Trace Elements Adsorption from Solutions and Acid Mine Drainage Using Agricultural By-products

To mitigate the trace elements (TE) dispersion in acid mine drainage (AMD), laboratory experiments were carried out comparing nine agricultural by-products. Five adsorbent materials were selected for adsorption batch experiments. Then, the biosorbents were tested to remove TE from AMD collected from oxidized tailings heaps, using equilibrium experiments. The As adsorption on carbonatite was high (15.4 g kg(-1)); Cd (4.1 g kg(-1)) on cow manure; Cu (17.9 g kg(-1)) on carbonatite; Pb (14.1 g kg(-1)), and Zn (16.4 g kg(-1)) on rabbit manure. The Zn adsorption on oat straw and carbonatite was well fit by Freundlich isotherm. The Langmuir equation mimics well Zn and Cd adsorption by peat moss and caw manure; Cu adsorption on peat moss and vermicompost. Except for vermicompost and carbonatite, the adsorption improved as the buffer capacity of the biosorbents increased, following a second-order equation. The FTIR analysis showed that the carboxylic, aromatic, and aliphatic aldehyde groups were involved in TE adsorption. Soluble-As, -Cd, -Cu, and -Zn from AMD were removed (90%) by the addition of 4 and 8% (m/v) of sheep manure, cow manure, rabbit manure, vermicompost, and carbonatite. Lead concentration in AMD was increased due to the addition of the biosorbents.