新型铁改性砂滤料吸附过滤去除水中的磷

Adsorption Removal of Phosphate from Aqueous Solution Using a New Type of Iron-Oxide-Coated Sand Filter Media

为进一步提高改性砂滤料对水中磷的去除效果,对现有过滤工艺进行改造,在前期研究的基础上,改进改性方法制备出新型铁改性砂(IOCS)滤料,对其进行了扫描电镜(SEM)和X射线衍射(XRD)的表面分析,研究了IOCS对溶液中P O34-的吸附性能和动态过滤再生循环利用.静态吸附实验表明,pH值、接触时间和铁改性砂含量等均会影响IOCS对溶液中P O34-的吸附.25,℃时,Langmuir、Freundlich和Temkin吸附等温线均可较好地拟合铁改性砂对溶液中PO34-的吸附(R 2>0.920,0),其拟合曲线的相关性大小顺序为Freundlich>Temkin>Langmuir.由Langmuir吸附等温式得出的IOCS对PO 34-的饱和吸附量为0.266 8 mg/g.与同类研究相比I,OCS具有更好的PO 34-吸附性能.吸附热力学研究表明I,OCS对P O34-的吸附过程是自发的、吸热的化学过程(ΔG°<0,ΔH°>0).共存阴离子对IOCS吸附PO 34-影响的大小顺序为HCO 3->S O 42->Cl–,但影响不大.过滤再生循环利用实验表明,吸附饱和后IOCS可以使用0.1 mol/L NaOH溶液多次再生重复利用,并保持较高的P O34-去除率,因而可以使用IOCS对现有水和废水处理中过滤除磷工艺进行升级改造.

In order to enhance phosphate removal from aqueous solution using iron-oxide-coated sand （IOCS） filter media, a new type of IOCS was prepared by improving coating process based on the previous study. The adsorbability of phosphate on IOCS, and the possibility of regeneration and reuse of phosphate adsorbed IOCS were investigated. Scanning electron microscopy （SEM） and X-ray diffraction spectroscopy （XRD） were used to observe the surface properties and morphology of the coated layer. Effects of pH, contact time and dose of IOCS on phosphate removal were studied in batch experiments. Three isotherm equations （Langmuir, Freundlich and Temkin）were used for data fitting. The results showed that the data obtained from isotherm experiments （at the temperature of 25 ℃） could be well described using the three isotherm equations, with the correlation coefficients R^2 〉0.920 0. The phosphate adsorption capacity of IOCS obtained from Langmuir fitting data was 0.266 8 mg/g. Compared with the IOCS in other studies of the same kind, the IOCS in this study has higher adsorption capacity for phosphate. The results of adsorptionthermodynamics of phosphate by IOCS indicate that the adsorption of phosphate on IOCS is spontaneous （ △G° 〈 0） and endothermic （△H° 〉0）. The sequence of anions studied affecting the adsorption of phosphate on IOCS is HCO3 ^-〉 SO4^-2 〉Cl^-, but their effect was not obvious. Column experiments indicate that IOCS has a high phosphate removal rate, and saturated IOCS can be regenerated effectively by 0.1 mol/L NaOH solution. This study demonstrates that IOCS can be used as an alternative filter media for water and wastewater treatment without any side effect or treatment process altemation.