Displaying publications 21 - 40 of 88 in total

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  1. Development of magnetic graphene oxide adsorbent for the removal and preconcentration of As(III) and As(V) species from environmental water samples
    Rashidi Nodeh H, Wan Ibrahim WA, Ali I, Sanagi MM
    Environ Sci Pollut Res Int, 2016 May;23(10):9759-73.
    PMID: 26850098 DOI: 10.1007/s11356-016-6137-z
    New-generation adsorbent, Fe3O4@SiO2/GO, was developed by modification of graphene oxide (GO) with silica-coated (SiO2) magnetic nanoparticles (Fe3O4). The synthesized adsorbent was characterized using Fourier transform infrared spectroscopy, X-ray diffractometry, energy-dispersive X-ray spectroscopy, and field emission scanning electron microscopy. The developed adsorbent was used for the removal and simultaneous preconcentration of As(III) and As(V) from environmental waters prior to ICP-MS analysis. Fe3O4@SiO2/GO provided high adsorption capacities, i.e., 7.51 and 11.46 mg g(-1) for As(III) and As(V), respectively, at pH 4.0. Adsorption isotherm, kinetic, and thermodynamic were investigated for As(III) and As(V) adsorption. Preconcentration of As(III) and As(V) were studied using magnetic solid-phase extraction (MSPE) method at pH 9.0 as the adsorbent showed selective adsorption for As(III) only in pH range 7-10. MSPE using Fe3O4@SiO2/GO was developed with good linearities (0.05-2.0 ng mL(-1)) and high coefficient of determination (R (2) = 0.9992 and 0.9985) for As(III) and As(V), respectively. The limits of detection (LODs) (3× SD/m, n = 3) obtained were 7.9 pg mL(-1) for As(III) and 28.0 pg mL(-1) for As(V). The LOD obtained is 357-1265× lower than the WHO maximum permissible limit of 10.0 ng mL(-1). The developed MSPE method showed good relative recoveries (72.55-109.71 %) and good RSDs (0.1-4.3 %, n = 3) for spring water, lake, river, and tap water samples. The new-generation adsorbent can be used for the removal and simultaneous preconcentration of As(III) and As(V) from water samples successfully. The adsorbent removal for As(III) is better than As(V).
    Matched MeSH terms: Oxides/chemistry
  2. Overview performance of lanthanide oxide catalysts in methanation reaction for natural gas production
    Rosid SJM, Toemen S, Iqbal MMA, Bakar WAWA, Mokhtar WNAW, Aziz MMA
    Environ Sci Pollut Res Int, 2019 Dec;26(36):36124-36140.
    PMID: 31748998 DOI: 10.1007/s11356-019-06607-8
    A rapid growth in the development of power generation and transportation sectors would result in an increase in the carbon dioxide (CO2) concentration in the atmosphere. As it will continue to play a vital role in meeting current and future needs, significant efforts have been made to address this problem. Over the past few years, extensive studies on the development of heterogeneous catalysts for CO2 methanation have been investigated and reported in the literatures. In this paper, a comprehensive overview of methanation research studies over lanthanide oxide catalysts has been reviewed. The utilisation of lanthanide oxides as CO2 methanation catalysts performed an outstanding result of CO2 conversion and improvised the conversion of acidity from CO2 gas to CH4 gas. The innovations of catalysts towards the reaction were discussed in details including the influence of preparation methods, the structure-activity relationships as well as the mechanism with the purpose of outlining the pathways for future development of the methanation process.
    Matched MeSH terms: Oxides/chemistry*
  3. Silylation of TEMPO oxidized nanocellulose from oil palm empty fruit bunch by 3-aminopropyltriethoxysilane
    Indarti E, Marwan, Rohaizu R, Wanrosli WD
    Int J Biol Macromol, 2019 Aug 15;135:106-112.
    PMID: 31128174 DOI: 10.1016/j.ijbiomac.2019.05.161
    Silylated cellulose has been successfully synthesized using TEMPO-oxidized nanocellulose (TEMPO-NC) from oil palm empty fruit bunch and 3-aminopropyltriethoxysilane (APS) in an ethanol/water medium at a low curing temperature of 40 °C as compared to those reported in the literature of above 100 °C. Confirmation of the grafting process can be seen from the new FTIR peaks at 810 cm-1 and 749 cm-1 which are attributed to the SiC stretching and SiC, and new 13C NMR signals at 10.3, 21.7 and 42.7 ppm which are assigned to C7, C8, and C9 of the silylated TEMPO-NC. The decrease in the intensities of the cellulose peaks of C2, C3, C6 and C6' in the 13C NMR indicates that silylation not only occurs on the hydroxyls, but more importantly on the TEMPO-NC carboxylic moiety of C6', which is postulated as being the primary factor for this successful modification. This is further corroborated by the emergence of three signals at 43, 61, and 69 ppm in the 29Si NMR spectrum which corresponds to Si(OSi)(OR)2R', Si(OSi)2(OR)R', and Si(OSi)3R' units respectively. Additional evidence is provided by the EDX which shows an increase in Si weight percent of 1.94 after reaction. This silylated cellulose from OPEFB has the potentials to be used as bionanocomposite reinforcing elements.
    Matched MeSH terms: Cyclic N-Oxides/chemistry*
  4. Fulltext Rapid adsorption of heavy metals by Fe3O4/talc nanocomposite and optimization study using response surface methodology
    Kalantari K, Ahmad MB, Masoumi HR, Shameli K, Basri M, Khandanlou R
    Int J Mol Sci, 2014;15(7):12913-27.
    PMID: 25050784 DOI: 10.3390/ijms150712913
    Fe3O4/talc nanocomposite was used for removal of Cu(II), Ni(II), and Pb(II) ions from aqueous solutions. Experiments were designed by response surface methodology (RSM) and a quadratic model was used to predict the variables. The adsorption parameters such as adsorbent dosage, removal time, and initial ion concentration were used as the independent variables and their effects on heavy metal ion removal were investigated. Analysis of variance was incorporated to judge the adequacy of the models. Optimal conditions with initial heavy metal ion concentration of 100, 92 and 270 mg/L, 120 s of removal time and 0.12 g of adsorbent amount resulted in 72.15%, 50.23%, and 91.35% removal efficiency for Cu(II), Ni(II), and Pb(II), respectively. The predictions of the model were in good agreement with experimental results and the Fe3O4/talc nanocomposite was successfully used to remove heavy metals from aqueous solutions.
    Matched MeSH terms: Oxides/chemistry
  5. Fulltext Infrared study of Er(3+)/Yb(3+) Co-Doped GeO(2)-PbO-Bi(2)O(3) glass
    Bahari HR, Sidek HA, Adikan FR, Yunus WM, Halimah MK
    Int J Mol Sci, 2012;13(7):8609-14.
    PMID: 22942723 DOI: 10.3390/ijms13078609
    Heavy metal oxide glasses, containing bismuth and/or lead in their glass structure are new alternatives for rare eart (RE) doped hosts. Hence, the study of the structure of these vitreous systems is of great interest for science and technology. In this research work, GeO(2)-PbO-Bi(2)O(3) glass host doped with Er(3+)/Yb(3+) ions was synthesized by a conventional melt quenching method. The Fourier transform infrared (FTIR) results showed that PbO and Bi(2)O(3) participate with PbO(4) tetragonal pyramids and strongly distort BiO(6) octahedral units in the glass network, which subsequently act as modifiers in glass structure. These results also confirmed the existence of both four and six coordination of germanium oxide in glass matrix.
    Matched MeSH terms: Oxides/chemistry*
  6. Fulltext Effect of ZnO on the physical properties and optical band gap of soda lime silicate glass
    Zaid MH, Matori KA, Aziz SH, Zakaria A, Ghazali MS
    Int J Mol Sci, 2012;13(6):7550-8.
    PMID: 22837711 DOI: 10.3390/ijms13067550
    This manuscript reports on the physical properties and optical band gap of five samples of soda lime silicate (SLS) glass combined with zinc oxide (ZnO) that were prepared by a melting and quenching process. To understand the role of ZnO in this glass structure, the density, molar volume and optical band gaps were investigated. The density and absorption spectra in the Ultra-Violet-Visible (UV-Visible) region were recorded at room temperature. The results show that the densities of the glass samples increased as the ZnO weight percentage increased. The molar volume of the glasses shows the same trend as the density: the molar volume increased as the ZnO content increased. The optical band gaps were calculated from the absorption edge, and it was found that the optical band gap decreased from 3.20 to 2.32 eV as the ZnO concentration increased.
    Matched MeSH terms: Oxides/chemistry*
  7. Fulltext Photopyroelectric spectroscopic studies of ZnO-MnO(2)-Co(3)O(4)-V(2)O(5) ceramics
    Rizwan Z, Zakaria A, Ghazali MS
    Int J Mol Sci, 2011;12(3):1625-32.
    PMID: 21673911 DOI: 10.3390/ijms12031625
    Photopyroelectric (PPE) spectroscopy is a nondestructive tool that is used to study the optical properties of the ceramics (ZnO + 0.4MnO(2) + 0.4Co(3)O(4) + xV(2)O(5)), x = 0-1 mol%. Wavelength of incident light, modulated at 10 Hz, was in the range of 300-800 nm. PPE spectrum with reference to the doping level and sintering temperature is discussed. Optical energy band-gap (E(g)) was 2.11 eV for 0.3 mol% V(2)O(5) at a sintering temperature of 1025 °C as determined from the plot (ρhυ)(2)versushυ. With a further increase in V(2)O(5), the value of E(g) was found to be 2.59 eV. Steepness factor 'σ(A)' and 'σ(B)', which characterize the slope of exponential optical absorption, is discussed with reference to the variation of E(g). XRD, SEM and EDAX are also used for characterization of the ceramic. For this ceramic, the maximum relative density and grain size was observed to be 91.8% and 9.5 μm, respectively.
    Matched MeSH terms: Oxides/chemistry*
  8. Fulltext Phase transformations of α-alumina made from waste aluminum via a precipitation technique
    Matori KA, Wah LC, Hashim M, Ismail I, Zaid MH
    Int J Mol Sci, 2012;13(12):16812-21.
    PMID: 23222685 DOI: 10.3390/ijms131216812
    We report on a recycling project in which α-Al(2)O(3) was produced from aluminum cans because no such work has been reported in literature. Heated aluminum cans were mixed with 8.0 M of H(2)SO(4) solution to form an Al(2)(SO(4))(3) solution. The Al(2)(SO(4))(3) salt was contained in a white semi-liquid solution with excess H(2)SO(4); some unreacted aluminum pieces were also present. The solution was filtered and mixed with ethanol in a ratio of 2:3, to form a white solid of Al(2)(SO(4))(3)·18H(2)O. The Al(2)(SO(4))(3)·18H(2)O was calcined in an electrical furnace for 3 h at temperatures of 400-1400 °C. The heating and cooling rates were 10 °C /min. XRD was used to investigate the phase changes at different temperatures and XRF was used to determine the elemental composition in the alumina produced. A series of different alumina compositions, made by repeated dehydration and desulfonation of the Al(2)(SO(4))(3)·18H(2)O, is reported. All transitional alumina phases produced at low temperatures were converted to α-Al(2)O(3) at high temperatures. The X-ray diffraction results indicated that the α-Al(2)O(3) phase was realized when the calcination temperature was at 1200 °C or higher.
    Matched MeSH terms: Oxides/chemistry
  9. Fulltext Optimization of lipase-mediated synthesis of 1-nonene oxide using phenylacetic acid and hydrogen peroxide
    Abdulmalek E, Arumugam M, Basri M, Rahman MB
    Int J Mol Sci, 2012;13(10):13140-9.
    PMID: 23202943 DOI: 10.3390/ijms131013140
    Herein, an efficient epoxidation of 1-nonene is described. In a simple epoxidation system, commercially available Novozym 435, an immobilized Candida antarctica lipase B, and hydrogen peroxide (H(2)O(2)) were utilized to facilitate the in situ oxidation of phenylacetic acid to the corresponding peroxy acid which then reacted with 1-nonene to give 1-nonene oxide with high yield and selectivity. The aliphatic terminal alkene was epoxidised efficiently in chloroform to give an excellent yield (97%-99%) under the optimum reaction conditions, including temperature (35 °C), initial H(2)O(2) concentration (30%), H(2)O(2) amount (4.4 mmol), H(2)O(2) addition rate (one step), acid amount (8.8 mmol), and stirring speed (250 rpm). Interestingly, the enzyme was stable under the single-step addition of H(2)O(2) with a catalytic activity of 190.0 Ug-1. The entire epoxidation process was carried out within 12 h using a conventional water bath shaker.
    Matched MeSH terms: Oxides/chemistry
  10. Fulltext The effect of remelting on the physical properties of borotellurite glass doped with manganese
    Hashim SP, Sidek HA, Halimah MK, Matori KA, Yusof WM, Zaid MH
    Int J Mol Sci, 2013;14(1):1022-30.
    PMID: 23296276 DOI: 10.3390/ijms14011022
    A systematic set of borotellurite glasses doped with manganese (1-x) [(B(2)O(3))(0.3)(TeO(2))(0.7)]-xMnO, with x = 0.1, 0.2, 0.3 and 0.4 mol%, were successfully synthesized by using a conventional melt and quench-casting technique. In this study, the remelting effect of the glass samples on their microstructure was investigated through density measurement and FT-IR spectra and evaluated by XRD techniques. Initial experimental results from XRD evaluation show that there are two distinct phases of glassy and crystallite microstructure due to the existence of peaks in the sample. The different physical behaviors of the studied glasses were closely related to the concentration of manganese in each phase. FTIR spectra revealed that the addition of manganese oxide contributes the transformation of TeO(4) trigonal bipyramids with bridging oxygen (BO) to TeO(3) trigonal pyramids with non-bridging oxygen (NBO).
    Matched MeSH terms: Oxides/chemistry
  11. Fulltext Simple room-temperature preparation of high-yield large-area graphene oxide
    Huang NM, Lim HN, Chia CH, Yarmo MA, Muhamad MR
    Int J Nanomedicine, 2011;6:3443-8.
    PMID: 22267928 DOI: 10.2147/IJN.S26812
    Graphene has attracted much attention from researchers due to its interesting mechanical, electrochemical, and electronic properties. It has many potential applications such as polymer filler, sensor, energy conversion, and energy storage devices. Graphene-based nanocomposites are under an intense spotlight amongst researchers. A large amount of graphene is required for preparation of such samples. Lately, graphene-based materials have been the target for fundamental life science investigations. Despite graphene being a much sought-after raw material, the drawbacks in the preparation of graphene are that it is a challenge amongst researchers to produce this material in a scalable quantity and that there is a concern about its safety. Thus, a simple and efficient method for the preparation of graphene oxide (GO) is greatly desired to address these problems. In this work, one-pot chemical oxidation of graphite was carried out at room temperature for the preparation of large-area GO with ~100% conversion. This high-conversion preparation of large-area GO was achieved using a simplified Hummer's method from large graphite flakes (an average flake size of 500 μm). It was found that a high degree of oxidation of graphite could be realized by stirring graphite in a mixture of acids and potassium permanganate, resulting in GO with large lateral dimension and area, which could reach up to 120 μm and ~8000 μm(2), respectively. The simplified Hummer's method provides a facile approach for the preparation of large-area GO.
    Matched MeSH terms: Oxides/chemistry
  12. Fulltext Down-top nanofabrication of binary (CdO)x (ZnO)1-x nanoparticles and their antibacterial activity
    Al-Hada NM, Mohamed Kamari H, Abdullah CAC, Saion E, Shaari AH, Talib ZA, et al.
    Int J Nanomedicine, 2017;12:8309-8323.
    PMID: 29200844 DOI: 10.2147/IJN.S150405
    In the present study, binary oxide (cadmium oxide [CdO])x (zinc oxide [ZnO])1-x nanoparticles (NPs) at different concentrations of precursor in calcination temperature were prepared using thermal treatment technique. Cadmium and zinc nitrates (source of cadmium and zinc) with polyvinylpyrrolidone (capping agent) have been used to prepare (CdO)x (ZnO)1-x NPs samples. The sample was characterized by X-ray diffraction (XRD), scanning electron microscopy, energy-dispersive X-ray (EDX), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy. XRD patterns analysis revealed that NPs were formed after calcination, which showed a cubic and hexagonal crystalline structure of (CdO)x (ZnO)1-x NPs. The phase analysis using EDX spectroscopy and FTIR spectroscopy confirmed the presence of Cd and Zn as the original compounds of prepared (CdO)x (ZnO)1-x NP samples. The average particle size of the samples increased from 14 to 33 nm as the concentration of precursor increased from x=0.20 to x=0.80, as observed by TEM results. The surface composition and valance state of the prepared product NPs were determined by X-ray photoelectron spectroscopy (XPS) analyses. Diffuse UV-visible reflectance spectra were used to determine the optical band gap through the Kubelka-Munk equation; the energy band gap was found to decrease for CdO from 2.92 to 2.82 eV and for ZnO from 3.22 to 3.11 eV with increasing x value. Additionally, photoluminescence (PL) spectra revealed that the intensity in PL increased with an increase in particle size. In addition, the antibacterial activity of binary oxide NP was carried out in vitro against Escherichia coli ATCC 25922 Gram (-ve), Salmonella choleraesuis ATCC 10708, and Bacillus subtilis UPMC 1175 Gram (+ve). This study indicated that the zone of inhibition of 21 mm has good antibacterial activity toward the Gram-positive B. subtilis UPMC 1175.
    Matched MeSH terms: Oxides/chemistry*
  13. Fulltext Exceedingly biocompatible and thin-layered reduced graphene oxide nanosheets using an eco-friendly mushroom extract strategy
    Muthoosamy K, Bai RG, Abubakar IB, Sudheer SM, Lim HN, Loh HS, et al.
    Int J Nanomedicine, 2015;10:1505-19.
    PMID: 25759577 DOI: 10.2147/IJN.S75213
    PURPOSE: A simple, one-pot strategy was used to synthesize reduced graphene oxide (RGO) nanosheets by utilizing an easily available over-the-counter medicinal and edible mushroom, Ganoderma lucidum.

    METHODS: The mushroom was boiled in hot water to liberate the polysaccharides, the extract of which was then used directly for the reduction of graphene oxide. The abundance of polysaccharides present in the mushroom serves as a good reducing agent. The proposed strategy evades the use of harmful and expensive chemicals and avoids the typical tedious reaction methods.

    RESULTS: More importantly, the mushroom extract can be easily separated from the product without generating any residual byproducts and can be reused at least three times with good conversion efficiency (75%). It was readily dispersible in water without the need of ultrasonication or any surfactants; whereas 5 minutes of ultrasonication with various solvents produced RGO which was stable for the tested period of 1 year. Based on electrochemical measurements, the followed method did not jeopardize RGO's electrical conductivity. Moreover, the obtained RGO was highly biocompatible to not only colon (HT-29) and brain (U87MG) cancer cells, but was also viable towards normal cells (MRC-5).

    CONCLUSION: Besides being eco-friendly, this mushroom based approach is easily scalable and demonstrates remarkable RGO stability and biocompatibility, even without any form of functionalization.

    Matched MeSH terms: Oxides/chemistry*
  14. Preparation and characterization of an amylase-triggered dextrin-linked graphene oxide anticancer drug nanocarrier and its vascular permeability
    Kiew SF, Ho YT, Kiew LV, Kah JCY, Lee HB, Imae T, et al.
    Int J Pharm, 2017 Dec 20;534(1-2):297-307.
    PMID: 29080707 DOI: 10.1016/j.ijpharm.2017.10.045
    We synthesized a dextrin (DEX)-conjugated graphene oxide (GO) nanocarrier (GO100-DEX) as a potential drug delivery system to respond to a tumor-associated stimulus, α-amylase, that has high permeability through the fenestrated endothelial barrier to the tumor site. At acidic pH and in the presence of α-amylase to simulate tumor conditions, GO100-DEX released a 1.5-fold higher amount of doxorubicin (DOX) than of GO100. Under the same conditions, the cytotoxic effects of GO100-DEX/DOX were 2-fold greater than those of free DOX and 2.9-fold greater than those of GO100/DOX. Employing an in vitro biomimetic microfluidic blood vessel model lined with human umbilical vein endothelial cells, we evaluated the tumor vasculature endothelial permeation of GO100-DEX and GO100 using dextrans of 10 and 70kDa for comparison and as standards to validate the microfluidic blood vessel model. The results showed that the permeabilities of GO100-DEX and GO100 were 4.3- and 4.9-fold greater than that of 70kDa dextran and 2.7- and 3.1-fold higher than that of 10kDa dextran, thus demonstrating the good permeability of the GO-based nanocarrier through the fenestrated endothelial barrier.
    Matched MeSH terms: Oxides/chemistry*
  15. Investigating the addition of SiO₂-CaO-ZnO-Na₂O-TiO₂ bioactive glass to hydroxyapatite: Characterization, mechanical properties and bioactivity
    Yatongchai C, Placek LM, Curran DJ, Towler MR, Wren AW
    J Biomater Appl, 2015 Nov;30(5):495-511.
    PMID: 26116020 DOI: 10.1177/0885328215592866
    Hydroxyapatite (Ca10(PO4)6(OH)2) is widely investigated as an implantable material for hard tissue restoration due to its osteoconductive properties. However, hydroxyapatite in bulk form is limited as its mechanical properties are insufficient for load-bearing orthopedic applications. Attempts have been made to improve the mechanical properties of hydroxyapatite, by incorporating ceramic fillers, but the resultant composite materials require high sintering temperatures to facilitate densification, leading to the decomposition of hydroxyapatite into tricalcium phosphate, tetra-calcium phosphate and CaO phases. One method of improving the properties of hydroxyapatite is to incorporate bioactive glass particles as a second phase. These typically have lower softening points which could possibly facilitate sintering at lower temperatures. In this work, a bioactive glass (SiO2-CaO-ZnO-Na2O-TiO2) is incorporated (10, 20 and 30 wt%) into hydroxyapatite as a reinforcing phase. X-ray diffraction confirmed that no additional phases (other than hydroxyapatite) were formed at a sintering temperature of 560 ℃ with up to 30 wt% glass addition. The addition of the glass phase increased the % crystallinity and the relative density of the composites. The biaxial flexural strength increased to 36 MPa with glass addition, and there was no significant change in hardness as a function of maturation. The pH of the incubation media increased to pH 10 or 11 through glass addition, and ion release profiles determined that Si, Na and P were released from the composites. Calcium phosphate precipitation was encouraged in simulated body fluid with the incorporation of the bioactive glass phase, and cell culture testing in MC-3T3 osteoblasts determined that the composite materials did not significantly reduce cell viability.
    Matched MeSH terms: Oxides/chemistry*
  16. Designing Calcium Silicate Cements with On-Demand Properties for Precision Endodontics
    Cahyanto A, Rath P, Teo TX, Tong SS, Malhotra R, Cavalcanti BN, et al.
    J Dent Res, 2023 Dec;102(13):1425-1433.
    PMID: 37861249 DOI: 10.1177/00220345231198185
    Calcium silicate (C3S) cements are available in kits that do not account for patients' specific needs or clinicians' preferences regarding setting time, radiopacity, mechanical, and handling properties. Moreover, slight variations in powder components and liquid content affect cement's properties and bioactivity. Unfortunately, it is virtually impossible to optimize several cement properties simultaneously via the traditional "one variable at a time" strategy, as inputs often induce trade-offs in properties (e.g., a higher water-to-powder ratio [W/P] increases flowability but decreases mechanical properties). Herein, we used Taguchi's methods and genetic algorithms (GAs) to simultaneously analyze the effect of multiple inputs (e.g., powder composition, radiopacifier concentration, and W/P) on setting time, pH, flowability, diametral tensile strength, and radiopacity, as well as prescribe recipes to produce cements with predicted properties. The properties of cements designed with GAs were experimentally tested, and the results matched the predictions. Finally, we show that the cements increased the genetic expression of odonto/osteogenic genes, alkaline phosphatase activity, and mineralization potential of dental pulp stem cells. Hence, GAs can produce cements with tailor-made properties and differentiation potential for personalized endodontic treatment.
    Matched MeSH terms: Oxides/chemistry
  17. Bera Lake water quality, past and present situation
    Gharibrezal M, Ashraf MA
    J Environ Biol, 2016 09;37(5 Spec No):1097-1104.
    PMID: 29989741
    Bera Lake is the largest natural fresh water reservoir in Malaysia. It has vital environmental and ecological importance for human and wild life. Nevertheless, water quality of this lake has been degraded during the last few decades due to land development projects at catchment area. Therefore, a comprehensive water quality assessment of Bera Lake was implemented in order to compare current water quality with the implementation of land development projects. In situ water quality surveying was implemented using calibrated full option Hydrolab DS 5. Eleven parameters viz., temperature, depth of sampling, salinity, Turbidity, total dried solid, pH, NH4(+), N03(-), Cl(-), saturation percentage of dissolved oxygen, specific conductivity were recorded in fifty one stations at 0.2h, 0.5h, and 0.8h depth. National Water Quality Standards for Malaysia (NWQS) and Water Quality were used to evaluate Bera Lake quality based on previous and resultant data. Vertical water quality analysis revealed a clear stratification in Bera Lake water profile in terms of temperature, dissolved oxygen, chloride (Cl(-)), nitrate (NO(3)), pH and specific conductivity (EC) parameters. Results clearly demonstrate the important role of land use changes since 1972 in the physico-chemical condition of water quality at Bera Lake. Classifications of water quality before and after land development project were calculated as class II and class V, respectively. A long-term and comprehensive monitoring of water quality assessment is recommended in order to reach plan of sustainable water resources use with conservation approach.
    Matched MeSH terms: Nitrogen Oxides/chemistry
  18. Removal of VOCs from gas streams with double perovskite-type catalysts
    Pan KL, Pan GT, Chong S, Chang MB
    J Environ Sci (China), 2018 Jul;69:205-216.
    PMID: 29941256 DOI: 10.1016/j.jes.2017.10.012
    Double perovskite-type catalysts including La2CoMnO6 and La2CuMnO6 are first evaluated for the effectiveness in removing volatile organic compounds (VOCs), and single perovskites (LaCoO3, LaMnO3, and LaCuO3) are also tested for comparison. All perovskites are tested with the gas hourly space velocity (GHSV) of 30,000hr-1, and the temperature range of 100-600°C for C7H8 removal. Experimental results indicate that double perovskites have better activity if compared with single perovskites. Especially, toluene (C7H8) can be completely oxidized to CO2 at 300°C as La2CoMnO6 is applied. Characterization of catalysts indicates that double perovskites own unique surface properties and are of higher amounts of lattice oxygen, leading to higher activity. Additionally, apparent activation energy of 68kJ/mol is calculated using Mars-van Krevelen model for C7H8 oxidation with La2CoMnO6 as catalyst. For durability test, both La2CoMnO6 and La2CuMnO6 maintain high C7H8 removal efficiencies of 100% and 98%, respectively, at 300°C and 30,000hr-1, and they also show good resistance to CO2 (5%) and H2O(g) (5%) of the gas streams tested. For various VOCs including isopropyl alcohol (C3H8O), ethanal (C2H4O), and ethylene (C2H4) tested, as high as 100% efficiency could be achieved with double perovskite-type catalysts operated at 300-350°C, indicating that double perovskites are promising catalysts for VOCs removal.
    Matched MeSH terms: Oxides/chemistry*
  19. Role of calcium oxide in sludge granulation and methanogenesis for the treatment of palm oil mill effluent using UASB reactor
    Ahmad A, Ghufran R, Abd Wahid Z
    J Hazard Mater, 2011 Dec 30;198:40-8.
    PMID: 22047724 DOI: 10.1016/j.jhazmat.2011.10.008
    The granulation process in palm oil mill effluent using calcium oxide-cement kiln dust (CaO-CKD) provides an attractive and cost effective treatment option. In this study the efficiency of CaO-CKD at doses of 1.5-20 g/l was tested in batch experiments and found that 10 g of CaO/l caused the greatest degradation of VFA, butyrate and acetate. An upflow anaerobic sludge blanket (UASB) reactor was operated continuously at 35°C for 150 days to investigate the effect of CaO-CKD on sludge granulation and methanogenesis during start-up. The treatment of POME emphasized the influence of varying organic loading rates (OLR). Up to 94.9% of COD was removed when the reactor was fed with the 15.5-65.5 g-CODg/l at an OLR of 4.5-12.5 kg-COD/m(3)d, suggesting the feasibility of using CaO in an UASB process to treat POME. The ratio of volatile solids/total solids (VS/TS) and volatile fatty acids in the anaerobic sludge in the UASB reactor decreased significantly after long-term operation due to the precipitation of calcium carbonate in the granules. Granulation and methanogenesis decreased with an increase in the influent CaO-CKD concentration.
    Matched MeSH terms: Oxides/chemistry*
  20. Parameters optimization of rice husk ash (RHA)/CaO/CeO2 sorbent for predicting SO2/NO sorption capacity using response surface and neural network models
    Dahlan I, Ahmad Z, Fadly M, Lee KT, Kamaruddin AH, Mohamed AR
    J Hazard Mater, 2010 Jun 15;178(1-3):249-57.
    PMID: 20137857 DOI: 10.1016/j.jhazmat.2010.01.070
    In this work, the application of response surface and neural network models in predicting and optimizing the preparation variables of RHA/CaO/CeO(2) sorbent towards SO(2)/NO sorption capacity was investigated. The sorbents were prepared according to central composite design (CCD) with four independent variables (i.e. hydration period, RHA/CaO ratio, CeO(2) loading and the use of RHA(raw) or pretreated RHA(600 degrees C) as the starting material). Among all the variables studied, the amount of CeO(2) loading had the largest effect. The response surface models developed from CCD was effective in providing a highly accurate prediction for SO(2) and NO sorption capacities within the range of the sorbent preparation variables studied. The prediction of CCD experiment was verified by neural network models which gave almost similar results to those determined by response surface models. The response surface models together with neural network models were then successfully used to locate and validate the optimum hydration process variables for maximizing the SO(2)/NO sorption capacities. Through this optimization process, it was found that maximum SO(2) and NO sorption capacities of 44.34 and 3.51 mg/g, respectively could be obtained by using RHA/CaO/CeO(2) sorbents prepared from RHA(raw) with hydration period of 12h, RHA/CaO ratio of 2.33 and CeO(2) loading of 8.95%.
    Matched MeSH terms: Oxides/chemistry*
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