRH. Comparison of the values of k(d) and k shows that k is much greater than k(d). This indicates clearly that the desorption process is the rate-determining step in bioregeneration and k(d) can be used to characterize the rate of bioregeneration. The trend of the variation of the k(d) values with the dosages of PAC or PRH used suggests that higher rate of bioregeneration can be achieved under non-excess adsorbent dosage condition.
    Chemosphere 01/2010; 78(5):510-6. DOI:10.1016/j.chemosphere.2009.11.041 · 3.50 Impact Factor
  • H C Tee, C E Seng, A Md Noor, P E Lim
    [Show abstract] [Hide abstract]
    ABSTRACT: This study aims to compare the performance of planted and unplanted constructed wetlands with gravel- and raw rice husk-based media for phenol and nitrogen removal. Four laboratory-scale horizontal subsurface-flow constructed wetland units, two of which planted with cattail (Typha latifolia) were operated outdoors. The units were operated at a nominal hydraulic retention time of 7 days and fed with domestic wastewater spiked with phenol concentration at 300 mg/L for 74 days and then at 500 mg/L for 198 days. The results show that planted wetland units performed better than the unplanted ones in the removal and mineralization of phenol. This was explained by the creation of more micro-aerobic zones in the root zone of the wetland plants which allow a faster rate of phenol biodegradation, and the phenol uptake by plants. The better performance of the rice husk-based planted wetland compared to that of the gravel-based planted wetland in phenol removal could be explained by the observation that more rhizomes were established in the rice husk-based wetland unit thus creating more micro-aerobic zones for phenol degradation. The role of rice husk as an adsorbent in phenol removal was considered not of importance.
    Science of The Total Environment 06/2009; 407(11):3563-71. DOI:10.1016/j.scitotenv.2009.02.017 · 3.16 Impact Factor
  • S L Ng, C E Seng, P E Lim
    [Show abstract] [Hide abstract]
    ABSTRACT: The bioregeneration efficiencies of powdered activated carbon (PAC) and pyrolyzed rice husk loaded with phenol and p-nitrophenol were quantified by oxygen uptake measurements using the respirometry technique in two approaches: (i) simultaneous adsorption and biodegradation and (ii) sequential adsorption and biodegradation. It was found that the applicability of the simultaneous adsorption and biodegradation approach was constrained by the requirement of adsorption preceding biodegradation in order to determine the initial adsorbent loading accurately. The sequential adsorption and biodegradation approach provides a good estimate of the upper limit of the bioregeneration efficiency for the loaded adsorbent in the simultaneous adsorption and biodegradation processes. The results showed that the mean bioregeneration efficiencies for PAC loaded with phenol and p-nitrophenol, respectively, obtained using the two approaches were in good agreement.
    Chemosphere 04/2009; 75(10):1392-400. DOI:10.1016/j.chemosphere.2009.02.049 · 3.50 Impact Factor
  • Source
    Ong SA, Lim PE, Seng CE
    [Show abstract] [Hide abstract]
    ABSTRACT: The present study is aimed to investigate the adsorption behavior of Cu(II) and Cd(II) ions onto rice husk and modified rice husk. The adsorption of the heavy metal ions over both the adsorbents was found to follow Langmuir and Freundlich adsorption isotherm models. It was observed that the adsorption capacity of rice husk increased after treated with nitric acid. The pseudo first-order, pseudo second-order, second order and intra-particle diffusion models were used to analyze the kinetic data and the rate constants were evaluated. The kinetic adsorption data fitted the pseudo second-order kinetic model well and also followed the intra-particle diffusion model up to 90 min, but diffusion is not the only rate controlling step.
    Electronic Journal of Environmental, Agricultural and Food Chemistry 02/2007; 6(2):1764-1774.
  • SA Ong, P E Lim, C E Seng
    [Show abstract] [Hide abstract]
    ABSTRACT: The sorption of Cu(II) and Cd(II) from synthetic solution by powdered activated carbon (PAC), biomass, rice husk (RH) and activated rice husk (ARH) were investigate under batch conditions. After activated by concentrated nitric acid for 15 hours at 60-65 degrees C, the adsorption capacity for RH was increased. The adsorbents arranged in the increasing order of adsorption capacities to the Langmuir Q degree parameter were biomass > PAC > ARH > RH. The addition of adsorbents in base mix solution had increased the specific oxygen uptake rate (SOUR) activated sludge microorganisms with and without the presence of metals. The increased of SOUR were due to the ability of PAC and RH in reducing the inhibitory effect of metals on microorganisms and provide a reaction site between activated sludge microorganisms and substrates.
    Annali di Chimica 02/2004; 94(1-2):85-92. DOI:10.1002/adic.200490007 · 0.99 Impact Factor
  • Source
    S A Ong, P E Lim, C E Seng
    [Show abstract] [Hide abstract]
    ABSTRACT: Wastewater treatment systems employing simultaneous adsorption and biodegradation processes have proven to be effective in treating toxic pollutants present in industrial wastewater. The objective of this study is to evaluate the effect of Cu(II) and the efficacy of the powdered activated carbon (PAC) and activated rice husk (ARH) in reducing the toxic effect of Cu(II) on the activated sludge microorganisms. The ARH was prepared by treatment with concentrated nitric acid for 15 h at 60-65 degrees C. The sequencing batch reactor (SBR) systems were operated with FILL, REACT, SETTLE, DRAW and IDLE modes in the ratio of 0.5:3.5:1:0.75:0.25 for a cycle time of 6 h. The Cu(II) and COD removal efficiency were 90 and 85%, respectively, in the SBR system containing 10 mg/l Cu(II) with the addition of 143 mg/l PAC or 1.0 g PAC per cycle. In the case of 715 mg/l ARH or 5.0 g ARH per cycle addition, the Cu(II) and COD removal efficiency were 85 and 92%, respectively. ARH can be used as an alternate adsorbent to PAC in the simultaneous adsorption and biodegradation wastewater treatment process for the removal of Cu(II). The specific oxygen uptake rate (SOUR) and kinetic studies show that the addition of PAC and ARH reduce the toxic effect of Cu(II) on the activated sludge microorganisms.
    Journal of Hazardous Materials 11/2003; 103(3):263-77. DOI:10.1016/j.jhazmat.2003.07.008 · 4.33 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Polyvinylpyrrolidone stabilized Pt and Pd colloids with mean particle sizes ranging from 1.5 to 3.1 nm were prepared and are effective catalysts for the selective hydrogenation of polyunsaturated soybean oil at 35 • C and atmospheric pressure. The rate constants for the three stages of hydrogenation from linoleneate to linoleate to oleate and to stearate were determined and their ratios, which signify the selectivity were calculated. Pt and Pd catalysts show different rates of hydrogenation towards the double bonds. Pt catalyst has lower oleate selectivity leading to higher yields of saturated product but lower percentage of trans-isomer than the Pd catalyst at comparable mean particle size of 1.5 nm. The oleate selectivity increases while the linoleate selectivity as well as the activity decreases with an increase of the mean particle size. An intermediate trans,trans-linoleate was detected for the Pt catalyst with larger particle mean size.
    Journal of Molecular Catalysis A Chemical 01/2003; 191(1):113-121. DOI:10.1016/S1381-1169(02)00351-5 · 3.68 Impact Factor
  • Source
    H.P Choo, K.Y Liew, H.F Liu, C.E Seng
    [Show abstract] [Hide abstract]
    ABSTRACT: Polyvinylpyrolidone stabilized Pt colloids with different polymer: Pt ratios with average particle sizes of between 1.4 and 2.9 nm and narrow size distribution were found to be active for the hydrogenation of palm olein at 35°C and atmospheric pressure. The initial hydrogen consumption rate was high, corresponding to the hydrogenation of the linoleate and slowed down thereafter, corresponding to the oleate hydrogenation. The rate constants for the two competing reactions were determined and the selectivity calculated to be between 10 and 100. The particle size of the Pt clusters influences the rate of the diene much more significantly than the monoene. The smaller the average particle size, the higher is the rate for the diene and hence the higher the selectivity. The trans-isomer formation was comparative low and was found to be a consequence of the partial saturation of the diene rather than the isomerization of the monoene.
    Journal of Molecular Catalysis A Chemical 01/2001; 165(1-2-165):127-134. DOI:10.1016/S1381-1169(00)00367-8 · 3.68 Impact Factor
  • Source
    C. E. Seng, C. G. Lee, K. Y. Liew
    [Show abstract] [Hide abstract]
    ABSTRACT: De-oiled spent bleaching clay was activated either by acid treatment followed by heat activation or by heat activation alone at temperatures between 200 and 800°C. The surface area of the heat-activated clay attained a maximal value of ≈120 m2 g−1 at temperatures between 400 and 500°C while the acid-heat-treated clay attained maximal surface area of ≈140 m2 g−1. The adsorption capacities of chromium [Cr(VI)] for both series studied increased as the activation temperature increased until 300°C and decreased again at higher temperatures. At lower pH, more than 95% of the Cr(VI) was absorbed in a solution with initial concentration of 1 mg L−1 per gram of adsorbent activated at 300°C. The adsorption patterns followed Freudlich's isotherms. Two maximal values of adsorption capacities of nickel [Ni(II)] were observed at activation temperatures of 200 and 500°C for acid-treated samples, whereas these were at 200 and 700°C for the nonacid-treated samples. The amount of Ni(II) adsorbed increased with the pH of the solution for all samples studied. The maximal adsorption capacities of the adsorbents in solution containing initial Ni(II) concentration of 5 mg L−1 per 0.5 g of adsorbent and at pH 6 were found to be 44 and 42%, respectively, for the acid-treated sample activated at 500°C and for the nonacid-treated sample activated at 700°C. They all obeyed both the Langmuir's and Freundlich's isotherms.
    Journal of Oil & Fat Industries 01/2001; 78(8):831-835. DOI:10.1007/s11746-001-0351-7 · 1.62 Impact Factor
  • Source
    C. G. Lee, C. E. Seng, K. Y. Liew
    [Show abstract] [Hide abstract]
    ABSTRACT: Various alcohols and hydrocarbons were used as solvents to extract the residual oil in spent bleaching clay from palm oil refining. The content of oil and minor components in the spent clay was >40% by weight. The efficiencies of extraction by the polar alcohols, except for methanol, were higher but with a slower initial rate than the nonpolar hydrocarbons. The free fatty acids contents, the Totox values (anisidine value+2 x peroxide value), and the color of the alcohol-extracted oil were also higher than that by the hydrocarbons resulting in poorer quality oils. All the extracted oils, irrespective of the solvent used, have poorer quality than crude palm oil. However, for regeneration of the residual spent clay, the polar alcohols should be more suitable as more of the impurities are removed.
    Journal of Oil & Fat Industries 10/2000; 77(11):1219-1223. DOI:10.1007/s11746-000-0190-6 · 1.62 Impact Factor
  • C. E. Seng, S. B. Teoh, K. Y. Liew
    [Show abstract] [Hide abstract]
    ABSTRACT: The viscosities of n-alkyl chlorides from pentyl to hexadecyl chloride were determined at temperatures between 15 to 80°C at 5°C intervals. The intrinsic volumes of the n-alkyl chlorides were determined by extrapolation of the plot of fluidity against molar volume to zero fluidity. Plots of the logarithm of viscosity vs. reciprocal absolute temperature were almost linear. The energies of activation for viscous flow for the n-alkyl chlorides were calculated and found to increase with increase in chain length. The fluidities, F, of the n-alkyl chlorides were found to obey the modified form of Hildebrand's equation.F = D[(V-Vo/Vo]\exp(-EB/RT) where D is a constant, V and Vo are the molar volume and the intrinsic molar volume, respectively, and EB is an energy term corresponding to the energy required for disrupting the association of the molecules. The activation energy for viscous flow consists of the sum of the energy required for the expansion of the void volume and the energy required to overcome intermolecular interactions. These energies were calculated and discussed.
    Journal of Solution Chemistry 01/1998; 27(8):761-770. DOI:10.1023/A:1022661708411 · 1.08 Impact Factor
  • K. Y. Liew, C. E. Seng, S. B. Teoh
    [Show abstract] [Hide abstract]
    ABSTRACT: Without Abstract
    Journal of Oil & Fat Industries 12/1995; 72(12):1595-1596. DOI:10.1007/BF02577861 · 1.62 Impact Factor
  • S. B. Teoh, C. E. Seng, K. Y. Liew
    [Show abstract] [Hide abstract]
    ABSTRACT: The densities ofn-alkyl chlorides from pentyl chloride to hexadecyl chloride were determined at temperatures between 15–80C at 5C intervals. The densities increase linearly with temperature and chainlength. A four-constant equation, V=n/(−3.6640 10−5 T+0.07151)+1/(−5.6526 10−5 T+0.04243), was formulated. This formula accurately predicted the molal volume and, hence, the density for all then-alkyl chlorides at any temperature within the range.
    Journal of Oil & Fat Industries 10/1995; 72(10):1227-1229. DOI:10.1007/BF02540995 · 1.62 Impact Factor
  • K. Y. Liew, C. E. Seng, C. G. Lee
    [Show abstract] [Hide abstract]
    ABSTRACT: The viscosities of seven n-alkylamines from n-butylamine to n-decylamine were determined from 15 to 80°C at 5°C intervals. The intrinsic volumes were determined by extrapolation of the plot of fluidity against molar volume to zero fluidity and found to be a linear function of the number of carbon atoms. Plots of the logarithm of viscosity vs. reciprocal absolute temperature were almost linear. The energies of activation for viscous flow for the n-alkylamines were calculated and found to increase with increase in the carbon number. The B values, based on Hildebrand's equation and representing a measure of a molecules resistance to transport of momentum, were calculated for each of the n-alkylamines. A modified form of the equation describing the change fluidity with temperature was then formulated. It is suggested that the activation energy for viscous flow consists of the sum of the energy required for the expansion of the void volume and the energy required to overcome intermolecular interactions. These energies were calculated and discussed.
    Journal of Solution Chemistry 12/1994; 23(12):1293-1300. DOI:10.1007/BF00974182 · 1.08 Impact Factor
  • K. Y. Liew, C. E. Seng, C. G. Lee
    [Show abstract] [Hide abstract]
    ABSTRACT: Densities of sevenn-alkylamines from 1-butylamine to 1-decylamine were determined from 15 to 80°C. The density was found to be a linear function of the temperature within this temperature range. At constant temperature, the molal volume was a linear function of the number of methylene units in the chain for the homologous series. A simple equation with four constants correlating the molal volume with the number of methylene units and temperature of then-alkylamines was formulated. Excellent agreement between the calculated, the measured and the literature values were obtained. Accurate molal volumes, and hence the densities of anyn-alkylamines, other than methylamine, within the temperature range can be calculated from the equation.
    Journal of Oil & Fat Industries 11/1994; 71(11):1297-1299. DOI:10.1007/BF02540556 · 1.62 Impact Factor
  • K. Y. Liew, C. E. Seng, B. H. Ng
    [Show abstract] [Hide abstract]
    ABSTRACT: Viscosities of five n-alcohols from 1-hexanol to 1-tetradecanol were determined from 15 to 80C at 5C intervals. Plot of the logarithm of viscosity vs. reciprocal absolute temperature were almost linear. The energies of activation for viscous flow were determined for each of the alcohols and found to increase with increase in chain length. The intrinsic molar volumes Vo were determined by extrapolation to zero fluidities. The fluidities f = B[(V - V\texto )/V\texto ]exp\text( - E\textB /RT\text)\phi = B[(V - V_{\text{o}} )/V_{\text{o}} ]exp{\text{( - }}E_{\text{B}} /RT{\text{)}} where B is a constant, V is the molar volume and E B is an energy term corresponding to the energy required for disrupting the association of the molecules. The values of E B were of the magnitude of the energy of hydrogen bond. These values decrease marginally as the chain length increase.
    Journal of Solution Chemistry 10/1993; 22(11):1033-1040. DOI:10.1007/BF00647727 · 1.08 Impact Factor
  • K. Y. Liew, C. E. Seng, B. H. Ng
    [Show abstract] [Hide abstract]
    ABSTRACT: Densities of seven even carbon number n-alcohols from 1- hexanol to 1-octadecanol from 15 to 80°C were determined at 5° intervals. The density was found to be a linear function of the temperature within this temperature range. A simple equation which correlates teh molar volume with the carbon number and temperature of the alcohols is presented. Excellent agreements between the calculated, measured, and literature values were obtained. Accurate predictions of the molar volume and hence the density of the n-alcohols from 1-propanol to 1-octadecanol including the odd carbon number 1-alcohols in the temperature range studied can be made using the equation.
    Journal of Solution Chemistry 11/1992; 21(11):1177-1183. DOI:10.1007/BF00651862 · 1.08 Impact Factor