针铁矿对再悬浮沉积物吸附磷动力学与固体浓度效应的影响

The effect of α-FeOOH on adsorption kinetics of phosphorus and the solid concentration effect of resuspended sediments

本文以渤海埕岛油田海域沉积物为对象,通过批次实验探究了无磷(P)针铁矿对再悬浮沉积物吸附解吸P的动力学过程与吸附P固体浓度效应的影响。结果表明:针铁矿提高了沉积物吸附P的速率与容量,增大了快吸附P量占动力学平衡时吸附P量的比例。解吸动力学平衡时,沉积物解吸占预吸附P量的比例随针铁矿添加量的升高而降低,说明针铁矿不利于沉积物解吸P。固体浓度为10 g/L,2 g/L沉积物Freundlich吸附系数的比值K_(F10)/K_(F2)随针铁矿添加量的升高更接近于1,说明针铁矿削弱了沉积物吸附P的固体浓度效应。通过KF与固体浓度(S)的关系式K_(F)=a*S^(-b),可以探讨固体浓度(S)变化对吸附可逆性的影响程度。固体浓度影响指数b随沉积物针铁矿含量升高而下降,说明针铁矿减小了固体浓度变化对沉积物吸附P可逆性的影响,使沉积物吸附P的固体浓度效应变弱,揭示了针铁矿对沉积物吸附P固体浓度效应的潜在影响机制。为不可逆性提高、固体浓度效应变弱的吸附体系提供案例。

The effect of phosphorus-freeα-FeOOH on the adsorption/desorption kinetics of phosphorus(P)and solid concentration effect of the resuspended sediments collected from Chengdao Oilfield in Bohai Sea were studied using batch experiments.The results indicated thatα-FeOOH improved the rate,capacity of sediments adsorbing P,and the ratio of the amount of P adsorbed at fast stage to that at kinetic equilibrium on the sediments.In addition,the ratio of the amount of P desorbed to that pre-adsorbed on the sediments decreased with increasingα-FeOOH content,suggesting thatα-FeOOH was unfavorable for sediments desorbing P.Freundlich coefficient(K_(F))ratio of sediments of 10 g/L to 2 g/L was closer to 1 with increasingα-FeOOH content in sediments,which meant the weakening of solid concentration effect.The effect of a concentration change of sediments on reversibility can be explored through the equation K_(F)=a*S^(-b).The index of solid concentration effect,b,decreased with increasing theα-FeOOH content in sediments,which revealed that the potential mechanism ofα-FeOOH weakening solid concentration effect was through reducing reversibility.This research provides an example for weakening the solid concentration effect under conditions of increasing the irreversibility of an adsorption system.