Abstract

ALVARADO-IBARRA, Juana; TERAN-SAMANIEGO, Karla; VARGAS-HERNANDEZ, Diana  and  BAUTISTA-OLIVAS, Ana Laura. Mexican natural clinoptilolite treated with silver for DDD removal from water. Biotecnia [online]. 2020, vol.22, n.3, pp.146-155.  Epub Feb 10, 2021. ISSN 1665-1456.

The capability of a natural clinoptilolite to remove DDD in function of the temperature and variation of silver concentration was studied. The MEB-EDX and BET techniques analyzed the natural and modified samples. By kinetic tests, it was found that equilibrium occurred at 180 minutes of contact and that silver increases the removal efficiency. The process displayed a chemisorption kinetic, since it was adjusted to the pseudo second-order model and the coefficients of determination varied in a range from 0.9933 to 0.9997. By the adsorption isotherms, the maximum adsorbed concentration was obtained at 0.19 mg/g. The data fit perfectly to the Langmuir model, in which a decrease was observed in constant b, related to the adsorption energy, when there was an increase in temperature. The latter indicates a decrease in adsorption at high temperatures, with the order of adsorption being 25° C> 35° C> 45° C. It is concluded that the process is exothermic, since the adsorption was greater when the temperature lowered, corroborated by the calculation of the thermodynamic parameters (ΔH°, ΔG° and ΔS°).

Keywords : natural clinoptilolite; kinetic of removal; adsorption isotherms; dichlorodiphenyl dichloroethane; silver.

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