Activated carbons developed in different activation conditions to improve nitrate adsorption performance

espanolLa idoneidad de carbones activados (CAs) con caracteristicas texturales y de quimica superfical diferentes se estudio para la eliminacion de nitratos bajo diferentes condiciones de pH. Para ello se utilizaron cuatro CAs; dos de ellos comerciales y otros dos manufacturados mediante activacion quimica y fisica a partir de cascara de naranja y de almendra, respectivamente. Los resultados obtenidos mostraron que el precursor y la metodologia de activacion influyen en las caracteristicas adsorbentes. En cuanto a la capacidad de adsorcion, su superficie quimica fue muy relevante, mientras que las propiedades texturales no ejercieron un efecto notable. Ademas, la adsorcion de nitrato mejoro a pH acido, especialmente en el caso de los adsorbentes basicos, lo cual se asocio a una mayor importancia de las contribuciones electrostaticas asi como, una menor adsorcion competitiva entre los iones hidroxilo y nitrato. EnglishThe suitability of activated carbons (ACs) with dissimilar textural and surface chemistry characteristics was studied for nitrate removal, under different pH conditions. For this task, four ACs were used; two of them were manufactured by chemical and physical steam activation from orange peel and almond shell, while the other two were commercial adsorbents. It was found that both the precursor and activation methodology influence the adsorbents characteristics. Regarding nitrate uptake, their chemical surface was very relevant, while the textural properties did not exert a remarkable effect. Also, nitrate adsorption under acid pH was improved, especially for basic adsorbents, in contrast with neutral conditions, in which case no adsorbent stood out. The amelioration of nitrate removal for basic adsorbents and acidic pH conditions was associated to a greater prominence of electrostatic contributions as well as a lower extent of adsorption competition between hydroxyl and nitrate ions.