Photoexcitation effect on the adsorption of hazardous gases on silica surface.
Photoexcitation effect on the adsorption of hazardous gases on silica surface.
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DOI：
10.1016/j.jhazmat.2017.07.052
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发表时间：
2018-01
影响因子：
13.6
通讯作者：
Yonggang Yang;Donglin Li;Chaozheng Li;Yufang Liu;Kai Jiang
中科院分区：
文献类型：
--
作者：
Yonggang Yang;Donglin Li;Chaozheng Li;Yufang Liu;Kai Jiang
光激发效应对吸附剂吸附性能的影响目前科学认识很少。以SARIN（propan-2-ylmethylphosphofluoridate）、MDCP（methyl dichlorophosphate）、TMP（trimethyl phosphate）和H_2S（H_2S）4种有害气体在SiO_2表面的吸附为目标样品。基态吸附能的顺序（MDCP < SARIN < TMP）与文献报道的SiO2表面羟基与有害气体分子间氢键（inter-HB）强度顺序以及三种气体的脱附顺序一致。当MDCP吸收短波紫外光后，随着吸附能的增加，SARIN和TMP的吸附能降低，吸附能的变化顺序为SARIN < TMP < MDCP。这种变化与第一激发态（S1）中MDCP的HB间减弱和第二激发态（S2）中TMP和SARIN的HB间增强相反。这种相反的变化是由MDCP分子间电荷转移态的形成以及SARIN和TMP的局部激发引起的。H2S在光激发后解离为S1态。光激发对吸附剂的吸附行为有显著影响，可作为吸附剂设计和吸附性能检测的新标准。
There is very little scientific understanding of photoexcitation effect on the adsorption properties of adsorbent. The adsorption of four hazardous gases (SARIN (propan-2-ylmethylphospho-nofluoridate), methyl dichlorophosphate (MDCP), trimethyl phosphate (TMP) and hydrogen sulfide (H2S)) on silica surface is taken as target sample in this work. The adsorption energy order (MDCP < SARIN < TMP) in the ground state is consistent with the strength order of intermolecular hydrogen bond (inter-HB) between hydroxyl group of silica surface and hazardous gas, and the desorption order of the three gases in previous reports. However, with the adsorption energy increase of MDCP and the decrease of SARIN and TMP, this order changes remarkably to SARIN < TMP < MDCP after photoexcitation to excited state by absorbing shortwave ultraviolet irradiation. This change is opposite to the inter-HB weakening of MDCP in the first excited (S1) state and the strengthening of TMP and SARIN in the second excited (S2) state. This opposite change is caused by formation of intermolecular charge transfer state of MDCP and local excitation of SARIN and TMP. The H2S is dissociated after photoexcitation to the S1state. This work presents photoexcitation as a new standard for the design and detection of adsorption properties of adsorbent for its striking effect on adsorption behaviors.