铝污泥酸化提取液改性沸石的除磷特性及机制

为了提高沸石的除磷能力并降低改性成本,以给水厂铝污泥为铝源,采用酸化提取液合成层状双氢氧化物(LDHs)覆膜于沸石表面制备改性沸石,分别测定原沸石、Al-Zn改性沸石及铝污泥改性沸石的表面特性和化学组分,分析等温吸附及吸附动力学特性,探讨铝污泥改性沸石的除磷性能及除磷机制.结果表明,最佳酸化提取条件为60 min、150 r·min~(-1)和p H1. 0,该条件下1 g铝污泥(干重)可提取77 mg的铝;改性沸石的饱和吸附容量和解吸性能较原沸石显著提高,尤其是铝污泥改性沸石,其理论最大吸附量从30. 24 mg·kg~(-1)提升至170. 40 mg·kg~(-1);改性使得沸石对磷酸盐的主要吸附类型由物理吸附向化学吸附转变.以铝污泥为铝源改性沸石能有效地提高其对磷酸盐的吸附能力及再生能力,在降低磷浓度过高引发的水体富营养化风险的同时,实现以废治废的目的.

Phosphorus Removal Performance and Mechanism of Modified Zeolite Using Alum Sludge Acidified Extraction Liquid

To improve the capacity for phosphorus removal and to reduce the cost of treatment, alum sludge from a water supply plant was obtained to prepare modified zeolite coated with layered double hydroxide (LDHs), which was synthesized using an acidified extraction liquid. The surface characteristics and chemical composition of raw zeolites, Al-Zn modified zeolites, and alum sludge modified zeolites were determined, and the isothermal adsorption and adsorption kinetics were analyzed. The performance and mechanism of phosphorus removal by the alum sludge modified zeolites were evaluated. The results showed that the optimum conditions for acidification extraction were 60 min treatment time, 150 r·min^-1, and pH 1.0, which achieved 77 mg aluminum extraction rate per gram of alum sludge. Compared to raw zeolites, the maximum saturated adsorption capacity and the desorption performance of the zeolites were significantly increased by this modification. In addition, the theoretical maximum adsorption capacity of alum sludge modified zeolites was increased from 30.24 mg·kg^-1 to 170.40 mg·kg^-1. The modification changed the main mode of phosphate adsorption by zeolite from physical adsorption to chemical adsorption. Alum sludge modification could improve the efficiency of phosphate adsorption and the regeneration capacity of zeolite, which could reduce the risk of water eutrophication caused by high phosphate concentrations, and could achieve the purpose of waste control by waste.