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An environmentally friendly lignin-based composite (Lignin-PEI) was facilely prepared via cross-linking enzymatic hydrolysis lignin matrix and branched poly (ethylene imine). The specific physicochemical and structural properties of lignin-PEI were characterized by elemental analysis, N 2 physisorption, GPC, TG, SEM, FT-IR and XPS. The nitrogen content of lignin-PEI was 9.02%, and the BET surface area was 20.32 m 2 /g. The synthetic composite showed high capacity and selectivity of Cr(VI) adsorption. The influence of solution pH, contact time, initial Cr(VI) concentration, and coexisting ions on Cr(VI) adsorption on lignin-PEI was systemically studied. The Cr(VI) adsorption on lignin-PEI was well described by the Langmuir model. According to the Langmuir model, the Cr(VI) adsorption capacity on lignin-PEI was as high as 898.2 mg/g at 318 K and pH 2.0. The calculated thermodynamic parameters, such as ΔG, ΔH, and ΔS, indicated the spontaneous and endothermic adsorption of Cr(VI) on lignin-PEI. The adsorption of Cr(VI) by lignin-PEI was following the pseudo-second-order kinetic model, indicating that it was a chemisorption process. The uptake mechanism was demonstrated to be electrostatic attraction, ion exchange, complexation and partial reduction. This work provided a promising candidate for Cr(VI) uptake with lignin-based biosorbents., (Copyright © 2020 Elsevier B.V. All rights reserved.)

A lignin-based biosorbent (LSMA) was prepared by cross-linking lignosulfonate and N-methylaniline with the aid of ammonium persulfate for efficient removal of Cr(VI) from aqueous solution. Since LSMA possessed both amino groups and oxygen-containing functional groups, such as phenolic, carboxyl, and sulfonic groups, the maximum adsorption capacity of 1264.8 mg/g was achieved at 318 K according to the Langmuir isotherm. LSMA also showed excellent performance at low Cr(VI) concentration solution. The hazardous Cr(VI) solution of 50 mg/L can be fully removed within 10 min. The adsorption process of LSMA fitted the pseudo-second-order kinetic model, suggesting the chemical adsorption characteristics. Moreover, the adsorption process was spontaneous and endothermic. LSMA worked very well even with high content of competing anions. The removal mechanism was demonstrated to be the adsorption of Cr(VI) anions on LSMA with abundant functional groups, and reduction of Cr(VI) to less toxic Cr(III) by the adjacent electron donor groups. The generated Cr(III) was immobilized on LSMA by surface complexation and precipitation. LSMA composite has a great potential for the treatment of Cr(VI)-contaminated water., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A lignin amphoteric surfactant and betaine could enhance the enzymatic hydrolysis of lignocellulose and recover cellulase. The effects of lignosulfonate quaternary ammonium salt (SLQA) and dodecyl dimethyl betaine (BS12) on enzymatic hydrolysis digestibility, ethanol yield, yeast cell viability, and other properties of high-solid enzymatic hydrolysis and fermentation of a corncob residue were studied in this research. The results suggested that SLQA and 1 g/L BS12 effectively improved the ethanol yield through enhancing enzymatic hydrolysis. SLQA had no significant effect on the yeast cell membrane and glucose fermentation. However, 5 g/L BS12 reduced the ethanol yield as a result of the fact that 5 g/L BS12 damaged the yeast cell membrane and inhibited the conversion of glucose to ethanol. Our research also suggested that 1 g/L BS12 enhanced the ethanol yield of corncob residue fermentation, which was attributed to the fact that lignin in the corncob adsorbed BS12 and decreased its concentration in solution to a safe level for the yeast.

Lignosulfonates(LSs), by-products from chemical pulping processes, are low-value products with limited dispersion properties. The ability of commercially available horseradish peroxidase (HRP) to polymerize LS macromolecules and improve the dispersion properties of LSs was investigated. The polymerization of LSs proceeded efficiently under mild reaction conditions in an aqueous solution with HRP/H2O2. Gel permeation chromatography showed a significant increase in weight-average molecular weight (M w ) of sulfonated kraft lignin and sodium lignosulfonate (NaLS) by 8.5-fold and 4.7-fold, respectively. The mechanism of polymerization was investigated by elemental analysis, surface charge measurement, headspace gas chromatography, infrared spectroscopy (IR), and hydrogen nuclear magnetic resonance spectrometry ((1)H-NMR). The functional group measurements indicated that HRP incubation did not reduce the sulfonic group content. However, it decreased the phenolic and methoxyl group contents. As the phenolic group content decreased, M w increased as a power function. The polymerization was proposed to involve the random coupling of phenoxy radical intermediates. The radicals coupled with each other to form different inter-unit linkages, most of which were the β-O-4' type, as the (1)H-NMR spectra indicated. Moreover, the HRP/H2O2 incubation induced a significant improvement in the adsorption and dispersion properties of LSs. Therefore, the HRP/H2O2 incubation is a promising approach for industrial applications of LSs.

• The HTC of BLS was conducted under different conditions and solvents. • The maximum bio-oil yield from HTC of BLS achieved at 53.4%. • The phenols in BLS bio-oil were mainly H-type. • BLS char showed excellent Cr(VI) adsorption performance. The hydrothermal conversion (HTC) of black liquor solid (BLS) was investigated for producing phenolics and hydrochar. For comparison, the precipitated lignin (PL) was also investigated. The HTC experiments were conducted under different temperatures, holding times and reaction solvents to examine the optimum conditions for producing bio-oil. The maximum bio-oil yield of BLS of 53.3% was achieved at 50 wt% ethyl acetate/water cosolvent under 300 °C for 30 min. For PL, it was 86.7% at 50 wt% ethanol/water cosolvent under 300 °C for 30 min. GC–MS analysis showed that phenolics were the main products in bio-oil. The phenolics obtained from PL HTC were mainly S-type, followed by G-type; while H-type phenols were the main products in bio-oil from BLS. The hydrochar was characterized by FT-IR, BET and SEM. Moreover, the adsorption performance for Cr(VI) was investigated, which indicated that hydrochar from BLS was a promising candidate for heavy metals adsorption. [ABSTRACT FROM AUTHOR]

In this work, industrial black liquor (BL) was directly used to prepare activated carbons with high surface area and large pore volume through K 2 CO 3 activation. The effect of activation temperature on the properties and the Cr(VI) removal performance of activated carbons were investigated. For comparison, the purified lignin (PL) was also investigated. The specific surface area and the total pore volume of BL derived carbon prepared at 800 °C (CBLS 800) were 1335.58 m2/g and 1.79 cm3/g, while those of PL derived carbon prepared at 900 °C (CPL 900) were 1715.16 m2/g and 1.12 cm3/g. The Cr(VI) removal process conforms to the pseudo-second-order kinetic model, indicating that the adsorption process is mainly controlled by chemical interaction. The fitting of isotherm was more consistent with Langmuir model. The maximum adsorption amount of Cr(VI) on CBLS 800 and CPL 900 was 669.70 and 645.73 mg/g at 45 °C and pH 2.0, respectively. The negative Δ G ° and positive Δ H ° confirmed that the adsorption of Cr(VI) onto CBLS 800 and CPL 900 was an endothermic and spontaneous process. The removal mechanism of Cr(VI) mainly includes three aspects: intra particle diffusion, electrostatic attraction and adsorption-coupled reduction. This work not only provides a theoretical basis for transforming BL into functionalized biochar materials, but also makes the efficient removal of Cr(VI) from wastewater possible. [Display omitted] • K 2 CO 3 activation was used to prepare black liquor-derived porous carbon (CBLS). • The specific surface area of CBLS 800 is 1335.58 m2/g. • The maximum adsorption amount of Cr(VI) on CBLS 800 is 669.70 mg/g. • The removal mechanism of Cr (VI) is mainly adsorption-coupled reduction. • The inherent alkali plays a role of self-chemical activation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pyrolysis characteristics and product distribution of BLS were studied. • The activation energy of BLS was higher than that of lignin. • The aromatic hydrocarbon content of BLS through down tube reactor pyrolysis was 90.15%. • The inorganic salt in BLS promoted the removal of phenolic hydroxyl groups. • The mechanism of bond breaking during PL pyrolysis was proposed. In this study, the pyrolysis behaviors, kinetics and product distribution of black liquor solid (BLS) and precipitated lignin (PL) were studied by TGA, Py-GC/MS and a homemade down tube reactor. Compared with PL, the pyrolysis process of BLS was more complex and the residue was lower based on TG/DTG analysis. The average activation energy of BLS (440 ~ 456 KJ/mol) calculated by three model-free methods were higher than that of PL (293 ~ 339 KJ/mol). Py-GC/MS analysis showed that the total content of aromatic monomers in BLS bio-oil products was 26.02 ~ 26.50% (750 ~ 850 °C), while it was 57.86 ~ 66.58% in PL bio-oil products. Moreover, BLS obtained a maximum aromatic hydrocarbon content of 90.15% (950 °C) through down tube reactor pyrolysis, while it was 81.38% for PL. The alkali catalysis of the inorganic salt in BLS promoted the removal of phenolic hydroxyl groups. [ABSTRACT FROM AUTHOR]

• Highly stretchable hydrogel was prepared from biomass lignin. • LCP hydrogel performed excellent viscoelasticity and stretchability. • Compared with PVA hydrogel, the elongation rate of LCP increased by 20 times. • LCP hydrogel showed good thermosensitivity and electrical conductivity. In this study, hydroxyethyl cellulose (HEC) and polyvinyl alcohol (PVA) as the framework, borax as the cross-linker, and biomass lignin from pulping black liquors and biorefinery as the plasticizer were used to synthesize the lignin-based HEC-PVA (LCP) self-healing conductive hydrogel with highly stretchable and thermosensitive properties by the one-step fabrication method. Compared with the PVA hydrogel, the maximum storage modulus and the elongation rate was increased by 7 times and 20 times, respectively. Uniformly distributed lignin could increase the mobility and distance of polymer molecular chains, therefore improve the viscoelasticity and stretchability of the LCP self-healing hydrogel. The LCP hydrogel could recover to the original state in 12 s after 10000% shear strain for 4 cycles. The LCP hydrogel also presented good thermosensitivity and electrical conductivity, and were very promising for applications in the fields of 3D printing and wearable electronic devices, that broadened the efficient utilization of biorefinery lignin. [ABSTRACT FROM AUTHOR]