期刊
JOURNAL OF COLLOID AND INTERFACE SCIENCE
卷 363, 期 1, 页码 92-97出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.jcis.2011.07.002
关键词
Sol-gel synthesis; Layered double hydroxides; Adsorption; 2,4-Dichlorophenoxyacetic acid; Langmuir isotherm
资金
- National Science Foundation [CHE-0809751]
- Direct For Mathematical & Physical Scien
- Division Of Chemistry [0809751] Funding Source: National Science Foundation
The adsorption equilibrium, kinetics, and thermodynamics of removal of 2,4-dichlorophenoxy-acetic acid (2,4-D) from aqueous solutions by a calcined Zn-Al layered double hydroxide incorporated with Zr4+ were studied with respect to time, temperature, pH, and initial 2,4-D concentration. Zr4+ incorporation into the LDH was used to enhance 2,4-D uptake by creating higher positive charges and surface/layer modification of the adsorbent. The LDH was capable of removing up to 98% of 2,4-D from 5 to 400 ppm aqueous at adsorbent dosages of 500 and 5000 mg L-1. The adsorption was described by a Langmuir-type isotherm. The percentage 2,4-D removed was directly proportional to the adsorbent dosage and was optimized with 8% Zr4+. ion content, relative to the total metals (Zr4+ + Al3+ + Zn2+). Selected mass transfer and kinetic models were applied to the experimental data to examine uptake mechanism. The boundary layer and intra-particle diffusion played important roles in the adsorption mechanisms of 2,4-D, and the kinetics followed a pseudo-second order kinetic model with an enthalpy, Delta H-ads of -27.7 +/- 0.9 kJ mol(-1). Regeneration studies showed a 6% reduction in 2,4-D uptake capacity over six adsorption-desorption cycles when exposed to an analyte concentration of 100 ppm. (C) 2011 Elsevier Inc. All rights reserved.
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