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难降解有机污染废水具有生物毒性,甚至致癌等严重问题[1]。因此,迫切需要开发经济有效的有机污染物废水处理技术[2]。高级氧化法作为一种能高效氧化降解有机污染物技术方法,被广泛应用于难降解有机污染物废水处理,其中的光催化法和类Fenton试剂法因其处理成本低、降解效率高和无二次污染等优点,具有很好的应用前景。然而,光催化法需要更加高效的催化剂,以提高废水中有机物的去除率。
水滑石(LDHs)是一种具有特殊层状结构的双金属氢氧化物,其化学式为[M2+1-xM3+x(OH)2]x+(An-)x/n·mH2O,因其具有主体层板金属阳离子可调变、层间阴离子可交换及粒径尺寸可调控等特点,故可成为优良催化材料的前驱体[3-4]。同时,LDHs具有易制备、合成成本低廉、比表面积较大、不产生二次污染等特点,属于环境友好型催化剂,近年来受到国内外各界学者的关注[5]。在可见光催化过程中,污染物的降解效率受限的主要原因有LDHs的电子传递效率低以及较弱的载流子迁移速率和较快的电子-空穴对复合速率,从而导致光催化效率和光催化活性偏低[9]。有研究[8]表明,Cu2+、Co2+及Fe2+等过渡金属具有良好的供电子能力,往往作为金属阳离子用于制备LDHs,以提高电子传递效率。目前,针对二元水滑石制备的报道较多,如MgAl-LDHs[6]、ZnAl-LDHs[7]等。另外,石墨烯是一种具有特殊结构和性质的单层石墨片,其具备高载流子迁移率和高比表面积等优点[10]。同时,石墨烯巨大的比表面积可以有效吸附有机污染分子,且增加光催化反应的活性位点,从而提高污染物降解效率[11]。YANG等[12]成功制备了CoZnAl-LDH/RGO/g-C3N4复合催化剂,可将CO2光催化还原为CO。此外,在可见光或UV氧化体系下,通过添加H2O2 促进Cu2O、CuO等催化效率,提高体系中超氧自由基(·
$ {{\rm{O}}_2}^ - $ )和羟基自由基(·OH) 生成效率,实现废水中难降解有机物的快速去除[13]。但在光催化体系下,通过将LDHs、石墨烯、H2O2三者有机组合以实现光催化去除有机物的研究尚鲜有报道[14]。基于此,本研究采用单滴共沉淀方法制备CuCoAl-LDHs/GO复合材料,以RhB和苯酚作为目标污染物,通过添加H2O2协同CuCoAl-LDHs/GO光催化体系降解目标污染物,并进一步分析不同H2O2和催化剂添加量下对目标污染物的降解效率影响。
H2O2协同强化CuCoAl-LDHs/GO复合材料光催化效能
Photocatalytic performance of CuCoAl-LDHs/GO composites synergistically enhanced by H2O2
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摘要: 采用单滴共沉淀法制备了氧化石墨烯负载到铜钴铝水滑石(CuCoAl-LDHs/GO)复合材料,并以罗丹明(RhB)和苯酚为目标降解物,开展了H2O2协同CuCoAl-LDHs/GO强化光催化降解的实验。结果表明:通过XRD、SEM、XPS及UV-Vis表征,发现复合材料中存在石墨烯和金属离子(Co3+、Co2+、Cu2+、Cu+、Al3+),且具备较高的光催化活性;H2O2存在的条件下,1 g·L−1 CuCoAl-LDHs/GO对RhB和苯酚的光催化降解率分别为99.3%和97.6%;H2O2和CuCoAl-LDHs/GO投加量增加有助于RhB的降解,循环6次后降解率仍达82.65%,表明H2O2可有效促进CuCoAl-LDHs/GO光催化降解性能,并具备多次循环利用的能力。以上研究结果可为实际水环境中微污染的治理修复提供参考。
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关键词:
- CuCoAl-LDHs/GO /
- 可见光 /
- H2O2 /
- 效能 /
- 强化作用
Abstract: The CuCuAl-LDHs/GO composite supported by GO was prepared by single drop co-precipitation method. The photocatalytic performance of CuCoAl-LDHs/GO reinforced by H2O2 was studied using rhodamine (RHB) and phenol as the target degradants. The results showed that through XRD, SEM, XPS and UV-Vis characterization, the presence of graphene and metal ions (CO3+, CO2+, Cu2+, Cu+, Al3+) in the composites was conducive to their high photocatalytic activity. The photocatalytic degradation rates of RhB and phenol by 1 g·L−1 CuCoAl-LDHS /GO were 99.3% and 97.6% in the presence of H2O2, respectively. The dosage of H2O2 and CuCoAl-LDHs/GO were positively proportional to the degradation rate of RhB; In the presence of H2O2, CuCoAl-LDHs/GO catalyst has good stability and photocatalytic degradation performance, the degradation rate of RhB was still up to 82.65% after six cycles, which can provide a new technical support for the treatment and remediation of micropollutants in the actual water environment.-
Key words:
- CuCoAl-LDHs/GO /
- visible light /
- H2O2 /
- efficiency /
- reinforcement
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