Amine-Cross-Linked Lignin-Based Polymer: Modification, Characterization, and Flocculating Performance in Humic Acid Coagulation

Abstract

In this study, a lignin-based flocculant (LNF) was synthesized by grafting amine groups into alkali lignin containing papermaking sludge. Characterization of LNF, such as FTIR, zeta potential, cationic degree, viscosity, and molecular weight, showed that the product was a cationic polymer with high solubility. LNF was used with aluminum sulfate (AS) and polyaluminum chloride (PAC) in humic acid coagulation to demonstrate its efficiency. Coagulation behavior and floc properties of LNF+PAC and LNF +AS dual-coagulant were comparatively evaluated. Results showed that the coagulation aid effect of LNF was independent of aluminum species. Addition of LNF could enhance humic acid removal efficiency and floc properties including size, strength, and fractal dimension significantly. The effect of solution pH on coagulation processes was also studied. Dual-coagulants showed the same variation trend as that of aluminum-based coagulants but enhanced coagulation performance during the investigative pH range. Flocs formed at pH 9 and pH 5 achieved maximum floc size in AS and PAC coagulation systems, respectively. Fractal dimension was relatively high at pH 7−9 due to the sweeping effect of aluminum hydrolysates. Overall, LNF brought in charge neutralization and absorption bridging effect and played a positive role in coagulation processes.

Production of Flocculants, Adsorbents, and Dispersants from Lignin

“…However, this method is inefficient for removing low molecular weight and hydrophilic compounds from wastewater [ 33 ]. To address this problem, Li and coworkers [ 34 ] synthesized a sludge-based flocculant by grafting amine groups onto the organics of sludge ( Figure 2 ). The sludge contained a major portion of lignin, and thus the chemical structure of lignin was considered for describing its reaction mechanisms with other chemicals in Figure 2 .…”

“…The AS and PAC were used for improving the efficiency of flocculation in a dual system. The results showed that the product could be used as a flocculant in this system and its efficiency was 25% higher under acidic conditions [ 34 ].…”

“… Reaction scheme for producing crosslinked amine-based sludge flocculant [ 34 ]. The sludge contained mainly lignin and hence the structure of lignin was selected to represent sludge as the raw material in this reaction.…”

Renewable bio-based adhesive fabricated from a novel biopolymer and soy protein

“…After grafting ESO onto EHLA to form EHL-ESO, the peaks at 1600, 1741, and 3409 cm −1 shifted to the lower wavenumbers at 1566, 1725, and 3376 cm −1 , respectively, indicating that ESO was successfully introduced onto EHLA. Moreover, a new peak appeared at 1643 cm −1 , corresponding to the bending vibration of N-H, 27 and a peak at 722 cm −1 disappeared, belonging to the bending (rocking) of –(CH 2 ) n – and –HC CH–. 26 Peak intensities at 825 and 843 cm −1 (epoxy group) 26 decreased and shifted to higher wavenumbers at 838 and 877 cm −1 , respectively, indicating that a ring-opening reaction occurred between amino groups (EHLA) and epoxy groups (ESO).…”

Investigation of multiple adsorption mechanisms for efficient removal of ofloxacin from water using lignin-based adsorbents

“…Among them, LN is the second largest natural polymer and largely exists in black liquor in paper manufacturing 22 . In fact, LN and its derivatives after some chemical modifications have been widely applied in water treatment, which could be used as adsorbents, flocculants, and scale inhibitors 23,24 . As effective adsorbents due to their having abundant oxygen-containing functional groups, lignin-based materials were employed to remove various contaminants in water such as heavy metals 25,26 and cationic dyes 27,28 in previous study.…”