To improve the dispersion capacity of poly(carboxylate ether) (PCE) in clay-containing cement paste, lignosulfonate (LS) was quaternized with 3-chloro-2-hydroxypropyl trimethylammonium chloride (CHPTAC), and the product quaternized lignosulfonate (QL) was characterized by FT-IR spectroscopy, element analysis, and zeta potential. The fluidity of the montmorillonite- (MMT-) containing cement paste was clearly improved upon the addition of 0.010 wt % QL, as the yield stress and the rheological behavior index of the paste were reduced. XRD analysis indicated that the adsorption of QL on MMT was driven by a strong electrostatic attraction, rather than intercalation, which was much stronger than that for LS. DLS also showed that the steric effect of QL was much stronger than that of PCE. As a result, when QL and PCE were added to the MMT-containing cement paste, QL adsorbed on the MMT surface preferentially and hindered the adsorption of PCE.Keywords: Adsorption; Clay tolerance; Fluidity; MMT-containing cement paste; Rheological properties;

Lignin is a vastly underutilized biomass resource. The preparation of water-dispersed lignin nanoparticles is an effective way to realize the high-value utilization of lignin. However, the currently reported preparation methods of lignin nanoparticles still have some drawbacks, such as the requirement for toxic organic solvent or chemical modification, complicated operation process, and poor dispersibility. Here, lignin/sodium dodecyl sulfate (SDS) composite nanoparticles (LSNPs) with outstanding water dispersibility and a size range of 70–200 nm were facilely prepared via acidifying the mixed basic solution of alkaline lignin and SDS. No harsh chemical was needed. The formation mechanism was systematically studied. Results indicated that the LSNPs were obtained by acid precipitation of the mixed micelles formed by the self-assembly of lignin and SDS. In addition, on the basis of the LSNP-stabilized Pickering emulsions, lignin/polyurea composite microcapsules combining the excellent chemical stability of a synthetic polyurea shell with the fantastic antiphotolysis and antioxidant properties of lignin were successfully prepared.Keywords: lignin; microcapsules; nanoparticle; Pickering emulsion;

Lignosulfonates obtained from pulping spent liquor are nontoxic and renewable polymers with excellent dispersibility as disperse dye dispersants. In order to reveal its dispersion mechanism on the dye, the adsorption characteristics of sodium lignosulfonate (NaLS) and sodium naphthalenesulfonic acid formaldehyde (NSF) were investigated using a quartz crystal microbalance with dissipation (QCM-D) and an atomic force microscope (AFM). The results showed that the adsorption of dispersant onto the dye film layer was low and unstable without salt, but the adsorption amount of NaSL or NSF onto dye film was increased significantly with the increase in ionic strength. This indicated that hydrophobic effect was the main interaction between dispersant and dye. The adsorption amounts of both dispersants were decreased with the increase in temperature. NaLS exhibited the better dispersion and improved stability at high temperature than NSF due to higher adsorption amount and the viscoelastic adsorption layer.

Aggregation-induced emission (AIE) characteristics of lignin, which has the intrinsic aggregation behavior, are detected and studied for the first time. A positive correlation between the growth multiple of fluorescence intensity (l1:9/l10:0) and the sulfonation degree was found in the water–ethanol system. The AIE phenomenon and mechanism were further studied by the addition of cetyltrimethyl ammonium bromide (CTAB) owing to the electrostatic interaction with lignosulfonate. It is well known that lignin contains carbonyl groups, stilbene (Ar–CαCβ) and α-carbonyl (Ar–CαO) building blocks. We deduce that cluster of the carbonyl groups and restriction of intramolecular rotation (RIR) effects together contribute to the AIE activity of lignin as lignin does not exhibit blue emission based on its limited conjugated structure. Our results provide a new prospective to understand the fluorescence in lignin and explore novel potential application for the AIE activity of lignin.

Water-soluble alkyl chain sulfobutylated lignosulfonate (ASLS) doped PEDOT was prepared with lignin as raw material. Water processable PEDOT:ASLS was applied as hole injection layer (HIL) to modify ITO. Blue phosphorescent organic light-emitting diode plays a key role for full color display and are very challenging. With PEDOT:ASLS as HIL, a highly enhanced current efficiency of 37.65 cd/A was achieved. Considering our device structure, the result is even better than that of the control device using PEDOT:PSS as HIL. Compared with PSS with regular structure, strong aggregation and oxidation behavior of ASLS contribute to the hole injection capability of PEDOT:ASLS. Considering that ASLS is of disordered and amorphous structure, which is very different from poly(styrene sulfonic acid), it is exciting that ASLS might be of promising potential as a sustainable dopant of PEDOT. More importantly, this work will guide the design of dopant of PEDOT.Keywords: Dopant; Hole transport material; Interface engineering; Organic electronic; PEDOT:PSS; Phenol radical; Solar cell

A water-soluble, ratiometric fluorescent pH probe, L-SRhB, was synthesized via grafting spirolactam Rhodamine B (SRhB) to lignosulfonate (LS). As the ring-opening product of L-SRhB, FL-SRhB was also prepared. The pH-response experiment indicated that L-SRhB showed a rapid response to pH changes from 4.60 to 6.20 with a pKa of 5.35, which indicated that L-SRhB has the potential for pH detection of acidic organelle. In addition, the two probes were internalized successfully by living cells through the endocytosis pathway and could distinguish normal cells from cancer cells by different cell staining rates. In addition, L-SRhB showed obvious cytotoxicity to cancer cells, whereas it was nontoxic to normal cells in the same condition. L-SRhB might have potential in cancer therapy. L-SRhB might be a promising ratiometric fluorescent pH sensor and bioimaging dye for the recognition of cancer cells. The results also provided a new perspective to the high-value utilization of lignin.Keywords: biomass; cancer sensing; FRET; ratiometric sensor; Rhodamine B;

Sulfonated lignin obtained from pulping waste liquor is a nontoxic and renewable polymer that can be used as a dispersant in the dyeing industry. In order to reveal the effect of the lignin dispersant’s molecular weights on disperse dye, three hydroxypropyl sulfonated alkali lignin (HSL) samples with different molecular weights were obtained by controlling the dosage of etherification to cross-link lignin molecules. The molecular weight of HSL can be adjusted from 8,100 to 14,830 Da. More than 80% of phenolic hydroxyl groups of HSL samples were blocked by etherification compared to that of AL and which decrease with increasing molecular weight. The increasing molecular weight of HSL causes a considerable reduction in the staining effect of HSL on fiber since the adsorption amount of HSL on the fiber decreases by reducing the phenolic hydroxyl group. HSL with Mw of 11,020 Da contains 2.10 mmol·g–1 of the sulfonic group and as low as 0.46 mmol·g–1 of the phenolic hydroxyl group (compared to 2.32 mmol·g–1 of AL), providing excellent dispersive ability and high temperature stability on dye. More importantly, the dye uptake with added HSL with Mw of 11,020 Da is the highest of 85.17% among all dispersants here. Therefore, the etherification modification is a promising approach to increase the molecular weight of lignin and for widespread applications of lignin as a highly efficient dye dispersant.Keywords: Dispersive ability; Dye dispersant; Dye uptake; Fiber staining effect; Hydroxypropyl sulfonated alkali lignin; Molecular weight

Alkali lignin (AL) is a by-product from alkali pulping and sulfomethylated alkali lignin (SL) with excellent water solubility was obtained from AL by sulfomethylation. A novel method to improve the sulfonic group content and molecular weight of SL by means of horseradish peroxidase/H2O2 catalysis was investigated. The structural changes of SL during HRP modification were characterized by gel permeation chromatography (GPC), UV-Visible spectroscopy, infrared spectroscopy (IR), hydrogen nuclear magnetic resonance spectrometry (1H-NMR) and headspace gas chromatography (HS-GC). The results showed that Mw and the sulfonation degree of SL by HRP modification increased remarkably by over 20-fold and 40%, respectively. In addition, during HRP modification, the carboxyl group in SL increased, while the phenolic and methoxyl groups decreased with the increase of Mw. The water solubility of SL improved and the methoxyl group decreased as the sulfonation degree of SL increased to improve SL's reactivity during HRP modification, and HRP modification could facilitate the radical sulfonation reaction of SL. Therefore, the sulfomethylation and HRP incubation in lignin modification had a synergistic effect. Besides, the adsorption properties of SL were significantly enhanced by the HRP modification.

Dipotassium hydrogen phosphate (K2HPO4) has been investigated as an excellent salting-out agent to recover (acetone + butanol + ethanol) (ABE) from a prefractionator. The increasing additions of K2HPO4·3H2O to the ABE system under unsaturated conditons show strong salting-out effects on the ABE. This favorable salting-out effect is based on the hydration of the charged ions. The HPO42– ions may destroy the “hydration shell”, but the crescent concentrations of K2HPO4 make positive salting-out effects on the ABE. More acetone, 1-butanol, and ethanol are recovered after higher-level concentrations of K2HPO4 solution are added to the ABE system. Meanwhile, the equilibrium time shortens. A higher temperature can also make the equilibrium time shorter. The smallest amount of K2HPO4 in the organic phase causes no trouble for the (salting-out + distillation) process in an industrial application.

A practical graft sulfonation process was developed to synthesize a lignin-based superplasticizer using acid-precipitated lignin from wheat straw black liquor as raw material. The graft-sulfonated lignin, prepared in optimal reaction conditions, was named GSL. The properties of GSL in a cementitious system were investigated. The adsorption isotherms of GSL fractions separated by ultrafiltration and the thickness of their absorbed films on cement particles were measured to reveal the dispersion mechanism. Also, it was found that the molecular weight of graft-sulfonated lignin increased with the dosage of acetone and formaldehyde, but having too high a molecular weight reduced its dispersive performance. High sulfonic group content in graft-sulfonated lignin severely inhibited the increase of molecular weight, resulting in a decrease of dispersive performance. GSL has stronger compressive strength enhancement in concrete and lower hydration heat temperature than the commercial naphthalene-sulfonated formaldehyde superplasticizer. Moreover, the strong dispersion of GSL with high molecular weight is mainly attributed to strong steric hindrance among cement particles.

This study conducted an investigation of the effect of lignosulfonate (LS) on enzymatic saccharification of lignocelluloses. Two commercial LSs and one laboratory sulfonated kraft lignin were applied to Whatman paper, dilute acid and SPORL (sulfite pretreatment to overcome recalcitrance of lignocelluloses) pretreated aspen, and kraft alkaline and SPORL pretreated lodgepole pine. All three lignin samples inhibited cellulose saccharification of Whatman paper, but enhanced the saccharification of the four lignocellulosic substrates. The level of enhancement was related to the molecular weight and degree of sulfonation of the lignin as well as the substrate lignin structure. When different molecular weight (MW) fractions of one commercial LS (SXP), generated from sulfite pulping of hardwood, were applied to the Whatman paper, the large MW fraction (SXP1) with the lowest degree of sulfonation inhibited cellulose saccharification while the intermediate (SXP2) and smallest (SXP3) MW fractions enhanced saccharification. All MW fractions enhanced saccharification of the four lignocellulosic substrates with maximal enhancement by the smallest MW fraction, SXP3. The enhancement was most significant for the kraft lodgepole pine substrate and least significant for the SPORL pretreated lodgepole pine using all three LS and SXP fractions. The results suggest that LS acts as a surfactant to enhance pure cellullose saccharification. When LS is applied to lignocelluloses, it acts as a surfactant to block bound lignin from binding cellulase nonproductively leading to enhanced saccharification.

Thirty compounds including salts, saccharides, and alkalies have been investigated as possible salting-out agents to recover (acetone + butanol + ethanol) (ABE) from a prefractionator. The most promising salt is potassium carbonate. The mechanisms of salting-out by potassium carbonate are summarized as hydration and hydrogen-bond breaking. The thermodynamic study of salting-out by potassium carbonate has been investigated and shows that the salting-out process is endothermic and a process of entropy increment. The extractant of saturated potassium carbonate solution should be double that of the sketchy ABE solution. When the salting-out process is performed at 333.15 K instead of 298.15 K, equilibrium time is shortened from 9 to 3 min. Energy demand in an industrial application shows that salting-out produces 25.13 %, even 35.42 % less energy consumption than that of the conventional distillation process.

High solid content coal–water slurries (abbreviated as CWS) with low viscosity and excellent stability are ideal for the combustion and storage, but it is very difficult to prepare the CWS with both properties in industry. In this study a new Polycarboxylic Acid (abbreviated as PC) hyper-dispersant containing fundamental chain, sulfonic groups, carboxyl and polyoxyethylene branches is designed and synthesized as additive to prepare the CWS with ideal solid content, viscosity and stability. The synthesized PC hyper-dispersant under optimized conditions can be used to prepare CWS with the 68.13 wt.% solid content and 645 mPa·s apparent viscosity at 0.4 wt.% dosage, and the CWS have no sediments during three days. The rheological property investigation shows that the CWS prepared using PC exhibit markedly shear-thinning characteristic, which is very advantageous to the static stability, pipe pumping and spray combustion under high-shear condition. Fundamental analysis considers that the carboxyl anchor on coal surface, exhibiting firm adsorption affinity. The sulfonic groups orient towards the solution, providing electronegativity on coal surface. The flexible polyoxyethylene branches orient towards the solution, forming a thick hydrophilic polyoxyethylene layer on coal surface. The excellent dispersing and stabilizing effects of PC hyper-dispersant for CWS are concluded to be due to the combined effects of steric hindrance, lubrication action and electrostatic repulsion force.The COO¯ groups of PC Hyper-dispersant molecule anchor on the electropositive sites of coal surface, the SO3¯ groups and polyoxyethylene branches orient to the solution. The PC has strong adsorptive capacity on coal surface, and gives the coal particles strong electrostatic repulsion force and steric hindrance, which prevent aggregation during storage. Therefore, the PC can realize the CWS with both the low viscosity and desire stability.Highlights► A polycarboxylic acid is synthesized to act as hyper-dispersant of high solid content CWS. ► The inherent viscosity, SO3¯ and COO¯ groups of PC are optimized. ► The rheological behavior of CWS prepared using PC is systematically investigated. ► The adsorption mechanism of PC in coal–water interface is disclosed.

Molecular iodine has been introduced into the alkali lignin (AL) solutions to adjust the π−π aggregation, and the effect of lignin−iodine complexes on the aggregation and assembly characteristics of AL have been investigated by using fluorescence, UV−vis spectroscopy, light scattering, and viscometric techniques. Results show that AL form π−π aggregates (i.e., J-aggregates) in THF driven by the π−π interaction of the aromatic groups in AL, and the π−π aggregates undergo disaggregation in THF-I2 media because of the formation of lignin−iodine charge-transfer complexes. By using iodine as a probe to investigate the aggregation behaviors and assembly characteristics, it is estimated that about 18 mol % aromatic groups of AL form π−π aggregates in AL molecular aggregates. When molecular iodine is introduced into the AL solutions, lignin−iodine complexes occur with charge-transfer transition from HOMO of the aromatic groups of AL to the LUMO of iodine. The formation of lignin−iodine complexes reduces the affinity of the aromatic groups approaching each other due to the electrostatic repulsion and then eliminates the π−π interaction of the aromatic groups. The disaggregation of the π−π aggregates brings a dissociation behavior of AL chains and a pronounced molecular expansion. This dissociation behavior and molecular expansion of AL in the dipping solutions induce a decrease in the adsorbed amount and an increase in the adsorption rate, when AL is transferred from the dipping solution to the self-assembled adsorbed films. Consequently, the adsorption behavior of AL can be controlled by adjusting the π−π aggregation. Above observations give insight into the occurrence of J-aggregation of the aromatic groups in the AL molecular aggregates and the disaggregation mechanism of AL aggregates induced by the lignin−iodine complexes for the first time. The understanding can provide an academic instruction in the efficient utilization of the alkali lignin from the waste liquor and also leads to further development in expanding functionalities of the aromatic compounds through manipulation of the π−π aggregation.

Lignosulfonate with low polydispersity index of 1.178–1.210 was isolated by gel column chromatography of Sephacryl S-100 eluted with 0.2 mol/L of NaNO3 aqueous solution, whereas nearly monodisperse ligosulfonate fraction with polydispersity of 1.067 can be obtained after chromatographic separation twice. This method provides an available approach to investigate the structure and characteristics of lignosulfonate.

The solution behavior of purified sodium lignosulfonate (PSL) at different pH values were investigated by means of acid–base titration, surface tension, viscosity, fluorescence spectrometry, dynamic light scattering (DLS) and environmental scanning electron microscopy (ESEM) experiments. Fluorescence experiments showed that the critical aggregate concentration (CAC) of PSL was 0.05 g/L. DLS results indicated that the average dimension of PSL molecule and PSL aggregate was about 8 nm and 80 nm, respectively. The surface charge of PSL molecules and the aggregation degree of PSL in solution increased with the increasing of pH due to the ionization of sulfonic and phenolic hydroxyl groups. The size of PSL aggregates and reduced viscosity of PSL solution increased as pH values increased because expansion of the PSL cores. A model for the assembly behavior of PSL was first proposed to explain the influence of pH on the molecular configuration and aggregation behaviors of lignosulfonate in aqueous solutions.

The effects of oxidant dosage, oxidation temperature and time on the degradation of soda lignin by hydrogen peroxide with and without the presence of microwave irradiation were investigated. It is found that the oxidative degradation of lignin includes the cleavage of ether bond in β-O-4 structure, the partial destruction of aromatic ring, and the re-condensation of the degraded lignin. Compared to the conventionally heated oxidation of lignin, the microwave irradiation efficiently facilitates the degradation of the lignin with high molecular weight and the re-condensation of that with low molecular weight at a low oxidant dosage, low oxidation temperature, or a short oxidation time, which leads to the formation of the degraded lignin with narrower molecular weight distribution and lower molecular weight. Additionally, the lignin degraded in the presence of microwave irradiation has the characteristics of higher content of phenolic hydroxyl group, lower content of methoxyl group, and lower degree of condensation, which enhances the reactivity of lignin. Therefore, the oxidative degradation of lignin assisted by microwave irradiation may be a new pretreatment approach for efficiently utilizing the soda lignin.

•Lignin-based polyoxyethylene was first applied in montmorillonite (MMT)-contained cement paste.•PEG-grafted-lignin had favor tolerance on MMT.•The adsorption amount of PEG-grafted-lignin was much larger.•UV adsorption and XRD were carried out to characterize the adsorption behavior on MMT.The dispersion ability of polycarboxylate ether (PCE) in fresh concrete is much impeded by clay impurities. To improve the dispersion of PCE in the clay-contained concrete, lignin-based polyoxyethylene ether (PEG-grafted-lignin) was synthesized through polyethylene glycol (PEG) grafted to kraft lignin (KL). The results showed that PEG-grafted-lignin increased the fluidity of MMT-contained cement paste when combined with PCE. It improved the rheological properties of MMT-contained cement paste by reducing the yield stress and the rheological behavior index. The adsorption of PEG-grafted-lignin on MMT was more quickly than KL and the equilibrium adsorption amount was 31.43 mg/g at an initial concentration of 100 mg/L. XRD revealed that PEG-grafted-lignin had inserted into the interlayer structure of MMT, while DLS disclosed the spatial effect of PEG-grafted-lignin was much stronger than PCE. This study put forward a new method in the anti-sludge study of PCE.Download high-res image (107KB)Download full-size image

•ABE from model solutions/fermentation broth was salted out by K3PO4.•More than 90 wt% of ABE was recovered and more than 99.75% of water was removed.•Higher solvents level permits the higher recovery of ABE.•ABE solubility in salt solution showed a linear relation with the molality of K3PO4.•Salting-out can reduce the energy consumption for the subsequent distillation.The acetone + 1-butanol + ethanol (ABE) fermentation has a long history but still faces the challenge of enhancing the low ABE concentration to reduce production cost. Nowadays there is an unprecedented resurgence of interest in separation and purification technology to recovery ABE from fermentation broth. Here we describe a simple salting out procedure for extracting ABE fermentation products efficiently from model solutions/fermentation broth by employing tripotassium phosphate (K3PO4). Increasing the K3PO4 content permits the liquid-liquid splits and enables the recovery of ABE. The liquid-liquid equilibria were mainly determined by the K3PO4 content and slightly affected by temperature and original solvents level. The correlation between the solubility of ABE and the molality of K3PO4 demonstrated this. More than 90 wt% of ABE was recovered from the model solutions/fermentation broth and more than 99.75% of water was removed. This study provides a means to reduce the energy demand of the subsequent distillation process for ABE purification.