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过量的磷是导致水体富营养化的主要原因[1]。有研究[2]表明,若水环境中总磷浓度达到 0.02 mg·L−1,对水体富营养化就起明显促进作用,达到 0.2 mg·L−1,水体就呈富营养状态。因此,在防治水体富营养化问题中控制水体中的磷含量更具有实际意义。现有除磷技术中,吸附法除磷工艺由于其具有高效清洁、可回收磷、可重复利用、工艺简单等优点,具有广泛的应用前景[3]。研究开发经济、高效的除磷技术已成为水污染控制工程研究的重点领域之一。
蒸压加气混凝土(autoclaved aerated concrete, AAC)碎料[4]是一种常见的建筑废料,使用水泥、生石灰、粉煤灰、砂、铝粉等材料,按照蒸压加气混凝土砌块的加工方法,制成建筑用轻质材料——蒸压加气混凝土砌块,进而加工破碎而成。由于蒸压加气混凝土碎料(crushed autoclaved aerated concrete, CAAC)富含钙、铝、铁等氧化物,且多孔、质轻、广泛易得,近年来开始应用在富营养化水体的治理中。LI等[5]和郭杏妹等[6]研究发现,不同浓度的碱改性CAAC的除磷效率大幅提高,其去除率可达98.67%和99.18%。但上述方法存在材料经过碱改性后的碱性残留问题,容易造成新的次生环境污染风险,从而增加了处理成本。而盐改性由于价格低廉、处理量大和去除率高等优点而广泛应用于水处理。有研究[7-9]表明,经铝改性的纳米纤维素、活性炭及水滑石等的除磷效率都有明显提高。
本研究以氯化铝作为改性剂,对蒸压加气混凝土材料进行改性,得到铝改性蒸压加气混凝土(aluminum modified autoclaved aerated concrete,Al-MAAC)材料,并用于低浓度含磷废水的处理中(总磷≤1 mg·L−1),考察除磷效果并确定最优改性条件,在此基础上,揭示除磷机理,以期得到除磷性能更好的材料,为富营养化水体深度除磷材料的选择及应用提供参考。
Effect of phosphorus removal by aluminum modified autoclaved aerated concrete
- Received Date: 11/10/2019
- Available Online: 10/08/2020
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Key words:
- aluminium chloride /
- autoclaved aerated concrete /
- total phosphorus /
- modification
Abstract: In order to further improve the phosphorus removal effect of autoclaved aerated concrete, aluminum modified autoclaved aerated concrete (Al-MAAC) was prepared by impregnation-roasting method. The effects of the optimum preparation conditions, reaction time, phosphorus concentration in influent and dosage on phosphorus removal were studied. The results showed that the optimium preparation conditions were following: 1 g autoclair aerated concrete powder material was mixed with 10 mL aluminum chloride solution of 0.2 mol·L−1 for 0.5 h. When the dosage was 0.5 g·L−1 and the reaction time was 1.5 h, the phosphorus removal rate of low concentration phosphorus-contained wastewater (total phosphorus≤1 mg·L−1) could reach 96.1%. Based on the above results, the dephosphorization mechanism of aluminum modified autoclaved aerated concrete was that the material could react with