Poggi’s differential coefficient of hysteresis (CHPoggi) has been shown to be a useful tool for describing the adsorptive-desorptive behavior of pollutants on solid matrices. The CHPoggi is defined as the ratio of the derivative of the adsorption isotherm to the derivative of the desorption isotherm, both evaluated in a point of interest J in the space q-C of the equilibrium relationship of the pollutant and solid matrix (Poggi-Varaldo et al., 2002, Interciencia 27 (3): 180-185). The aim of this work was to evaluate the adsorptive-desorptive behavior of lindane in an agricultural soil using CHPoggi. In addition, a useful and simple algebraic equation for CHPoggi was obtained for the particular case when the adsorption isotherm is linear and the desorption isotherm follows the equation of Langmuir. The model solid matrix was an agricultural soil, pH 7.1, with low clay and high organic matter contents. The adsorption of lindane onto this soil was described by a linear isotherm given by the equation qa = 3.91*C, whereas the desorption was better described by a Langmuir-like isotherm given by the equation qd = (32.9*C)/(1 + 1.1*C), with q in mg/kg and C in mg/L. Based on the definition of CHPoggi a simple equation was derived, namely, CHPoggi = qmax *b/kl , where qmax = maximum capacity of adsorption of the Langmuir desorption isotherm (mg/kg); b = coefficient of curve growth-shape in the Langmuir desorption isotherm (L/mg); kl = coefficient of the linear adsorption isotherm (L/Kg). The value of Poggi´s coefficient of hysteresis was calculated at the point of interest J (qj = 28.8 mg/kg, Cj = 6 mg/L) using two different methods: first, a numerical method based on the ratio of the tangents to both isotherms in J (as an approximation to the corresponding derivatives), and second, the algebraic equation already given in the above paragraph. The first method yielded CHPoggi = 6.6, whereas the second one gave CHPoggi = 8.4. The agreement between the two methods indicates that the more simple algebraic equation can be used for calculation of CHPoggi whenever the isotherm equations are known. The value of CHPoggi suggests that the hysteresis lindane-soil is moderate.

A Minireview on Slurry Bioreactors for Bioremediation of Soils and Sediments (Paper B-33) / I.V. Robles-González; E. Rios-Leal; F. Esparza-García; J. Barrera-Córtes; R. Ferrera-Cerrato; J. Galíndez-Mayer; S. Caffarel-Méndez; F. Fava; N. Rinderknecht-Seijas; H.M. Poggi-Varaldo. - ELETTRONICO. - (2006). (Intervento presentato al convegno FIFTH INTERNATIONAL CONFERENCE ON REMEDIATION OF CHLORINATED AND RECALCITRANT COMPOUNDS tenutosi a MONTEREY, California nel MAY 2006).

A Minireview on Slurry Bioreactors for Bioremediation of Soils and Sediments (Paper B-33)

FAVA, FABIO;
2006

Abstract

Poggi’s differential coefficient of hysteresis (CHPoggi) has been shown to be a useful tool for describing the adsorptive-desorptive behavior of pollutants on solid matrices. The CHPoggi is defined as the ratio of the derivative of the adsorption isotherm to the derivative of the desorption isotherm, both evaluated in a point of interest J in the space q-C of the equilibrium relationship of the pollutant and solid matrix (Poggi-Varaldo et al., 2002, Interciencia 27 (3): 180-185). The aim of this work was to evaluate the adsorptive-desorptive behavior of lindane in an agricultural soil using CHPoggi. In addition, a useful and simple algebraic equation for CHPoggi was obtained for the particular case when the adsorption isotherm is linear and the desorption isotherm follows the equation of Langmuir. The model solid matrix was an agricultural soil, pH 7.1, with low clay and high organic matter contents. The adsorption of lindane onto this soil was described by a linear isotherm given by the equation qa = 3.91*C, whereas the desorption was better described by a Langmuir-like isotherm given by the equation qd = (32.9*C)/(1 + 1.1*C), with q in mg/kg and C in mg/L. Based on the definition of CHPoggi a simple equation was derived, namely, CHPoggi = qmax *b/kl , where qmax = maximum capacity of adsorption of the Langmuir desorption isotherm (mg/kg); b = coefficient of curve growth-shape in the Langmuir desorption isotherm (L/mg); kl = coefficient of the linear adsorption isotherm (L/Kg). The value of Poggi´s coefficient of hysteresis was calculated at the point of interest J (qj = 28.8 mg/kg, Cj = 6 mg/L) using two different methods: first, a numerical method based on the ratio of the tangents to both isotherms in J (as an approximation to the corresponding derivatives), and second, the algebraic equation already given in the above paragraph. The first method yielded CHPoggi = 6.6, whereas the second one gave CHPoggi = 8.4. The agreement between the two methods indicates that the more simple algebraic equation can be used for calculation of CHPoggi whenever the isotherm equations are known. The value of CHPoggi suggests that the hysteresis lindane-soil is moderate.
2006
PROCEEDINGS OF THE FIFTH INTERNATIONAL CONFERENCE ON REMEDIATION OF CHLORINATED AND RECALCITRANT COMPOUNDS
A Minireview on Slurry Bioreactors for Bioremediation of Soils and Sediments (Paper B-33) / I.V. Robles-González; E. Rios-Leal; F. Esparza-García; J. Barrera-Córtes; R. Ferrera-Cerrato; J. Galíndez-Mayer; S. Caffarel-Méndez; F. Fava; N. Rinderknecht-Seijas; H.M. Poggi-Varaldo. - ELETTRONICO. - (2006). (Intervento presentato al convegno FIFTH INTERNATIONAL CONFERENCE ON REMEDIATION OF CHLORINATED AND RECALCITRANT COMPOUNDS tenutosi a MONTEREY, California nel MAY 2006).
I.V. Robles-González; E. Rios-Leal; F. Esparza-García; J. Barrera-Córtes; R. Ferrera-Cerrato; J. Galíndez-Mayer; S. Caffarel-Méndez; F. Fava; N. Rinderknecht-Seijas; H.M. Poggi-Varaldo
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/45405
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