Adsorption of Nitrate on Kaolinite Surfaces: A Theoretical Study

Abstract

The interactions of HNO(3) and NO(3)(-) with kaolinite surfaces are important in the reaction of airborne clay mineral particles with atmospheric trace gases. Theoretical calculations at the B3LYP/6-311++G(d,p) level were performed on surface clusters of HNO(3) on kaolinite, on monodentate, on bidentate, and on two bridged complex structures of NO(3)(-) on kaolinite and on gas phase and solvated NO(3)(-). The results are compatible with the ranges assigned in the literature for NO(3)(-) on mineral surfaces for the frequency of the vibrational symmetric stretches (ν(1)) and for the low-frequency branch of the asymmetric stretches (ν(3)), with slightly higher frequencies reported for the bridged models. For the higher-frequency branch of the asymmetric stretches measured on kaolinite (Angelini et al.), our calculations match the assigned values for the monodentate surface complex, while predicting an inverse assignment for the frequencies of the bidentate and bridged complexes.

Investigating the Low Temperature Formation of CuII‐(N,O) Species on Cu‐CHA Zeolites for the Selective Catalytic Reduction of NOx

“…[19b, 20, 22] This assignment has been recently discussed on the basis of theoretical calculations, proposing ah igherf requency for the chelating structures with respectt ob ridging ones, in relation to am ore strained O-N-O angle and shorterN =Od istance in the former. [23] This implies that the n N=O frequency alone cannot be used to discriminate betweent he two bidentate structures involving one or two Cu II ions.…”

The Adsorption of Cr3+ onto Na+-Saturated Kaolinite

“…Adsorption band that appeared at the wave number 3673 cm -1 was a vibration OHstretching which bonded with Al on the surface [8]. The absorption band at wave numbers 2107 cm -1 and 2111 cm -1 were from vibration of-OH surface groups of H-bending to H2O [5]. Adsorption band that appeared at the wave number 1119 cm -1 , 1043 cm -1 , 694 cm -1 , 535 cm -1 showed vibration of strings Si-O-, vibration Al-O vibration helping O-Si-O, vibration of Si-O-Al(IV), which was a typical absorption of the mineral kaolinite [6], [7].…”

“…Adsorption method is generally based on the interaction between metal and functional groups contained in the adsorbent, which is through formation of the complex and cations exchange. The material that is usually used as the adsorbent in the adsorption process of heavy metals are materials that contain tannins (activated carbon, sawdust, bark), zeolite, chitosan, seaweed, lignin, and kaolinite (clay) [5].…”

“…Kaolinite is a whitecoloured mineral that has many functions. Kaolinite is powdery white and has a hexagonal crystal [5]. (Tribe et al, 2012).…”

“…Kaolinite is powdery white and has a hexagonal crystal [5]. (Tribe et al, 2012). In Indonesia, the hill that contains kaolinite can also be found in the regions of Sumatra, Sulawesi and Kalimantan [5].…”