CELLULOSE
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2020
·Vol. 27
·期 15
·8757-8768
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IF 4.21
Peng Xiongyi,Wu Zijun,Li Zhili
Abstract Lignocellulosic materials have received wide interest in adsorption of contaminants in water due to their abundance, eco-friendliness, and low cost. However, the development of new adsorbents from lignocellulose with excellent performance is still a big challenge. In this work, a new bowl-shaped biosorbent (BSB) with surface functionality is prepared from lignin that is extracted from the abundant sugarcane bagasse. The product is characterized by scanning electron microscopy, infrared spectrum, thermo gravimetric analysis and N 2 adsorption techniques. The results show that the obtained BSB is obviously bowl-shaped in microscale with an enlarged surface area, and contains numerous oxygen and nitrogen functional groups. It exhibits an enhanced adsorption capacity toward Cd 2+ that is 3.2 times of the original lignin. The adsorption process of Cd 2+ by the BSB is well fitted by the Freundlich isothermal model and the pseudo-second-order kinetic model, respectively. The adsorption mechanism involves surface complexation, ion-exchange, electrostatic attraction, chemical precipitation and physical adsorption, etc., among them, the surface complexation is the rate-controlling step. Moreover, it shows a good reusability during five repeated cycling for Cd 2+ adsorption. Graphic abstract
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ACS Omega
·
2020
·
IF 2.87
Baojie Liu,Chengrong Qin,Fuqiang Zhang,Shuo Wang,Chen Liang,Shuangxi Nie,Shuangfei Wang,Shuangquan Yao
In fact, the chemical reaction rate of traditional chlorine dioxide bleaching of pulp is too fast to observe the intermediate process. The mechanism behind the reaction of 4-hydroxy-3-methoxyacetophenone (APO), a phenolic lignin model compound, with high concentrations of chlorine dioxide was investigated. Individual solutions of each compound and a mixture of the two were analyzed by UV–vis spectrophotometry, and an absorbance band at 260 nm was observed for the stable benzoquinone intermediates at room temperature. Free chlorine dioxide displayed an absorbance at 360 nm and changes in this absorbance were studied with different APO concentrations. A fixed molar ratio of 1:3 was obtained between APO and chlorine dioxide consumption. The intermediate absorbance demonstrated a linear relationship with the APO concentration. The reaction path between APO and chlorine dioxide at high concentrations was speculated, and it was observed that the activity of C1, C2, C3, C5, and C6 on the APO benzene ring was enhanced when high concentrations of chlorine dioxide were present. From these results, a new method for efficient and clean chlorine dioxide bleaching can be developed.
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JOURNAL OF CATALYSIS
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2021
·
IF 7.92
Lin Dong,Jie Xia,Yong Guo,Xiaohui Liu,Haifeng Wang,Yanqin Wang
Efficient and selective cleavage of C aromatic -C linkages in lignin to enhance the productivity of monocyclic aromatic hydrocarbons is an extremely challenging and attractive task. Previously, we reported a Ru/NbOPO 4 catalyst that realized the catalytic cleavage of both interunit C-C and C-O bonds in one-pot lignin conversions [ Chem , 2019, 5, 1521–1536]. However, the roles of NbO x species in the selective C aromatic -C cleavage are not clear and need to be extensively studied. Herein, we focus on the exploration of the catalytic mechanisms of C aromatic -C bond cleavage over NbO x -supported Ru catalyst, by comparing with those of Ru/TiO 2 , Ru/ZrO 2 , and Ru/Al 2 O 3 catalysts. It shows that the Ru/Nb 2 O 5 catalyst exhibits high activity and remarkable selectivity to monocyclic hydrocarbons. A combined diffuse reflectance infrared Fourier Transform spectra (DRIFTS) and density functional theory (DFT) calculation analysis unambiguously confirmed that (i) NbO x not only can strongly adsorb phenylcyclohexane via benzene ring, but also selectively activate C aromatic -C bond between benzene ring and cyclohexane ; (ii) NbO x can promote the protonation of phenylcyclohexane with the assistance of H 3 PO 4 ; and (iii) NbO x can significantly reduce the barrier of C aromatic -C bonds cleavage of the carbocation intermediate (C 6 H 5 (H)C 6 H 11 + ). A detail underlying mechanism has been established, which would have further implications to promote the design of new, high efficient catalysts.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2020
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IF 5.162
Haichuan Zhang,Yang Liu,Shiyu Fu,Yulin Deng
Upgrading of lignin derived bio-oil is an essential step for producing sustainable bio-based chemicals and fuel. Taken into account that α hydroxyl is the abundant functional group in lignin, high effective and selective catalytic alcoholysis for cleaving the C α -OH linkages would be desirable. However, an in-depth understanding of the reaction mechanisms involved in the cleavage of C aromatic -C α and C α -O bonds over a novel catalyst is still needed. Herein, we report an efficient liquid-phase hydrogen transfer strategy for the selective hydrodeoxygenation of a non-phenolic lignin model compound, 3,4-dimethoxybenzyl (veratryl) alcohol, under mild conditions. By employing iso-propanol as solvent and H-donor, and palladium nanoparticles immobilized on nitrogen-doped carbon (Pd/CN X ) as efficient multifunctional catalyst, veratryl alcohol dehydroxylation exhibited almost 100% conversion along with very high selectivity for 1,2-dimethoxy-benzene (46%) and 3,4-dimethoxytoluene (54%). Compared with other Pd catalysis, the Pd/CN X has excellent catalytic performances and exhibits higher selectivity for 3,4-dimethoxytoluene under incorporation with 1% HCOOH at 220 °C. The proportion of Pd (0) significantly increases in Pd/CN X catalyst when introduced into N precursor because of its highly dispersed Pd NPs and preventing the reoxidation of Pd (0). The dehydrogenation reaction occurred through the hydrogen generation of a secondary alcohol. Then, the C α -OH and C aromatic -C α bonds of veratryl alcohol were selectively cleaved by catalytic transfer hydrogenolysis . The alcoholysis mechanism is supported by dispersion-corrected density functional theory computations.
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FUEL
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2020
·
IF 5.578
Shanshuai Chen,Qiqi Lu,Wanying Han,Puxiang Yan,Hongliang Wang,Wanbin Zhu
Recently, a two-step strategy involving oxidative activation and reductive depolymerization becomes very popular for lignin conversion. However, both positive and negative results are obtained, and the detailed mechanism is still unknown. This study thoroughly investigated the effects of several key factors, including hydrogen pressure, reaction temperature, and catalyst compositions, on the reductive conversion of oxidized lignin (lignin OX ) to aromatics. For lignin oxidative activation, FT-IR, 2D NMR, and TG/DTG were used to prove that hydroxyl groups at lignin side chains had been successfully oxidized to carbonyl groups by AcNH-TEMPO/HNO 3 /HCl system. For lignin OX reductive conversion, pathways and mechanisms were explored, and the applicable conditions of this strategy were determined. Under relative moderate hydrogen pressure (e.g. 2 Mpa) over metal–acid catalysts, e.g. Ru/γ-Al 2 O 3 combined with Hf(OTf) 4 ), an obvious advantage of lignin OX conversion was found. Yield of valuable product from lignin OX was 42.98% which was much higher than that (10.99%) from unoxidized lignin. While, under high hydrogen pressure or promoted by catalysts with high hydrogenation activities, lignin OX tended to be reconverted to original lignin structures with loss of its conversion advantage. 2-phenoxyacetophenone as a lignin OX model was used to verify this speculation and to predict reaction pathways over different catalytic systems. These results proved that a catalyst with both hydrogenolysis and hydrolysis activity was essential for efficient lignin OX depolymerization.
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Sustainable Energy & Fuels
·
2020
·Vol. 4
·期 11
·5588-5594
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IF 5.503
Shi Qiu,Meng Wang,Yunming Fang,Tianwei Tan
Reductive catalytic fractionation (RCF) is a promising lignin-first biorefinery strategy that yields a deeply depolymerized lignin and nearly theoretical amounts of lignin monomers with reductive catalysts. Theoretically, the immediate stabilization with a catalyst is a key step in the RCF process, but the experimental support is lacking and few researchers have investigated the timeliness of stabilization. In this study, an on-line catalyst addition device was used to realize the flexible addition of a catalyst at different times in a high-pressure batch reactor. It was found that immediate stabilization is definitely indispensable for high lignin monomer yield, and the timeliness of stabilization mainly depends on the occurrence of repolymerization. Fast repolymerization occured at temperatures from 200 °C to 250 °C and more seriously around 250 °C, suggesting that the RCF process can be realized as long as adding the catalyst occurs before the temperature reaches 200 °C. Further this proves the feasibility of splitting delignification and stabilization/hydrogenation processes, and explains the reason for the reaction temperatures used in effective semi-continuous RCF processes at lower than 200 °C.
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ACS Sustainable Chemistry & Engineering
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2020
·
IF 7.632
Xueqin Zhang,Sarah Keck,Yujie Qi,Stefan Baudis,Yuxia Zhao
Under natural light, lignin can produce a small amount of free radicals, resulting in yellowing of lignin-related products. However, the activity of these free radicals is very low, so that few studies on exploring the application potential of lignin as photoinitiator (PI) in photopolymerization have been reported. In this study, based on dealkaline lignin (DAL), two alkylated DAL (DAL-11ene and DAL-12ane) were synthesized through facile one-step esterification reactions between DAL and undecanoyl chloride or dodecanoyl chloride. The photoinitiation properties of DAL, DAL-11ene, and DAL-12ane were investigated by real-time FTIR spectroscopy and NIR-photorheology using 1,6-hexanediol diacrylate as a monomer. The formation of reactive species was elucidated by laser flash photolysis and electron spin resonance. The results indicated that DAL itself showed a certain photoinitiating ability, especially when it was combined with an amine co-initiator, while both DAL-11ene and DAL-12ane presented much higher photoinitiating efficiencies compared with DAL. Moreover, DAL-11ene containing a polymerizable group could be bonded into the network of final polymer products, which can increase their biosafety. 3D structures of polyacrylates were fabricated successfully using DAL-11ene and DAL-12ane as PIs through digital light processing 3D printing upon 405 nm exposure, indicating their large potentials in photopolymerization.
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Iranian Journal of Biotechnology
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2020
·
IF 0.973
Shuang Feng Li,Huai Wang,Jia Li Chen,Hui Xia Zhu,Ri-Sheng Yao,Huan Wu
Background: Lignin is the largest natural aromatic polymer in nature and is also a unique aromatic-based biopolymer, accountingfor nearly 30% of the earth’s organic carbon. Generally, lignin is regarded as waste and is mainly used as a low- valuefuel that is burned to generate heat and energy to solve the problem of biomass waste; for this obstacle of lignin,highly efficient biodegradation plays a critical role in developing an environmentally friendly technique for lignin biotransformation. Objectives: This study intends to isolate and purify several microbial strains from nature. It also explores how their lignin degradationis able to enhance the biodegradation and recycling of biomass and the reclamation of lignin in wastewater from pulp and paper mills. Materials and Methods: Lignin-degrading microbial strains were isolated from soil using medium containing sodium lignosulphonate as the sole carbonsource. They were then screened by aniline blue and guaiacol plate, and then the best strain was chosen and identified.The conventional one-factor method was used to optimize various parameters that affect lignin’s degradation ability. Results: The strain possessing the highest lignin biodegradation ability was identified and denominated as Aspergillus Flavus F-1. After optimization, the maximum degradation rate of lignin, 44.6% within 3 days, was obtained at pH 7.0, 30 ℃, 2.5 g·L -1 ammoniumsulfate, 2 g·L -1 lignin and 0.5 g·L -1 glucose. The results show the LiP and Lac secreted from Aspergillus Flavus F-1 played the main role in the degradation of lignin. Conclusion: One microbial strain, Aspergillus Flavus F-1, was successfully isolated with a lignin-degrading abilitythat can cut the lignin into fragments. This provides a promising candidate for the transformation and utilization of crop waste biomass for various industrial purposes.
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MOLECULES
·
2020
·Vol. 25
·期 9
·2109
·
IF 3.267
Changzhou Chen,Peng Liu,Haihong Xia,Minghao Zhou,Jiaping Zhao,Brajendra K. Sharma,Jianchun Jiang
It is of great importance to explore the selective hydrogenolysis of β-O-4 linkages, which account for 45–60% of all linkages in native lignin, to produce valued-added chemicals and fuels from biomass employing UV light as catalyst. TiO2exhibited satisfactory catalytic performances in various photochemical reactions, due to its versatile advantages involving high catalytic activity, low cost and non-toxicity. In this work, 20 wt.% Ni/TiO2and oxidant PCC (Pyridinium chlorochromate) were employed to promote the cleavage of β-O-4 alcohol to obtain high value chemicals under UV irradiation at room temperature. The Ni/TiO2photocatalyst can be magnetically recovered and efficiently reused in the following four consecutive recycling tests in the cleavage of β-O-4 ether bond in lignin. Mechanism studies suggested that the oxidation of β-O-4 alcohol to β-O-4 ketone by oxidant PCC first occurred during the reaction, and was followed by the photocatalysis of the obtained β-O-4 ketone to corresponding acetophenone and phenol derivates. Furthermore, the system was tested on a variety of lignin model substrates containing β-O-4 linkage for the generation of fragmentation products in good to excellent results.Keywords:lignin;β-O-4;photocatalyst;Ni/TiO2;oxidant PCC
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REACTIVE & FUNCTIONAL POLYMERS
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2020
·
IF 3.333
Chang-an Xu,Guokang Chen,Zhiyou Tan,Zhuorong Hu,Zhencai Qu,Qian Zhang,Maoping Lu,Kun Wu,Mangeng Lu,Liyan Liang
Polysiloxane-based polyurethane/lignin elastomers are synthesized via pre-polymerization. Isophorone diisocyanate (IPDI) reacts with polycarbonate (PCDL) and polydimethylsiloxane (PDMS) polyol to produce a linear thermoplastic elastomer. Lignin is added to the matrix of the polyurethane , where lignin not only acts as a crosslinking agent but also as filler. The effects of polysiloxane-based polyurethane/lignin elastomers on thermal properties, mechanical properties , surface hydrophobicity , and cytotoxicity in vitro are investigated. The heat resistance, surface hydrophobicity and mechanical strength of the materials are improved, and a decreased cytotoxic behavior against HeLa cells by MTT assay is observed, which should be attributed to the semi-interpenetrating network structure and low toxicity of lignin, respectively. With the addition of 1 wt% of lignin, cell viability increases to 65.2%, mechanical strength increases to 17.1 Mpa and contact angle increases to 108.2°.
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CATALYSIS TODAY
·
2020
·
IF 5.825
Genkuo Nie,Yiying Dai,Junjian Xie,Xiangwen Zhang,Lun Pan,Ji-Jun Zou
Fuel blending generally exhibits better low-temperature flow properties (i.e. low viscosity, low freezing point) than pure component fuel. Here, a fuel bending containing bicyclohexane and (cyclopentylmethyl)cyclohexane was synthesized directly by hydroisomerization of cyclohexylphenol to reduce the freezing point. The selectivity of (cyclopentylmethyl)cyclohexane formed by isomerization is enhanced through inhibiting the quick hydrogenation of intermediates using mixing acid catalyst and metal catalyst. Zeolite with strong Brønsted acid site and big surface area, such as HZSM-5 is better for the isomerization. Catalyzed by mixture of Pd/C and HZSM-5, the obtained fuel blending improves the freezing point from 2.6 °C to−22 °C compared with pure bicyclohexane, meanwhile keep the high density of 0.880 g/mL unchanged. The improved low-temperature property is contributed to the formation of (cyclopentylmethyl)cyclohexane. Moreover, the pathways of isomerization and its competition with hydrodeoxygenation are also investigated.
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LANGMUIR
·
2020
·
IF 3.557
Mei Cui,Yuhao Duan,Yuanyuan Ma,Khaled W.A. Al-Shwafy,Yudong Liu,Xudong Zhao,Renliang Huang,Wei Qi,Zhimin He,Rongxin Su
Expansin has nonhydrolytic disruptive activity and synergistically acts with cellulases to enhance the hydrolysis of cellulose. The adsorption–desorption of expansin on noncellulosic lignin can greatly affect the action of expansin on lignocellulose. In this study, three lignins with different sources (kraft lignin (KL), sodium lignin sulfonate (SLS), and enzymatic hydrolysis lignin (EHL)) were selected as the substrates. The real-time adsorption–desorption of Bacillus subtilis expansin (BsEXLX1) on lignins was monitored using quartz crystal microgravimetry with dissipation (QCM-D). The effects of temperature and Tween 80 on the adsorption–desorption behaviors were also investigated. The results show that BsEXLX1 exhibited high binding ability on lignin and achieved maximum adsorption of 283.2, 273.8, and 266.9 ng cm–2 at 25 °C on KL, SLS, and EHL, respectively. The maximum adsorption decreased to 148.2–192.8 ng cm–2 when the temperature increased from 25 to 45 °C. Moreover, Tween 80 competitively bound to lignin and significantly prevented expansin adsorption. After irreversible adsorption of Tween 80, the maximum adsorption of BsEXLX1 greatly decreased to 33.3, 37.2, and 10.3 ng cm–2 at 25 °C on KL, SLS, and EHL, respectively. Finally, a kinetic model was developed to analyze the adsorption–desorption process of BsEXLX1. BsEXLX1 has a higher adsorption rate constant (kA) and a lower desorption rate constant (kD) on KL than on SLS and EHL. The findings of this study provide useful insights into the adsorption–desorption of expansin on lignin.
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