Synthesis and application of lignin-based flocculants

doi:10.11949/0438-1157.20250290

Abstract

Abstract:

As a renewable polymer compound with abundant reserves in nature, lignin has shown great application potential in the field of sewage treatment due to its unique structural characteristics and environmental friendliness. We review the preparation strategies, flocculation mechanisms, key influencing factors, and practical application challenges of lignin-based flocculants. Through chemical modification approaches such as graft copolymerization, amination, cross-linking, and sulfonation, the molecular weight of lignin can be effectively regulated, with functional group activity optimized, and spatial configuration tailored. As a result, the flocculation performance can be significantly enhanced. Flocculation mechanisms include charge neutralisation, adsorption bridging, and sweep coagulation. Flocculation efficiency is synergistically influenced by factors such as concentration, pH and temperature. Experimental studies have shown that lignin-based flocculants exhibit excellent performance in turbidity removal, dye removal, and heavy metal removal. For example, the removal rate of anionic dyes can reach more than 94%, and the removal rate of heavy metal ions (such as Cu²⁺, Pb²⁺) is close to 100%. Compared with conventional flocculants, lignin-based flocculants offer advantages of low toxicity and biodegradability. However, their practical application still faces challenges such as complex modification processes and potential residual toxic reagents. To promote large-scale application, further optimization of green modification techniques is required to balance performance requirements with environmental considerations, along with establishing efficient and sustainable synthesis pathways and application protocols.

Key words: lignin, flocculant, chemical reaction, biomass, renewable energy

摘要：

木质素作为自然界储量丰富的可再生高分子化合物，因其独特的结构特性及环境友好性，在污水处理领域展现出巨大应用潜力。系统综述了木质素基絮凝剂的制备策略、絮凝机理、关键影响因素及其实际应用问题。通过接枝共聚、胺化反应、交联改性和磺化改性等化学手段，可有效调控木质素分子量，优化官能团活性，并优化空间构型，从而显著提升其絮凝性能。电荷中和、吸附桥接及网捕作用是木质素絮凝剂的絮凝机理。絮凝效率受浓度、pH和温度等因素的协同影响。实验研究表明，木质素基絮凝剂在浊度去除、染料去除及重金属去除方面表现优异。如对阴离子染料的去除率可达94%以上，对重金属离子（如Cu²⁺、Pb²⁺）的去除率接近100%。与传统絮凝剂相比，木质素基絮凝剂具有低毒、可生物降解的优点，但其实际应用仍面临改性工艺复杂、潜在毒性试剂残留等问题。为推动木质素基絮凝剂的规模化应用，仍需进一步优化绿色改性工艺，平衡性能需求与环保要求，并建立高效可持续的合成路径和应用方案。

关键词: 木质素, 絮凝剂, 化学反应, 生物质, 再生能源

CLC Number:

TQ 317

Zequan LI, Tianyu CAI, Jiajun LIU, Qizhi CHEN, Peiwen XIAO, Xiaofei XU, Shuangliang ZHAO. Synthesis and application of lignin-based flocculants[J]. CIESC Journal, 2025, 76(9): 4709-4722.

李泽权, 蔡天宇, 刘家骏, 陈奇志, 肖沛文, 徐小飞, 赵双良. 木质素基絮凝剂的合成与应用[J]. 化工学报, 2025, 76(9): 4709-4722.

Figures/Tables 11

Fig. 1 Chemical model structures of several typical bonds in lignin and three phenylpropane precursors, and basic units

Fig. 2 Comparison between the properties of conventional flocculants and lignin flocculants

Table 1 Examples of monomers used in graft copolymerization reactions for the preparation of lignin-based flocculants

类型	单体
非离子型	丙烯酰胺（AM）
阳离子型	丙烯酰氧乙基三甲基氯化铵（DAC）
	甲基丙烯酰氧乙基三甲基氯化铵（DMC）
	3-氯-2-羟丙基三甲基氯化铵（CHPTAC）
	(3-丙烯酰胺丙基)三甲基氯化铵（ATMAC）
	二甲基二烯丙基氯化铵（DMDMAC）
阴离子型	丙烯酸（AA）
	苯乙烯磺酸（SSA）
	2-丙烯酰胺-2-甲基丙磺酸（AMPS）

Fig. 3 Synthesis route of flocculants formed by grafting DMC and AM onto enzymatic hydrolysis lignin

Fig.4 Mannich reaction of lignin

Table 2 Commonly used aliphatic amines and aldehydes in lignin Mannich reaction

脂肪胺与醛类	种类	举例
脂肪胺	多胺	乙二胺、己二胺、三乙基四胺、四乙基五胺
脂肪胺	氨基酸	甘氨酸、亚氨基二乙酸
醛类	单醛	甲醛、乙醛、丙醛、苯甲醛、糠醛
	二醛	戊二醛、乙二醛
	不饱和醛	丙烯醛、丁烯醛

Fig.5 Synthetic routes to the cross-linked products of sodium lignosulfonate

Fig. 6 A synthetic route to synthesize amino-functionalized and sulfonated lignans by combining amino and sulfonated groups[41]

Fig.7 Schematics of the flocculation mechanism

Fig.8 Flow scheme of flocculation process

Fig.9 Summary and outlook

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