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Clostridium acetobutylicum has been extensively exploited to produce biofuels and solvents and its biofilm could dramatically improve the productivities. However, genetic control of C. acetobutylicum biofilm has not been dissected so far. Here, to identify potential genes controlling C. acetobutylicum biofilm formation, over 40 gene candidates associated with extracellular matrix, cell surface, cell signaling or gene transcription, were tried to be disrupted to examine their individual impact. A total of 25 disruptants were finally obtained over years of attempts, for which biofilm and relevant phenotypes were characterized. Most of these disruptants formed robust biofilm still, or suffered both growth and biofilm defect. Only a strain with a disrupted histidine kinase gene (CA_C2730, designated bfcK in this study) abolished biofilm formation without impairing cell growth or solvent production. Further analysis revealed that bfcK could control flagellar biogenesis and cell motility at protein levels. The bfcK also appeared to repress the phosphorylation of a serine/threonine protein kinase (encoded by CA_C0404) that might negatively regulate biofilm formation. Based on these findings, possible bfcK-mediated mechanisms for biofilm formation were proposed. This is a big step toward understanding the biofilm formation in C. acetobutylicum and will help further engineering of its biofilm-based industrial processes.

Compared with the traditional suspension fermentation, immobilised biofilm fermentation has advantages of strong resistance, high yield and continuous fermentation and is conducive to improving the industrial fermentation methods. The formation of a biofilm on correct supports is critical to immobilised fermentation. In this study, Pichia pastoris was used to understand and control the modification of surface properties of supports and cells. Following deletion of gene PAS_chr2-1_0773, in P. pastoris △0773, the cell-surface negative charge density decreased and hydrophobicity improved, which was conducive to adhesion. Therefore, according to the changing trend of cell surface properties, cotton fibre was used with succinic anhydride (SA) to modify the carrier for changing the surface properties for efficient conduction of immobilised fermentation. In the fermentation process, the adhesion between the modified cotton fibre and yeast was better than that between an unmodified cotton fibre and yeast, and the additive amount increased by ∼25 %. The enzyme activity of the △0773-cotton-SA fermentation system reached 302.7 U/mL, which was 39.6 % higher than that of the original fermentation system. Therefore, this study provides a guide for significant improvement of immobilised fermentation of fungi.

To effectively immobilize an enzyme while maintaining its high activity and stability, the design of supports with controlled geometric structures and heterogeneous surface properties is desirable. Towards this goal, heterogeneous titanium dioxide (TiO2) surfaces with controlled pore sizes were synthesized in this study and used to efficiently immobilize lipase. The immobilized lipase activity increased by a factor of 1.31 with an increase in the TiO2 pore size from 11.46 to 21.14 nm. The highest protein loading of 15.52 mg/g was achieved in ethenyl triethoxy silane (ETS)-modified TiO2 (E-P25) after immobilizing the enzymes at 30 ℃, pH 7.33 for 3 h and using a protein concentration in solution of 0.176 mg/mL. Among the different surface functionalities, the highest activity yield of 428.04 % was accomplished by using TiO2 calcinated at 650 ℃ and modified by ETS as immobilization support. The immobilized enzymes showed excellent storage stability and retained almost 95 % of their activity after being stored at 4 ℃ for 8 weeks. This research provides experimental evidence that highlights the importance of studying of enzyme immobilization on the supports with synergistically designed geometric structures and surface chemical properties.

Industrially, lignin in pulp liquor not only obstructed the realization of value-added products, but also threatened the aquatic ecosystem. A magnetic composite Ca(OH)2/Fe3O4, combining the eco-friendliness of Ca-based flocculants with the convenience of magnetic flocculation, was simply compounded to efficiently flocculate lignin from papermaking black liquor. Morphologic and structural features of the flocculant before and after flocculation were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM) and X-ray photoelectron spectroscopy (XPS). The flocculant Ca(OH)2/Fe3O4 presented mesoporous and core-shell structure, which acted directly in the sodium lignin aqueous solution without pH neutralization, maintaining high lignin removal between 91% and 95%. Ca(OH)2/Fe3O4 showed a wider salts (0–1 mol/L NaCl) and pH (9–12.5) tolerance. In actual pulp black liquor, Ca(OH)2/Fe3O4 exhibited high removal of 90.16% and 85.93% for lignin and chemical oxygen demand (COD), respectively. The flocculation performance of Ca(OH)2/Fe3O4 outdistanced that of the traditional flocculant polyacrylamide (PAM). It displayed magnetically separable with a good reusability. The removal of lignin could attain 90.54% even after 6 cycles. Charge neutralization, micro-bridging, destabilization and sedimentation were involved in the process of lignin flocculation. Consequently, Ca(OH)2/Fe3O4 presented huge potential in papermaking black liquor treatment.

Chemoenzymatic catalysis can give full play to the advantages of versatile reactivity of chemocatalysis and excellent chemo-, regio-, and stereoselectivities of biocatalysis. These chemoenzymatic methods can not only save resource, cost, and operating time but also reduce the number of reaction steps, and avoid separating unstable intermediates, leading to the generation of more products under greener circumstances and thereby playing an indispensable role in the fields of medicine, materials and fine chemicals. Although incompatible challenges between chemocatalyst and biocatalyst remain, strategies such as biphasic system, artificial metalloenzymes, immobilization or supramolecular host, and protein engineering have been designed to overcome these issues. In this review, chemoenzymatic catalysis according to different chemocatalysis types was classifiably described, and in particular, the classic dynamic kinetic resolutions (DKR) and cofactor regeneration were summarized. Finally, the bottlenecks and development of chemoenzymatic catalysis were summarized, and future development was prospected.

High-value utilization of hemicellulose is critical to improve the append value of integrated biorefineries. In this research, the alkali-soluble sugarcane bagasse hemicellulose was sulfated using chlorosulfonic acid and N,N-dimethylformamide/LiCl under homogeneous conditions. With the aid of flow technique, a rapid, mild, and efficient method for the synthesis of xylan sulfate with high molecular weight and controllable degree of substitution was achieved. The results showed that the reaction time and the degradation of xylan chain were drastically reduced compared to the “in flask” batch conditions. High molecular weight of the product (Mw = 148,217) with a reasonable degree of substitution (DS = 1.49) could be obtained even at room temperature in 10 min under the present flow system. Anticoagulant experiments showed good anticoagulant activity of the resultant xylan sulfate, which could significantly prolong the activated partial thromboplastin time and thrombin time. This work not only provides a novel method for the synthesis of xylan sulfate, but also offers new opportunities for the production of other functional polysaccharide derivatives under the flow reaction conditions.

This study evaluated the feasibility of ethanol production from expired rice by surface immobilization technology fermentation. The process was carried out using temperature tolerant active fresh yeast TH-AADY cells immobilized on cotton fiber placed in a reticular hollow sphere. A 320-ton pilot reactor with a multi-layer packed bed immobilized structure and multi-branch circulation path was used instead of the typical cylindrical immobilized reactor. The average values of the alcohol degree and fermentation efficiency of the immobilized yeast cells were 12.46% (v/v) and 83.72%, respectively, which were 0.45% (v/v) and 3.2% higher than those of a free-cell fermentation. The fermentation was repeated for 32 batches with good reusability and long-term stability. In addition, fermentation via cell immobilization created an extra benefit of 6.37% per ton of fuel alcohol based on the mean market price in China. The results obtained in this study indicate that ethanol production from expired rice using immobilized yeast in the new bioreactor is feasible and may meet the demands of industrial production based on the fermentation indexes and economic evaluation.

Molecular self-assembly plays a vital role in the nucleation process and sometimes determines the nucleation outcomes. In this study, ultrasound technology was applied to control polymorph nucleation. For the first time, different ultrasonic application methods based on the nucleation mechanisms have been proposed. For PZA-water and DHB-toluene systems that the molecular self-assembly in solution resembles the synthon in crystal structure, ultrasound pretreatment strategy was conducted to break the original molecular interactions to alter the nucleated form. When the solute molecular self-associates can't give sufficient information to predict the nucleated polymorph like INA-ethanol system, the method of introducing continuous ultrasonic irradiation in the nucleation stage was applied. The induction of ultrasound during nucleation process can break the original interactions firstly by shear forces and accelerate the occurrence of nucleation to avoid the reorientation and rearrangement of solute molecules. These strategies were proved to be effective in polymorph control and have a degree of applicability.

Enzyme catalysis has clear advantages in the process of oxidizing glucose to produce gluconic acid. In the enzyme cascade, the improvement of the cascade efficiency is desired but challenging. Graphene oxide (GO) and ZIF-8 composites as enzyme support offer the promising opportunity that not only the cascade efficiency can be improved by control the distance between two enzymes, but also the stability can be improved. Here, a new strategy of GO assisted co-growth of ZIF-8 and enzyme was carried in a one-pot synthesis. Glucose oxidasecatalase immobilized in the ZIF-8/GO composites can obtain 98% residual activity after 15 days of storage with almost no enzyme shedding. The residual activity is still higher than 75% after 5 repeated uses. The presented method of controllable growth of metal organic frameworks on 2D nanosheet can also be extended for renewable energy devices, gas storage and separation of small molecules.

Azo dyes are the most widely applied chemical dyes that have also raised great concerns for environmental contamination and human health issues. There has been a growing interest in discovering bioremediation methods to degrade azo dyes for environmental and economic purposes. Azoreductases are key enzymes evolved in nature capable of degrading azo dyes. The current work reports the identification, expression, and properties of a novel azoreductase (AzoRed2) from Streptomyces sp. S27 which shows an excellent stability against pH change and organic solvents. To overcome the requirements of coenzyme while degrading azo dyes, we introduced a coenzyme regeneration enzyme, Bacillus subtilis glucose 1-dehydrogenase (BsGDH), to construct a recycling system in living cells. The whole-cell biocatalyst containing AzoRed2 and BsGDH was used to degrade a representative azo dye methyl red. The degradation rate of methyl red was up to 99% in 120 min with high substrate concentration (250 μM) and no external coenzyme added. The degradation rate was still 98% in the third batch trial. To sum up, a novel azoreductase with good properties was found, which was applied to construct whole-cell biocatalyst. Both the enzymes and whole-cell biocatalysts are good candidates for the industrial wastewater treatment and environmental restoration.

In order to solve the toxic and hazardous issues of the agents in the chemical reduction process of graphene oxide (GO), disodium guanosine 5′-monophosphate (GMP-2Na) was used as an ideal reducing agent for the synthesis of functionalized GO (FGO) for lipase immobilization. At the condition of low amount adsorption of GMP-2Na indicated by the N1s spectra of X-ray photoelectron spectroscopy (XPS), the C/O atomic ratio of the FGO increased from 2.09 to 3.12, indicating the reduction of GO. As the amount of GMP-2Na increased, the intensity of the characteristic peak of GO in the XRD pattern decreased, and the I D /I G peak intensity of Raman spectra increased during the functionalization process. It was found that when the concentration of GMP-2Na is 0.20 mg/mL, the degree of hydrophobicity of FGO is conducive to the formation of optimal conformation of lipase. After immobilization, the activity of the immobilized enzyme reaches twice the value of free enzyme. At the same time, the protein loading reaches to 600 mg/g. The immobilized enzyme showed enhanced durability since no obvious decrease was observed after incubation for 8 h at pH 6.0 and pH 7.0. After storage for 35 days, the activity of GO-G@ enzyme was 54.47% higher than that of free enzyme. GO reduced by GMP-2Na provides a possibility to obtain a highly efficient lipase immobilization carrier.

A series of hafnyl phosphates HfO(PO4)x (x = 1.0, 1.5 and 2.0) were prepared by coprecipitation of HfCl4 with KH2PO4, which were explored for efficient production of HMF from cellulose in NaCl-H2O/THF biphasic system. An excellent HMF yield of 69.8% was achieved over HfO(PO4)2.0 at 190 °C for 240 min. Levulinic acid was barely produced during the reaction since the strength of HfO(PO4)2.0 is not enough to rehydrate HMF, and humins deposition was almost eliminated due to its poorer HMF adsorption (9.3 mg/g). The results showed that the role of the phosphate group in the catalyst could be in deactivation of unselective Lewis acid sites. Furthermore, high yields of HMF from other carbohydrates such as fructose (94.8%), glucose (90.5%), cellobiose (79.3%), sucrose (86.6%), starch (75.3%), inulin (80.4%), as well as wheat straw (18.6%) could be achieved using HfO(PO4)2.0 as a catalyst. During catalyst recyclable test, the catalytic performance of HfO(PO4)2.0 is well maintained after five catalytic cycles. Characterization analysis of fresh and recycled HfO(PO4)2.0 with SEM, XRD, and FT-IR indicated the catalyst has good stability and robustness.

Bacterial cellulose (BC) is a biodegradable material with many excellent properties for enzyme immobilization. However, hydroxyl groups of low reactivity in glucose units cannot directly react with the amines of enzymatic proteins. In this work, amino-functionalized bacterial cellulose was firstly used as carrier to immobilize horseradish peroxidase (HRP) via glutaraldehyde coupling. SEM, FT-IR, XPS, BET, and TGA were used to characterize the properties of modified BC and showed that it is more suitable for enzyme immobilization. The optimum pH range for immobilized HRP (pH 5.5–8.5) was wider than that of free enzyme (pH 6–8), and the immobilized HRP exhibited good adaptability to environmental alkalinity. The relative activity of immobilized HRP at 25–40 °C was greater than 90%, significantly surpassing that of free HRP. Furthermore, the obtained kinetic constant values showed that modified BC had decreased affinity for the substrate. Additionally, modified BC-immobilized HRP was reused efficiently for 10 cycles with greater than 70% of its original activity retained. Under optimal conditions, coupling ratio and specific activity could reach 86.7% and 41.7 Ug -1 min -1 , respectively. These results show that the immobilization of HRP on amino-functionalized BC enhanced its appropriateness for a future use in various biotechnological and environmental applications.

To achieve efficient one-step production of gluconic acid, cascade reactions of glucose oxidase (GOD) and catalase (CAT) have been advocated in the biocatalysis system. In this work, the methodology of co-immobilization of GOD and CAT was investigated in details for obtaining improved enzyme loading and activity. The maximum adsorption capability of GOD and CAT was 24.18 and 14.33 mg·g−1, respectively. The matching between dimensions of enzymes and hierarchical pore sizes of carriers are critical to the success of immobilization process. The simultaneous self-assembly on glutaraldehyde cross-linked mesoporous carriers exhibited favorable properties in comparison with sequential immobilization of GOD and CAT. The conversion of glucose under adequate air by co-localized GOD&CAT sustained the activity more than 90% after repeated utilization in the production of sodium gluconate and gluconic acid, suggesting that the co-immobilized GOD&CAT could be a promising catalyst for gluconate and gluconic acid production in some chemical and food industries.

Biocatalysis has become the main approach to produce cytidine diphosphate choline (CDP-choline), which has been applied for treatment of acute craniocerebral injury and consciousness after brain surgery. However, salt accumulates with the production and inhibits enzyme activity, and eventually reduces yield and product accumulation rate. Our work provided a possible solution to this problem by applying a computational designed halophilic choline kinase. The halotolerant CKI (choline kinase) was designed following a unique strategy considering the most variable residue positions on the protein surface among target enzymes from different sources. The basic and neutral surface residues were replaced with acidic ones. This approach was enlightened by features of natural halophilic enzymes. Mutants in the work represented higher catalytic activities and IC50 (inhibit activity by 50%) at high salt concentrations (over 1200 mM). Furthermore, when the mutant was used in fed-batch production, the CDP-choline accumulation rate doubled comparing with process using wild-type CKI at acetate concentration of over 700 mM. The maximum titer was 151 ± 3.2 mM, the productivity was 5.8 ± 0.1 mM·L−1 h−1, and molar yield to CMP and utilization efficiency of energy were 85.3 and 63.5%. The idea of computational design in our work can also be applied to modify other enzymes in industry, and sheds light on alleviating effect of salt accumulation during industrial manufacturing process.

The widely available reagent ethylenediaminetetraacetic acid (EDTA) was used as a temperature-responsive catalyst to produce 5-hydroxymethylfurfural (HMF) from fructose. Using this catalyst, a remarkable HMF yield of 89 ± 3% was achieved in a water-MIBK biphasic system containing polyvinylpyrrolidone (PVP) and 2-butanol. The pH of the reaction system based on EDTA as a catalyst was shown to be temperature-responsive. Moreover, the EDTA catalyst could be recycled simply by cooling the reaction liquid to room temperature due to its temperature-dependent solubility in water. A slight decrease in the yield of HMF (from 89 ± 3 to 81 ± 2%) was observed after EDTA repeated use for five cycles, and a yield of 88 ± 2% was achieved again after purification of the recycled EDTA via recrystallization with NaOH/HCl. The FTIR spectrum of recycled EDTA was almost the same as that of fresh catalyst, and TG analysis showed the decomposition temperature of EDTA is about 260 °C. Furthermore, a leaching test revealed that only 4.3 ± 0.2% of the initial EDTA was lost after five-time reuse.

Surface amine modification could not only improve the microenvironment near the active sites of enzyme, but also enhance the multi-point chemical crosslinking between the enzyme and carrier. The linear structured polymer of e-poly- l -lysine (EPL) is an ideal donor of amino with much more exposed on the surface for enzyme attachment. Analysis of the result of dynamic light scattering (DLS) and circular dichroism (CD) demonstrated the favorable electrostatic interactions and negligible impact on the conformation of enzymes, Glucose Oxidase and Catalase (GOx&CAT). Titration and dissociation curve together with Zeta-potential characterization revealed that enzymes (EPL@GOx&CAT) under the protection of EPL had more stable structure and better activity and stability in acidic reaction environment. Meanwhile, the activity recovery of immobilized EPL@GOx&CAT increased to 1.56 times higher than that of GOx&CAT, and the acid resistance was improved by 1.44 times with the optimum pH shifting to acidic by 0.50 unit. The substrate affinity was raised with the decrease of Km from 5.98 to 4.35 mg mL−1. Thus, the gluconic acid production in low pH system could be increased by pH-engineering of the enzyme microenvironment via conjugation with positively charged polyelectrolyte.

Ion exclusion chromatography (IEC) is an efficient technique used for the separation of strong electrolytes from weak electrolytes and nonelectrolytes. This work focuses on the assessment of mass transfer process and separation mechanism of H2SO4 and Al2(SO4)3 on the strong base quaternary ammonium I anion exchange resin A-853E. A dynamic model for IEC was proposed and explicitly taken into account the Donnan equilibrium. The result showed that Donnan effect played a significant role in the mass transfer process of ionic species, which was interpreted as the inability of co-ion (Al3+) to pass through Donnan membrane, while the counterion (SO42-) can enter resin pores due to electrostatic attraction. Meanwhile, a column model, based on Donnan equilibrium and cooperative adsorption isotherm, was then developed. The model successfully predicted the concentration profiles of mixed-ion (Al3+ and SO42-) at the outlet of the fixed-bed in the dynamic separation process. The results indicated that the Al3+ promoted the adsorption of SO42- on the resin in view of presence of ‘concentration’ phenomenon. The separation mechanism of Al3+ and SO42- was presented combining model prediction and experimental results. Finally, the influence of three different valence states of metal ions (Na+, Fe2+, Al3+) on the degree of H2SO4 ‘concentration’ was investigated to further verify the Donnan effect.

Microstructure and phase transformation of disodium guanosine 5′-monophosphate (5′-GMPNa 2 ) are extremely important for controlling the process and understanding the mechanism of crystallization. In this work, the thermodynamic properties of polymorphous 5′-GMPNa 2 especially the solubility were studied, the solubility results show that 5′-GMPNa 2 is more soluble in ethanol–water (E–W) than in isopropanol–water (I–W). The amorphous form of 5′-GMPNa 2 is more soluble than the crystalline form at the same mole fraction and temperature. Meanwhile, the crystalline forms and morphologies of the residual solids were characterized by PXRD and SEM. The results indicate that solid forms of 5′-GMPNa 2 transformed spontaneously from amorphous to crystalline when the ethanol proportion is ≥ 20%. In addition, increasing the pH facilitates the dissolution of 5′-GMPNa 2 and helps to maintain the crystalline form. The associated Gibbs free energy values were calculated to verify the trend of transformation from amorphous to crystalline 5′-GMPNa 2 . These results should help to guide the industrial crystallization process and to obtain the crystalline form of 5′-GMPNa 2 .

The efficiency of current methods for industrial production of citric acid is limited. To achieve continuous citric acid production with enhanced yield and reduced cost, immobilized fermentation was employed in an Aspergillus niger 831 repeated fed-batch fermentation system. We developed a new type of material (PAF201), which was used as a carrier for the novel adsorption immobilization system. Hydrophobicity, pore size and concentration of carriers were researched in A. niger immobilization. The efficiency of the A. niger immobilization process was analyzed by scanning electron microscopy. Then eight-cycle repeated fed-batch cultures for citric acid production were carried out over 600 h, which showed stable production with maximum citric acid concentrations and productivity levels of 162.7 g/L and 2.26 g L−1 h−1, respectively. Compared with some other literatures about citric acid yield, PAF201 immobilization system is 11.3% higher than previous results. These results indicated that use of the new adsorption immobilization system could greatly improve citric acid productivity in repeated fed-batch fermentation. Moreover, these results could provide a guideline for A.niger or other filamentous fungi immobilization in industry.

ρ-coumaric acid with strong antibacterial activity is produced during the pretreatment and hydrolysis of lignocellulosic biomass to monomeric sugars. The cell growth and metabolism of C. beijerinckii NCIMB 8052 is significantly inhibited by ρ-coumaric acid. In this study, adaptation of C. beijerinckii NCIMB 8052 to ρ-coumaric acid was remarkably enhanced after disruption of the intracellular electron transport chain, and the antibacterial activity assay showed a 2-fold increase in cell viability in the presence of 0.5 g/L ρ-coumaric acid 24 h after inoculation. Additionally, electricity generation in the wild-type and recombinant strains was measured using microbial fuel cell devices, and the intracellular levels of co-factor NAD(P)H were determined by the enzyme cycling method to show disturbed intracellular electron transfer after disruption of gene Cbei_2996. Furthermore, the metabolism of ρ-coumaric acid by C. beijerinckii was analyzed. These data indicated that gene Cbei_2996 plays a significant role in regulating ρ-coumaric acid tolerance in C. beijerinckii; the metabolism of ρ-coumaric acid mainly coupled with co-factor NADH is catalyzed by reductase. The strategy used in this study provides a potential approach for producing dominant microorganisms with high inhibitor tolerance for butanol production using renewable lignocellulosic materials.

The development of an orientation immobilization technique via affinity between polyhistidine tags and metal ions aims at maintaining biocatalytic activity of the enzymes. In this work, to tackle the issue of the immobilization of adenylate cyclase (AC), a simple and effective approach of synthesizing iminodiacetic acid (IDA)-Ni2+ particles was applied for simultaneously purifying and immobilizing his-tagged AC. We chose agarose particles as carriers, and then decorated them with IDA, leading to the formation of a coordination combination of Ni2+. The porous carriers with a large pore size of 50 nm and a specific surface area of 45.8 m2/g exhibited favorable enzymatic activity and loading capacity. The optimal pH of the immobilized enzyme increased from 8.0 to 9.0 and the optimal temperature increased from 30 °C to 35 °C, compared to the free AC. Moreover, the immobilized AC retained a residual activity of approximately 80% after storing it at 25 °C for 48 h, whereas only 40% of the activity was left in the free AC at the same conditions. Maximum yield of cyclic adenosine-3′, 5′- monophosphate (cAMP) reached up to the summit of the reaction. The immobilized AC by affinity adsorption will provide a promising route for the industrial production of cAMP.

Orientation immobilization of enzymes has attracted intensive interest owing to the retainable specific activity and stability. Specially, glycoprotein immobilized onto Concanavalin A (Con A) modified carriers induces the orientation of the enzyme. However, the effects of the interface properties of carriers and enzymes are still not well understood yet. In this study, we synthesized the activated porous poly (styrene- divinylbenzene) resin carriers with 30 nm pore sizes and 72 m2 g−1 specific surface areas and decorated with Con A. The resultant loading capacity of NP1 on Con A modified carriers was as high as 4.02 mg g−1 wet support as a result of strong affinity between the enzyme and Con A decorated on carriers. It was found that the acid resistance, thermal stability, reusability and degradation efficiency of the immobilized enzyme on Con A modified porous carriers were significantly improved. The reduction of Km from 18.40 ± 0.55 mg mL−1 to 17.19 ± 0.51 mg mL−1 illustrated the improved substrate affinity of HA-GA-ConA-NP1. Moreover, Con A-affinity NP1 exhibited the best operational stability that only 7% of its initial activity was lost even after 9 batches repeated reaction. This work demonstrates that surface property manipulation of porous carriers and its derivatives has great potential in efficient biocatalytic systems.

This study prepared ternary composites PBAT/thermoplastic starch (TPS)/lignin containing 20, 30 and 40 wt% of TPS/lignin fillers via thermal compounding, and found that lignin imposes compatibilization effect on PBAT and TPS. Thermal analysis shows that the incorporation of lignin results in higher thermal stability, reduced crystallization temperatures, broader crystallization exotherms and increased Tg due to the rigid aromatic structure of lignin. Tensile tests exhibit that strain at break and tensile strength reaches a maximum at loading 10 wt% of lignin. The reinforcement of lignin is reflected as the enhanced elastic modulus, Shore-D hardness, and more prominent yielding behavior of the composites. Rheological and microscope measurements show that the incorporation of lignin leads to higher approximation to theoretical Han curve, and reduced TPS particle size in the composites, indicating that lignin improves the interfacial compatibility between the PBAT and TPS phases. Contact angle and water absorption results demonstrate that lignin improves the hydrophobicity and water repelling ability of the composites, which are favorable for products with prolonged mechanical properties and shelf life.

In this study, a lignin-based adsorbent modified with epichlorohydrin and pentaethylenehexamine (LO-PEHA) was controllably synthesized via epoxidation and Mannich reaction to scavenge ferrous (Fe2+) ions in the super acidic solution. Various kinds of characterization were executed to investigate the structural morphological characteristics of the resulting adsorbent. The well-designed adsorbent showed a rich mesoporous structure with intricate channels. The ferrous ions entrapment by the adsorbent followed the Langmuir model with the maximum adsorption capacity of 862.9 mg/g at dosage of 0.05 g/20 mL under 298 K. And the adsorption kinetics complied with the pseudo-second-order model. The adsorbent possessed substantial adsorption efficiency (qe: 188.9–198.3 mg/g) for ferrous ions with sulfuric acid concentration of 5–250 g/L. It also demonstrated reliable performance with ferrous ions removal of 92.23% in the actual pickling waste liquor, slightly lower than that in the simulated system (99.24%). Furthermore, the mass transfer process of ferrous ions was predicted considerably well under the pore volume diffusion model (PVDM) with the effective pore volume diffusion coefficient of 4.5 × 10−10 m2/s, essentially commanded by the intraparticle resistance. Meaningfully, the tailor-made adsorbent is prospective as an efficient alternative for ferrous ions elimination, inspiring the future development of competent adsorbents for industrial effluent treatment.

The precision design of surface properties of supports and immobilization methodologies is essential for improving the biocatalytic activity of immobilized enzymes. In this study, we proposed a surface heterogeneity regulation strategy of graphene oxide (GO) to oriented immobilize adenylate cyclase (AC). The grafted flexible chain of polyethylene glycol amine (PEG-NH2) and maleic anhydride (MAH) on GO surface can adjust the interaction between support and AC. The achieved immobilized AC can eliminate the non-specific adsorption and introduce cushioning effect for the AC's catalytic reaction under extreme conditions. Therefore, the active center of the enzyme can be retained. The introduction of PEG-NH2 improves the activity recovery with 113%. Compared to GO-Ni2+@ AC, 8 arm-PEG-NH2 modified GO immobilized AC has 117 times higher catalytic activity. The method proposed in this study provides a possibility to address the issues in enzyme application, such as the purification of enzyme, low enzyme activity caused by cross-linking, and non-specific adsorption due to molecular force on the surface of the supports. The strategy should provide deeper understanding of the oriented immobilization and support modification for improving the activity and stability of the immobilized enzyme.

An innovative benign process for recovery lactic acid from its fermentation broth is proposed using a novel hyper-cross-linked meso-micropore resin and water as eluent. This work focuses on modeling the competitive adsorption behaviors of glucose, lactic acid and acetic acid ternary mixture and explosion of the adsorption mechanism. The characterization results showed the resin had a large BET surface area and specific pore structure with hydrophobic properties. By analysis of the physicochemical properties of the solutes and the resin, the mechanism of the separation is proposed as hydrophobic effect and size-exclusion. Subsequently three chromatographic models were applied to predict the competitive breakthrough curves of the ternary mixture under different operating conditions. The pore diffusion was the major limiting factor for the adsorption process, which was consistent with the BET results. The novel HD-06 resin can be a good potential adsorbent for the future SMB continuous separation process.

A novel and efficient organic amine and organosolv synergetic pretreatment method was developed to overcome the recalcitrance of lignocellulose to produce fermentable sugars and high-quality salt-free lignin. After optimization of the process parameters, a delignification of 81.7% and total sugar yield of 83.2% (87.1% glucose, 75.4% xylose) could be obtained using n-propylamine (10mmol/g, biomass) as a catalyst and aqueous ethanol (60%, v/v) as a solvent. The susceptibility of the substrates to enzymatic digestibility was explained by their physical and chemical characteristics. The physical structure of extracted lignin showed higher β-aryl ether bonds content and functionalities, offering the potential for further downstream upgrading. The role of organic amine catalyst and a synergistic mechanism is proposed for the present system.

Adsorption breakthrough behavior of 1-butanol was studied on the hydrophobic materials ZSM-5, ZSM-12, and Beta zeolites and compared with the zeolitic imidazolate framework ZIF-8 from an ABE (acetone-1-butnaol-ethanol) model solution. Adsorption equilibrium and adsorption kinetics were analyzed in single-component systems. Our results showed that the equilibrium adsorption amounts for ZIF-8 were much higher than that of the zeolites but zeolites equilibrium time are shorter (10 min) than that of ZIF-8 (60 min). These phenomena were the result of kinetics effects and flexibility in the ZIF-8. We also evaluated the breakthrough characteristics of the fixed-bed in ABE ternary-component systems, and found that the adsorptive separation mechanism of zeolites was the thermodynamic effect, and that of ZIF-8 was a combination of thermodynamic and kinetic effects. We show that zeolite, especially Beta, is a very attractive material because it exhibits shorter equilibrium time for 1-butanol and better separation breakthrough performance for an ABE model solution and more suitable industrial application.

Fabrication of biocompatible micro- and nanoparticles is attractive because of their potential for application as enzyme immobilization tools. Mesoporous TiO 2 microparticles with high crystallinity, high hydroxyl density, and large pore size (20 nm) were prepared by solid-state calcination and a soft chemistry method. The large pores of the microparticles were efficient in adenosine deaminase (ADA) encapsulation. The hydroxyl-coated microparticles could optimize amino-silane modification and be efficiently utilized as ADA-immobilization carriers. However, the adsorbed enzymes were easily leached when cycled. Sequential application of the coupling agent 3-aminopropyltriethoxysilane and cross-linker glutaraldehyde (GLU) enabled effective ADA coupling. After eight batch cycles, the immobilized ADA retained 80% of its initial activity, much higher than that by direct enzyme adsorption (30%). GLU prevented enzyme desorption and loss of activity. We thus improved ADA loading efficiency, recycling, and stability. TiO 2 microparticles could be suitable ADA immobilization candidates for detection and industrial inosinic acid production.

Biobutanol is an important alternative fuel source, but current processing methods suffer from low yields. This study aimed to develop and optimize a pretreatment protocol for biobutanol production from cornstalks. Fractionation of cornstalks into carbohydrate (cellulose and hemicellulose) and lignin was performed by alkali-catalyzed organosolv pretreatment (ACOS). After optimization of the process parameters, more than 80% of the total lignin was removed, with minimal hemicellulose degradation, at 110 °C, 4% (w/w dry cornstalk) NaOH, 90 min reaction time, and 60% (v/v) ethanol. After enzymatic hydrolysis, the maximum recovery of total monosaccharide was 83.7% (85.0% cellulose, 82.0% hemicellulose). In acetone-butanol-ethanol (ABE) fermentation, a slightly higher total ABE concentration (12.8 g/L vs. 11.9 g/L) was produced from the enzymatic hydrolysate, compared with that from a glucose control. The physical structure and chemical properties of alkali-catalyzed organosolv lignin (ACOSL) showed higher phenolic group content and antioxidant capacity compared with alkali lignin. ACOS pretreatment is an economical method for the production of fermentable monosaccharide and high-value lignin, for use in biofuel production.

A novel magnetic lignin-based adsorbent modified with sodium citrate (L-SC@Fe3O4) was simply manufactured by one-step hydrothermal method to eliminate calcium ions and methylene blue from aqueous solution. Various characterization methods were applied to explore the structural morphological features of the obtained sample. The as-designed adsorbent possessed high specific surface area, rough surface and rich mesoporous structure. Adsorption experimental data accorded with the Langmuir isotherm with maximum adsorption amount of 339.4 mg/g and 281.4 mg/g for calcium ions and methylene blue, respectively. Kinetic data fitted well with the pseudo-second-order model. Furthermore, the adsorption mass transfer process of calcium ions and methylene blue was predicted by the pore volume diffusion model, virtually governed by intraparticle resistance. The adsorbent showed considerable efficiency toward calcium ions and methylene blue within a broad pH range of 4–8 and 4–10, separately. The resulting adsorbent also exhibited strong anti-salts interference and possessed good regenerability with magnetic separation feasibility. Altogether, the tailor-made magnetic adsorbent is promising as an efficient and sustainable adsorbent for calcium ions and methylene blue removal, illuminating the future design of competent adsorbents for scavenging metal ions and dyes from real complex waste liquid.

Alkali lignin and NaOH are two main components in the black liquors from alkaline pulp. Adding sulfuric acid directly to precipitate lignin results in high consumption of acid as well as production of waste salts (Na2SO4). In this work, a benign process was proposed to separate alkali lignin and NaOH using ultra-high crosslinked non-ionic microporous resin Mn270 as an adsorbent and water as an eluent. Special attention was paid to explore the separation mechanism and establish a proper chromatographic model for this process. First, the adsorption isotherms showed the presence of alkali lignin increased the adsorption capacity of NaOH on the Mn270 resin. The separation mechanism was assumed to be size exclusion. Simultaneously, the alkali lignin promotes the adsorption of NaOH on the resin, which was verified by analysis of the interaction energy among NaOH-resin-Alkali lignin from a molecular dynamics simulation point of view. Afterwards, a linear driving force model combined with binary isotherms was used to predict the breakthrough / elution profiles of the two components on the column system fairly well. Finally, the alkaline pulp was used as a feed solution and got a good separation effect. After removal of NaOH, the amount of sulfuric acid and the corresponding salts were reduced by 37.86% in subsequent acid precipitation process.