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

Abstract

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.

Characterization and Performance of Peanut Shells in Caffeine and Triclosan Removal in Batch and Fixed-Bed Column Tests

“…This value is lower than those reported in previous studies (2.4 and 5.0 m²/g) [ 21 , 22 ]. The variance is likely due to differences in peanut species and particle size (177–250 µm and 250–500 µm) [ 18 , 23 ] The pore volume and pore diameter, determined using the Barrett–Joyner–Halenda (BJH) method, were 0.005 cm³/g and 3.14 nm, respectively. According to the IUPAC, a pore diameter within the range of 2 to 50 nm characterizes mesoporous materials [ 31 ].…”

“…In these systems, agricultural residues have also proven to be effective in removing several contaminants. Residual yam pulp (Cr = 28.0 mg/g, Ni = 28.0 mg/g), residual banana pulp (Cr = 18.3 mg/g, Ni = 22.1 mg/g) [ 18 ], activated carbon from chichá-do-cerrado fruit husks (caffeine = 83.9 mg/g) [ 17 ], coconut shell-activated carbon (caffeine = 5.3 mg/g, saccharin = 4.3 mg/g, sulfamethoxazole = 6.2 mg/g, sucralose = 2.5 mg/g) [ 19 ], and peanut shell-activated carbon (naphthenic acids = 884 mg/g) [ 20 ] have been used. The efficiency of fixed-bed columns is related to the operational conditions and hydraulic performance of the fixed-bed column (flow rate, bed height, particle size of the bed material), making it highly desirable to optimize these parameters [ 17 ].…”