TY - JOUR
T1 - Adsorption-desorption characteristics of nitrate, phosphate and sulfate on Mg-Al layered double hydroxide
AU - Halajnia, A.
AU - Oustan, S.
AU - Najafi, N.
AU - Khataee, A. R.
AU - Lakzian, A.
PY - 2013
Y1 - 2013
N2 - The adsorption-desorption behavior of nitrate on Mg-Al layered double hydroxide (4:1) was compared with that of phosphate and sulfate as two common anions in soil solution. Based on the results, the kinetics of anion adsorption on the LDH followed a pseudo-second order model. The adsorption process was found to be exothermic for nitrate and endothermic for phosphate and sulfate. The adsorption data were best described by the Freundlich model for nitrate and by the Langmuir model for phosphate and sulfate. In this study, the synthesized LDH exhibited higher adsorption rate and adsorption capacity for nitrate compared to sulfate and phosphate. The maximum adsorption capacity values were 1.90, 0.28 and 0.13mmolg-1 for nitrate, phosphate and sulfate, respectively. However, the Langmuir equation constants related to the adsorption energy were found to be 0.210, 10.731 and 3.021Lmmol-1, respectively. The distribution coefficient (Kd) was higher for nitrate than phosphate and sulfate at high initial concentrations. Moreover, the values of hysteresis index based on the Freundlich exponent were 97.5, 22.5 and 79.0% for nitrate, phosphate and sulfate, respectively. The FTIR spectroscopy indicated a strong band related to the nitrate intercalated into the interlayer space of the LDH.
AB - The adsorption-desorption behavior of nitrate on Mg-Al layered double hydroxide (4:1) was compared with that of phosphate and sulfate as two common anions in soil solution. Based on the results, the kinetics of anion adsorption on the LDH followed a pseudo-second order model. The adsorption process was found to be exothermic for nitrate and endothermic for phosphate and sulfate. The adsorption data were best described by the Freundlich model for nitrate and by the Langmuir model for phosphate and sulfate. In this study, the synthesized LDH exhibited higher adsorption rate and adsorption capacity for nitrate compared to sulfate and phosphate. The maximum adsorption capacity values were 1.90, 0.28 and 0.13mmolg-1 for nitrate, phosphate and sulfate, respectively. However, the Langmuir equation constants related to the adsorption energy were found to be 0.210, 10.731 and 3.021Lmmol-1, respectively. The distribution coefficient (Kd) was higher for nitrate than phosphate and sulfate at high initial concentrations. Moreover, the values of hysteresis index based on the Freundlich exponent were 97.5, 22.5 and 79.0% for nitrate, phosphate and sulfate, respectively. The FTIR spectroscopy indicated a strong band related to the nitrate intercalated into the interlayer space of the LDH.
KW - Adsorption capacity
KW - Adsorption kinetics
KW - Adsorption selectivity
KW - FTIR spectroscopy
KW - Hysteresis index
UR - http://www.scopus.com/inward/record.url?scp=84883460834&partnerID=8YFLogxK
U2 - 10.1016/j.clay.2013.05.002
DO - 10.1016/j.clay.2013.05.002
M3 - Article
AN - SCOPUS:84883460834
SN - 0169-1317
VL - 80-81
SP - 305
EP - 312
JO - Applied Clay Science
JF - Applied Clay Science
ER -