HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Mikutta, C. Articles by Kaupenjohann, M. Search for Related Content PubMed Articles by Mikutta, C. Articles by Kaupenjohann, M. Agricola Articles by Mikutta, C. Articles by Kaupenjohann, M. Related Collections Diffusion Kinetics Plant and Soil Interactions

Kinetics of Phosphate Sorption to Polygalacturonate-coated Goethite

Dep. of Soil Science, Institute of Ecology, Berlin Univ. of Technology, Salzufer 12, D-10587 Berlin, Germany

View larger version (209K): [in a new window]   Fig. 1. Scanning electron microscopy images of (a) pure goethite, and goethite coated with polygalacturonate of different C loadings: (b) 5.5 mg C g–1, (c) 7.6 mg C g–1, and (d) 10 mg C g–1. Multidomainic goethite crystals are visible in Fig. 1a; Fig. 1b shows in more detail the clustering of goethite crystals induced by PGA at low PGA-C content; Fig. 1c and 1d give overviews of PGA-goethite clusters on differently sized aggregates of goethite.

View larger version (21K): [in a new window]   Fig. 2. Changes in phosphate sorption with time of PGA-coated and pure goethite. The solid concentration was 0.5 g L–1. Subsample variability was typically <2%. Figures after ‘G’ refer to the rounded C content of the sample in milligram C per gram.

View larger version (15K): [in a new window]   Fig. 3. Changes in -potential of pure and PGA-coated goethite during phosphate sorption (I = 0.01 M KNO3, pH = 5). Note that x-axis is log scale. Error bars indicating the standard error of 10 replicate measurements are within the symbol size. Initial -potentials of the samples (no phosphate contact) are presented in Table 1. Figures after ‘G’ refer to the rounded C content of the sample in milligram C per gram.

View larger version (22K): [in a new window]   Fig. 4. Kinetics of phosphate sorption and PGA-C desorption in samples with low (G6) and intermediate PGA-C content (G7) at an initial phosphate concentration of 250 µM in 0.01 M KNO3 at pH 5 with a solid concentration of 0.5 g L–1. Figures after ‘G’ refer to the rounded C content of the sample in milligram C per gram.

View larger version (21K): [in a new window]   Fig. 5. Amount of phosphate slowly immobilized versus fractional PGA-C release after 2 wk. The amount of phosphate slowly immobilized was calculated as the difference between the total amount of phosphate sorbed after 2 wk and the total amount sorbed fast (cm of Eq. [2]). Figures after ‘G’ refer to the rounded C content of the sample in milligram C per gram. Error bars represent standard error.

View larger version (22K): [in a new window]   Fig. 6. Relationship between the amount of phosphate sorbed after 2 wk and the micro- (<2 nm) and small mesopore volume (2–10 nm) of the samples analyzed with N2 adsorption at 77 K. Horizontal error bars indicate standard error, vertical error bars indicate mean range.