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Efficient and rapid capture of organic pollutants from wastewater is an urgent problem to be solved by adsorbents. Nitrogen-doped magnetic porous carbon (M-PLAC) with three-dimensional porous structure was synthesized from lignin to adsorb MB and TC in wastewater. M-PLAC had high specific surface area (1252.21 m2/g) and N element content (7.44%). The calculated equilibrium adsorption amount by M-PLAC for MB and TC was 645.52 and 1251.09 mg/g, respectively. The adsorption of MB and TC on M-PLAC conformed to the pseudo-second-order kinetic model, demonstrating that the adsorption process was attributed to chemisorption. The excellent adsorption performance was a synergistic effect among various adsorption mechanisms. The removal of MB and TC by M-PLAC showed fast and efficient characteristics, and exhibited high selectivity for TC in binary system. In addition, M-PLAC was suitable for a variety of complex water environments and had good regeneration performance, demonstrating potential advantages in practical wastewater treatment.

A novel and general approach for the rational design of a S-scheme heterojunction coupled with doping and co-catalyst modification via a reduction strategy assisted by thermal dissolution for photocatalytic HER.

The photoreforming of lignocellulose is a novel method to produce clean and sustainable H2 energy. However, the catalytic systems usually show low activity under ultraviolet light; thus, this reaction is very limited at present. Visible light-responsive metal-free two-dimensional graphite-phased carbon nitride (g-C3N4) is a good candidate for photocatalytic hydrogen production, but its activity is hindered by a bulky architecture. Although reported layered g-C3N4 modified with active functional groups prepared by the chemical exfoliation enhances the photocatalytic activity, it lost the intrinsic structure and thus is not conducive to understand the structure-activity relationship. Herein, we report an intrinsic monolayer g-C3N4 (∼0.32 nm thickness) prepared by nitrogen-protected ball milling in water, which shows good performance of photoreforming lignocellulose to H2 driven by visible light. The exciton binding energy of g-C3N4 was estimated from the temperature-dependent photoluminescence spectra, which is a key factor for subsequent charge separation and energy transfer. It is found that monolayer g-C3N4 with smaller exciton binding energy increases the free exciton concentrations and promotes the separation efficiency of charge carriers, thereby effectively improving its performance of photocatalytic reforming of lignocellulose, even the virgin lignocellulose and waste lignocellulose. This result could lead to more active catalysts to photoreform the raw biomass, making it possible to provide clean energy directly from locally unused biomass.

In this work, the coordination-based energy sacrificial bonds have been constructed in the interphase between lignin and polyolefin elastomer to prepare high performance lignin-based thermoplastic elastomers (TPEs). The strength and toughness of lignin-based TPEs can be adjusted by choosing different nitrogen heterocyclic compounds as reactive assistants and Fe3+ or Zn2+ as metal coordination centers. It was demonstrated that 3-Amino-1,2,4-triazole with three nitrogen atoms in the heterocyclic ring and one nitrogen branch chain could form the most efficient coordination bond system and generate the best mechanical performance. The system with ferric iron as coordination center exhibited better enhancement effect than divalent zinc. By adjusting the nitrogen-containing reactive additives or metal salts as coordination centers, the mechanical performance of the lignin-based TPE can be regulated, which provides a method for making green bio-composites with good strength and toughness, and also promotes the high value utilization of lignin in polymer materials.

Fast-response artificial phototropic materials are a promising tool for solar energy utilisation, yet their preparation remains challenging. Herein, we report the so-called photothermal domino strategy for constructing fast-response artificial phototropic materials. In this strategy, photothermal generation, heat conduction and thermal actuation are sequentially optimised by a coordination effect. For the first time, lignin-based organic radicals boosted by this coordination effect are used to significantly enhance photothermal conversion. Interfacial coordination bonds between lignin and an elastomer matrix promote interfacial heat conduction. Light-stimulated thermal actuation is significantly improved by coordination-assisted mechanical training. The prepared biomimetic phototropic material exhibits excellent phototropic ability, with a 2.5 s light-tracking process, showing great application potential for efficient solar energy utilisation. This strategy shows great significance for fabricating high-performance intelligent phototropic materials using widely available, green raw materials.

Due to the poor enzyme thermal stability, the efficient conversion of high crystallinity cellulose into glucose in aqueous phase over 50 °C is challenging. Herein, an enzyme-induced MOFs encapsulation of β-glucosidase (β-G) strategy was proposed for the first time. By using various methods, including SEM, XRD, XPS, NMR, FTIR and BET, the successful preparation of a porous channel-type flower-like enzyme complex (β-G@MOFs) was confirmed. The prepared enzyme complex (β-G@MOFs) materials showed improved thermal stability (from 50 °C to 100 °C in the aqueous phase) and excellent resistance to ionic liquids (the reaction temperature was as high as 110 °C) compared to the free enzyme (β-G). Not only the catalytic hydrolysis of cellulose by single enzyme (β-G) in ionic liquid was realized, but also the high-temperature continuous reaction performance of the enzyme was significantly improved. Benefiting from the significantly improved heat resistance, the β-G@MOFs exhibited 32.1 times and 34.2 times higher enzymatic hydrolysis rate compared to β-G for cellobiose and cellulose substrates, respectively. Besides, the catalytic activity of β-G@MOFs was retained up to 86 % after five cycles at 110 °C. This was remarkable because the fixation of the enzyme by the MOFs ensured that the folded structure of the enzyme would not expand at high temperatures, allowing the native conformation of the encapsulated protein well-maintained. Furthermore, we believe that this structural stability was caused by the confinement of flower-like porous MOFs.

The recovery of cellulase at room temperature by adding recyclable thermoresponsive zwitterionic surfactants is more significant for reducing the cost of the production of cellulosic ethanol. Sulfobetaines can exhibit a thermoresponsive upper critical solution temperature (UCST) in acetate buffer solutions. Here, the performance was optimised by adjusting the carbon chain length and concentration of sulfobetaines. As an example, octadecyl sulfobetaine (SB3-18) showed sensitive UCST-responsive performance at 25–50 °C (0–0.40 g L−1). Interestingly, SB3-18 and cellulase precipitated together, and 0.20 g L−1 SB3-18 could recover 58.9% of cellulase by cooling down to 25 °C. In addition, SB3-18 could recover more than 50% of cellulase during the enzymatic hydrolysis of corncob residues (CCRs). Finally, hydrophobic interaction is the main driving force for the recovery of cellulase as revealed by quartz crystal microbalance by the dissipation (QCM-D) test. In this work, the process of recovering cellulase is simple and green and does not require acids and alkalis. This recovery method is applicable for the separation and purification of some other hydrophobic proteins.

In order to reduce the enzyme cost of lignocellulosic enzymatic hydrolysis, upper critical solution temperature (UCST) additives are used to recover and reuse cellulase by regulating the temperature. A sulfobetaine polymer, PSPE, showed a sensitive UCST response in buffer, and its UCST-performance was optimised by adjusting the molecular weight of the polymer. PSPE-3 (Mw = 355.1 kDa) was added to the cellulase buffer at 50 °C, and PSPE-3 and cellulase were co-precipitated by cooling to the room temperature of 25 °C. PSPE-3 and cellulase co-precipitated mainly through hydrophobic interactions via cooling. Compared with octadecyl sulfobetaine (SB3–18), PSPE-3 had a more sensitive UCST response and stronger cellulase recovery ability. Adding only 40% PSPE-3 (accounting for the mass fraction of cellulase) can save more than 50% cellulase in the enzymatic hydrolysis system of eucalyptus chips pre-treated with dilute acid (Eu-DA). However, for the Eu-DA system, adding 100% SB3–18 can only save about 30% of cellulase. In this work, efficient recycling of cellulase was achieved at room temperature by adding UCST-type PSPE. The process is green without consuming acid and alkali, and this work provides a new idea for reducing the production cost of cellulosic ethanol.

The technical enzymatic hydrolysis lignin (EHL) and alkali lignin (AKL) were pretreated via alkaline depolymerization and organic solvent extraction process, respectively. The molecular weight of l...

A Pd-catalyzed highly regioselective hydrocarboxylation of alkynes with carbon dioxide has been established. By the combination of Pd(PPh3)4 and 2,2′-bis(diphenylphosphino)-1,1′-binaphthalene (bina...

To solve the poor absorbance on ultraviolet A (UVA) radiations and dark color, alkali lignin (AL) was modified via atom transfer radical polymerization (ATRP) grafting of 2-4-benzoyl-3-hydroxypheny...

Using a co-precipitation approach, we introduce Co into LiNi0.5Mn1.5O4 to prepare a series of Co-doped cathode materials in which the Co substitutes partial Ni and Mn. We then systematically study the effects of Co doping at these various sites. The structural and electrochemical properties are investigated by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller analysis, galvanostatic charge–discharge tests, and electrochemical impedance spectroscopy. The Co-doped samples experience a slight capacity loss, but their cycling stability and rate properties are significantly improved. When Ni and Mn are simultaneously substituted, the capacities at 0.1 C and 2.0 C of a battery using this doped material as the cathode stay at 99.7% and 96.8%, respectively, after 80 cycles, which is much better than the results for a battery with undoped material as the cathode.

Pickering emulsion stabilized by lignin/sodium dodecyl sulfate composite nanoparticles (LSNP) was used as template to prepare the avermectin @ lignin/polyurea composite microcapsules (AVM@LPMC) through ion cross-linking and interfacial polymerization. The inner wall of the microcapsules is a firm and compact polyurea layer, and the outer wall is a loose lignin layer. The effects of stirring speed, dosage of sodium dodecyl sulfate (SDS), and pH value in aqueous phase on the formation of microcapsules were systematically studied. The results showed that the optimal stirring speed was 200 rpm, and the optimal dosage ratio in water phase was HCl (mmol):SDS (mmol):lignin AL (g) = 0.375:1.25:1 in fixed oil-water ratio (1:9) and oil phase composition. In this way, the encapsulation efficiency of microcapsules could reach up to 85.4%, while it would slightly decrease with the increase of lignin content in the wall materials. The polyurea layer played a key role in supporting the spherical structure of the capsule wall and delaying the release of avermectin, while the loose lignin layer contributed less to the slow release performance of microcapsule. By changing the amount of lignin, the polyurea-layer thickness could be regulated to adjust the release rate of microcapsule. Remarkably, a small amount of lignin introduced in the wall material could significantly improve the anti-photolysis performance of avermectin in microcapsules.

The advancement of anti-tumor nanomedicines is restricted by the delivery efficiency owing to a lack of insight into the intratumoral delivery mechanism, especially traversing the biological barriers. Herein, we explore a new strategy focusing on controlling excessive high tumor interstitial fluid pressure (TIFP) caused by lymphatic lack, which hampers the convective diffusion of nanomedicines to the tumor center. We construct a “nano-lymphatic” system (DOX/g-C3N4/luminol@cytomembrane, DCL@M) based on graphitic carbon nitride (g-C3N4) for photocatalytic water splitting, which can decrease the volume of the tumor interstitial fluid to ameliorate the transfer resistance derived from the high TIFP. In the tumor microenvironment, lactic acid as a sacrificial agent in catalysis greatly promoted the water-splitting efficiency; thus, TIFP in the tumor tissue was reduced to 62.11%, causing an enhancement in blood perfusion to the tumor. The accumulation of the “nano-lymphatic” system (16.73%) in the tumor was 15.9- and 3.31-fold greater than those of free doxorubicin hydrochloride (DOX, 1.05%) and DOX/g-C3N4@cytomembrane (DC@M, 3.03%), respectively. The penetration efficiency of the “nano-lymphatic” system was 8.98% at the tumor center. The “nano-lymphatic” strategy produced reactive oxygen species associated with water splitting to suppress the tumor growth; thus, we define the strategy as hydrodynamic therapy, which provides a new avenue for nanomedicines in traversing biological barriers and achieves a better therapeutic effect.

This study evaluated maleic acid (MA) as a green hydrotrope for efficient wood fractionation at atmospheric pressure and ≤100 °C. MA hydrotropic fractionation (MAHF) resulted in esterified lignin with a low degree of condensation and a very light color. 2D 1H–13C HSQC and HMBC NMR analyses of reaction products of a lignin model compound guaiacylglycerol-beta-guaiacyl ether with MA identified bonding through the γ-OH group. The surface charge of lignocellulosic MAHF water insoluble solids (WIS), induced by lignin esterification (carboxylation), enhanced enzymatic sugar yield by reducing nonproductive cellulase binding to lignin through pH-mediated electrostatic repulsion and also enhanced the lubrication effect of lignin in mechanical nanofibrillation for producing cellulose nanofibrils from WIS. Preliminary studies indicated that disssolved xylan can be dehydrated into furfural by MA in the fractionated liquor at a good yield of 70% and MA can be reused for repeated fractionation with minimal loss of less than 5%.

Recycling cellulase can reduce the cost of lignocellulosic enzymatic hydrolysis. Here, a lignin-grafted sulfobetaine (LSB) was first synthesized by grafting sulfobetaine (SB) on enzymatic hydrolysis lignin (EHL). LSB had a sensitive response of pH and temperature. LSB dissolved under the conditions of lignocellulosic enzymatic hydrolysis (pH 5.0, 50 °C). After hydrolysis, LSB co-precipitated with cellulase when lowering pH of the hydrolysate to 4.0 and cooling to 25 °C. When 3.0 g/L LSB-100 was added to the hydrolysis system of corncob residue (CCR), 70 % of amount of cellulase was saved. LSB had a remarkable response and stronger cellulase recovery capacity. This was attributed that carboxylate radical in LSB was protonated, and positive and negative ions of SB associated to form salt at 25 °C. This work provides a new idea for reducing the cost for preparing fermentable sugars from lignocellulose, and increasing the added value of EHL.

The photoreforming of lignocellulose is a novel method to produce clean and sustainable H

Highly recyclable pH-responsive lignin-polyethylene glycol (L-PEG) was synthesized to achieve enhanced lignocellulosic hydrolysis and recycling cellulase. The performance of L-PEG could be easily regulated by adjusting the molecular weight and the amount of PEG. The large molecular weight facilitated L-PEG to reduce the invalid adsorption of cellulase on lignin during hydrolysis and enhance its flocculation effect at around pH 3.0. L-PEG1000-40 obtained by adding 40 wt% (based on lignin) PEG1000 could effectively enhance the enzymatic hydrolysis of lignocelluloses and recover most of cellulase after hydrolysis through simply adjusting the pH of hydrolysate. During eucalyptus hydrolysis, using L-PEG1000-40 to recycle cellulase could not only save 40% cellulase, but also increase the glucose yield by 121%. Due to the low synthesis cost of L-PEG and the simple and convenient recovery operation, this new method is beneficial to the improvement of lignocellulosic saccharification process and the high-value utilization of lignin.

Lignin nanospheres with broad-spectrum UV adsorption and excellent antioxidant properties were obtained by demethoxylation of alkali lignin (AL) and grafting the benzophenone moiety (UV-0) followed...

The isoelectric point (pI) of lignin-based surfactant is an important factor in the enhancement on the enzymatic hydrolysis of lignocellulose. In this work, lignin carboxylate (LC) and quaternary ammonium lignin carboxylates (LCQ-x, x%: the mass ratio of quaternizing agent to enzymatic hydrolysis lignin) with different isoelectric points were synthesized. LC or LCQ-x with pI significantly lower or higher than 4.8 reduced the non-productive adsorption of cellulase on lignin, but for the significant inhibitory effect on cellulase activity, their enhancements on the enzymatic hydrolysis of lignocellulose were not remarkable. However, LCQ-x with pI around 4.8 preserved the cellulase activity, and significantly reduced the non-productive adsorption of cellulase, therefore remarkably enhanced the enzymatic hydrolysis. 2 g/L LC, LCQ-40 (pI = 5.0) and LCQ-100 (pI = 9.2) increased the enzymatic digestibility of pretreated eucalyptus from 35.2% to 53.4%, 95.3% and 60.4% respectively. In addition, for the excellent pH-response performance, LCQ could be efficiently recovered after enzymatic saccharification.

A linear pH-responsive zwitterionic copolymer P(MDB) was synthesized from functional monomers methacrylic acid, 2-(dimethylamino) ethyl methacrylate (DMA) and benzyl methacrylate (BMA) through free radical polymerization to recover cellulases and enhance the enzymatic hydrolysis. The hydrophobicity and molecular weight of the copolymer was controlled by the feed ratio of monomers and the mass ratio of initiator to monomers, respectively. UV-turbidity showed P(MDB) exhibited sensitive pH-responsiveness with dissolution–precipitation ΔpH about 1 pH unit. The precipitation pHφ of P(MDB) was 5.0–5.5 and over 90% of P(MDB) could precipitate in the vicinity of its isoelectric point. Increasing the hydrophobicity or molecular weight of P(MDB) could improve its pH sensitivity and precipitation rate. P(MDB) could enhance the enzymatic hydrolysis of dilute acid pretreated Eucalyptus by 10–25%. P(MDB) could recover the free cellulases in enzymatic hydrolysate by co-precipitation. SDS-PAGE analysis showed that P(MDB) could recover 100% β-glucosidase (β-GL) and the recovery rates of cellobiohydrolase (CBH) and endoglucanase (EG) increased as the hydrophobicity and molecular weight of P(MDB) increased. The mechanism was proposed that hydrophobic affiliation was the main binding force of P(MDB) to cellulases. Increasing the hydrophobicity and molecular weight of copolymer could increase its binding force and the number of binding sites to cellulases thus the overall cellulase recovery performance was improved.

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.

Sulfonation degree is an important structural parameter of lignosulfonates which affect their water solubility, surface activity, and dispersing performance. Presently, the methods for determining sulfonation degree include elemental analysis and potentiometric titration; they have some shortcomings such as complex purification process, high equipment requirements, and time-consuming. Hence, a simple and rapid method to determine the sulfonation degree of lignosulfonates was proposed based on the electrostatic interaction between cationic surfactant (hexadecyl trimethyl ammonium bromide (CTAB)) and anionic lignosulfonates. CTAB was added and co-precipitated with lignosulfonates and then the ultraviolet absorbance of the supernatant was determined. The sulfonation degree of lignosulfonates was calculated according to the titration curve of the supernatant absorbance to the amount of CTAB. This method is applicable to lignosulfonates recovered from acid pulping as well as sulfonation products of alkali lignin. Because of the easy operation process and no purification process for lignosulfonates, this method was simple and rapid when compared to existing methods for sulfonation degree determination of lignosulfonates.

Enzymatic conversion of lignocelluloses into fermentable sugar is a key step in the production of cellulosic ethanol. In this work, enzymatic hydrolysis lignin (EHL)-grafted phosphobetaine (EHLPB) was prepared, and the phosphobetaine intermediate, 3-chloro-2-hydroxypropyl(2-(trimethylammonio)ethyl)phosphate, was synthesized from phosphocholine chloride calcium salt and epichlorohydrin. EHLPB showed a pH-sensitive response. When pH ≥ 5.0, it was completely dissolved in the buffer solution, whereas 95.5% of EHLPPB was precipitated when pH ≤ 3.0. Adding 1.2 wt % EHLPB-210 can increase the high-solid enzymatic digestibility of Eu-SPORL (sulfite pretreatment to overcome recalcitrance of eucalyptus) and CCR (corncob residue) from 33.6% and 52.6% to 71.5% and 73.6%, respectively. After the enzymatic hydrolysis of Eu-SPORL, 95% of EHLPB-210 was recovered by adjusting the slurry pH from 5 to 3. The recovered EHLPB-210 still kept the ability to enhance enzymatic hydrolysis of lignocelluloses. Adding 1.2 wt % recove...

The origin, amount, hydrophilicity, charge, molecular weight and its distribution of lignin have significant influences on the enzymatic hydrolysis of lignocellulose. The enzymatic hydrolysis of lignocellulose was essentially enhanced by lignin-based polyoxyethylene ether (EHL-PEG), whereafter followed by PEG4600 and lignosulfonate (LS). The effect of LS, EHL-PEG and PEG4600 on the adsorption and enzymatic hydrolysis kinetics of cellulase on the gold surface and cellulose film was investigated by Quartz Crystal Microbalance with dissipation monitoring (QCM-D). Results showed that the interaction of LS or EHL-PEG with cellulase was electrostatic attractive and hydrophobic effect, respectively, and formed hydrophilic cellulase aggregates. LS-Cellulase peeled off the cellulose film layer by layer, while the hydrophobic phenylpropane structure of EHL-PEG-Cellulase acted as a cellulose binding domain to hydrolysis cellulose through "Hollow" effect and made cellulose become more loose and swollen. At last, a strategy to enhance the enzymatic hydrolysis of lignocellulose by lignin-based amphiphilic polymers was proposed as well.

In China, the rapid development greatly promotes the national economic power and living standard but also inevitably brings a series of environmental problems. In order to resolve these problems fundamentally, Chinese scientists have been undertaking research in the area of green chemical engineering (GCE) for many years and achieved great progresses. In this paper, we reviewed the research progresses related to GCE in China and screened four typical topics related to the Chinese resources characteristics and environmental requirements, i.e. ionic liquids and their applications, biomass utilization and bio-based materials/products, green solvent-mediated extraction technologies, and cold plasmas for coal conversion. Afterwards, the perspectives and development tendencies of GCE were proposed, and the challenges which will be faced while developing available industrial technologies in China were mentioned.