The effect of dissolved chlorides on the photocatalytic degradation properties of titania in wastewater treatment.
The effect of dissolved chlorides on the photocatalytic degradation properties of titania in wastewater treatment.
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废水处理中溶解氯化物对二氧化钛光催化降解性能的影响
DOI：
10.1039/d2cp03140j
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Delarmelina M
中科院分区：
文献类型：
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作者：
Delarmelina M
考察了氯化物对锐钛矿型和金红石型二氧化钛光催化降解苯酚的影响。我们展示了溶解的氯化物如何影响两种晶型上的羟基自由基的形成，从而对它们的光降解活性产生整体影响。首先，研究了锐钛矿型和金红石型光催化剂在标准水和盐水中对苯酚降解的光催化活性。加入锐钛矿型催化剂后，苯酚的转化率显著降低(由准一级速率常数k=5.3×10−3min−1降至k=3.5×10−3min−1)。相反，在相同的反应条件下(从2.3×10−3min−1到4.8×10−3min−1)，增溶氯化物的存在导致金红石活性的提高。周期密度泛函方法被广泛使用，我们发现在模拟的二氧化钛体系中产生电荷分离后，吸附的氯化物是部分空穴局域化的优先位置，尽管在吸附的氯离子或羟基上计算了部分局域化的空穴密度之间的小的能量差。此外，氯化物可以降低或抑制r-TiO2110和a-TiO2101体系在板条结构中定域极化子的能力。这些结果表明，空穴清除和空穴局域抑制这两种机制都可能是氯化物对两种多晶型二氧化钛光催化活性影响的根源。这些结果为深入了解二氧化钛晶型的光催化性能和阐明吸附阴离子对有机污染物的自由基形成和氧化分解的影响提供了基础。
We investigate the effect of chlorides on the photocatalytic degradation of phenol by titania polymorphs (anatase and rutile). We demonstrate how solubilised chlorides can affect the hydroxyl radical formation on both polymorphs with an overall effect on their photodegradative activity. Initially, the photocatalytic activity of anatase and rutile for phenol degradation is investigated in both standard water and brines. With anatase, a significant reduction of the phenol conversion rate is observed (from a pseudo-first-order rate constant k = 5.3 × 10−3 min−1 to k = 3.5 × 10−3 min−1). In contrast, the presence of solubilised chlorides results in enhancement of rutile activity under the same reaction conditions (from 2.3 × 10−3 min−1 to 4.8 × 10−3 min−1). Periodic DFT methods are extensively employed and we show that after the generation of charge separation in the modelled titania systems, adsorbed chlorides are the preferential site for partial hole localisation, although small energy differences are computed between partially localised hole densities over adsorbed chloride or hydroxyl. Moreover, chlorides can reduce or inhibit the ability of r-TiO2 (110) and a-TiO2 (101) systems to localise polarons in the slab structure. These results indicate that both mechanisms – hole scavenging and the inhibition of hole localisation – can be the origin of the effect of chlorides on photocatalytic activity of both titania polymorphs. These results provide fundamental insight into the photocatalytic properties of titania polymorphs and elucidate the effect of adsorbed anions over radical formation and oxidative decomposition of organic pollutants.