Showing 2 results for Freundlich.
A. Mohammadi, M. Chorom, N.hosseini Zare, H. Amerikhah, A. Ramazan Poor,
Volume 17, Issue 65 (12-2013)
Abstract
The purpose of this study was to investigate cadmium adsorption through Freundlich and Langmuir equations in sediments of Karun River in three hydrometric stations (5th Ahvaz Bridge, Darkhovin and Khorramshahr) in the low-water and high-water seasons. Fitting of data from experiments on cadmium absorption to Freundlich and Langmuir equation showed they are compatible. According to the conducted experiments, there was a significant difference at 0.01 levels between b coefficient of Langmuir equation with the organic matter percentage and the clay content in both Low and high water seasons, while there was no significant difference between k coefficient of Langmuir equation with the organic matter percentage and the clay content for the two seasons. The results also suggested that there is a significant relationship between Kf of Freundlich equation with the organic matter percentage and clay content, at significant levels of 0.05 and 0.01 for the organic matter percentage and the clay content, respectively. Comparison of the means of low and high water seasons revealed that there is no significant relationship between Langmuir coefficients, whereas in Freundlich equation, a significant difference at 0.01 level was observed between kf coefficients. Generally, the obtained results indicated that cadmium adsorption by sediments in low-water season is higher than high-water season. Also, cadmium adsorption by the 5th Ahvaz Bridge sediments due to the sandy texture was less than those adsorbed by both Darkhovin and Khorramshahr sediments.
E. Chavoshi, M. Afyuni , M. Ali. Hajabbasi,
Volume 19, Issue 73 (11-2015)
Abstract
The sorption and desorption of fluoride by soil can play an important role in the transport of fluoride in soil. The study was conducted on the soil from Isfahan University of Technology research station site (two depths of 0-30 and 30- 60 cm). Fluoride sorption reactions were examined by equilibrating 0, 2.5, 5, 10, 25, 50 and 100 mg L-1 NaF solution with soils for 23 hr. The desorption experiments were performed using 0.03 mol L-1 NaCL solutions immediately following the completion of sorption experiments. The sorption isotherms of F were well described by the Langmuir and Freundlich models. The n values for Freundlich isotherm were 0.57 and 0.55 for two depths of the studied soil, respectively. The kF values for Freundlich isotherm were 0.026 and 0.025 mg (1-n) Ln g-1 for two depths, respectively. Maximum monolayer sorption capacities (q max) were obtained to be 0.4 and 0.35 mg g-1 for 1 and 2 layers of the studied soil, respectively. The desorption isotherms of F were well described by the Freundlich model. The fitted model parameters’ (kF and n) values for desorption branches were larger than these values for sorption branches. Also, the results showed a positive hysteresis (ndesrb sorb and kdesorb >Ksorb). It seems fluoride sorption to be reversible.
