Displaying publications 261 - 280 of 468 in total

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  1. Distribution of linear alkylbenzenes (LABs) in riverine and coastal environments in South and Southeast Asia
    Isobe KO, Zakaria MP, Chiem NH, Minh le Y, Prudente M, Boonyatumanond R, et al.
    Water Res, 2004 May;38(9):2448-58.
    PMID: 15142807
    This paper reports the result of sewage pollution monitoring conducted in South and Southeast Asia during 1998-2003 using linear alkylbenzenes (LABs) as molecular tracers of sewage contamination. Eighty-nine water samples collected from Malaysia, Vietnam, and Japan (Tokyo), and 161 surface sediment samples collected from Tokyo, Thailand, Malaysia, Philippines, Vietnam, Cambodia, Indonesia, and India were analyzed for alkylbenzenes. The concentration range of SigmaLABs in river water particles in Southeast Asia (<0.005-0.913 microg/L) was comparable to or higher than those found in Tokyo (<0.005-0.638 microg/L). I/E ratios (a ratio of internal to external isomers of LABs) in tropical Asian waters were close to the value of LABs in raw sewage ( approximately 1) and much lower than those in secondary effluents (3-5). This suggests that untreated or inadequately treated sewage is discharged into the water. SigmaLABs concentrations in sediments from South and Southeast Asia ranged from <0.002-42.6 microg/g-dry with the highest concentration occurring at several populous cities. Low I/E ratios of the sediments with high SigmaLABs concentrations suggest a heavy load of untreated sewage. Clearly in view of the current data and evidence of the implications of sewage pollution, this paper highlights the necessity of the continuation of water treatment system improvement in tropical Asia.
    Matched MeSH terms: Fresh Water/chemistry
  2. Composition, sources, and bioavailability of nitrogen in a longitudinal gradient from freshwater to estuarine waters
    Jani J, Toor GS
    Water Res, 2018 06 15;137:344-354.
    PMID: 29571112 DOI: 10.1016/j.watres.2018.02.042
    Nitrogen (N) transport from land to water is a dominant contributor of N in estuarine waters leading to eutrophication, harmful algal blooms, and hypoxia. Our objectives were to (1) investigate the composition of inorganic and organic N forms, (2) distinguish the sources and biogeochemical mechanisms of nitrate-N (NO3-N) transport using stable isotopes of NO3- and Bayesian mixing model, and (3) determine the dissolved organic N (DON) bioavailability using bioassays in a longitudinal gradient from freshwater to estuarine ecosystem located in the Tampa Bay, Florida, United States. We found that DON was the most dominant N form (mean: 64%, range: 46-83%) followed by particulate organic N (PON, mean: 22%, range: 14-37%), whereas inorganic N forms (NOx-N: 7%, NH4-N: 7%) were 14% of total N in freshwater and estuarine waters. Stable isotope data of NO3- revealed that nitrification was the main contributor (36.4%), followed by soil and organic N sources (25.5%), NO3- fertilizers (22.4%), and NH4+ fertilizers (15.7%). Bioassays showed that 14 to 65% of DON concentrations decreased after 5-days of incubation indicating utilization of DON by microbes in freshwater and estuarine waters. These results suggest that despite low proportion of inorganic N forms, the higher concentrations and bioavailability of DON can be a potential source of N for algae and bacteria leading to water quality degradation in the estuarine waters.
    Matched MeSH terms: Fresh Water/chemistry
  3. Bioseparation of phycocyanin from Phormidium tergestinum using an aqueous two-phase system
    Tan JS, Abbasiliasi S, Lalung J, Tam YJ, Murugan P, Lee CK
    Prep Biochem Biotechnol, 2021;51(3):260-266.
    PMID: 32876520 DOI: 10.1080/10826068.2020.1808793
    This study aimed at purification of phycocyanin (PC) from Phormidium tergestinum using an aqueous two-phase system (ATPS) comprised of polyethylene glycol (PEG) and salts. The partitioning efficiency of PC in ATPS and the effect of phase composition, pH, crude loading, and neutral salts on purification factor and yield were investigated. Results showed that PC was selectively partitioned toward bottom phase of the system containing potassium phosphate. Under optimum conditions of 20% (w/w) PEG 4000, 10% (w/w) potassium phosphate, 20% (v/v) crude load at pH 7, with addition of 0.5% (w/w) NaCl, PC from P. tergestinum was partially purified up to 5.34-fold with a yield of 87.8%. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the molecular weight of PC was ∼19 kDa. Results from this study demonstrated ATPS could be used as a potential approach for the purification of PC from P. tergestinum.
    Matched MeSH terms: Water/chemistry
  4. Salinity effect on growth and toxin production of four tropical Alexandrium species (Dinophyceae)
    Lim PT, Ogata T
    Toxicon, 2005 May;45(6):699-710.
    PMID: 15804519
    Four tropical PSP toxins-producing dinoflagellates, Alexandrium minutum, Alexandrium tamiyavanichii, Alexandrium tamarense and Alexandrium peruvianum from Malaysian waters were studied to investigate the influences of salinity on growth and toxin production. Experiments were conducted on constant temperature 25 degrees C, 140 microE mol m(-2) s(-1) and under 14:10 light:dark photo-cycle with salinity ranged from 2 to 30 psu. The PSP-toxin congeners, GTX 1-6, STX, dcSTX, NEO and C1-C2 were analysed by high performance liquid chromatography. Salinity tolerance of the four species in decreasing order is A. minutum>A. peruvianum>A. tamarense>A. tamiyavanichii. Specific growth rates and maximum densities varied among these species with A. minutum recorded as the highest, 0.5 day(-1) and 6 x 10(4) cells L(-1). Toxin content decreased with elevated salinities in A. minutum, the highest toxin content was about 12 fmole cell(-1) at 5 psu. In A. tamiyavanichii, toxin content peaked at optimal growth salinity (20 and 25 psu). Toxin content of A. tamarense, somehow peaked at sub-optimal growth salinity (15 and 30 psu). Results of this study implied that salinity fluctuation not only influenced the growth physiology but also toxin production of these species.
    Matched MeSH terms: Water/chemistry*
  5. Fulltext Contamination of faecal coliforms in ice cubes sampled from food outlets in Kubang Kerian, Kelantan
    Noor Izani NJ, Zulaikha AR, Mohamad Noor MR, Amri MA, Mahat NA
    Trop Biomed, 2012 Mar;29(1):71-6.
    PMID: 22543605 MyJurnal
    The use of ice cubes in beverages is common among patrons of food outlets in Malaysia although its safety for human consumption remains unclear. Hence, this study was designed to determine the presence of faecal coliforms and several useful water physicochemical parameters viz. free residual chlorine concentration, turbidity and pH in ice cubes from 30 randomly selected food outlets in Kubang Kerian, Kelantan. Faecal coliforms were found in ice cubes in 16 (53%) food outlets ranging between 1 CFU/100mL to >50 CFU/ 100mL, while in the remaining 14 (47%) food outlets, in samples of tap water as well as in commercially bottled drinking water, faecal coliforms were not detected. The highest faecal coliform counts of >50 CFU/100mL were observed in 3 (10%) food outlets followed by 11-50 CFU/100mL and 1-10 CFU/100mL in 7 (23%) and 6 (20%) food outlets, respectively. All samples recorded low free residual chlorine concentration (<0.10mg/L) with the pH ranging between 5.5 and 7.3 and turbidity between 0.14-1.76 NTU. Since contamination by faecal coliforms was not detected in 47% of the samples, tap water and commercially bottled drinking water, it was concluded that (1) contamination by faecal coliforms may occur due to improper handling of ice cubes at the food outlets or (2) they may not be the water sources used for making ice cubes. Since low free residual chlorine concentrations were observed (<0.10mg/ L) in all samples as well as in both tap water and commercially bottled drinking water, with the pH ranged between 5.5-7.3, ineffective disinfection of water source as a contributing factor to such high counts of faecal coliforms in ice cubes also could not be ruled out. Therefore, a periodical, yet comprehensive check on the food outlets, including that of ice cube is crucial in ensuring better food and water for human consumption.
    Matched MeSH terms: Water/chemistry
  6. Fulltext An evaluation of the effectiveness of water iodinator system to supply iodine to selected schools in Terengganu, Malaysia
    Lim KK, Siti Rohana D, Zawiah A, Wan Nazaimoon WM
    Trop Biomed, 2006 Dec;23(2):172-8.
    PMID: 17322819 MyJurnal
    This is a cross-sectional study conducted from January to September 2004 in a group of school children aged 8 -10 years old. The schools and study subjects were selected using stratified systematic sampling technique. A total of 44 schools and 1100 subjects were selected from schools with iodinator and schools without iodinator. Samples collected were spot urine and drinking water. Dietary and iodised water consumption data were obtained from interviews. A total of 931 subjects (84.6%) responded; 558 (50.7%) from schools with iodinator and 373 (33.9%) from schools without iodinator. Results showed that in more than half (53.8%) of the schools with iodinators, mean water iodine level was below 25 microg/L. The study population in Terengganu was found to be mildly iodine deficient with an overall median urine iodine concentration (uIC) of 74 microg/L. Based on WHO criteria, 4.1% with uIC <20 microg/L (severe), 19.5% with uIC between 20-49 microg/L (moderate), 49.2% with uIC between 50-99 microg/L (mild) and 27.2% was iodine sufficient with uIC >100 microg/L. Majority of the study subjects were found to have high seafood intake (> 90%) and low in goitrogen food intake. This study suggests water iodinator system may not be a suitable method of supplying iodine and an alternative is needed in order to eradicate the iodine deficiency problem seen in some parts of Malaysia.
    Matched MeSH terms: Water/chemistry*
  7. Evaluating photo-degradation of COD and TOC in petroleum refinery wastewater by using TiO2/ZnO photo-catalyst
    Aljuboury DA, Palaniandy P, Abdul Aziz HB, Feroz S, Abu Amr SS
    Water Sci Technol, 2016 Sep;74(6):1312-1325.
    PMID: 27685961
    The aim of this study is to investigate the performance of combined solar photo-catalyst of titanium oxide/zinc oxide (TiO2/ZnO) with aeration processes to treat petroleum wastewater. Central composite design with response surface methodology was used to evaluate the relationships between operating variables for TiO2 dosage, ZnO dosage, air flow, pH, and reaction time to identify the optimum operating conditions. Quadratic models for chemical oxygen demand (COD) and total organic carbon (TOC) removals prove to be significant with low probabilities (<0.0001). The obtained optimum conditions included a reaction time of 170 min, TiO2 dosage (0.5 g/L), ZnO dosage (0.54 g/L), air flow (4.3 L/min), and pH 6.8 COD and TOC removal rates of 99% and 74%, respectively. The TOC and COD removal rates correspond well with the predicted models. The maximum removal rate for TOC and COD was 99.3% and 76%, respectively at optimum operational conditions of TiO2 dosage (0.5 g/L), ZnO dosage (0.54 g/L), air flow (4.3 L/min), reaction time (170 min) and pH (6.8). The new treatment process achieved higher degradation efficiencies for TOC and COD and reduced the treatment time comparing with other related processes.
    Matched MeSH terms: Waste Water/chemistry*
  8. Improvement of COD removal by controlling the substrate degradability during the anaerobic digestion of recalcitrant wastewater
    Kawai M, Nagao N, Kawasaki N, Imai A, Toda T
    J Environ Manage, 2016 Oct 01;181:838-846.
    PMID: 27449962 DOI: 10.1016/j.jenvman.2016.06.057
    The recalcitrant landfill leachate was anaerobically digested at various mixing ratios with labile synthetic wastewater to evaluate the degradation properties of recalcitrant wastewater. The proportion of leachate to the digestion system was increased in three equal steps, starting from 0% to 100%, and later decreased back to 0% with the same steps. The chemical oxygen demand (COD) for organic carbon and other components were calculated by analyzing the COD and dissolved organic carbon (DOC), and the removal efficiencies of COD carbon and COD others were evaluated separately. The degradation properties of COD carbon and COD others shifted owing to changing of substrate degradability, and the removal efficiencies of COD carbon and COD others were improved after supplying 100% recalcitrant wastewater. The UV absorptive property and total organic carbon (TOC) of each molecular size using high performance liquid chromatography (HPLC)-size exclusion chromatography (SEC) with UVA and TOC detectors were also investigated, and the degradability of different molecular sizes was determined. Although the SEC system detected extracellular polymeric substances (EPS), which are produced by microbes in stressful environments, during early stages of the experiment, EPS were not detected after feeding 100% recalcitrant wastewater. These results suggest that the microbes had acclimatized to the recalcitrant wastewater degradation. The high removal rates of both COD carbon and COD others were sustained when the proportion of labile wastewater in the substrate was 33%, indicating that the effective removal of recalcitrant COD might be controlled by changing the substrate's degradability.
    Matched MeSH terms: Waste Water/chemistry
  9. Investigation of mass attenuation coefficient of almond gum bonded Rhizophora spp. particleboard as equivalent human tissue using XRF technique in the 16.6-25.3 keV photon energy
    Ababneh B, Tajuddin AA, Hashim R, Shuaib IL
    Australas Phys Eng Sci Med, 2016 Dec;39(4):871-876.
    PMID: 27628943 DOI: 10.1007/s13246-016-0482-6
    This paper reports the novel use of almond gum as a binder in manufacturing Rhizophora spp. particleboard. X-ray fluorescence spectroscopy was employed for analysis under photon energy range of 16.6-25.3 keV. Results showed that almond gum-bonded Rhizophora spp. particleboard can be used as tissue-equivalent phantom in diagnostic radiation. The calculated mass attenuation coefficients of the particleboards were consistent with the values of water calculated using XCOM program for the same photon energies, with p values of 0.056, 0.069, and 0.077 for samples A8, C0, and C8, respectively. However, no direct relationship was found between the percentage of adhesive and the mass attenuation coefficient. The results positively supported the use of almond gum as a binding agent in the fabrication of particleboards, which can be used as a phantom material in dosimetric and quality control applications.
    Matched MeSH terms: Water/chemistry
  10. The application of iron mesh double layer as anode for the electrochemical treatment of Reactive Black 5 dye
    Mook WT, Ajeel MA, Aroua MK, Szlachta M
    J Environ Sci (China), 2017 Apr;54:184-195.
    PMID: 28391928 DOI: 10.1016/j.jes.2016.02.003
    In this work a novel anode configuration consisting of an iron mesh double layer is proposed for the electrochemical treatment of wastewater. The removal of Reactive Black 5 dye (RB5) from synthetic contaminated water was used as a model system. At a constant anode surface area, identical process operating parameters and batch process mode, the iron mesh double layer electrode showed better performance compared to the conventional single layer iron mesh. The double layer electrode was characterized by RB5 and chemical oxygen demand (COD) removal efficiency of 98.2% and 97.7%, respectively, kinetic rate constant of 0.0385/min, diffusion coefficient of 4.9×10(-5)cm(2)/sec and electrical energy consumption of 20.53kWh/kgdye removed. In the continuous flow system, the optimum conditions suggested by Response Surface Methodology (RSM) are: initial solution pH of 6.29, current density of 1.6mA/cm(2), electrolyte dose of 0.15g/L and flow rate of 11.47mL/min which resulted in an RB5 removal efficiency of 81.62%.
    Matched MeSH terms: Waste Water/chemistry
  11. Treatment of urea manufacturing facility effluent by Hopea odorata and Khaya ivorensis
    Yavari S, Malakahmad A, Sapari NB, Yavari S
    Water Sci Technol, 2017 Apr;75(7-8):1684-1692.
    PMID: 28402310 DOI: 10.2166/wst.2017.043
    Phytoremediation is an environmentally friendly and sustainable alternative for treatment of nitrogen-enriched wastewaters. In this study, Ta-khian (Hopea odorata) and Lagos mahogany (Khaya ivorensis), two tropical timber plants, were investigated for their performances in treatment of urea manufacturing factory effluent with high nitrogen (N) content. Plant seedlings received four concentrations of N (190, 240, 290 and 340 mg/L N) in laboratory-scale constructed wetlands every 4 days for a duration of 8 weeks. The solution volumes supplied to each container, amount of N recovered by plants and plant growth characteristics were measured throughout the experiment. Results showed that Ta-khian plants were highly effective at reducing N concentration and volume of water. A maximum of 63.05% N recovery was obtained by Ta-khian plants grown in 290 mg/L N, which was assimilated in the chlorophyll molecule structure and shoot biomass. Significant positive correlations have been shown between N recovery percentages and plant growth parameters. Ta-Khian plants can be applied as suitable phytoremediators for mitigating N pollution in water sources.
    Matched MeSH terms: Waste Water/chemistry
  12. Photocatalytic degradation of oilfield produced water using graphitic carbon nitride embedded in electrospun polyacrylonitrile nanofibers
    Alias NH, Jaafar J, Samitsu S, Yusof N, Othman MHD, Rahman MA, et al.
    Chemosphere, 2018 Aug;204:79-86.
    PMID: 29653325 DOI: 10.1016/j.chemosphere.2018.04.033
    Separation and purification of oilfield produced water (OPW) is a major environmental challenge due to the co-production of the OPW during petroleum exploration and production operations. Effective capture of oil contaminant and its in-situ photodegradation is one of the promising methods to purify the OPW. Based on the photocatalytic capability of graphitic carbon nitride (GCN) which was recently rediscovered, photodegradation capability of GCN for OPW was investigated in this study. GCN was synthesized by calcination of urea and further exfoliated into nanosheets. The GCNs were incorporated into polyacrylonitrile nanofibers using electrospinning, which gave a liquid-permeable self-supporting photocatalytic nanofiber mat that can be handled by hand. The photocatalytic nanofiber demonstrated 85.4% degradation of OPW under visible light irradiation, and improved the degradation to 96.6% under UV light. Effective photodegradation of the photocatalytic nanofiber for OPW originates from synergetic effects of oil adsorption by PAN nanofibers and oil photodegradation by GCNs. This study provides an insight for industrial application on purification of OPW through photocatalytic degradation under solar irradiation.
    Matched MeSH terms: Water/chemistry*
  13. Development of a PVS2 droplet-vitrification cryopreservation technique for Aranda Broga Blue orchid protocorm-like bodies (PLBs)
    Ping KS, Poobathy RR, Zakaria R, Subramaniam S
    Cryo Letters, 2018 5 8;38(4):290-298.
    PMID: 29734430
    　　BACKGROUND: Conservation of commercially important ornamental plants is important to maintain its unique beauty to cater the market demands.

    OBJECTIVE: The main objective is to develop an efficient cryopreservation technique for Aranda Broga Blue orchid PLBs using droplet-vitrification method.

    MATERIALS AND METHODS: Several critical factors in cryopreservation were accessed such as preculture concentrations and durations, choice of vitrification solutions, two-step or three-step vitrification, growth recovery medium and PVS2 exposure duration.

    RESULTS: The best growth regeneration percentage (5%) was obtained when 3-4mm PLBs were precultured in 0.2M sucrose for 3 days, followed by osmoprotection for 20 minutes, dehydration in PVS2 for 20 minutes at 0 degree C, LN storage, thawed and unloading for 20 minutes, and growth regeneration in VW10 medium. PLBs were found to be very sensitive to osmotic stress imposed by high molecular weight cryoprotectant such as sucrose and glycerol. Osmotic potential of growth recovery medium is one of the main factors that affect growth recovery in cryopreserved PLBs.

    CONCLUSION: Current report showed possibilities in cryopreserving Aranda Broga Blue PLBs using droplet-vitrification technique. However, further improvement of growth recovery can be done by focussing on approaches that facilitate sufficient water removal from PLBs without causing severe osmotic injuries to the plant cells.

    Matched MeSH terms: Water/chemistry
  14. Characterisation of β-carotene partitioning in protein emulsions: Effects of pre-treatments, solid fat content and emulsifier type
    Wan Mohamad WAF, McNaughton D, Augustin MA, Buckow R
    Food Chem, 2018 Aug 15;257:361-367.
    PMID: 29622223 DOI: 10.1016/j.foodchem.2018.03.027
    Understanding the bioactive partitioning between the phases of an emulsion system underpins strategies for improving the efficiency of bioactive protection against degradation. We analysed partitioning of β-carotene in emulsions with various formulations in-situ using confocal Raman microscopy (CRM). The partitioning of β-carotene into the aqueous phase of emulsions increased when whey protein isolate (WPI) was heat or high pressure-treated prior to emulsion formation. However, increasing the concentration of high pressure-treated WPI reduced the β-carotene partitioning into the aqueous phase. Increasing the solid fat content in the carrier oil favoured the migration of β-carotene into the aqueous phase. The use of WPI as the emulsifier resulted in a greater partitioning of β-carotene into the aqueous phase compared to when Tween 40 was the emulsifier. This study demonstrates that partitioning of β-carotene between the aqueous and oil phase is dependent on the characteristics of the oil phase, emulsifier type and processing.
    Matched MeSH terms: Water/chemistry
  15. Fulltext Novel preparation of highly photocatalytically active copper chromite nanostructured material via a simple hydrothermal route
    Beshkar F, Zinatloo-Ajabshir S, Bagheri S, Salavati-Niasari M
    PLoS One, 2017;12(6):e0158549.
    PMID: 28582420 DOI: 10.1371/journal.pone.0158549
    Highly photocatalytically active copper chromite nanostructured material were prepared via a novel simple hydrothermal reaction between [Cu(en)2(H2O)2]Cl2 and [Cr(en)3]Cl3.3H2O at low temperature, without adding any pH regulator or external capping agent. The as-synthesized nanostructured copper chromite was analyzed by transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy, energy dispersive X-ray microanalysis (EDX), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. Results of the morphological investigation of the as-synthesized products illustrate that the shape and size of the copper chromite depended on the surfactant sort, reaction duration and temperature. Moreover, the photocatalytic behavior of as-obtained copper chromite was evaluated by photodegradation of acid blue 92 (anionic dye) as water pollutant.
    Matched MeSH terms: Fresh Water/chemistry
  16. Fulltext Green Synthesis of Zinc Oxide Nanoparticles for Enhanced Adsorption of Lead Ions from Aqueous Solutions: Equilibrium, Kinetic and Thermodynamic Studies
    Azizi S, Mahdavi Shahri M, Mohamad R
    Molecules, 2017 Jun 08;22(6).
    PMID: 28594362 DOI: 10.3390/molecules22060831
    In the present study, ZnO nanoparticles (NPs) were synthesized in zerumbone solution by a green approach and appraised for their ability to absorb Pb(II) ions from aqueous solution. The formation of as-synthesized NPs was established by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), and UV-visible studies. The XRD and TEM analyses revealed high purity and wurtzite hexagonal structure of ZnO NPs with a mean size of 10.01 ± 2.6 nm. Batch experiments were performed to investigate the impact of process parameters viz. Pb(II) concentration, pH of solution, adsorbent mass, solution temperature, and contact time variations on the removal efficiency of Pb(II). The adsorption isotherm data provided that the adsorption process was mainly monolayer on ZnO NPs. The adsorption process follows pseudo-second-order reaction kinetic. The maximum removal efficiencies were 93% at pH 5. Thermodynamic parameters such as enthalpy change (ΔH⁰), free energy change (ΔG⁰), and entropy change (ΔS⁰) were calculated; the adsorption process was spontaneous and endothermic. The good efficiency of the as-synthesized NPs makes them attractive for applications in water treatment, for removal of heavy metals from aqueous system.
    Matched MeSH terms: Water/chemistry
  17. Simultaneous electromembrane extraction of cationic and anionic herbicides across hollow polymer inclusion membranes with a bubbleless electrode
    Mamat NA, See HH
    J Chromatogr A, 2017 Jun 30;1504:9-16.
    PMID: 28499598 DOI: 10.1016/j.chroma.2017.05.005
    A new electric-field driven extraction approach based on the integration of a bubbleless electrode into the electromembrane extraction (EME) across hollow polymer inclusion membranes (HPIMs) was demonstrated for the first time. The bubbleless electrode was prepared based on an in-situ synthesised polyacrylamide within a fused silica capillary. The electrode functions as a salt bridge, which conducts the electrical current between the acceptor phase in the lumen of the HPIM and the acceptor solution in the reservoir connected to a high voltage supply through a platinum electrode. Two types of HPIMs were employed, which consisted of desired proportions of cellulose acetate as base polymer, tris(2-ethylhexyl)phosphate as plasticizer, and di-(2-ethylhexyl)phosphoric acid as anionic carrier or Aliquat 336 as cationic carrier, respectively. The EME strategy was evaluated for the simultaneous determination of cationic quaternary ammonium and anionic chlorophenoxy acetic acid herbicides present in the river water, respectively. The analysis was carried out using capillary electrophoresis coupled with UV and contactless conductivity detection. Under the optimised conditions, enrichment factors in the range of 152-185-fold were obtained from 4mL of river water sample with a 20min extraction time and an applied voltage of 3000V. The proposed method provided good linearity with correlation coefficients ranging from 0.9982 to 0.9997 over a concentration range of 1-1000μg/L. The detection limits of the method for the herbicides were in the range of 0.3-0.4μg/L, with relative standard deviations of between 4.8% and 8.5%. The relative recoveries obtained when analysing the spiked river water ranged from 99.1% to 100%. A comparison was also made between the newly developed approach with the conventional EME setup by placing the platinum electrode directly in the lumen of the HPIMs.
    Matched MeSH terms: Fresh Water/chemistry
  18. Optimisation of Reactive Black 5 dye removal by electrocoagulation process using response surface methodology
    Mook WT, Aroua MK, Szlachta M, Lee CS
    Water Sci Technol, 2017 02;75(3-4):952-962.
    PMID: 28234295 DOI: 10.2166/wst.2016.563
    In this work, a regression model obtained from response surface methodology (RSM) was proposed for the electrocoagulation (EC) treatment of textile wastewater. The Reactive Black 5 dye (RB5) was used as a model dye to evaluate the performance of the model design. The effect of initial solution pH, applied current and treatment time on RB5 removal was investigated. The total number of experiments designed by RSM amounted to 27 runs, including three repeated experimental runs at the central point. The accuracy of the model was evaluated by the F-test, coefficient of determination (R(2)), adjusted R(2) and standard deviation. The optimum conditions for RB5 removal were as follows: initial pH of 6.63, current of 0.075 A, electrolyte dose of 0.11 g/L and EC time of 50.3 min. The predicted RB5 removal was 83.3% and the percentage error between experimental and predicted results was only 3-5%. The obtained data confirm that the proposed model can be used for accurate prediction of RB5 removal. The value of the zeta potential increased with treatment time, and the X-ray diffraction pattern shows that iron complexes were found in the sludge.
    Matched MeSH terms: Waste Water/chemistry*
  19. Dynamic Interfacial Adhesion through Cucurbit[n]uril Molecular Recognition
    Liu J, Tan CSY, Scherman OA
    Angew Chem Int Ed Engl, 2018 07 16;57(29):8854-8858.
    PMID: 29663607 DOI: 10.1002/anie.201800775
    Supramolecular building blocks, such as cucurbit[n]uril (CB[n])-based host-guest complexes, have been extensively studied at the nano- and microscale as adhesion promoters. Herein, we exploit a new class of CB[n]-threaded highly branched polyrotaxanes (HBP-CB[n]) as aqueous adhesives to macroscopically bond two wet surfaces, including biological tissue, through the formation of CB[8] heteroternary complexes. The dynamic nature of these complexes gives rise to adhesion with remarkable toughness, displaying recovery and reversible adhesion upon mechanical failure at the interface. Incorporation of functional guests, such as azobenzene moieties, allows for stimuli-activated on-demand adhesion/de-adhesion. Macroscopic interfacial adhesion through dynamic host-guest molecular recognition represents an innovative strategy for designing the next generation of functional interfaces, biomedical devices, tissue adhesives, and wound dressings.
    Matched MeSH terms: Water/chemistry
  20. Cloud-point extraction of green-polymers from Cupriavidus necator lysate using thermoseparating-based aqueous two-phase extraction
    Leong YK, Lan JC, Loh HS, Ling TC, Ooi CW, Show PL
    J Biosci Bioeng, 2017 Mar;123(3):370-375.
    PMID: 27745851 DOI: 10.1016/j.jbiosc.2016.09.007
    Polyhydroxyalkanoates (PHAs), a class of renewable and biodegradable green polymers, have gained attraction as a potential substitute for the conventional plastics due to the increasing concern towards environmental pollution as well as the rapidly depleting petroleum reserve. Nevertheless, the high cost of downstream processing of PHA has been a bottleneck for the wide adoption of PHAs. Among the options of PHAs recovery techniques, aqueous two-phase extraction (ATPE) outshines the others by having the advantages of providing a mild environment for bioseparation, being green and non-toxic, the capability to handle a large operating volume and easily scaled-up. Utilizing unique properties of thermo-responsive polymer which has decreasing solubility in its aqueous solution as the temperature rises, cloud point extraction (CPE) is an ATPE technique that allows its phase-forming component to be recycled and reused. A thorough literature review has shown that this is the first time isolation and recovery of PHAs from Cupriavidus necator H16 via CPE was reported. The optimum condition for PHAs extraction (recovery yield of 94.8% and purification factor of 1.42 fold) was achieved under the conditions of 20 wt/wt % ethylene oxide-propylene oxide (EOPO) with molecular weight of 3900 g/mol and 10 mM of sodium chloride addition at thermoseparating temperature of 60°C with crude feedstock limit of 37.5 wt/wt %. Recycling and reutilization of EOPO 3900 can be done at least twice with satisfying yield and PF. CPE has been demonstrated as an effective technique for the extraction of PHAs from microbial crude culture.
    Matched MeSH terms: Water/chemistry*
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