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水资源利用中需要处理水体中的大量排放的污染物,工业废水的有机污染物、农业废水的农药和生活污水中的各种细菌及病毒等,尤其是全球化的趋势下病毒及病原微生物的传播迅速[1],水消毒已成为全球公共关注的问题[2]. 常用的水消毒工艺包括紫外线消毒和化学消毒两种方式,其中化学消毒中两种主流消毒工艺为液氯消毒和臭氧消毒[3]. 液氯和臭氧均对微生物有很强的杀灭作用,但均会形成多种消毒副产物,对水体造成二次污染[4]. 紫外消毒工艺更加便利安全,能够被广泛应用于污水处理,但其在水中的穿透能力有限且存在光复活现象同样也限制了其实际应用[5]. 因此,需要开发高效抗菌且环境友好的抗菌材料.
近年来,半导体光催化材料可利用光能,产生催化作用使底物发生氧化或还原反应,达到降解废水或空气中的有机污染物[6],光解水制备氢气[7]、CO2还原[8]以及产生活性氧杀灭或抑制细菌[9 − 10]等目的. 光催化水消毒由Matsunaga等[11]率先提出,利用二氧化钛紫外光照射下的光催化效应对细菌进行灭活,后续研究者也证实了TiO2能够加速紫外光对细菌的作用[12]. 但二氧化钛禁带宽度较宽(锐钛矿3.2 eV,金红石3.0 eV),激发光波段集中在紫外光区,且光生电子与空穴复合率高[13]. 因此,需要对其进行改性使其成为一种既能有效利用可见光又具有优良性能的光催化剂. 类石墨型氮化碳(g-C3N4)是一种不含金属元素的无机半导体光催化材料,因其较窄的禁带宽度(2.7 eV)、能够吸收较宽波长范围内的光(约460 nm)且稳定性高被广泛研究[14]. 将g-C3N4与其他半导体复合构筑异质结,能够促进光催化过程中光生电子与空穴的分离,显著提高光催化性[15]. 较常见的是将两种半导体通过一种电子导体连接,常用的电子导体有Ag、Pt、Au等贵金属以及石墨烯、碳纳米纤维等导电材料[16]. 细菌纤维素(BC)具有多孔的纳米网状结构、高纯度、高结晶度、优异的生物相容性等优点,是一种天然可再生高分子材料,BC经高温碳化成碳化细菌纤维素(CBC),不仅拥有BC的各项优点,还保留三维纳米网状结构,将其作为异质结的导电材料可以增加半导体的分散性.
本研究将g-C3N4、TiO2和CBC通过不同的合成包裹方法复合构建三元异质结光催化剂,选择TiO2、g-C3N4作为电子载体和受体,CBC作为电子传递的桥梁,拟定该体系可以有效的抑制e-和h+复合,从而提高光催化性能,增强杀菌效果. 由不同制备方法合成该体系的两种复合材料CNTC和TCNC,表征了两种复合材料的结构形貌、光学性质,并对其光电化学性能及光催化杀菌性能进行了分析和比较,通过自由基捕获实验验证了材料的光催化抗菌机理和Z型异质结的构建,并且在水消毒循环抗菌实验中展现了其稳定性的差异,本研究为构建g-C3N4和TiO2异质结光催化剂体系奠定理论基础,提供简单方便的制备高效光催化抗菌剂的方法,可应用于光催化水消毒方面.
碳化细菌纤维素掺杂的氮化碳/二氧化钛光催化杀菌剂的制备及性能
Preparation and properties of photocatalytic bactericide of carbonized Bacterial Cellulose doped Carbon Nitride/Titanium Dioxide
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摘要: 目前环境修复中面临大量水体有机污染和水体致病菌的问题,可见光驱动的光催化杀菌材料在环境修复及医疗领域有巨大的应用潜力. 本研究开发了一种由氮化碳/二氧化钛/碳化细菌纤维素(g-C3N4/TiO2/CBC)复合的新型三元异质结光催化剂,采用水热法和煅烧法生成氮化碳负载二氧化钛掺杂CBC(g-C3N4/TiO2-CBC,CNTC)和氮化碳包覆二氧化钛掺杂CBC(TiO2/g-C3N4-CBC,TCNC)两种复合材料,对它们的红外吸收光谱、物相组成、微观形貌、光催化机理和抗菌性能进行了分析和比较. 结果表明,两种复合物在可见光下的抗菌活性均远高于g-C3N4和TiO2单体,CNTC和TCNC在模拟太阳光下光照30 min产生了h+、e−、
$ {·\mathrm{O}}_{2}^{-} $ 、•OH和1O2,对大肠杆菌的灭菌率分别为99.99%以上和97.5%以上,在可见光照射水消毒测试中,CNTC和TCNC经过3次循环再利用,仍保持优异的抗菌性能,杀菌率分别为99.87%和74.70%. 证明了CNTC有更优异的抗菌性能和稳定性,在环境水消毒的应用中具有较好的潜力.Abstract: Currently, environmental restoration is faced with a large number of problems of organic pollution and pathogenic bacteria in water. High-efficiency visible light-driven photocatalytic sterilization materials have great application potential in the field of environmental remediation and medical treatment. In this study, a novel ternary heterojunction photocatalyst composed of carbon nitride/titanium dioxide/carbonized bacterial cellulose (g-C3N4/TiO2/CBC) was developed. CBC doped Carbon nitride loaded titanium dioxide (g-C3N4/TiO2-CBC, CNTC) and CBC doped carbon nitride coated titanium dioxide (TiO2/g-C3N4-CBC, TCNC) were synthesized hydrothermal method and calcination method, and their infrared absorption spectrum, phase composition, micro-morphology, photocatalytic mechanism and antibacterial properties were analyzed and compared. The results show that the antibacterial activities of the two complexes are much higher than those of g-C3N4 and TiO2 monomers. CNTC and TCNC produced h+、e−、$ {·\mathrm{O}}_{2}^{-} $ 、•OH and 1O2 under visible light for 30 min, and the sterilization rates of E.coli were above 99.99% and 97.5% respectively. In the disinfection test of water irradiated by visible light, CNTC and TCNC remained excellent antibacterial properties after being recycled for three times, and the sterilization rates were 99.87% and 74.70% respectively. The results were demonstrated that CNTC has better antibacterial performance and stability, and has good potential in the application of environmental water disinfection.-
Key words:
- photocatalyst /
- carbon nitride /
- titanium dioxide /
- water disinfection.
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