Titania containing natural clay doped with carbon nanotubes for enhanced natural photocatalytic discoloration of wastewater
Titania containing natural clay doped with carbon nanotubes for enhanced natural photocatalytic discoloration of wastewater
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DOI：
10.1007/s11051-021-05194-5
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发表时间：
2021-04-01
影响因子：
2.5
通讯作者：
Mamba, B. B.
中科院分区：
文献类型：
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作者：
Muleja, A. A.;Mubiayi, M. P.;Mamba, B. B.
染料污染的水对人类和环境有害。研究了天然粘土（GOL）与碳纳米管（CNT）复合光催化剂对废水中亮黑（BB）的去除效果。利用FESEM-EDS、XRD、XRF、FTIR和UV-vis DRS等手段对材料进行了表征。SEM显示碳纳米管在粘土中分散均匀。DRS光谱在380 nm以上有两个吸收带。GOL中的CNT使GOL和10% CNT-GOL的能带隙分别从2.75和3.25 eV显著降低到1.53和2.90 eV。在可见光照射45 min后，GOL和10% CNT-GOL的光催化活性分别从66%提高到95%。这种改善可以归因于粘土和CNT的界面异质结的协同作用。CNT的存在减少了e（-）和h（+）（e（-）/ h（+））对的重组，并促进了负责染料衰变的活性氧物质的产生。向实验中加入H2 O2（2 mmoL）证实了空穴和羟基自由基的作用。用10% CNT-GOL去除85%的BB碳含量，表明发生了矿化。可见光照射45 min后，降解动力学研究遵循二级反应，R-2 = 0.997。因此，天然粘土-CNT纳米复合材料可用于处理含染料废水。
Water contamination with dyes is harmful to humans and the environment. This study investigated the photocatalytic activity of natural clay (GOL) mixed with carbon nanotubes (CNT) for removal of brilliant black (BB) in wastewater. The materials were characterized with FESEM-EDS, XRD, XRF, FTIR and UV-vis DRS. The natural clay contains 2.34 % TiO2 which is 75% more than most natural clays. SEM showed that CNT were well dispersed and mixed with clay. DRS spectra showed two absorption bands above 380 nm. CNT in GOL has decreased significantly the energy band gaps from 2.75 and 3.25 eV to 1.53 and 2.90 eV for GOL and 10% CNT-GOL, respectively. Photocatalytic activity was enhanced with degradation of BB increased from 66 to 95% with GOL and 10% CNT-GOL respectively after 45 min of visible light irradiation. The improvement can be attributed to the synergy of the interface heterojunction of clay and CNT. The presence of CNT reduces the e(-) and h(+) (e(-) / h(+)) pairs recombination and facilitates the production of reactive oxygen species responsible for the decay of dye. The addition of H2O2 to the experiment (2 mmoL) confirmed the role of holes and hydroxyl radicals. Eighty-five percent of BB carbon content was removed with 10% CNT-GOL suggesting that mineralization occurred. After 45 min of visible light irradiation, the degradation kinetic studies followed a second-order reaction with a R-2 = 0.997. Therefore, natural clay-CNT nanocomposites can be applied to treat dyes containing wastewaters.