Removal of Pb(II) by lignin-sodium alginate composite in a fixed-bed column

• Published in: Environmental technology Vol. 45; no. 4; pp. 681 - 694
• Main Authors: Zheng, Chunli, Yong, Yingying, Wang, Qiaorui, Lin, Zishen, Wang, Yujie, Zhang, Youwen, He, Chi
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis 2024; Taylor & Francis Ltd
• Subjects: Adsorbents; Adsorption; Alginates; Alginic acid; Breakthrough curves; Fixed-bed column; Hydrogels; Inflow; Infrared analysis; Lead; Lignin; Pb(II); Regeneration; Sodium; Sodium alginate; Spectroscopy, Fourier Transform Infrared; Wastewater; Water Pollutants, Chemical; Pb(II); Regeneration; Adsorption; Fixed-bed column; Breakthrough curves
• ISSN: 0959-3330; 1479-487X
• DOI: 10.1080/09593330.2022.2119609

A kind of adsorbent (Hydrogel-I) derived from sodium alginate and modified alkaline lignin (MAL) has been proved to possess a good adsorption performance for Pb(II)-loaded wastewater based on batch experiments. However, practical removal of Pb(II)-loaded-wastewater is a continuous and dynamic process. Herein, Hydrogel-I was further evaluated by packing it into a fixed-bed column. The breakthrough curves were established under different inflow rates (0.159-0.318 L/min), inflow directions (down-inflow mode and top-inflow mode), initial concentrations (5-20 mg/L) of Pb(II), and bed depths (20-60 cm). The results indicated that the slower inflow rate (0.159 L/min), down-inflow mode, lower initial concentration (5 mg/L), and higher bed depth (60 cm) prolonged breakthrough times (t
b
) and saturation times (t
s
). Compared to the top-inflow mode, the down-inflow mode guaranteed enough contact between Hydrogel-I and Pb(II). The values of adsorption capacity at t
b
, t
s,
and the removal efficiency under the down-inflow mode were higher than that under top-inflow mode by 2.33, 0.78, and 0.07 times, respectively. Hydrogel-I beads exhibited better adsorption performance than other adsorbents by comparing the rate constant (k
AB
) and the adsorption capacity (N
0
). The k
AB
and N
0
of Hydrogel-I beads were calculated to be 0.0034 L/(mg·min
−1
) and 678 mg/L. Hydrogel-I beads showed good regeneration ability in a three-adsorption-desorption cycle. Meanwhile, FT-IR analysis showed that the groups of -NH/-NH
2
, C=S, and C-S were proved to be the adsorption sites. This study could prove valuable insight into the practical application of Hydrogel-I for dynamic removal of Pb(II) in an inflow-through column.