Strategy to prevent calcification by restricting surface adhesion of Ca2+: Reduced affinity of extracellular polymeric substances for Ca2+ by mild acidic conditions.

Controlling CaCO3 precipitation within anaerobic granular sludge (AnGS) is crucial for the anaerobic treatment of paper recycling wastewater. A viable strategy was proposed to control calcification by adjusting a mild acidic condition in an anaerobic reactor without hindering organic degradation. The results indicated that lowering the bulk pH (6.5 to 6.8) reduced calcium precipitation by 60.1 % in calcium-rich influent (Ca2+ 1200 mg/L) and eradicated CaCO3 deposition on AnGS. Extracellular polymeric substances (EPS) have proven to be crucial participants in Ca2+ migration. The acidic solution weakens the interactions between EPS and Ca2+ and then diminishes the EPS adsorption capacity and affinity for Ca2+. The mild acidic environment goes beyond reducing CaCO3 formation in wastewater. EPS protonation reduced the probability of Ca2+ adhering to the AnGS surface, which halted calcium transportation from bulk liquid to granule. This work offers a feasible strategy to prevent AnGS calcification in high-calcium wastewater.

Self-Healable, Solvent Response Cellulose Nanocrystal/Waterborne Polyurethane Nanocomposites with Encryption Capability.

Cellulose nanocrystal (CNC)-based chiral nematic structure is widely used in stimulus response and sensing. A popular area of research is enhancing the mechanical characteristics and environmental adaptability of chiral nematic materials. In this paper, a flexible photonic film with self-healing ability (FPFS) was prepared by combining waterborne polyurethane containing dynamic covalent disulfide bonds (SSWPU) with CNC. The results found that the FPFS showed excellent toughness under the action of stretching, bending, twisting, and folding. The FPFS exhibited an amazing self-healing efficiency, which can be self-healed within 2 h at room temperature. Moreover, the FPFS could respond immediately and produce reversible color change when it was soaked in typical solvents. In addition, when ethanol was used as ink to paint on the FPFS, a visible pattern only under polarized light was formed. This study offers fresh perspectives in the areas of self-healing, biological anticounterfeiting, solvent response, and flexible photonic materials.

Design of a Superhydrophobic Strain Sensor with a Multilayer Structure for Human Motion Monitoring.

A flexible strain sensor is of significant importance in wearable electronics since it can help monitor the physical signals from the human body. Among various strain sensors, the polyurethane (PU)-based ones have received widespread attention owing to their excellent toughness, large working range, and nice gas permeability. However, the hydrophobicity of these sensors is not good enough, which may affect their use life and sensitivity. In this work, a high-performance strain sensor composed of PU, reduced graphene oxide (rGO), polydopamine (PDA), and 1H,1H,2H,2H-perfluorodecane-thiol (PFDT) was designed and prepared. The results revealed that this PU/rGO/PDA/PFDT device possessed good superhydrophobicity with a water contact angle of 153.3°, a wide working strain range of 590%, and an outstanding gauge factor as high as 221 simultaneously. Because of these above advantages, the sensor worked effectively in detecting both subtle and large human movements (such as joint motion, finger motion, and vocal cord vibration) even in a high humidity environment. This strain sensor with high sensitivity, wide working range, and suitable modulus may have great potential in the field of flexible and wearable electronics in the near future.

Effect of various pretreatments on improving cellulose enzymatic digestibility of tobacco stalk and the structural features of co-produced hemicelluloses.

Hereon, tobacco stalk was deconstructed by lyophilization, ball-milling, ultrasound-assisted alkali extraction, hydrothermal pretreatment (HTP), and alkali presoaking, respectively, followed by dilute alkali cooking to both improve its enzymatic digestibility and isolate the hemicellulosic streams. It was found that a maximum cellulose saccharification rate of 93.5% was achieved from the integrated substrate by ball-milling and dilute alkali cooking, which was 4.4-fold higher than that from the raw material. Interestingly, in this case, 76.9% of hemicelluloses were simultaneously recovered during the integrated treatment. Structural determination indicated that the hemicelluloses released from tobacco stalk by dilute alkali cooking were mixed polysaccharides, and the (1 â†’ 4)-linked ß-D-Xylp backbone branched with L-Araf units at O-2/O-3 and 4-O-Me-α-D-GlcpA units at O-2 of the xylose residues was the main structure. In comparison, ultrasound-assisted alkali extraction, ball-milling, and HTP favored the extraction of hemicelluloses with less branched structure and lower molecular weights in the following alkali cooking.

Structural elucidation of lignin macromolecule from abaca during alkaline hydrogen peroxide delignification.

To maximize the utilization of Abaca lignin in the current biorefinery, structural characteristics of native lignin from Abaca were firstly comprehensively investigated. Parallelly, effective delignification of Abaca was achieved by alkaline hydrogen peroxide (AHP) process, which facilitated the production of specialty paper in industry. The structural changes of lignin macromolecules during the AHP delignification were illustrated by comparing the structural differences of the released lignin fraction and corresponding native lignin, which were analyzed via the advanced analytical methods, such as 2D-HSQC NMR, 31P NMR, pyrolysis-GC/MS, and GPC techniques. It was found that Abaca lignin is a HGS-type lignin, which is overwhelmingly composed of ß-O-4 linkages and abundant hydroxycinnamic acids (mainly p-coumaric acid). In addition, partial cleavage of ß-O-4 linkages and p-coumarate in lignin occurred during the AHP delignification process. Meanwhile, AHP process also led to the elevation of H-type lignin units in AHPL. Considering that ß-O-4 bond is vulnerable in the catalytic degradation process of lignin, the lignin with abundant ß-O-4 linkages is beneficial to the downstream conversion of lignin into aromatic chemicals.

Structural Features of Alkaline Dioxane Lignin and Residual Lignin from Eucalyptus grandis × E. urophylla.

In the present study, lignin from eucalyptus was extracted with 80% alkaline dioxane (0.05 M NaOH) from ball-milled wood and subsequently fractionated by gradient acid precipitation from the filtrate. Meanwhile, the residual lignin was prepared by a double enzymatic hydrolysis process. The yield of the lignin extracted by alkaline dioxane (LA-2) was 29.5%. The carbohydrate contents and molecular weights of the gradient acid precipitated lignin fractions gradually decreased from 4.90 to 1.36% and from 7770 to 5510 g/mol, respectively, with the decline of the pH value from 6 to 2. Results from two-dimensional heteronuclear single quantum coherence nuclear magnetic resonance (NMR) and 31P NMR spectroscopy showed an evident reduction of ß- O-4 ' linkages with the pH value decrease, while the contents of aliphatic -OH, phenolic -OH, and carboxylic groups displayed an increasing trend. Moreover, the residual lignin exhibited the highest molecular weight (11690 g/mol), the most abundant ß- O-4 ' linkages (71.1%), and the highest S/G ratio (4.68).

Selective precipitation and characterization of lignin-carbohydrate complexes (LCCs) from Eucalyptus.

MAIN CONCLUSION: Six types of lignin-carbohydrate complex (LCC) fractions were isolated from Eucalyptus. The acidic dioxane treatment applied significantly improved the yield of LCCs. The extraction conditions had a limited impact on the LCC structures and linkages. Characterization of the lignin-carbohydrate complex (LCC) structures and linkages promises to offer insight on plant cell wall chemistry. In this case, Eucalyptus LCCs were extracted by aqueous dioxane, and then precipitated sequentially by 70% ethanol, 100% ethanol, and acidic water (pH = 2). The composition and structure of the six LCC fractions obtained by selective precipitation were investigated by sugar analysis, molecular weight determination, and 2D HSQC NMR. It was found that the acidic (0.05-M HCl) dioxane treatment significantly improved the yield of LCCs (66.4% based on Klason lignin), which was higher than the neutral aqueous dioxane extraction, and the extraction condition showed limited impact on the LCC structures and linkages. In the fractionation process, the low-molecular-weight LCCs containing a high content of carbohydrates (60.3-63.2%) were first precipitated by 70% ethanol from the extractable solution. The phenyl glycoside (PhGlc) bonds (13.0-17.0 per 100Ar) and highly acetylated xylans were observed in the fractions recovered by the precipitation with 100% ethanol. On the other hand, such xylan-rich LCCs exhibited the highest frequency of ß-O-4 linkages. The benzyl ether (BE) bonds were only detected in the fractions obtained by acidic water precipitation.

[Treating cassava starch wastewater by up-flow multistage anaerobic reactor].

The performance and the characteristics of a laboratory scale up-flow multistage anaerobic reactor (UMAR) were investigated using cassava starch wastewater. The experimental results showed that the formation of anaerobic granules in UMAR system was facilitated and short period to start up. Usually, in 40 d after starting up, COD removal efficiency was kept above 84% and VSS/TSS increased from 78% to 90.4%. The UMAR reactor was high effective. Its COD removal keeps about 75% when HRT is 4 h, inflow COD concentration is 6 250 mg/L and volumetric loading is 24 kg/(m3 x d). And UMAR reactor has excellent resistance to the impact of high load, low pH and variation of water quality.