[Influences of cation species on adsorption and desorption of oxytetracycline in two typical soils of China].
On the basis of the OECD Guideline 106, batch sorption methods were employed to reveal the effect of different cations (0.01 mol x L(-1) Ca2+, K+ and Na+) on oxytetracycline (OTC) adsorption and desorption process in two tested soils (cinnamon soil and red soil). Results show that the Freundlich model is the best isotherm to describe the experimental data of adsorption and desorption, and the average fitting correlation coefficient is 0.989. Except for the adsorption isotherm of cinnamon soil on OTC in 0.01 mol x L(-1) KCl, the other isotherms resemble the L-type curves. To the same cation, OTC adsorption capacity (lgKf) in the red soil (ranging from 2.907 to 3.173) is always higher than in the cinnamon soil (ranging from 2.577 to 2.885), and the adsorption strength (1/n) in the red soil (ranging from 0.672 to 0.825) is always lower than the cinnamon (ranging from 0.713 to 1.005). The dominant mechanism is physical adsorption in two soils. To the same soil, cation species don't affect OTC adsorption capacity (lgKf) (p > 0.05). And Ca2+ can reduce significantly the adsorption strength (p < 0.05), comparing with K+ and Na+. The apparent adsorption-desorption hysteresis is found, and the average hysteresis index (HI) in all soils are from 0.015 to 0.053. To the same cation, OTC HI is significantly higher than that of red soil (p < 0.05). In cinnamon soil, there is significantly HI difference (p < 0.01) between K+ and Ca2+, Na+. However, three cations have no significantly difference effect on HI in red soil.
Bao
Yan-Yu
YY
Key Laboratory of Pollution Processes and Environmental Criteria at Ministry of Education, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China. baoyanyu77@163.com
Zhou
Qi-Xing
QX
Zhang
Hao
H
D000327:Adsorption; D002118:Calcium / Q000737:chemistry; D002412:Cations / Q000737:chemistry*; D002681:China; D010118:Oxytetracycline / Q000737:chemistry*; D011188:Potassium / Q000737:chemistry; D012989:Soil Pollutants / Q000737:chemistry*
D002412:Cations; D012989:Soil Pollutants; D011188:Potassium; D002118:Calcium; D010118:Oxytetracycline