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为了增加混凝出水中Cr(VI)的去除率,使用铁表面改性的石英砂进行了不同条件下的Cr(VI)吸附实验,实验结果表明,在实验p H值(2.0~13.0)范围内,表面附着的铁具有较高的稳定性。铁表面改性后石英砂的等电点向碱性范围内移动,有助于吸附去除带负电的Cr(VI)。随着吸附时间的增加,改性石英砂对Cr(VI)的去除能力逐渐提高。Cr(VI)的浓度逐渐减少,改性石英砂对Cr(VI)的吸附动力下降,110 min后,吸附基本达到平衡。腐殖酸对于Cr(VI)在改性滤料表面吸附的影响主要体现在与Cr(VI)的竞争吸附和对Cr(VI)的还原作用。随着Cr(VI)浓度的增加,Cr(VI)的去除率呈现先增大后降低的趋势,当Cr(VI)浓度为2.0 mg/L时去除率达到最高。未改性的石英砂对于混凝沉后水中的剩余Cr(VI)无明显的去除作用。当使用改性砂柱对AS混凝出水进行过滤时,30 min之内Cr(VI)的去除率仍然能够达到接近100%。当体系中无腐殖酸存在,Al_(30)做混凝剂时,Cr(VI)在较短的时间(20 min)通过滤柱。
In order to increase the removal rate of Cr (VI) in the coagulation effluent, Cr (VI) adsorption experiments were carried out using iron surface modified quartz sand under different conditions. The experimental results show that in the range of experimental p H value (2.0-13.0) The iron attached to the surface is highly stable. After the surface modification of the quartz sand, the isoelectric point of the quartz sand moves to the alkaline range, which helps to adsorb and remove the negatively charged Cr (VI). With the increase of adsorption time, the removal capacity of modified quartz sand on Cr (VI) gradually increased. The concentration of Cr (VI) gradually decreased, and the adsorption kinetics of Cr (VI) decreased with modified quartz sand. After 110 min, the adsorption basically reached balance. The effect of humic acid on the adsorption of Cr (VI) on the surface of modified filter media is mainly reflected in the competitive adsorption with Cr (VI) and the reduction of Cr (VI). With the increase of the concentration of Cr (VI), the removal rate of Cr (VI) firstly increased and then decreased, and reached the highest when the concentration of Cr (VI) was 2.0 mg / L. The unmodified quartz sand had no obvious removal effect on the remaining Cr (VI) in the coagulated sediment water. When the modified sand column is used to filter the AS coagulation effluent, the removal rate of Cr (VI) can reach nearly 100% within 30 min. When there is no humic acid in the system, Cr (VI) passes through the filter column in a short time (20 min) when Al 30 is used as the coagulant.