Efeito do pH na adsorção e dessorção de cádmio em Latossolos brasileiros

摘要: Adsorption and desorption reactions of metals in soils are influenced by the surface soil colloid attributes solution composition. This study evaluated effect pH on Cd adsorption (Cdads) (Cddes) l7 Brazilian Oxisol samples that differed their chemical, physical mineralogical attributes. Samples each soil, suspended 5 mmol L-1 Ca(NO3)2 (pH adjusted to 4.5; 5.5, 6.5; ratio soil:solution 1:67) were placed react with 0.20 Cd(NO3)2 (final 1:100) for 72 h, after which they centrifuged concentration determined. Thereafter, 25 mL added remaining residue desorb retained samples. An increase from 4.5 6.5 5.5 caused a 1.3; 2.2 1.7-fold adsorption, respectively. The mean percentage adsorbed (Cd%ads) was 27 4.5), 35 5.5) 55% 6.5). Cdads only evidenced at 6.5, correlations between organic matter, specific superficial area (SSA), CEC 7.0 (CEC), kaolinite, hematite, oxalate-and-DCB-Fe clay contents. However, content, SSA, included model prediction, obtained through regression analyses. values higher did not propitiate reduction Cddes, around 20% 40% 6.5. small proportions these Oxisols, mainly lower values, an indication high mobility bioavailability, reinforces need adoption appropriate criteria use or discard residues containing agricultural areas close aquifers.