Phenomenological Changes in Lignin Following Polymerization and Its Effects on Flocculating Clay Particles

Abstract

Cationic kraft lignin (CKL) macromolecules were produced via polymerizing kraft lignin (KL) with [2-(acryloyloxy)ethyl]trimethylammonium chloride (ATAC) or [2-(methacryloyloxy)ethyl]trimethylammonium methyl sulfate (METAM). Despite slightly different charge densities (2.3−2.5 mmol/g) of CKL, lignin−METAM (KL−METAM) had a significantly larger molecular weight and radius of gyration. A correlation was observed between the structure of CKLs and their impacts on the surface hydrophilicity of kaolin particles. In interacting with kaolin particles, KL−METAM generated larger and stronger flocs with looser structures than did KL−ATAC. Compared to ATAC, METAM had one additional methyl substituent on its structure, which provided fundamental evidence on how a small group (i.e., a methyl group) on the structure of a cationic monomer can have a substantial influence on its polymerization with lignin and subsequently on the efficiency of the induced macromolecule as a flocculant in a kaolin suspension system.

Polarity of Cationic Lignin Polymers: Physicochemical Behavior in Aqueous Solutions and Suspensions

“…In this work, HL-METAC and HL-MAPTAC were produced following free radical polymerization (see the Supporting Information, Scheme S1). [7,17] As both CHL polymers had asymmetric molecular structures, the dipole moment (μ) vectors on each polymer cannot cancel each other creating polar molecules. As shown in Scheme 1, the larger electronegativity of the oxygen atom in the METAC structure of HL-METAC makes this macromolecule interact more with colloidal particles in an aqueous solution (i. e., electrostatic interactions).…”

“…Cationic hydrolysis lignin (CHL) was synthesized in a semi-dried condition based on the method developed in the previous work. [17] In this set of experiments, 2 g of HL was mixed with water to make a mixture of 60 wt % solid content. The polymerization reaction was performed at different reaction temperatures (70,80, and 90°C), times (1, 2, and 3 h), Na 2 S 2 O 8 dosages (0.75 wt % and 1.5 wt % based on lignin mass) and cationic monomer (METAC or MAPTAC)/lignin mole ratios (0.4, 0.8, 1.2, 1.6 and 2.4 mol mol À 1 ).…”

“…[16] Our previous studies focused on the polymerization of kraft lignin with [2-(acryloyloxy)ethyl]trimethyl ammonium chloride (ATAC), [2-(methacryloyloxy)ethyl] trimethyl ammonium methyl sulfate (METAM) and [2-(methacryloyloxy) ethyl] trimethylammonium chloride (METAC) in an acidic environment to produce cationic flocculants for simulated wastewater effluents. [7,17] However, to the our knowledge, [3-(methacryloylamino)propyl] trimethylammonium chloride (MAPTAC) has not been studied for producing bioflocculants. Although both METAC and MAPTAC monomers contain amino groups to introduce cationic charges to lignin, their structures are different, which may affect their polymerization performance and the properties of induced lignin polymers.…”

Pickering/Non‐Pickering Emulsions of Nanostructured Sulfonated Lignin Derivatives

“…[23] Structurally,l ignin is composed of both a hydrophobic skeleton (phenylpropanem onomers) and hydrophilic functional groups, such as carbonyl and phenolic hydroxy groups. [24,25] Lignin extractedi nt he pulp and paper industry was suggested to have potential for variousa pplications, such as bio-based adhesives, stabilizers, and nano-and microscale carriers by producing water-dispersed lignin nanoparticles. [26,27] For example, Wei et al [17] reported generating unmodified lignin particles by adjusting the pH value of aqueous lignin solutions from an alkaline system.…”

“…However, lignin is still considered as an underutilized material because only 1–2 % of its vast production annually (50–70 million tons) is utilized for the production of value‐added products . Structurally, lignin is composed of both a hydrophobic skeleton (phenylpropane monomers) and hydrophilic functional groups, such as carbonyl and phenolic hydroxy groups . Lignin extracted in the pulp and paper industry was suggested to have potential for various applications, such as bio‐based adhesives, stabilizers, and nano‐ and microscale carriers by producing water‐dispersed lignin nanoparticles .…”