Photocatalytic inactivation of algae using floating visible-light-responsive photocatalyst Ag2CrO4-g-C3N4-TiO2/modified expanded perlite
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摘要: 以Al2O3改性的膨胀珍珠岩(mEP)为载体,采用溶胶凝胶-浸渍沉积法制备Ag2CrO4-g-C3N4-TiO2/mEP漂浮型可见光催化材料。对制备的光催化材料使用XRD、N2吸附/脱附、FESEM-EDS、XPS和UV-vis DRS等分析方法进行材料表征。实验结果表明,不同的Ag2CrO4含量可对复合催化剂的晶型和比表面积产生影响,过高的Ag2CrO4可在催化剂的表面形成团聚颗粒不利于催化剂对藻细胞的吸附和光催化灭活。以铜绿微囊藻为处理对象,光催化剂中Ag2CrO4/TiO2的理论摩尔比为0.05,初始藻细胞浓度为2.75×106 cells/mL时,单纯暗吸附8 h藻细胞的去除率为10.3%,在吸附和光催化的协同作用下,藻细胞的去除率可达81.88%。光催化除藻过程中起主要作用的为光生空穴h+,该催化剂在重复利用三次后对藻细胞仍有72.19%的去除率,催化剂有较好的稳定性。Abstract: Based on Al2O3 modified expanded perlite (mEP), floating visible-light responsive photocatalysts Ag2CrO4-g-C3N4-TiO2/mEP were prepared via a sol-gel-impregnation deposition method. The synthesized photocatalysts were characterized using XRD, N2 adsorption/desorption, FESEM-EDS, XPS and UV-vis DRS. The results show that the concentration of Ag2CrO4 has influence on the crystal structure and specific surface area of the photocatalysts. High concentration of Ag2CrO4 could form agglomerated particles on the surface of the photocatalyst which are not conductive to the adsorption and photocatalytic inactivation of algae. When the theoretical molar ratio of Ag2CrO4/TiO2 is 0.05 and the initial algal cell concentration of Microcystis aeruginosa is 2.75×106 cells/mL, the removal rate of algal after adsorption for 8 h was 10.3%. Under the synergistic effect of adsorption and photocatalysis, the removal rate of algal could reach 81.88%. The inactivation of algae cell mainly ascribed to the attack by the photo-generated holes (h+). The removal rate of algae could reach to 72.19% after three successive cycles which indicated the stability of the photocatalst.
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Key words:
- Ag2CrO4 /
- g-C3N4 /
- visible-light photocatalysis /
- floating /
- algae removal
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图 1 TiO2/Al2O3改性膨胀珍珠岩(mEP)、g-C3N4-TiO2/mEP及Ag2CrO4-g-C3N4-TiO2/mEP系列材料的XRD图谱 (a),EP、mEP及Ag2CrO4-g-C3N4-TiO2/mEP系列材料的N2吸附脱附曲线 (b)
Figure 1. XRD patterns of TiO2/Al2O3 modified expanded perlite (mEP), g-C3N4-TiO2/mEP and Ag2CrO4-g-C3N4-TiO2/mEP-x% (x=1, 5, 10, 15) (a) , N2 sorption-desorption isotherms of EP, mEP and Ag2CrO4-g-C3N4-TiO2/mEP- x% (x=1, 5, 10, 15) (b)
表 1 EP、mEP及Ag2CrO4-g-C3N4-TiO2/mEP系列材料的比表面积、孔径及孔容
Table 1. Specific surface area, average pore diameter and total pore volume of EP, mEP and Ag2CrO4-g-C3N4-TiO2/mEP-x%(x=1, 5, 10, 15)
Photocatalyst Specific surface area/(m2·g−1) Average pore size/mm Total pore volume/(cm3·g−1) EP 2.3 10.4 0.006 mEP 66.5 2.5 0.041 Ag2CrO4-g-C3N4-TiO2/mEP-1% 73.4 3.0 0.055 Ag2CrO4-g-C3N4-TiO2/mEP-5% 37.2 4.7 0.044 Ag2CrO4-g-C3N4-TiO2/mEP-10% 33.6 4.1 0.027 Ag2CrO4-g-C3N4-TiO2/mEP-15% 42.5 3.6 0.033 -
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