摘要
砷污染问题已经在世界范围内引起了广泛关注,砷的去除也随即成为有待解决的问题,三价砷的毒性远远高于五价砷,地下水中砷主要以三价砷存在。水体中砷的除去与其水化特征密切相关,而有关不同质子化亚砷酸[H_(m)AsO_(3)]^(m-3)(m=2,3)周围水化特征的研究少之甚少,更无[H_(m)AsO_(3)]^(m-3)(m=2,3)水化层的红外光谱特征研究。利用B3LYP/6-311G(d,p)方法优化并计算了[H_(m)AsO_(3)(H_(2)O)_(12)]^(m-3)(m=3,2)水化能,采取约化密度梯度函数填色等值面分析水分子与[H_(m)AsO_(3)]^(m-3)(m=3,2)物种相互作用类型、位置及强度,并详尽解析[H_(m)AsO_(3)(H_(2)O)_(12)]^(m-3)(m=3,2)水化团簇红外光谱特征。研究得出,[H_(m)AsO_(3)(H_(2)O)_(12)]^(m-3)(m=3,2)水化团簇中H_(m)AsO_(3)倾向分布在水化团簇的表面,H_(3)AsO_(3)比H_(2)AsO_(3)^(-)水化能力低。有趣地发现,H_(3)AsO_(3)第一水化层通过氢键形成了一个变形的六元环,氢键的平均键长为1.79;而H_(2)AsO_(3)^(-)第一水化层通过氢键形成了一个变形的五元环,氢键的平均键长也为1.79。红外光谱中,[H_(3)AsO_(3)(H_(2)O)_(12)]0的As—O P(质子化O)伸缩振动峰701和637 cm^(-1)与FTIR实验光谱中的数据一致,而[H_(2)AsO_(3)(H_(2)O)_(12)]-的As—O P伸缩振动峰为573,562和449 cm^(-1),发生了明显红移,其As—O N(未质子化O)伸缩振动峰为798 cm^(-1)。[H_(3)AsO_(3)(H_(2)O)_(12)]0中独立O P—H伸缩振动峰为3696 cm^(-1),O P—H…O_(W)中O P—H伸缩振动峰3598和3105 cm^(-1);[H_(2)AsO_(3)(H_(2)O)_(12)]-中独立O P—H伸缩振动峰为3678 cm^(-1),O P—H…O_(W)中O P—H伸缩振动峰为3576 cm^(-1)。H_(3)AsO_(3)第一水化层组成的六元环中O_(W)—H_(W)…O_(W)的O_(W)—H_(W)特征伸缩振动峰为3233和2911 cm^(-1)且弯曲振动峰为1606 cm^(-1),而当第一水化层中水与H_(3)AsO_(3)中H或O P形成氢键导致O_(W)—H_(W)伸缩振动峰和弯曲振动峰都蓝移。H_(2)AsO_(3)^(-)第一水化层组成的五元环中O_(W)—H_(W)…O_(W)的O_(W)—H_(W)特征伸缩振动峰为3383 cm^(-1),且O_(W)—H_(W)弯曲振动峰为1680,1674和1660 cm^(-1);当H_(2)AsO_(3)^(-)第一水化层中水与H_(2)AsO_(3)^(-)的H形成H_(W)—O_(W)…H时导致O_(W)—H_(W)伸缩振动峰蓝移而弯曲振动峰红移,第一水化层中水与H_(2)AsO_(3)^(-)的O P或O N形成氢键时导致O_(W)—H_(W)伸缩振动峰红移而弯曲振动峰蓝移。相对于H_(3)AsO_(3)第一水化层红外特征,H_(2)AsO_(3)^(-)第一水化层O_(W)—H_(W)伸缩振动峰和弯曲振动峰都发生了蓝移。
Arsenic pollution has aroused widespread concern worldwide,and the removal of arsenic has immediately become a problem to be solved.The toxicity of trivalent arsenic is far higher than that of pentavalent arsenic.Arsenic mainly exists in groundwater with trivalent arsenic.The removal of arsenic in water is closely related to its hydration characteristics.However,there are few studies on the hydration characteristics around different protonated arsenite[H_(m)AsO_(3)]^(m-3)(m=2,3),let alone the infrared spectral characteristics of[H_(m)AsO_(3)]^(m-3)(m=2,3)hydration layer.In this paper,the B3LYP/6-311G(d,p)method was used to optimize and calculate the hydration energy of[H_(m)AsO_(3)(H_(2)O)_(12)]^(m-3)(m=3,2).The type,location and intensity of interaction between water molecules and[H_(m)AsO_(3)]^(m-3)(m=3,2)species were analyzed by using a reduced density gradient function colorimetric isosurface.The IR characteristics of[H_(m)AsO_(3)(H_(2)O)_(12)]^(m-3)(m=3,2)hydrated clusters were analyzed in detail.The results show that H_(m)AsO_(3)tends to be distributed on the surface of[H_(m)AsO_(3)(H_(2)O)_(12)]^(m-3)(m=3,2)hydrated clusters.H_(3)AsO_(3)has a lower hydration capacity than H_(2)AsO_(3)^(-).Interestingly,the first hydration layer of H_(3)AsO_(3)forms a deformed six-membered ring through a hydrogen bonds,with an average bond length of 1.79.However,the first hydration layer of H_(2)AsO_(3)^(-) forms a deformed five-membered ring through hydrogen bond,and the average bond length of hydrogen bond is also 1.79.In the infrared spectrum,the As—O P(proton-O)stretching vibration peaks of[H_(3)AsO_(3)(H_(2)O)_(12)]0 are 701 and 637 cm^(-1),which are consistent with the FTIR spectra,while the As—O P stretching vibration peaks of[H_(2)AsO_(3)(H_(2)O)_(12)]-are 573,562 and 449 cm^(-1).The As—O N(unprotonated O)stretching vibration peak is 798 cm^(-1).In[H_(3)AsO_(3)(H_(2)O)_(12)]0,the independent O P—H stretching vibration peaks are 3696 cm^(-1),and the O P—H stretching vibration peaks in O P—H…O_(W)are 3598 and 3105 cm^(-1).The independent O P—H stretching vibration peak in[H_(2)AsO_(3)(H_(2)O)_(12)]-is 3678 cm^(-1),and the O P—H…O_(W)stretching vibration peak is 3576 cm^(-1).The O_(W)—H_(W)characteristic stretching vibration peaks of O_(W)—H_(W)…O_(W)in the six-membered ring composed of the first hydration layer of H_(3)AsO_(3)are 3233 and 2911 cm^(-1),and the bending vibration peak is 1606 cm^(-1).When the water in the first hydration layer forms a hydrogen bond with H or O P in H_(3)AsO_(3),both O_(W)—H_(W)stretching vibration peak and bending vibration peak shift blue.The O_(W)—H_(W)characteristic stretching vibration peak of O_(W)—H_(W)…O_(W)in the five-member ring composed of the first hydration layer is 3383 cm^(-1),and the O_(W)—H_(W)bending vibration peaks are 1680,1674,and 1660 cm^(-1).When the water in the first hydration layer of H_(2)AsO_(3)^(-) forms H_(W)—O_(W)…H with H of H_(2)AsO_(3)^(-),the O_(W)—H_(W)stretching vibration peak shifts blue,and the bending vibration peak shifts red.When the water in the first hydration layer forms a hydrogen bond with O P or O N of H_(2)AsO_(3)^(-),the O_(W)—H_(W)stretching vibration peak shifts red and the bending vibration peak shifts blue.Compared with the infrared characteristics of the first hydration layer of H_(3)AsO_(3),the O_(W)—H_(W)stretching and bending vibration peaks for the first hydration layer of H_(2)AsO_(3)^(-) have a blue shift.
作者
李会吉
李艳雯
于卫卫
黄汝梦
孙海杰
彭智昆
LI Hui-ji;LI Yan-wen;YU Wei-wei;HUANG Ru-meng;SUN Hai-jie;PENG Zhi-kun(School of Chemistry and Chemical Engineering,Zhengzhou Normal University,Zhengzhou 450044,China;Huadian Zhengzhou Machinery Design and Research Institute Co.,Ltd.,Zhengzhou 450046,China;Henan Institutes of Advanced Technology,Zhengzhou University,Zhengzhou 450003,China)
出处
《光谱学与光谱分析》
SCIE
EI
CAS
CSCD
北大核心
2023年第7期2090-2094,共5页
Spectroscopy and Spectral Analysis
基金
国家自然科学基金项目(21908203)
河南省科技攻关项目(222102320190)
河南省高等学校重点科研项目(21B150021)
郑州师范学院青年骨干教师资助培养计划(QNGG-211562)
郑州师范学院科研启动专项经费(2018)
郑州师范学院大学生科研创新基金项目(2021008)资助。
关键词
亚砷酸
水化特征
红外光谱
Arsenite
Hydration characteristics
Infrared spectrum
