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| Registros recuperados: 43 | |
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| Qaiser,Suleman; Saleemi,Anwar R; Umar,Muhammad. |
| The biosorption of lead(II) and chromium(VI) on groundnut hull was investigated. Batch biosorption experiments were conducted to find the equilibrium time and biosorption capacity. Effect of parameters like pH, temperature and initial metal concentration was studied. The maximum biosorption capacity of lead(II) and chromium(VI) was found to be 31.54 ± 0.63 and 30.21 ± 0.74 mg g-1, respectively. The optimum pH for lead(II) and chromium(VI) removal was 5 ± 0.1 and 2 ± 0.1, respectively. The temperature change, in the range of 20 - 45ºC affected the biosorption capacity. The maximum removal of lead(II) was achieved at 20 ± 2ºC, where as maximum uptake of chromium(VI) was observed at 40 ± 2ºC. The biosorption data was fitted to the Langmuir and the Freundlich... |
| Tipo: Journal article |
Palavras-chave: Biosorption; Equilibrium; Groundnut hull; Kinetics; Thermodynamics. |
| Ano: 2009 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582009000400003 |
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| Ahmed,Sibtain; Imdad,Syeda Sana; Jamil,Amer. |
| Xylanases assume special importance in the paper and pulp industry as they replace toxic chemicals such as chlorine and chlorine dioxide for developing eco-friendly processes. This study evaluated xylanases produced by two fungi, the mesophilic fungus Trichoderma harzianum and a thermophilic fungus Chaetomium thermophilum. Among the polymeric substrates studied for xylanase production by both the fungi, birch wood xylan was found to be the best inducer of xylanases. Xylanases induction was subject to glucose repression. Partially purified xylanases preparation from T. harzianum and C. thermophilum exhibited optimal activities at pH 5 and 6 and at 60ºC and 70ºC, respectively. The apparent Km and Vmax values for the partially purified xylanase from T.... |
| Tipo: Journal article |
Palavras-chave: C. thermophilum; Kinetics; T. harzianum; Xylanase. |
| Ano: 2012 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582012000300003 |
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| Oliva-Merencio,Deny; Pereda-Reyes,Ileana; Schimpf,Ulrike; Koehler,Stefan; Silva,Ariovaldo J. da. |
| ABSTRACT This paper studied the effect of adding an enzyme (ellulose) on anaerobic digestion of maize silage. We compared materials at chopping lengths of 8 mm (MSL), 4mm (MSS) and natural size (Ms) under a mesophilic and discontinuous operation (batch process). Hence, we found the process to be significantly influenced by particle size. Moreover, the ellulose addition did not significantly impact biogas production after a 35-day digestion period. Ms and MSS displayed an improved response to all variables when compared with MSL and MSL+C, with significant differences. Studies on the refractory fraction at infinite time (R0) have demonstrated that the lowest values correspond to Ms and MSS (0.122 and 0.155, respectively). The Kinetic approach and the... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Ellulose; Silage; Biogas; Kinetics; Biodegradability. |
| Ano: 2015 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-69162015000500951 |
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| Jauzein, Cecile; Couet, Douglas; Blasco, Thierry; Lemee, Rodolphe. |
| Environmental factors that shape dynamics of benthic toxic blooms are largely unknown. In particular, for the toxic dinoflagellate Ostreopsis cf. ovata, the importance of the availability of nutrients and the contribution of the inorganic and organic pools to growth need to be quantified in marine coastal environments. The present study aimed at characterizing N-uptake of dissolved inorganic and organic sources by O. cf. ovata cells, using the 15N-labelling technique. Experiments were conducted taking into account potential interactions between nutrient uptake systems as well as variations with the diel cycle. Uptake abilities of O. cf. ovata were parameterized for ammonium (NH4+), nitrate (NO3−) and N-urea, from the estimation of kinetic and inhibition... |
| Tipo: Text |
Palavras-chave: Uptake; Nitrogen; Dinoflagellate; Ostreopsis; Kinetics; Interactions. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00382/49368/49840.pdf |
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| Metian, M; Warnau, M; Oberhansli, F; Teyssie, J; Bustamante, Paco. |
| The uptake and loss kinetics of Cd were determined in two species of scallops from the European coasts, the variegated scallop Chlamys varia and the king scallop Pecten maximus, following exposures via seawater, phytoplankton and sediment using highly sensitive radiotracer techniques (Cd-109). Results indicate that, for seawater and dietary pathways, C. varia displays higher bioaccumulation capacities in terms of uptake rate from water and fraction absorbed from ingested food (assimilation efficiency) than Pecten maximus. Regarding sediment exposure, P. maximus displayed low steady-state Cd transfer factor (TFSS < 1); however, once incorporated, a very large part of Cd transferred from sediment (92%) was strongly retained within R maximus tissues.... |
| Tipo: Text |
Palavras-chave: Subcellular distribution; Scallops; Metal; Kinetics; Cadmium; Bivalves. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-3581.pdf |
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| Baron, Regis; Couedel, Marielle; Joret, Camille; Garen, Pierre; Truquet, Philippe; Masselin, Pierre; Bardouil, Michele; Lassus, Patrick. |
| A simple system was used to simulate the effect of alternating toxic (paralytic shellfish poisoning toxins) and non-toxic microalgal diets on oyster feeding behaviors and rates of toxin accumulation. These experimental conditions were meant to reflect, to some extent, the incoming and outgoing fluxes of toxic algae observed at the mouth of the Penze estuary (Northern Brittany, France). Physiological and toxicological parameters were estimated based oil fluorescence measurements recorded continuously at the outlet of each experimental tank, which contained a single oyster. Q(tox), this variable describes toxin uptake in oysters, it was used (instead of the toxin ingestion rate): i) in simple graphical analyses, ii) as well as in one- and two-compartment... |
| Tipo: Text |
Palavras-chave: Skeletonema costatum; Alexandrium minutum; Fluorescence; Modeling; Kinetics; Toxin uptake; Shellfish toxin; PSP. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-1400.pdf |
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| Richaud, Emmanuel; Le Gac, Pierre-yves; Verdu, Jacques. |
| Thermal ageing of thin films of unstabilized polydicyclopentadiene (pDCPD) at several temperatures ranging from 120 to 30°C was investigated by means of carbonyl build up by FTIR with ammonia derivatization, double bond titration, mass uptake measurement, hydroperoxides titration by iodometry and DSC coupled with sulfur dioxide treatment. In the temperature range under investigation, pDCPD is in glassy state and it oxidizes faster than common polymers oxidized at rubbery state (e.g. polydienic elastomers). Using the kinetic analysis, these results were ascribed to increased initiation rate due to catalyst residues, some possible intramolecular processes favoring propagation, or a very low termination rate of oxidation radical chains because of the control... |
| Tipo: Text |
Palavras-chave: Polydicyclopentadiene; Thermal oxidation; Kinetics; Molecular mobility. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00175/28646/27073.pdf |
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| Le Gac, Pierre Yves; Roux, Gerard; Verdu, Jacques; Davies, Peter; Fayolle, Bruno. |
| Thermal oxidation in air at atmospheric pressure, in the 80-140°C temperature range and in oxygen at 100°C in the 0.02-3 MPa pressure range, of unvulcanized, unstabilized, unfilled polychloroprene (CR) has been characterized using FTIR and chlorine concentration measurement. The kinetic analysis was focused on double bond consumption. A mechanistic scheme involving unimolecular and bimolecular hydroperoxide decomposition, oxygen addition to alkyl radicals, hydrogen abstraction on allylic methylenes, alkyl and peroxyl additions to double bonds and terminations involving alkyl and peroxy radicals was elaborated. The corresponding rate constants were partly extracted from the literature and partly determined from experimental data using the kinetic model... |
| Tipo: Text |
Palavras-chave: Polychloroprene; Oxidation; Radical chain; Kinetics. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00199/31010/29413.pdf |
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| Ruffine, Livio. |
| To gain in-depth understanding of natural gas hydrate behavior it is necessary to identify key parameters that affect their formation, distribution and destabilization within sediments. Hydrate formation kinetics in porous media is amongst the aspects which deserve important considerations as it may provide useful information on the formation history and the formation mechanisms of natural gas hydrate accumulations. Yet, it is at its early stage. In this paper, experiments on methane hydrate formation and dissociation in porous media are reported and discussed. The first part of this work is devoted to the investigation of the kinetics of methane hydrate formation within silica sand using a custom-design apparatus. The latter is suitable for investigating... |
| Tipo: Text |
Palavras-chave: Geologic matrices; Hydrate morphology; Kinetics; Methane hydrates; Novel apparatus. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00245/35580/34209.pdf |
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| Abdel Wahab, O.. |
| The present investigation deals with the utilization of marine green algae (GA), Ulva lactuca, and an activated carbon prepared from green algae (CGA) as adsorbents for the removal of copper from wastewater. A series of experiments were conducted in a batch system to evaluate the effect of system variables. The effect of pH, initial copper concentration, dose of adsorbents were considered. The optimal pH value of copper (II) adsorption onto GA and CGA was found to be pH 5.0. The maximum uptake capacities were 24.5 and 32.3 mg copper (II) per gram of GA and CGA, respectively. The efficiency of removal was slightly changed by replacing an aqueous solution by saline water or wastewater containing the same copper concentration. Adsorption kinetic data were... |
| Tipo: Journal Contribution |
Palavras-chave: Laboratory Study; Adsorption; Kinetics; Isotherms; Waste water; Adsorption; Http://aims.fao.org/aos/agrovoc/c_137. |
| Ano: 2007 |
URL: http://hdl.handle.net/1834/1910 |
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| Roekens, E.J.; Van Grieken, R.E.. |
| The rate of iron(II) oxidation in the North Sea water of pH 5.5-10 in the range 10-25°C has been studied. The oxygenation rate depends linearly on the iron(II) and dissolved oxygen concentrations. The second-order dependence on (OH<sup>-</sup>), found by several investigators for synthetic solutions, was confirmed in seawater, but only for pOH>6.9. For pOH<5.9 the rate appeared to be independent of the pOH. In the intermediate range, pOH<5.9-6.9, corresponding to the natural pH of seawater, a first-order dependence on the pOH is obeyed. The important discrepancy in the literature between the second-order rate constant for NaCHO<sub>3</sub> solutions and for seawater can be attributed predominantly to the incorrect... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Iron; Kinetics; Oxidation. |
| Ano: 1983 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3293 |
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| Registros recuperados: 43 | |
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