有机酸根与铝氧化物表面吸附磷的解吸

研究了有机酸根离子与合成铝氧化物表面吸附磷解吸的相互关系。结果表明:（1）有有机酸时比无有机酸时吸附的磷具有更高的解吸率，无草酸且加磷pH为4时，0.01molL-1KCI对磷的解吸率最低，草酸与磷共存且pH为6时磷的解吸率最高;（2）高浓度有机酸可解吸低浓度有机酸难解吸的磷，草酸难解吸的磷可为等浓度的柠檬酸极解吸;（3）不同浓度草酸和柠檬酸对铝-草酸复合物吸附磷的解吸率比对Al（OH)x的低，而对铝-柠檬酸复合物吸附磷的解吸率则比对Al（OH）x的高;（4）柠檬酸对铝-磷复合物中磷的解吸量随柠檬酸浓度升高而增大。这些结果证明，有机酸对铝氧化物吸附磷的解吸机理包括配位交换和溶解，有机酸可促进磷的解吸，提高磷的有效性。

EFFECT OF ORGANIC ACIDS ON DESORPTION OF PHOSPHATE FROM ALUMINUM OXIDES SURFACE

The desorption of phosphate from Al hydroxides by 0.01 mol/L KCl in the presence of different organic acids and from Al-OH, Al-P and Al-oxalate, Al-citrate complexes by organic acids were studied. The results showed: 1) When phosphate adsorbed on Al(OH)x in the presence and absence of oxalate was desorbed sequentially twice using 0.01 mol/L KCl, the total desorption rate with 0.5～2.0 mmol /L oxalate were 4. 10% ～4. 75%, however, without any organic acid, it was only 2. 05%; 2) The hlgher concentratlon of organic acld in adsorption solution, the more phosphorus was desorbed by 0.01 mol/L KCl to some extent. Some phosphate, which could not be desorbed by oxalate, would be desorbed by citrate at same concentration; 3)When phosphate was desorbed using a series of oxalate and citrate,the total rate of phosphate desorption from Al-oxalate complex was less than that from Al hydroxide, while the rate of phosphate desorption from Al-citrate complex was the highest; 4] Citrate could release the phosphate from Al-P complex, and the amount of phosphate desorption increased with the increment of citrate concentration. All these indlcated that the mechanism of phosphate desorption involved ligand exchange and dissolution by organic acid. Organic acids could obviously strengthen the desorption of phosphate and improve the efficiency of phosphate in acid soil.