三种铁氧化物的磷吸附解吸特性以及与磷吸附饱和度的关系

Phosphorus adsorption and desorption properties of three synthetic iron oxides and their relation to phosphorus adsorption saturation

采用三种人工合成铁氧化物(针铁矿、赤铁矿和水铁矿)比较了结晶态和无定形铁氧化物对磷的吸附—解吸特性以及与磷吸附饱和度的关系。结果表明,三种铁氧化物的磷吸附特性均可用Langumir方程来描述,相关系数均大于0.9,达到极显著水平。从磷最大吸附量(Qm)、吸附反应常数(K)和最大缓冲容量(MBC)三项吸附参数综合考虑,水铁矿(无定形)对磷的吸附无论在容量还是强度方面均比结晶态铁氧化物针铁矿和赤铁矿大得多。水铁矿吸附的磷比针铁矿和赤铁矿所吸附的磷更难解吸;水铁矿的大量活性表面并没有表现出增加磷释放的作用。磷吸附饱和度有望作为评价土壤或铁氧化物磷吸附—解吸的强度和容量因子的一个综合指标。

The differences of P adsorption-desorption characteristics of amorphous and crystalline iron oxides and their relation to P adsorption saturation were studied by using three synthetic iron oxides. The results showed that P adsorption properties of these three synthetic iron oxides could be described by Langnmir equation with a correlation coefficient larger than 0.9 being statistical significant at 1% level. It was found by comprehensively taking Qm （maximum quantity of adsorption）, K （adsorption constant） and MBC （maximum buffing capacity） into account, ferrihydrate （amorphous） was much larger than crystalline iron oxides （goethite and hematite） in both intensity and capacity of P adsorption. P adsorbed by ferrihydrate was much more difficult to be desorbed than those by goethite and hematite. The large active surfaces of ferrihydrate contribute little on P desorption. It was suggested by our results that P adsorption saturation might be a promising integrated index for estimating the intensity and capacity of P adsorption-desorption in soils or iron oxides.