INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
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2021
·Vol. 23
·期 1
·413
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IF 5.924
Wen-Jie Guo,Jia-Kun Xu,Sheng-Tao Wu,Shu-Qin Gao,Ge-Bo Wen,Xiangshi Tan,Ying-Wu Lin
The treatment of environmental pollutants such as synthetic dyes and lignin has received much attention, especially for biotechnological treatments using both native and artificial metalloenzymes. In this study, we designed and engineered an efficient peroxidase using the O2carrier myoglobin (Mb) as a protein scaffold by four mutations (F43Y/T67R/P88W/F138W), which combines the key structural features of natural peroxidases such as the presence of a conserved His-Arg pair and Tyr/Trp residues close to the heme active center. Kinetic studies revealed that the quadruple mutant exhibits considerably enhanced peroxidase activity, with the catalytic efficiency (kcat/Km) comparable to that of the most efficient natural enzyme, horseradish peroxidase (HRP). Moreover, the designed enzyme can effectively decolorize a variety of synthetic organic dyes and catalyze the bioconversion of lignin, such as Kraft lignin and a model compound, guaiacylglycerol-β-guaiacyl ether (GGE). As analyzed by HPLC and ESI-MS, we identified several bioconversion products of GGE, as produced via bond cleavage followed by dimerization or trimerization, which illustrates the mechanism for lignin bioconversion. This study indicates that the designed enzyme could be exploited for the decolorization of textile wastewater contaminated with various dyes, as well as for the bioconversion of lignin to produce more value-added products.Keywords:heme enzymes;protein design;dye-decolorizing peroxidase;kraft lignin bioconversion
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Reaction Kinetics Mechanisms and Catalysis
·
2023
·Vol. 136
·期 3
·1407-1421
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IF 1.8
Zheng Yuxin,Wu Kejing,Zhu Yingming,Liu Yingying,Wang Binshen,Lu Houfang,Liang Bin
In this study, different solid acids were used as catalysts for demethylation of model compound 2-methoxy-4-methylphenol (creosol) to produce 4-methylcatechol (4-MeCat) in halogen-free aqueous system. The results showed that a high 4-MeCat yield of 48.5% was achieved over TiO 2 supported on activated carbon, while the Nb 2 O 5 catalyst with suitable Brønsted/Lewis acid site exhibited the highest average production rate of 0.053 min −1 . The high total acidity improves the 4-MeCat yield and a suitable ratio of Brønsted to Lewis acid sites benefits the catalytic activity over unit acid sites. The stable crystal and acid sites of Nb 2 O 5 catalyst result in high activity stability, while the supported TiO 2 catalyst is deactivated much faster. The loss of acid sites and acid site coverage are the main deactivation reasons for demethylation in aqueous medium.
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ACS Sustainable Chemistry & Engineering
·
2023
·
IF 8.4
Kaiyue Wang,Mengqi Zhu,Zhaolin Yang,Long Bai,Siqi Huan,Chengyu Wang
Spherical lignin nanoparticles (SLNs) are able to formulate Pickering emulsions with various applications. However, SLN-stabilized emulsions commonly comprise droplets in the micron range, resulting in inevitable instability upon storage. Herein, nonadsorbing cellulose nanofibrils (CNF) are shown to induce stabilization of the diluted SLN-stabilized Pickering emulsions via concentration-dependent depletion effects. Two regimes for such depletion interactions are established, including depletion flocculation-induced droplet aggregation at intermediate CNF concentrations and depletion stabilization of micron-sized droplets over critical CNF concentrations (0.2 wt %). The long-term stability of the SLN-based emulsions against creaming is over two months. The universality of the findings is tested with different initial oil volume fractions and droplet diameters. Overall, this study unveils the depletion effects in SLN-stabilized Pickering emulsions induced by renewable CNF, offering a simple, sustainable route for tailoring their phase behavior and creating ultrastable systems that are available for formulating green products.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Zixin Qi,Zhaofeng Zhang,Tianyu Ren,Nan Jiang,Mengfan Wang,Shengping You,Wei Qi,Rongxin Su
Because of the high complexity of the product and the similar physicochemical properties between G and S counterparts, the separation of aromatic monomers is one of the greatest challenges in the lignin chemical valorization, which limits its further utilization and conversion. In this study, the preparation method of the dihydroconiferyl alcohol & dihydrosinapyl alcohol-enriched oil and high purity dihydrosinapyl alcohol from reductive catalytic fractionation products catalyzed by Pd/C was first reported. Moreover, a purification process with alkali extraction - organic solvent extraction - dichloromethane reverse extraction - crystallization in the KOH ethanol solution as the main unit operation was designed. As a result, a monomer-enriched oil in which dihydroconiferyl alcohol (G-3OH) and dihydrosinapyl alcohol (S-3OH) could totally account for more than 83% was obtained, and S-3OH with a purity of 90.2% was separated by crystallization. In addition, this purification process was scaled up to 10 times. The monomer-enriched oil with a G-3OH and S-3OH content of 87.2% was obtained. The recoveries of G-3OH and S-3OH were 81.0% and 91.5%, respectively. The purity of S-3OH was 89.4%, and the recovery was 51.6%. The integrated process realizes the effective separation of the reductive depolymerization products of lignin, which can provide technical support for its industrial production.
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GREEN CHEMISTRY
·
2023
·Vol. 25
·期 13
·5150-5159
·
IF 9.8
Yuzhen Hu,Yanbin Cui,Shuoxiao Zhao,Xuelai Zhao,Xiaohong Hu,Zhenlong Song,Wei Fan,Qi Zhang
Selective cleavage of C–C bonds in the lignin structure is crucial for the depolymerization of lignin and producing value-added chemicals. In this study, we reported that Pd/CeO2 catalysts can selectively catalyze the Cα–Cβ bond cleavage of oxidized lignin model components and authentic lignin in an aqueous phase under mild conditions (50 °C, ambient pressure). A variety of β-O-4 and β-1 ketones with representative Cα–Cβ bonds were successfully cleaved yielding aromatic acids and phenols in 76.8–94.9% yields. Their unique catalytic properties are derived from the electron transfer between Pd and CeO2 support which facilitates active Pd2+ sites and reactive oxygen species formation. A mechanistic study elucidates that base-mediated C–H bond activation via enolization and in situ reactive oxygen species (˙O2−) formation are the key steps for the selective Cα–Cβ cleavage. Furthermore, the applicability of the system for the bond cleavage in an authentic lignin sample was demonstrated. Nearly 54.2 wt% of oxidized bamboo lignin was converted, generating aromatic monomer yields up to 35.9 wt%, with a high selectivity for aromatic aldehydes.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2023
·
IF 8.2
Man Zhang,Rubo Tian,Siyang Tang,Kejing Wu,Binshen Wang,Yingying Liu,Yingming Zhu,Houfang Lu,Bin Liang
The structure and properties of lignin can vary depending on the type of lignocellulosic biomass it comes from and the separation techniques used, and also affects its suitability for different applications. In this work, the structure and properties of lignin isolated from moso bamboo, wheat straw, and poplar wood by different treatment processes were compared. Results show that deep eutectic solvent (DES) extracted lignin exhibits well-preserved structures (including β-O-4, β–β, and β-5 linkages), a low molecular weight ( M n = 2300–3200 g/mol), and relatively homogeneous lignin fragments (1.93 < PDI < 2.33) compared to dealkaline lignin (DL) and milled wood lignin (MWL). Besides, lignin samples extracted by DES have a regular nanostructure, higher carbon residue content (>40 %), and excellent antioxidant properties (the free radical scavenging index >20). Among the three types of biomass, the structural destruction of lignin in straw is the most obvious, which is due to the degradation of β-O-4 and β-β linkages during DES treatment. These findings can contribute to a better understanding of the structural changes that occur in various treatment processes from different lignocellulosic biomass, and help maximize the targeted development of their applications based on the characteristics of lignin.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2021
·
IF 6.953
Yongqin Wang,Jie Hou,Yangze Huang,Yu Fu
Polylactic acid (PLA) is increasingly being considered as an ideal biodegradable candidate to replace petroleum-based polymers. However, its practical applications are often hampered by the poor mechanical robustness and solo functionality. Herein, based on the mechanical property improvement of PLA we proposed a simple process of assembling lignin-hybridized modifier and PLA matrix, as opposed to the traditional trade-off between mechanical strength and functionality, while anchoring a biofluorescent moiety onto lignin surfaces. Specifically, the fluorophore group could act as interfacial compatibilizer of complex and facilitate the shape-tailored hybrids for promoting functionality flexibility. With the bimetallic hetero-particles, the preferable lignin-assembled complex could be controllably configured as an antibacterial, fluorophore and photothermal agent. Thus, mechanical enhancement, fluorescence introduction and favorable photothermal ability of the resulting PLA composites were successfully achieved for integrated unification of structural robustness, geometric integrity and functional multiplicity, which was never seen in the other reports. The results showed that PLA composites containing 5 wt% modified lignin, 10 wt% zinc oxide, and 5 wt% silver presented excellent mechanical, fluorescent, photothermal conversion properties. By controlling the ZnO content and morphology, strong inhibition of Escherichia coli (Gram-negative) than that of Staphylococcus Aureus (Gram-positive) was also observed. The flake-shaped ZnO /Ag hybrids contributed to better overall performance of PLA composites than the rod-shaped ZnO/Ag. In this work we developed a facile strategy to assemble a bioderived fluorophore with lignin particles for constructing a structure-controlled complex as a multitasking modifier, featuring mechanical unity and functional adaptability. Specifically, the lignin reinforcement and bimetallic hybrids with different morphologies were explored as an effective fluorophore, antibacterial and photothermal agent. Through multiple dehydration reactions, a conjugating fluorophore was successfully grafted on lignin surfaces to serve as an interface modifier without physical changing its structural robustness. And morphology-tailored hybrid was advantageously immobilized on predefined hetero-particle carrier of fluorescent lignin and endowed composites with desirable antimicrobial properties . The developed strategy would expand the functional applications of PLA materials in food packaging, biopharmaceuticals and simple fluorescent anti-counterfeiting.
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ACS Sustainable Chemistry & Engineering
·
2021
·
IF 8.198
Xiangchen Kong,Chao Liu,Yuyang Fan,Weicong Xu,Rui Xiao
Production of jet fuel precursors from waste kraft lignin through a depolymerization and hydrodeoxygenation (DHDO) method with a complex copper acid catalyst is reported. The kraft lignin undergoes a high degree of depolymerization, deoxygenation, hydrogenation, and C–C coupling. Monomers and dimers with molecular weights in the ranges of <200 Da and 354–452 Da are obtained with optimized yields reaching 93.29 and 39.30 C% at 360 °C for 8 h, while trimers and oligomers with higher molecular weights are also generated with lower contents. The high carbon yields of monomers and dimers are given by the incorporation of methanol solvent. The double bond equivalent (DBE) and polydispersity index (PDI) decrease from 14.77 and 2.77 in kraft lignin to 9.05 and 1.35 in the products, while the high heating value (HHV) increases from 24.53 to 36.47 MJ/kg after reaction. Furthermore, over 45% of the optimized products have boiling points in the range of that of commercial jet fuel (60–280 °C). All these results demonstrate the appropriate properties of the products from kraft lignin DHDO as potential jet fuel precursors.
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INDUSTRIAL CROPS AND PRODUCTS
·
2021
·
IF 5.645
Liping Tan,Yongchao Zhang,Weihua Zhang,Rongwen Zhao,Yue Ru,Tongjun Liu
Valorization of lignin is imperative since lignin is still an underutilized biomaterial. Herein, a facile fabrication method for lignin-based magnetic biosorbent (LMB) is proposed via assembling magnetic inorganic particles (Fe 3 O 4 ) on lignin in-situ for eliminating heavy metal ions (HMIs) from wastewater without the utilization of organic solvents. Chemical and structural characterizations, which were determined by different analytical tools, including Fourier transform infrared (FTIR), Scanning electron microscope (SEM), X-ray diffraction (XRD), High-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS) confirmed that LMB was successfully formed via the feasible and green process. Then, LMB was found to exhibit highly effective removal performance for HMIs. The adsorption capacity of the LMB reached 152.58 mg/g for Pb 2+ and 46.81 mg/g for Cu 2+ , with equilibrium attained within 30 min. Adsorption kinetics and isothermal adsorption of lead and copper ions by LMB were also examined. This study delivers a new perspective on lignin valorization for lignocellulose biorefineries and establishes a path for synthesizing a cost-efficient and green adsorbent for removing HMIs from wastewater.
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Journal of Cleaner Production
·
2021
·
IF 9.297
Huiting Lin,Shijie Qiu,Zhihao Wu,Xiaoxia Ye,Minghua Liu
Efficient removal of oxytetracycline hydrochloride (OTC) from wastewater is of great significance but extremely challenging. Herein, a novel adsorbent lignin-based multi-metal ferrite biochar (FeNiZn-LBC) was synthesized through pyrolysis with controllable temperature and hydrothermal reaction using lignin of sinocalamus oldhami as raw material. The adsorption property of FeNiZn-LBC for OTC was systematically researched, and the results displayed that adsorption of FeNiZn-LBC to OTC accorded with the Langmuir model and the equilibrium adsorption capacity was 476 mg g −1 . Notably, FeNiZn-LBC can be regenerated with 0.100 mol L −1 NaOH. Additionally, we raised rational explanations for the mechanisms of adsorption behavior based on the zeta potential and XPS spectra. The adsorption of FeNiZn-LBC for OTC was mainly controlled by the electrostatic interactions, hydrogen bonds and complexation involving FeNiZn-LBC and OTC, especially the metal-oxide bond (M-O) generated after loaded with multi-metal ferrite played a positive role in the removal of OTC from water. Our work highlighted the potential of FeNiZn-LBC for excellent adsorption of OTC in next generation.
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Frontiers in Energy Research
·
2021
·
IF 4.008
Li Jiayi,Zhou Wei,Huang Yuming,Gao Jihui
Replacing the oxygen evolution reaction (OER), which is of high energy consumption and slow kinetics, with the more thermodynamically favorable reaction at the anode can reduce the electricity consumption for hydrogen production. Here we developed a lignin-assisted water electrolysis (LAWE) process by using Ti/PbO2 with high OER overpotential as the anode aimed at decreasing the energy consumption for hydrogen production. The influence of key operating parameters such as temperature and lignin concentration on hydrogen production was analyzed. Compared with alkaline water electrolysis (AWE), the anode potential can be decreased from 0.773 to 0.303 (V vs. Hg/HgO) at 10 mA/cm2 in LAWE, and the corresponding cell voltage can be reduced by 546 mV. With increasing the temperature and lignin concentration, current density and H2 production rate were efficiently promoted. Furthermore, the anode deactivation was investigated by analyzing the linear sweep voltammetry (LSV) and cyclic voltammetry (CV) tests. Results showed that the anode deactivation was affected by the temperature.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2021
·
IF 6.953
Guifeng Liu,Can Jin,Shuping Huo,Zhenwu Kong,Fuxiang Chu
A series of lignin-based epoxy resins (LEPs) were prepared by the reaction of epichlorohydrin with lignin oligomers derived from partial reductive depolymerization of lignin. To overcome the high viscosity and brittleness defects in practical applications, the LEPs were blended with renewable epoxied cardanol glycidyl ether (ECGE) and then cured with methyltetrahydrophthalic anhydride (MeTHPA) to form high-performance epoxy thermosets. The effects of degree of lignin depolymerization , chemical composition of lignin oligomers and dosage of ECGE on thermal and mechanical properties of the cured products were investigated. The LEP/MeTHPA thermosets exhibited good thermal and mechanical properties. Especially, by separating monomer-rich fractions from lignin oligomers, the thermal and mechanical properties of the cured product were improved obviously. Notably, the incorporation of ECGE also possessed a positive effect on reinforcing and toughening the cured products. With 20 wt% ECGE loadings, the tensile, flexural and impact strength of the cured product reached the maximum value of 77 MPa, 115 MPa and 14 kJ/m 2 , respectively, which were equivalent to the commercial bisphenol A epoxy resins thermosets. These findings indicated that the novel bio-based epoxy resins from lignin oligomers and cardanol could be utilized as renewable alternatives for BPA epoxy resins.
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