Sorption and Desorption Behavior of 4-Nonylphenol and a Branched Isomer on Soils with Long-Term Reclaimed Water Irrigation

摘要

4-Nonylphenol (4-NP) is one of the endocrine disrupter chemicals (EDCs) in reclaimed water. With agricultural soil widely irrigated by reclaimed water, groundwater and soil are contaminated by EDCs. Sorption and desorption behavior of 4-NP and a branched 4-NP (4-NP111) on three reclaimed water-irrigated soils (S1, S2, and S3) were carried out by kinetic and thermodynamic experiments. Kinetic experimental results showed that amp;90 of sorption of 4-NP on soils occurred during the initial rapid stage within 15 min. Isothermal sorption of 4-NP on soils conformed to a linear model. Sorption coefficients (K-d) were 767.9, 133.5, and 128.0 L/kg for S1, S2, and S3, respectively, at the condition of pH 7, 25 degrees C, 0.01 M CaCl2. Sorption coefficient of pollutants on organic carbon compounds (K-oc) were 4.47 x 10(4) L/kg for S1, 1.78 x 10(3) L/kg for S2 and 2.04 x 10(3) L/kg for S3, respectively, indicating that 4-NP was limited to migrate to deep soil. Sorption capacity of 4-NP and 4-NP111 on soils decreased with the increasing pH and temperature, and increased with the concentration of Ca2+. The K-d were maximum when the solution pH was 3, the experimental temperature was 25 degrees C and the concentration of Ca2+ was 0.2 M. The contribution of humic acid (HA) to the sorption of 4-NP exceeded 90. Variation of peak intensity at 2,900-3,400 cm(-1) of the Fourier transform infrared spectrometer spectra for the NP-adsorbed soil suggested some NP may be entrapped within the cavity of HA in soil.