X

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Lang, Friederike  (6)
Type of Medium
Publisher
Person/Organisation
Language
Years
Subjects(RVK)
  • 1
    Online Resource
    Online Resource
    Soil Organic Matter Clogs Mineral Pores : Evidence from 1 H‐NMR and N 2 Adsorption
    Wiley ; 2004
    In:  Soil Science Society of America Journal Vol. 68, No. 6 ( 2004-11), p. 1853-1862
    Details
    In: Soil Science Society of America Journal, Wiley, Vol. 68, No. 6 ( 2004-11), p. 1853-1862
    Abstract: Recent N 2 adsorption studies have suggested a ‘pore clogging’ effect on mineral soil phases caused by organic matter coatings. For methodological reasons, this pore clogging effect has been studied only after drying. Our hypothesis was that pore clogging is affected by drying of organic coatings. In our study, we used AlOOH, which has been equilibrated with dissolved organic matter (DOM) and polygalacturonic acid [PGA; (C 6 H 8 O 6 ) n ]. To test our hypothesis, we determined the porosity of moist and freeze‐dried AlOOH samples. Freeze‐dried samples were analyzed by N 2 adsorption, moist samples by 1 H‐nuclear magnetic resonance (NMR). In addition, the samples were characterized by environmental scanning electron microscopy—energy dispersive x‐ray spectroscopy (ESEM‐EDX). Both, DOM and PGA significantly reduced specific surface area (SSA BET ) of AlOOH by 34 m 2 g −1 (15%) and 77 m 2 g −1 (36%). The reduction in SSA BET normalized to the amount of C sorbed was 1.0 m 2 mg −1 DOM‐C and 5.9 m 2 mg −1 PGA‐C. Dissolved OM reduced the pore volume of micro‐ and small mesopores 〈 3 nm whereas PGA also reduced the volume of larger pores. The 1 H‐NMR results of moist samples showed that PGA sorption reduced the amount of water in pores 〈 4 nm. In addition, the pore size maximum of AlOOH increased by 150%. Polygalacturonic acid coatings created new interparticle pores of about 10‐ to 70‐nm size that are not stable upon freeze‐drying. Porosity changes upon DOM‐treatment were not commensurable by 1 H‐NMR. Our results indicate that clogging of micro‐ and small mesopores is not an artifact of freeze‐drying. Polygalacturonic acid seems not only to cover the mouth of AlOOH‐nanometer pores but also to fill them.
    Type of Medium: Online Resource
    ISSN: 0361-5995 , 1435-0661
    URL: Article
    DOI: 10.2136/sssaj2004.1853
    RVK:
    RA 4845
    Language: English
    Publisher: Wiley
    Publication Date: 2004
    detail.hit.zdb_id: 241415-6
    detail.hit.zdb_id: 2239747-4
    detail.hit.zdb_id: 196788-5
    detail.hit.zdb_id: 1481691-X
    SSG: 13
    SSG: 21
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
  • 2
    Online Resource
    Online Resource
    Phosphate Desorption from Goethite in the Presence of Galacturonate, Polygalacturonate, and Maize Mucigel ( Zea mays L.)
    Wiley ; 2006
    In:  Soil Science Society of America Journal Vol. 70, No. 5 ( 2006-09), p. 1731-1740
    Details
    In: Soil Science Society of America Journal, Wiley, Vol. 70, No. 5 ( 2006-09), p. 1731-1740
    Abstract: Uronates are important constituents of maize mucilage and polyuronates are used as a simplified model of the soil–root interface. We tested whether galacturonate (GA) and polygalacturonate (PGA) impair the diffusion of phosphate (PO 4 ) into and out of pores of a synthetic goethite (147 m 2 g −1 ) and whether the effect of maize mucigel (MU) is comparable to PGA. We measured the PO 4 desorption kinetics of goethites in batch experiments over 2 wk at pH 5. One part of the goethite was equilibrated with organic substances before PO 4 addition, another part after addition of PO 4 Before the desorption experiments, the porosity of our samples was analyzed by N 2 gas adsorption. In each treatment a rapid initial desorption was followed by a slow desorption reaction, which is assigned to the diffusion of PO 4 out of mineral pores. No consistent relation between the micro‐ and mesoporosity and the rate of the slow PO 4 desorption was observed. Compared with the C‐free control, only PGA and MU affected the fraction of PO 4 mobilized by the fast and slow desorption reaction: when PGA was sorbed to goethite before PO 4 , twice as much PO 4 was mobilized via the fast reaction than in the treatment where PO 4 was sorbed before PGA, suggesting a decreased accessibility of goethite pores to PO 4 Mucigel, however, showed reversed effects, which is ascribed to its differing chemical composition. In conclusion, PGA seems inappropriate as a model substance for maize MU collected from non‐axenic sand cultures. Under the experimental conditions chosen, the efficacy of all organic substances to increase PO 4 solution concentrations by pore clogging and sorption competition is small.
    Type of Medium: Online Resource
    ISSN: 0361-5995 , 1435-0661
    URL: Article
    DOI: 10.2136/sssaj2005.0414
    RVK:
    RA 4845
    Language: English
    Publisher: Wiley
    Publication Date: 2006
    detail.hit.zdb_id: 241415-6
    detail.hit.zdb_id: 2239747-4
    detail.hit.zdb_id: 196788-5
    detail.hit.zdb_id: 1481691-X
    SSG: 13
    SSG: 21
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
  • 3
    Online Resource
    Online Resource
    Citrate impairs the micropore diffusion of phosphate into pure and C-coated goethite
    Elsevier BV ; 2006
    In:  Geochimica et Cosmochimica Acta Vol. 70, No. 3 ( 2006-2), p. 595-607
    Details
    In: Geochimica et Cosmochimica Acta, Elsevier BV, Vol. 70, No. 3 ( 2006-2), p. 595-607
    Type of Medium: Online Resource
    ISSN: 0016-7037
    URL: Article
    DOI: 10.1016/j.gca.2005.10.032
    RVK:
    TE 1000
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2006
    detail.hit.zdb_id: 300305-X
    detail.hit.zdb_id: 1483679-8
    SSG: 13
    SSG: 16,12
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
  • 4
    Online Resource
    Online Resource
    Restructuring of polygalacturonate on alumina upon hydration—Effect on phosphate sorption kinetics
    Elsevier BV ; 2006
    In:  Geochimica et Cosmochimica Acta Vol. 70, No. 12 ( 2006-6), p. 2957-2969
    Details
    In: Geochimica et Cosmochimica Acta, Elsevier BV, Vol. 70, No. 12 ( 2006-6), p. 2957-2969
    Type of Medium: Online Resource
    ISSN: 0016-7037
    URL: Article
    DOI: 10.1016/j.gca.2006.03.007
    RVK:
    TE 1000
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2006
    detail.hit.zdb_id: 300305-X
    detail.hit.zdb_id: 1483679-8
    SSG: 13
    SSG: 16,12
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
  • 5
    Online Resource
    Online Resource
    Acid Polysaccharide Coatings on Microporous Goethites : Controls of Slow Phosphate Sorption
    Wiley ; 2006
    In:  Soil Science Society of America Journal Vol. 70, No. 5 ( 2006-09), p. 1547-1555
    Details
    In: Soil Science Society of America Journal, Wiley, Vol. 70, No. 5 ( 2006-09), p. 1547-1555
    Abstract: Organic coatings on Fe oxides can decrease the accessibility of intraparticle pores for oxyanions like phosphate. We hypothesized that the slow sorption of phosphate to goethite coated with polygalacturonate (PGA) is controlled by the accessibility of external goethite surfaces to phosphate rather than by diffusion of phosphate into micropores (Ø 〈 2 nm). We studied the phosphate sorption kinetics of pure and PGA‐coated goethites that differed in their microporosity (N 2 at 77 K, 46 vs. 31 mm 3 g −1 ). Because drying may affect the structure or surface coverage of PGA, we also tested the effect of freeze‐drying on the slow phosphate sorption. The samples were examined by gas adsorption (N 2 , CO 2 ) and electrophoretic mobility measurements. Phosphate sorption and PGA‐C desorption were studied in batch experiments for 3 wk at pH 5. In PGA‐coated samples, the slow phosphate sorption was independent of micropore volume. Phosphate displaced on average 57% of PGA‐C within 3 wk. Similar to phosphate sorption, the PGA‐C desorption comprised a rapid initial desorption, which was followed by a slow C desorption. Sorption competition between phosphate and presorbed PGA depended on the 〈 10‐nm porosity and the C loading of the adsorbent. The efficacy of phosphate to desorb PGA generally increased after freeze‐drying. We conclude for PGA‐coated goethites that (i) freeze‐drying biased the slow phosphate sorption by changing the structure/surface coverage of PGA, and (ii) within the time frame studied, micropores did not limit the rate of the slow phosphate sorption. Rather, the slow, gradual desorption of PGA and/or the diffusion of phosphate through PGA coatings controlled the slow phosphate sorption to PGA‐coated goethite.
    Type of Medium: Online Resource
    ISSN: 0361-5995 , 1435-0661
    URL: Article
    DOI: 10.2136/sssaj2005.0340
    RVK:
    RA 4845
    Language: English
    Publisher: Wiley
    Publication Date: 2006
    detail.hit.zdb_id: 241415-6
    detail.hit.zdb_id: 2239747-4
    detail.hit.zdb_id: 196788-5
    detail.hit.zdb_id: 1481691-X
    SSG: 13
    SSG: 21
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
  • 6
    Online Resource
    Online Resource
    Kinetics of Phosphate Sorption to Polygalacturonate‐coated Goethite
    Wiley ; 2006
    In:  Soil Science Society of America Journal Vol. 70, No. 2 ( 2006-03), p. 541-549
    Details
    In: Soil Science Society of America Journal, Wiley, Vol. 70, No. 2 ( 2006-03), p. 541-549
    Abstract: Biogenetic polysugars may affect the sorption characteristics of soil mineral particles in the rhizosphere. We hypothesized that polygalacturonate [PGA, (C 6 H 7 O 6 ) n − ] coatings on goethite reduce the diffusion of phosphate into the pores of the adsorbent. Goethite was preloaded with PGA (0–10 mg C g −1 ). The samples were characterized by N 2 and CO 2 adsorption, electrophoretic mobility measurements, and scanning electron microscopy/energy dispersive X‐ray analysis (SEM‐EDX). The phosphate sorption kinetics was studied with batch experiments over 2 wk at pH 5 and an initial phosphate concentration of 250 μ M Pore volume and specific surface area of the goethite samples declined after PGA addition. The PGA coatings reduced the ζ‐potential of goethite from 42.3 to −39.6 mV at the highest C loading. With increasing PGA‐C content and decreasing ζ‐potential the amount of phosphate sorbed after 2 wk decreased linearly ( P 〈 0.001). Sorption of phosphate to pure and PGA‐coated goethite showed an initial fast sorption followed by a slow sorption reaction. At the smallest C loading (5.5 mg C g −1 ) the portion of phosphate retained by the slow reaction was smaller than for the treatment without any PGA, while at higher C loadings the fraction of slowly immobilized phosphate increased. Our results suggest that at low C‐loadings PGA impaired the intraparticle diffusion of phosphate. In contrast, the slow step‐by‐step desorption of PGA ( 〈 52% within 2 wk) or the diffusion of phosphate through PGA coatings or both are rate limiting for the slow phosphate reaction at C loadings 〉 5.5 mg C g −1
    Type of Medium: Online Resource
    ISSN: 0361-5995 , 1435-0661
    URL: Article
    DOI: 10.2136/sssaj2005.0250
    RVK:
    RA 4845
    Language: English
    Publisher: Wiley
    Publication Date: 2006
    detail.hit.zdb_id: 241415-6
    detail.hit.zdb_id: 2239747-4
    detail.hit.zdb_id: 196788-5
    detail.hit.zdb_id: 1481691-X
    SSG: 13
    SSG: 21
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
Nothing or not found what you are looking for? Please check your search query or use the Interlibrary Loan Search.
Close ⊗
This website uses cookies and the analysis tool Matomo. Further information can be found on the KOBV privacy pages