Batch and Packed Bed Column Study for the Removal of Cr (VI) and Ni (II) Using Agro-Industrial Wastes

The objective of this study was to prepare bio adsorbents from agro-industrial wastes from yam starch (YSR) and plantain (PSR) production for its use in the removal of Cr (VI) and Ni (II) in aqueous solution in batch and continuous packed-bed column systems. Bromatological analysis showed that the biomaterials are rich in cellulose, lignin, hemicellulose, and SEM micrographs that evidence a mesoporous structure characteristic of materials of lignocellulosic origin. FTIR evidenced functional groups such as hydroxyl, carbonyl, and methyl, possibly involved in the uptake of metal ions. EDS and FTIR analysis after adsorption confirmed that the retention of the metals on the surface of the adsorbent materials was successful. Cr (VI) and Ni (II) removal efficiencies above 80% were achieved using YSR and PSR in batch systems at the different conditions evaluated. The optimum conditions for removing Ni (II) on PSR were a bed height of 11.4 cm and a temperature of 33 °C, while for YSR, they were: 43 °C and 9 cm for temperature and bed height respectively. The variable with the most significant influence on the removal of Cr (VI) in a batch system on the two bio adsorbents was temperature. In contrast, the adsorbent dose and temperature are relevant factors for PSR Ni (II) removal. Therefore, the residues from the preparation of yam and plantain starch have high potential for removing heavy metals from wastewater and are presented as an alternative for their final disposal