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| Influence of values of C/M(organic matter/mineral component)on the formation and sorption behavior of kaolin-humic acid complexes |
| Received:January 04, 2018 |
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| KeyWord:C/M change;subcritical water treatment;organo-mineral complexes;carbamazepine;sorption |
| Author Name | Affiliation | E-mail | | PENG Liu-yue | Key Laboratory of Water Resources and Environmental Engineering, School of Water Resources and Environment, China University of Geosciences, Beijing 100083, China | | | HE Jiang-tao | Key Laboratory of Water Resources and Environmental Engineering, School of Water Resources and Environment, China University of Geosciences, Beijing 100083, China | jthe@cugb.edu.cn | | WANG Fei | Key Laboratory of Water Resources and Environmental Engineering, School of Water Resources and Environment, China University of Geosciences, Beijing 100083, China | |
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| Abstract: |
| To investigate the impact of changes in C/M (the ratio of organic matter to the mineral component) which on the formation of organo-mineral complexes (Com) under high pressure-temperature (HPT) conditions (which the temperature is 250℃, pressure is 4 MPa), subcritical water treatment was used to simulate the formation of Com. Under the conditions of HPT and normal pressure-temperature (NPT), Com samples with C/M values of 10%, 5%, 2%, 1%, and 0.5% were made. Surface properties, changes in functional groups, and microstructure were characterizedvia specific surface area analysis (SSA), Fourier-transform infrared spectroscopy (FTIR), and scanning electronmicroscopy (SEM). Results showed that the increase in C/M affects the combination mode between kaolinite (KL) and humic acid (HA) and subsequently influences the structure of Com.When the value of C/M was less than 1%, HA was adsorbed on to the surface and in the pores of KL under NPT. While under HPT, HA and KL formed a stable structure. When the value of C/M was higher than 1%, HA separated from Com owing to hydrogen-bondinteractionor adsorbed onto Com through electrostaticinteraction under NPT. However, under HPT, HA combined with the outer-sphere HA of Com, forming a polymer.To prove this mechanism, batch experiments of carbamazepine (CBZ) sorption by Com were conducted. The results showed that the sorption linearity increased with increasing C/M. The Kf and N (parameter of the Freundlich isotherm, Kf related to the sorption property, N shows the linearity nature of the isotherm) of the Freundlich isotherm showed that when the value of C/M was low, under NPT, KL and HA were both important in the sorption of CBZ and the sorption was linear. When the value of C/M increased, HA in the outer space became the main sorbent of CBZ. Under HPT, HA was in the form of macromolecules gathering together as clusterson the surface of Com, which could inhibit the contact between CBZ and the inner Com, resulting in a slow increase in the adsorption capacity. |
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