Displaying publications 1 - 20 of 233 in total

Abstract:
Sort:
  1. Decontamination of textile wastewater via TiO2/activated carbon composite materials
    Foo KY, Hameed BH
    Adv Colloid Interface Sci, 2010 Sep 15;159(2):130-43.
    PMID: 20673570 DOI: 10.1016/j.cis.2010.06.002
    Water scarcity and pollution rank equal to climate change as the most urgent environmental turmoil for the 21st century. To date, the percolation of textile effluents into the waterways and aquifer systems, remain an intricate conundrum abroad the nations. With the renaissance of activated carbon, there has been a steadily growing interest in the research field. Recently, the adoption of titanium dioxide, a prestigious advanced photo-catalyst which formulates the new growing branch of activated carbon composites for enhancement of adsorption rate and discoloration capacity, has attracted stern consideration and supports worldwide. Confirming the assertion, this paper presents a state of art review of titanium dioxide/activated carbon composites technology, its fundamental background studies, and environmental implications. Moreover, its major challenges together with the future expectation are summarized and discussed. Conclusively, the expanding of activated carbons composites material represents a potentially viable and powerful tool, leading to the plausible improvement of environmental conservation.
    Matched MeSH terms: Water Pollutants, Chemical/chemistry*
  2. Biosensor based on glutamate dehydrogenase immobilized in chitosan for the determination of ammonium in water samples
    Azmi NE, Ahmad M, Abdullah J, Sidek H, Heng LY, Karuppiah N
    Anal Biochem, 2009 May 1;388(1):28-32.
    PMID: 19454217 DOI: 10.1016/j.ab.2009.02.005
    An optical biosensor based on glutamate dehydrogenase (GLDH) immobilized in a chitosan film for the determination of ammonium in water samples is described. The biosensor film was deposited on a glass slide via a spin-coating method. The ammonium was measured based on beta-nicotinamide adenine dinucleotide (NADH) oxidation in the presence of alpha-ketoglutaric acid at a wavelength of 340 nm. The biosensor showed optimum activity at pH 8. The optimum chitosan concentrations and enzyme loading were found to be at 2% (w/v) and 0.08 mg, respectively. Optimum concentrations of NADH and alpha-ketoglutaric acid both were obtained at 0.15 mM. A linear response of the biosensor was obtained in the ammonium concentration range of 0.005 to 0.5 mM with a detection limit of 0.005 mM. The reproducibility of the biosensor was good, with an observed relative standard deviation of 5.9% (n=8). The biosensor was found to be stable for at least 1 month when stored dry at 4 degrees C.
    Matched MeSH terms: Water Pollutants, Chemical/chemistry
  3. Biosorption of As (III) by non-living biomass of an arsenic-hypertolerant Bacillus cereus strain SZ2 isolated from a gold mining environment: equilibrium and kinetic study
    Mohd Bahari Z, Ali Hamood Altowayti W, Ibrahim Z, Jaafar J, Shahir S
    Appl Biochem Biotechnol, 2013 Dec;171(8):2247-61.
    PMID: 24037600 DOI: 10.1007/s12010-013-0490-x
    The ability of non-living biomass of an arsenic-hypertolerant Bacillus cereus strain SZ2 isolated from a gold mining environment to adsorb As (III) from aqueous solution in batch experiments was investigated as a function of contact time, initial As (III) concentration, pH, temperature and biomass dosage. Langmuir model fitted the equilibrium data better in comparison to Freundlich isotherm. The maximum biosorption capacity of the sorbent, as obtained from the Langmuir isotherm, was 153.41 mg/g. The sorption kinetic of As (III) biosorption followed well the pseudo-second-order rate equation. The Fourier transform infrared spectroscopy analysis indicated the involvement of hydroxyl, amide and amine groups in As (III) biosorption process. Field emission scanning electron microscopy-energy dispersive X-ray analysis of the non-living B. cereus SZ2 biomass demonstrated distinct cell morphological changes with significant amounts of As adsorbed onto the cells compared to non-treated cells. Desorption of 94 % As (III) was achieved at acidic pH 1 showing the capability of non-living biomass B. cereus SZ2 as potential biosorbent in removal of As (III) from arsenic-contaminated mining effluent.
    Matched MeSH terms: Water Pollutants, Chemical/chemistry
  4. Fulltext Optimal reduction of chemical oxygen demand and NH3-N from landfill leachate using a strongly resistant novel Bacillus salmalaya strain
    Dadrasnia A, Azirun MS, Ismail SB
    BMC Biotechnol, 2017 Nov 28;17(1):85.
    PMID: 29179747 DOI: 10.1186/s12896-017-0395-9
    BACKGROUND: When the unavoidable waste generation is considered as damaging to our environment, it becomes crucial to develop a sustainable technology to remediate the pollutant source towards an environmental protection and safety. The development of a bioengineering technology for highly efficient pollutant removal is this regard. Given the high ammonia nitrogen content and chemical oxygen demand of landfill leachate, Bacillus salmalaya strain 139SI, a novel resident strain microbe that can survive in high ammonia nitrogen concentrations, was investigated for the bioremoval of ammonia nitrogen from landfill leachate. The treatability of landfill leachate was evaluated under different treatment parameters, such as temperature, inoculum dosage, and pH.

    RESULTS: Results demonstrated that bioaugmentation with the novel strain can potentially improve the biodegradability of landfill leachate. B. salmalaya strain 139SI showed high potential to enhance biological treatment given its maximum NH3-N and COD removal efficiencies. The response surface plot pattern indicated that within 11 days and under optimum conditions (10% v/v inoculant, pH 6, and 35 °C), B. salmalaya strain139SI removed 78% of ammonia nitrogen. At the end of the study, biological and chemical oxygen demands remarkably decreased by 88% and 91.4%, respectively. Scanning electron microscopy images revealed that ammonia ions covered the cell surface of B. salmalaya strain139SI.

    CONCLUSIONS: Therefore, novel resistant Bacillus salmalaya strain139SI significantly reduces the chemical oxygen demand and NH3-N content of landfill leachate. Leachate treatment by B. salmalaya strain 139SI within 11 days.

    Matched MeSH terms: Water Pollutants, Chemical/chemistry
  5. Fulltext Heavy Metal Adsorption onto Kappaphycus sp. from Aqueous Solutions: The Use of Error Functions for Validation of Isotherm and Kinetics Models
    Rahman MS, Sathasivam KV
    Biomed Res Int, 2015;2015:126298.
    PMID: 26295032 DOI: 10.1155/2015/126298
    Biosorption process is a promising technology for the removal of heavy metals from industrial wastes and effluents using low-cost and effective biosorbents. In the present study, adsorption of Pb(2+), Cu(2+), Fe(2+), and Zn(2+) onto dried biomass of red seaweed Kappaphycus sp. was investigated as a function of pH, contact time, initial metal ion concentration, and temperature. The experimental data were evaluated by four isotherm models (Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich) and four kinetic models (pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion models). The adsorption process was feasible, spontaneous, and endothermic in nature. Functional groups in the biomass involved in metal adsorption process were revealed as carboxylic and sulfonic acids and sulfonate by Fourier transform infrared analysis. A total of nine error functions were applied to validate the models. We strongly suggest the analysis of error functions for validating adsorption isotherm and kinetic models using linear methods. The present work shows that the red seaweed Kappaphycus sp. can be used as a potentially low-cost biosorbent for the removal of heavy metal ions from aqueous solutions. Further study is warranted to evaluate its feasibility for the removal of heavy metals from the real environment.
    Matched MeSH terms: Water Pollutants, Chemical/chemistry*
  6. Fulltext Health Risk Assessment of Heavy Metals from Smoked Corbicula fluminea Collected on Roadside Vendors at Kelantan, Malaysia
    Dee KH, Abdullah F, Md Nasir SNA, Appalasamy S, Mohd Ghazi R, Eh Rak A
    Biomed Res Int, 2019;2019:9596810.
    PMID: 31663001 DOI: 10.1155/2019/9596810
    Corbicula fluminea serves as traditional food to the local people in Kelantan, Malaysia. Concerns regarding river contamination, smoking method, and associated adverse effects on public health had been increasing. Hence, this study aims to measure the level of heavy metals (Cd, Cu, Mn, Pb, and Zn) and assess human health risk in C. fluminea consumption at Kelantan. Heavy-metal analysis was done using flame atomic absorption spectrophotometry, while human health risk was assessed using provisional tolerable weekly intake (PTWI), target hazard quotient (THQ), and hazard index (HI). The estimated weekly intake (EWI) for all metals was found within PTWI, while THQ for Cd, Cu, Mn, Pb, and Zn was 0.12, 0.06, 0.04, 0.41, and 0.03, respectively. The HI was calculated at 0.61 which is less than 1, considered as the safe consumption level. Therefore, C. fluminea consumption in this study was found safe from the health risk of noncarcinogenic effect over a lifetime.
    Matched MeSH terms: Water Pollutants, Chemical/chemistry
  7. Sequential nitrification and denitrification in a novel palm shell granular activated carbon twin-chamber upflow bio-electrochemical reactor for treating ammonium-rich wastewater
    Mousavi S, Ibrahim S, Aroua MK
    Bioresour Technol, 2012 Dec;125:256-66.
    PMID: 23026342 DOI: 10.1016/j.biortech.2012.08.075
    In this study, a twin-chamber upflow bio-electrochemical reactor packed with palm shell granular activated carbon as biocarrier and third electrode was used for sequential nitrification and denitrification of nitrogen-rich wastewater under different operating conditions. The experiments were performed at a constant pH value for the denitrification compartment. The effect of variables, namely, electric current (I) and hydraulic retention time (HRT), on the pH was considered in the nitrification chamber. The response surface methodology was used based on three levels to develop empirical models for the study on the effects of HRT and current values as independent operating variables on NH(4)(+)-N removal. The results showed that ammonium was reduced within the function of an extensive operational range of electric intensity (20-50 mA) and HRT (6-24h). The optimum condition for ammonium oxidation (90%) was determined with an I of 32 mA and HRT of 19.2h.
    Matched MeSH terms: Water Pollutants, Chemical/chemistry
  8. Newly developed baffled subsurface-flow constructed wetland for the enhancement of nitrogen removal
    Tee HC, Lim PE, Seng CE, Nawi MA
    Bioresour Technol, 2012 Jan;104:235-42.
    PMID: 22130081 DOI: 10.1016/j.biortech.2011.11.032
    The objectives of this study are to compare the performance of newly developed baffled and conventional horizontal subsurface-flow (HSF) constructed wetlands in the removal of nitrogen at the hydraulic retention times (HRT) of 2, 3 and 5 days and to evaluate the potential of rice husk as wetland media for wastewater treatment. The results show that the planted baffled unit achieved 74%, 84% and 99% ammonia nitrogen (NH(4)(+)-N) removal versus 55%, 70% and 96% for the conventional unit at HRT of 2, 3 and 5 days, respectively. The better performance of the baffled unit was explained by the longer pathway due to the up-flow and down-flow conditions sequentially thus allowing more contact of the wastewater with the rhizomes and micro-aerobic zones. Near complete total oxidized nitrogen was observed due to the use of rice husk as wetland media which provided the COD as the electron donor in the denitrification process.
    Matched MeSH terms: Water Pollutants, Chemical/chemistry
  9. Hexavalent chromium adsorption on impregnated palm shell activated carbon with polyethyleneimine
    Owlad M, Aroua MK, Wan Daud WM
    Bioresour Technol, 2010 Jul;101(14):5098-103.
    PMID: 20156679 DOI: 10.1016/j.biortech.2010.01.135
    Removal of Cr(VI) ions from aqueous solution was investigated using modified palm shell activated carbon. Low Molecular Weight Polyethyleneimine (LMW PEI) was used for impregnation purpose. The maximum amount of LMW PEI adsorbed on activated carbon was determined to be approximately 228.2mg/g carbon. The adsorption experiments were carried out in a batch system using potassium dichromate K(2)Cr(2)O(7) as the source of Cr(VI) in the synthetic waste water and modified palm shell activated carbon as the adsorbent. The effects of pH, concentration of Cr(VI) and PEI loaded on activated carbon were studied. The adsorption data were found to fit well with the Freundlich isotherm model. This modified Palm shell activated carbon showed high adsorption capacity for chromium ions.
    Matched MeSH terms: Water Pollutants, Chemical/chemistry
  10. Colour removal from landfill leachate by coagulation and flocculation processes
    Aziz HA, Alias S, Adlan MN, Faridah, Asaari AH, Zahari MS
    Bioresour Technol, 2007 Jan;98(1):218-20.
    PMID: 16386895
    A study was conducted to investigate the efficiency of coagulation and flocculation processes for removing colour from a semi-aerobic landfill leachate from one of the landfill sites in Malaysia. Four types of coagulant namely aluminium (III) sulphate (alum), ferric (III) chloride, ferrous (II) sulphate and ferric (III) sulphate were studied using standard jar test apparatus. Results indicated that ferric chloride was superior to the other coagulants and removed 94% of colour at an optimum dose of 800 mg/l at pH 4. The effect of coagulant dosages on colour removal showed similar trend as for COD, turbidity and suspended solids. This suggested that colour in landfill leachate was mainly contributed by organic matters with some insoluble forms that exhibited turbidity and suspended solids readings. The results from this study suggested that ferric chloride could be a viable coagulant in managing colour problems associated with landfill leachate.
    Matched MeSH terms: Water Pollutants, Chemical/chemistry*
  11. Cationic and anionic modifications of oil palm empty fruit bunch fibers for the removal of dyes from aqueous solutions
    Sajab MS, Chia CH, Zakaria S, Khiew PS
    Bioresour Technol, 2013 Jan;128:571-7.
    PMID: 23211482 DOI: 10.1016/j.biortech.2012.11.010
    Oil palm empty fruit bunch (EFB) fibers were employed to remove dyes from aqueous solutions via adsorption approaches. The EFB fibers were modified using citric acid (CA) and polyethylenimine (PEI) to produce anionic and cationic adsorbents, respectively. The CA modified EFB fibers (CA-EFB) and PEI-modified EFB fibers (PEI-EFB) were used to study the efficiency in removing cationic methylene blue (MB) and anionic phenol red (PR) from aqueous solutions, respectively, at different pHs, temperatures and initial dye concentrations. The adsorption data for MB on the CA-EFB fitted the Langmuir isotherm, while the adsorption of PR on the PEI-EFB fitted the Freundlich isotherm, suggesting a monolayer and heterogeneous adsorption behavior of the adsorption processes, respectively. Both modified fibers can be regenerated up to seven adsorption/desorption cycles while still providing as least 70% of the initial adsorption capacity.
    Matched MeSH terms: Water Pollutants, Chemical/chemistry
  12. Human hair-derived high surface area porous carbon material for the adsorption isotherm and kinetics of tetracycline antibiotics
    Ahmed MJ, Islam MA, Asif M, Hameed BH
    Bioresour Technol, 2017 Nov;243:778-784.
    PMID: 28711807 DOI: 10.1016/j.biortech.2017.06.174
    In this work, a human hair-derived high surface area porous carbon material (HHC) was prepared using potassium hydroxide activation. The morphology and textural properties of the HHC structure, along with its adsorption performance for tetracycline (TC) antibiotics, were evaluated. HHC showed a high surface area of 1505.11m(2)/g and 68.34% microporosity. The effects of most important variables, such as initial concentration (25-355mg/L), solution pH (3-13), and temperatures (30-50°C), on the HHC adsorption performance were investigated. Isotherm data analysis revealed the favorable application of the Langmuir model, with maximum TC uptakes of 128.52, 162.62, and 210.18mg/g at 30, 40, and 50°C, respectively. The experimental data of TC uptakes versus time were analyzed efficiently using a pseudo-first order model. Porous HHC could be an efficient adsorbent for eliminating antibiotic pollutants in wastewater.
    Matched MeSH terms: Water Pollutants, Chemical/chemistry*
  13. Heavy metal concentrations in fishes from Juru River, estimation of the health risk
    Idriss AA, Ahmad AK
    Bull Environ Contam Toxicol, 2015 Feb;94(2):204-8.
    PMID: 25564001 DOI: 10.1007/s00128-014-1452-x
    This study examined the concentration of heavy metals in 13 fish species. The results indicated that shellfish species (clams) have the highest metal concentrations, followed by demersal and pelagic fishes. The mean concentration of metals in clams are Zn 88.74 ± 11.98 µg/g, Cu 4.96 ± 1.06 µg/g, Pb 1.22 ± 0.19 µg/g, Cd 0.34 ± 0.04 µg/g dry wt. basis, whereas the same measure in fish tissues was 58.04 ± 18.51, 2.47 ± 1.21, 0.58 ± 0.27 and 0.17 ± 0.08 µg/g dry wt. basis. The concentrations of heavy metals in clams and fish tissues were still lower than the maximum allowable concentrations as suggested by the Malaysian Food Act (1983) and are considered safe for local human consumption.
    Matched MeSH terms: Water Pollutants, Chemical/chemistry*
  14. Adsorption and photocatalytic degradation of anionic dyes on Chitosan/PVA/Na-Titanate/TiO2 composites synthesized by solution casting method
    Habiba U, Islam MS, Siddique TA, Afifi AM, Ang BC
    Carbohydr Polym, 2016 09 20;149:317-31.
    PMID: 27261756 DOI: 10.1016/j.carbpol.2016.04.127
    Chitosan/PVA/Na-titanate/TiO2 composite was synthesized by solution casting method. The composite was analyzed via Fourier Transform Infrared Spectroscopy, X-ray diffraction, Field Emission Scanning Electron Microscopy, Thermal gravimetric analysis and water stability test. Incorporation of Na-titanate shown decrease of crystallinity for chitosan but increase water stability. However, the composite structure was deteriorated with considerable weight loss in acidic medium. Two anionic dyes, methyl orange and congo red were used for the adsorption test. The adsorption behavior of the composites were described by pseudo-second-order kinetic model and Lagergren-first-order model for methyl orange and congo red, respectively. For methyl orange, adsorption was started with a promising decolorization rate. 99.9% of methyl orange dye was removed by the composite having higher weightage of chitosan and crystalline TiO2 phase. On the other hand, for the congo red the composite having higher chitosan and Na-titanate showed an efficient removal capacity of 95.76%. UV-vis results showed that the molecular backbone of methyl orange and congo red was almost destroyed when equilibrium was obtained, and the decolorization rate was reaching 100%. Kinetic study results showed that the photocatalytic degradation of methyl orange and congo red could be explained by Langmuir-Hinshelwood model. Thus, chitosan/PVA/Na-titanate/TiO2 possesses efficient adsorptivity and photocatalytic property for dye degradation.
    Matched MeSH terms: Water Pollutants, Chemical/chemistry
  15. Preparation of methacrylamide-functionalized crosslinked chitosan by free radical polymerization for the removal of lead ions
    Sutirman ZA, Sanagi MM, Abd Karim KJ, Wan Ibrahim WA
    Carbohydr Polym, 2016 Oct 20;151:1091-1099.
    PMID: 27474659 DOI: 10.1016/j.carbpol.2016.06.076
    A new poly(methacrylamide) grafted crosslinked chitosan was prepared for removal of lead, Pb(II) ion from aqueous solution. Crosslinked chitosan, in beads form, was grafted with methacrylamide (MAm) using ammonium persulfate (APS) as free radical initiator. Evidence of grafting was determined by comparing FTIR, TGA, SEM and (13)C NMR analyses of chitosan and graft copolymer. The optimal conditions for grafting reaction were as follow: crosslinked chitosan beads (1g), MAm (17.62×10(-1)M), APS (2.63×10(-1)M), reaction time (3h) and temperature (60°C). The modified chitosan bead was then used in laboratory batch experiments to evaluate the removal of Pb(II) ion from water samples. The Langmuir and Freundlich adsorption models were also applied to describe the equilibrium isotherms. The results revealed that the adsorption of Pb(II) ions onto the beads fitted very well with the Langmuir model with the maximum capacity (qmax) of 250mgg(-1).
    Matched MeSH terms: Water Pollutants, Chemical/chemistry*
  16. Novel Ag/cellulose-doped CeO2 quantum dots for efficient dye degradation and bactericidal activity with molecular docking study
    Ikram M, Hayat S, Imran M, Haider A, Naz S, Ul-Hamid A, et al.
    Carbohydr Polym, 2021 Oct 01;269:118346.
    PMID: 34294353 DOI: 10.1016/j.carbpol.2021.118346
    In the present study, the novel Ag/cellulose nanocrystal (CNC)-doped CeO2 quantum dots (QDs) with highly efficient catalytic performance were synthesized using one pot co-precipitation technique, which were then applied in the degradation of methylene blue and ciprofloxacin (MBCF) in wastewater. Catalytic activity against MBCF dye was significantly reduced (99.3%) for (4%) Ag dopant concentration in acidic medium. For Ag/CNC-doped CeO2 vast inhibition domain of G-ve was significantly confirmed as (5.25-11.70 mm) and (7.15-13.60 mm), while medium- to high-concentration of CNC levels were calculated for G + ve (0.95 nm, 1.65 mm), respectively. Overall, (4%) Ag/CNC-doped CeO2 revealed significant antimicrobial activity against G-ve relative to G + ve at both concentrations, respectively. Furthermore, in silico molecular docking studies were performed against selected enzyme targets dihydrofolate reductase (DHFR), dihydropteroate synthase (DHPS), and DNA gyrase belonging to folate and nucleic acid biosynthetic pathway, respectively to rationalize possible mechanism behind bactericidal potential of CNC-CeO2 and Ag/CNC-CeO2.
    Matched MeSH terms: Water Pollutants, Chemical/chemistry
  17. Simultaneous determination of organochlorine pesticides and bisphenol A in edible marine biota by GC-MS
    Santhi VA, Hairin T, Mustafa AM
    Chemosphere, 2012 Mar;86(10):1066-71.
    PMID: 22197311 DOI: 10.1016/j.chemosphere.2011.11.063
    A study to assess the level of organochlorine pesticides (OCPs) and bisphenol A (BPA) in edible marine biota collected from coastal waters of Malaysia was conducted using GC-MS and SPE extraction. An analytical method was developed and validated to measure the level of 15 OCPs and BPA simultaneously from five selected marine species. It was observed that some samples had low levels of p,p'-DDE, p,p'-DDT and p,p'- DDD ranging from 0.50 ng g(-1) to 22.49 ng g(-1) dry weight (d.w) but significantly elevated level of endosulfan I was detected in a stingray sample at 2880 ng g(-1) d.w. BPA was detected in 31 out of 57 samples with concentration ranging from below quantification level (LOQ: 3 ng g(-1)) to 729 ng g(-1) d.w. The presence of OCPs is most likely from past use although there is also indication of illegal use in recent times. The study also reveals that BPA is more widely distributed in coastal species caught off the coast of the most developed state. The potential health risk from dietary intakes of OCPs and BPA from the analysed fish species was negligible.
    Matched MeSH terms: Water Pollutants, Chemical/chemistry*
  18. Ozonation of parabens in aqueous solution: kinetics and mechanism of degradation
    Tay KS, Rahman NA, Abas MR
    Chemosphere, 2010 Dec;81(11):1446-53.
    PMID: 20875662 DOI: 10.1016/j.chemosphere.2010.09.004
    This study investigated the reaction kinetics and degradation mechanism of parabens (methylparaben, ethylparaben, propylparaben and butylparaben) during ozonation. Experiments were performed at pH 2, 6 and 12 to determine the rate constants for the reaction of protonated, undissociated and dissociated paraben with ozone. The rate constants for the reaction of ozone with dissociated parabens (3.3 × 10(9)-4.2 × 10(9)M(-1)s(-1)) were found to be 10(4) times higher than the undissociated parabens (2.5 × 10(5)-4.4 × 10(5)M(-1)s(-1)) and 10(7) times higher than with the protonated parabens (1.02 × 10(2)-1.38 × 10(2)M(-1)s(-1)). The second-order rate constants for the reaction between parabens with hydroxyl radicals were found to vary from 6.8 × 10(9) to 9.2 × 10(9)M(-1)s(-1). Characterization of degradation by-products (DBPs) formed during the ozonation of each selected parabens has been carried out using GCMS after silylation. Twenty DBPs formed during ozonation of selected parabens have been identified. Hydroxylation has been found to be the major reaction for the formation of the identified DBPs. Through the hydroxylation reaction, a variety of hydroxylated parabens was formed.
    Matched MeSH terms: Water Pollutants, Chemical/chemistry*
  19. Estrogenic chemicals and estrogenicity in river waters of South Korea and seven Asian countries
    Duong CN, Ra JS, Cho J, Kim SD, Choi HK, Park JH, et al.
    Chemosphere, 2010 Jan;78(3):286-93.
    PMID: 19931116 DOI: 10.1016/j.chemosphere.2009.10.048
    The effects of treatment processes on estrogenicity were evaluated by examining estradiol equivalent (EEQ) concentrations in influents and effluents of sewage treatment plants (STPs) located along Yeongsan and Seomjin rivers in Korea. The occurrence and distribution of estrogenic chemicals were also estimated for surface water in Korea and compared with seven other Asian countries including Laos, Cambodia, Vietnam, China, Indonesia, Thailand and Malaysia. Target compounds were nonylphenol (NP), octylphenol (OP), bisphenol A (BPA), estrone (E1), 17beta-estradiol (E2), 17alpha-ethynylestradiol (EE2) and genistein (Gen). Water samples were pretreated and analyzed by liquid-liquid extraction (LLE) and gas chromatography/mass spectrometry (GC/MS). The results showed that the treatment processes of Korean STPs were sufficient to reduce the estrogenic activity of municipal wastewater. The concentrations of phenolic xenoestrogens (i.e., NP, OP and BPA) in samples of Yeongsan and Seomjin rivers were smaller than those reported by previous studies in Korea. In most samples taken from the seven Asian countries, the presence of E2 and EE2 was a major contributor toward estrogenic activity. The EEQ concentrations in surface water samples of the seven Asian countries were at a higher level in comparison to that reported in European countries, America and Japan. However, further studies with more sampling frequencies and sampling areas should be carried out for better evaluation of the occurrence and distribution of estrogenic compounds in these Asian countries.
    Matched MeSH terms: Water Pollutants, Chemical/chemistry
  20. Fluoride removal by palm shell waste based powdered activated carbon vs. functionalized carbon with magnesium silicate: Implications for their application in water treatment
    Choong CE, Wong KT, Jang SB, Nah IW, Choi J, Ibrahim S, et al.
    Chemosphere, 2020 Jan;239:124765.
    PMID: 31520981 DOI: 10.1016/j.chemosphere.2019.124765
    In this study, palm shell activated carbon powder (PSAC) and magnesium silicate (MgSiO3) modified PSAC (MPSAC) were thoroughly investigated for fluoride (F-) adsorption. F- adsorption isotherms showed that PSAC and MPSAC over-performed some other reported F- adsorbents with adsorption capacities of 116 mg g-1 and 150 mg g-1, respectively. Interestingly, the MgSiO3 impregnated layer changed the adsorption behavior of F- from monolayer to heterogeneous multilayer based on the Langmuir and Freundlich isotherm models verified by chi-square test (X2). Thermodynamic parameters indicated that the F- adsorption on PSAC and MPSAC was spontaneous and exothermic. PSAC and MPSAC were characterized using FESEM-EDX, XRD, FTIR and XPS to investigate the F- adsorption mechanism. Based on the regeneration tests using NaOH (0.01 M), PSAC exhibited poor regeneration (<20%) while MPSAC had steady adsorption efficiencies (∼70%) even after 5 regeneration cycles. This is due to highly polarized C-F bond was found on PSAC while Mg-F bond was distinguished on MPSAC, evidently denoting that the F- adsorption is mainly resulted from the exchange of hydroxyl (-OH) group. It was concluded that PSAC would be a potential adsorbent for in-situ F- groundwater remediation due to its capability to retain F- without leaching out in a wide range pH. MPSAC would be an alternative adsorbent for ex-situ F- water remediation because it can easily regenerate with NaOH solution. With the excellent F- adsorption properties, both PSAC and MPSAC offer as promising adsorbents for F- remediation in the aqueous phase.
    Matched MeSH terms: Water Pollutants, Chemical/chemistry
Related Terms
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links