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Se investigó el uso de quitosano cuaternario entrecruzado, QC2, en la remoción de ion cromo (VI) a partir de soluciones acuosas a temperatura ambiente, mediante experimentos de adsorción discontinuos. Los parámetros que se ha evaluado en la capacidad de adsorción del ion mencionado, el adsorbente, fueron efecto de: pH, masa de adsorbente, concentración del ion, cinética de adsorción y fuerza iónica, apoyados por los análisis FTIR, SEM, TGA. Los resultados se han analizado usando los modelos matemáticos de Langmuir y Freundlich; los resultados muestran que la adsorción se da mediante un mecanismo mixto. Los parámetros calculados demuestran una alta afinidad adsorbente/adsorbato para QC2 con una máxima capacidad de adsorción de 208,3 mg g-1, elucidando el potencial uso de este adsorbente para la remoción de ion cromo (VI) en soluciones acuosas, mediante una cinética de seudo segundo orden con una constante de velocidad de 0,289 g mg-1 min-1. La desorción es eficiente en una mezcla NaCl / NaOH (1,0 M) con 99,78 % de remoción a pH 4,5. Altas concentraciones de fuerza iónica afectan la capacidad de adsorción de cromo (VI).
In this work, the stoichiometric amounts of the amino-quaternaries and cross-linker were studied to produce the most stable cross-linked quaternary Chitosan (QC2). Preliminary assays were carried out to test the improvement in their mechanical and chemical properties (extreme conditions, surface area and thermogravimetry). Then, the adsorption of chromium (VI) on the QC2 was studied at changing experimental conditions like: pH, adsorbent dose, initial chromium concentration and ionic strength. Moreover, the kinetics of the process was also evaluated as well as the optimization, the desorption of chromium (VI) from the adsorbent for metal recovery and adsorbent recycling. Finally, was characterized by using instrumental techniques such as FTIR, SEM. These tools allowed us to investigate the adsorption mechanism. The calculated parameters indicate a high adsorbent/adsorbato affinity for QC2 with a maximum adsorption capacity of 208 mg g-1 for Cr (VI), elucidating its potential use for the removal of chromium from aqueous solutions. Also showed a pseudosecond order adsorption kinetics with a velocity constant of 0.289 g.mg-1.min-1. Desorption of chromium was efficiently accomplish with a mixture of 1M of NaCl and NaOH, reaching a recovery up to 99.78% of the initial metal concentration at pH 4.5. Finally, high ionic strength shows an effect on the adsorption of chromium (VI) onto the studied adsorbents.
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