Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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    We will mail you new results for this query: keywords==calcium carbonate
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Thermally Responsive Capillary Suspensions
Das, Anupam A.K. ; Dunstan, Timothy S. ; Stoyanov, Simeon D. ; Starck, Pierre ; Paunov, Vesselin N. - \ 2017
ACS Applied Materials and Interfaces 9 (2017)50. - ISSN 1944-8244 - p. 44152 - 44160.
agarose - calcium carbonate - capillary structuring - capillary suspension - methyl cellulose - thermally responsive hydrogels
We demonstrate that stimulus-responsive capillary-structured materials can be formed from hydrophobized calcium carbonate particles suspended in a non-polar phase (silicone oil) and bridged by very small amounts of a hydrogel as the secondary aqueous phase. Inclusion of thermally responsive polymers into the aqueous phase yielded a capillary-structured suspension whose rheology is controlled by a change in temperature and can increase its complex modulus by several orders of magnitude because of the gelation of the capillary bridges between the solid particles. We demonstrate that the rheology of the capillary suspension and its response upon temperature changes can be controlled by the gelling properties as little as 0.1 w/w % of the secondary aqueous phase containing 2 wt % of the gelling carbohydrate. Doping the secondary (aqueous) phase with methyl cellulose, which gels at elevated temperatures, gave capillary-structured materials whose viscosity and structural strength can increase by several orders of magnitude as the temperature is increased past the gelling temperature of the methyl cellulose solution. Increasing the methyl cellulose concentration from 0 to 2 w/w % in the secondary (aqueous) phase increases the complex modulus and the yield stress of the capillary suspension of 10 w/w % hydrophobized calcium carbonate in silicone oil by 2 orders of magnitude at a fixed temperature. By using an aqueous solution of a low melting point agarose as a secondary liquid phase, which melts as the temperature is raised, we produced capillary-structured materials whose viscosity and structural strength can decrease by several orders of magnitude as the temperature is increased past the melting temperature of the agarose solution. The development of thermally responsive capillary suspensions can find potential applications in structuring of smart home and personal care products as well as in temperature-triggered change in rheology and release of flavors in foods and actives in pharmaceutical formulations.
Invloed van eiwitgehalte en toevoeging calciumchloride op de ammoniakemissie uit vleesvarkensstallen = Effects of protein content and addition of calcium chloride in the diet on ammonia enission from houses for growing-finishing pigs
Smits, M.C.J. ; Hol, J.M.G. ; Peet-Schwering, C.M.C. van der; Aarnink, A.J.A. - \ 2012
Wageningen : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 588) - 38
varkenshouderij - vleesproductie - varkensstallen - stalklimaat - ammoniakemissie - monitoring - varkensvoeding - voersamenstelling - calciumcarbonaat - calciumchloride - pig farming - meat production - pig housing - stall climate - ammonia emission - pig feeding - feed formulation - calcium carbonate - calcium chloride
The effects on the emissions from pig houses of a low protein diet with and without the partial replacement of calcium carbonate by calcium chloride were studied.
Impact of location of CaCO3 precipitation on the development of intact anaerobic sludge
Langerak, E.P.A. van; Ramaekers, H. ; Wiechers, J. ; Veeken, A.H.M. ; Hamelers, H.V.M. ; Lettinga, G. - \ 2000
Water Research 34 (2000)2. - ISSN 0043-1354 - p. 437 - 446.
afvalwaterbehandeling - anaërobe behandeling - calciumcarbonaat - chemische precipitatie - biofilms - modellen - slib - waste water treatment - anaerobic treatment - calcium carbonate - chemical precipitation - models - sludges
The development of intact anaerobic granular sludge was studied in UASB reactors under varying conditions of CaCO3 precipitation and biomass yield. Varying precipitating quantities were obtained using different calcium concentrations in the influent and different biomass yields were obtained by feeding with completely or partly acidified substrate. Four reactors were operated at a constant organic loading rate of 13<space>g COD l-1 d-1. Treatment of completely acidified waste water with high calcium concentrations (780-1560 mgCa2 l-1) resulted in the rapid formation of dense granules with a high ash content of which the specific methanogenic activity rapidly dropped and which easily agglomerated, leading to serious cementation of the sludge bed. At a lower influent calcium concentration (390 mgCa2 l-1), treatment of completely acidified waste water resulted in precipitation on reactor compartments, while precipitation within the aggregates did hardly take place. The presence of a fraction of non-acidified substrate retarded cementation of the sludge bed and resulted in development of sludge with a high ash content and a satisfactory quality. The biofilm model developed was shown to provide a clear, qualitative insight in the factors that affect the location of precipitation, and thereby the quality of high ash content sludge. Moreover, it explains the differences observed in the location of precipitation during the experiments. A low Ca/Na ratio, a small granule diameter and a high crystallization rate constant (=low CaCO3 growth inhibition) were found to stimulate precipitation in the bulk solution, and are considered to be favourable parameters for the development of sludge with a high ash content and a good quality.
Control of calcium carbonate precipitation in anaerobic reactors
Langerak, E.P.A. van - \ 1998
Agricultural University. Promotor(en): G. Lettinga. - S.l. : Van Langerak - ISBN 9789054859239 - 112
anaërobe behandeling - afvalwater - calcium - calciumcarbonaat - neerslag - anaërobe omstandigheden - chemische precipitatie - rioolslib - biomassa - fosfaat - kristallisatie - anaerobic treatment - waste water - calcium carbonate - precipitation - anaerobic conditions - chemical precipitation - sewage sludge - biomass - phosphate - crystallization
<p>Anaerobic treatment of waste waters with a high calcium content may lead to excessive precipitation of calcium carbonate. So far, no proper methods were available to predict or reduce the extent of precipitation in an anaerobic treatment system. Moreover, it also was not clear to what extent precipitation in an anaerobic reactor can be tolerated because adequate knowledge on the structure and quality of methanogenic sludges with high calcium carbonate content was lacking. In this thesis, the feasibility of anaerobic treatment of waste waters with a high calcium content was investigated.</p><p>The development of high ash content anaerobic sludges was studied under varying conditions of biomass yield, precipitating quantities of CaCO <sub>3</sub> and particle size of the seed sludge. The location of CaCO <sub>3</sub> precipitation, within the aggregates or in the bulk solution, appeared to be an important factor determining the quality of high ash content sludges. Precipitation in the bulk solution is considered as favourable for the development of these sludges and can in example be stimulated by seeding with the smallest possible granules or by maintaining the phosphate concentration as low as possible. Operating a reactor containing heavy sludge is often problematical because the crystals will tend to agglomerate, resulting in cementation of the sludge bed. This cementation can be retarded by decreasing the degree of pre-acidification.</p><p>Two different options can be distinguished to reduce the extent of calcium carbonate precipitation in an anaerobic reactor. It was found that phosphate, in concentrations of 0.5 - 5 mgP.l <sup>-1</SUP>, can drastically reduce the quantity of calcium carbonate precipitation. Additives that only inhibit the formation of calcite and not that of aragonite (e.g. iron) are not suitable, because in that case aragonite, of which the solubility is only slightly lower than of calcite, will accumulate in the reactor. The second option is to remove calcium from the influent in a crystallization reactor reusing the anaerobic effluent alkalinity.</p><p>The amount of calcium carbonate precipitation in an anaerobic reactor can be estimated with equilibrium models as developed in this dissertation, which take into account kinetic factors that influence the apparent solubility of calcium carbonate, being the influent composition, the hydraulic retention time and the value of the crystallization rate constant.</p><p>In this dissertation, insights have been provided for the design and application of integrated anaerobic-physical-chemical technologies which enable the control of the calcium carbonate precipitation in the anaerobic treatment of waste water with a high calcium content, which appear e.g. in the waste-paper and food processing industries.</p>
Invloed van bekalking van rivierklei met calciumcarbonaat en calciumsulfaat, in combinatie met ijzer, mangaan en borium, op het optreden van stip en zacht bij Cox's Orange Pippin appels
Lune, P. van - \ 1981
Haren : Instituut voor Bodemvruchtbaarheid (Rapport / Instituut voor Bodemvruchtbaarheid no. 8-81) - 61
appels - calciumcarbonaat - zware kleigronden - gips - kalk - malus - stip - zacht (ziekte bij appels) - afwijkingen, planten - zwavelmeststoffen - nederland - mangaan - boriummeststoffen - ijzerhoudende meststoffen - apples - calcium carbonate - clay soils - gypsum - lime - bitter pit - water core - plant disorders - sulfur fertilizers - netherlands - manganese - boron fertilizers - iron fertilizers
Verslag van bemestingsproeven van 1969-1977 van Cox's Orange appels op onderstammen, met nadruk op het optreden van gebreksziekten
De aanwezigheid van calcium - magnesium - carbonaat naast calciumcarbonaat in kleigronden en de ontleding dezer carbonaten onder invloed van zoutzuur, azijnzuur en de bodemzuren
Bruin, P. - \ 1938
's-Gravenhage : [s.n.] (Verslagen van landbouwkundige onderzoekingen 44.15) - 46
calciumcarbonaat - magnesiumcarbonaat - bodemtextuur - bodemtypen - zoutzuur - azijnzuur - calcium carbonate - magnesium carbonate - soil texture - soil types - hydrochloric acid - acetic acid
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