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Membrane technology provides a green approach to recover sucrose from cane molasses. However, the trade-off between color removal and sucrose permeation by membrane filtration debases the efficiency and limits the application. In this study, ten commercially-available and one self-made ultrafiltration (UF) and nanofiltration (NF) membranes were used for decoloration of molasses. By investigating the effect of membrane properties, molasses components, and operating parameters on the molasses filtration behaviors, the mechanisms of high sucrose retention were clarified. For polyether sulfone (PES) membrane, the high retention of pigments and sucrose was mainly caused by the serious irreversible fouling as an additional selective layer. Polyamide (PA) NF membranes showed high antifouling ability, and a suitable pore size (~ 500 Da) was important to achieve high color removal and sucrose permeation. Although regenerated cellulose (RC) membranes exhibited excellent antifouling performance to molasses, the severe membrane swelling induced by salts and high temperature (60 °C) limited their application. Reducing sugar in molasses produced negligible effect on the sucrose retention, while inorganic salts resulted in pore swelling and solute dehydration due to "salting-out" effect, thus improving the sucrose permeation. However, such positive effect was weakened or eliminated by the pigments in molasses, and irreversible fouling became more serious in the presence of the molasses salts, especially for PES membranes. Based on the underlying mechanisms, the pore swelling and sucrose dehydration effects were "reappeared" by simply removing the non-polar pigments via macroporous resin adsorption, thus decreasing sucrose retention. High temperature could accelerate the sucrose permeation, but it also attenuated concentration polarization layer, thus intensifying the sucrose retention increase induced by high permeate flux. If a loose NF membrane was selected for decoloration of molasses, minimizing fouling formation, reappearing salt effect on membrane and sucrose, operating at high temperature and low permeate flux could minimize sucrose retention. [ABSTRACT FROM AUTHOR]

α,ω-Dicarboxylic acids (DC) are versatile chemical intermediates with different chain length. For biosynthesis of DC, to obtain the highly pure product via crystallization, it is required to remove pigments and proteins in fermentation broth. However, a trade-off between decolorization/deproteinization ratio and DC recovery during the purification process was found, which impeded DC production by fermentation. When ultrafiltration (UF) was applied to treat α,ω-dodecanedioic acid (DC12) broth, 93.4% of DC12 recovery, 80.5% of decolorization ratio and 61.7% of deproteinization ratio were achieved by a PES 3 membrane. However, the membrane technology could not effectively retain the pigments or proteins with low molecular weight when a high DC12 permeation was required. Meanwhile, the selected activated charcoal or macroporous resins were not good adsorbents for the present system. Furthermore, an integrated process for decolorization and deproteinization was developed. After filtration with PES3 membrane, an activated charcoal was used to remove the small proteins and pigments in the UF permeate. As a result, 91.4% of DC12 recovery, 94.7% of decolorization ratio and 84.8% of deproteinization ratio were obtained by such two-stage strategy. These results would serve as a valuable guide for process design and practical operation in subsequent industrial application. [ABSTRACT FROM AUTHOR]

Abstract: β‐poly (L‐malic acid) (PMLA) is a biopolyester which has attracted industrial interest for its potential application in medicine and other industries. A high dissolved oxygen concentration (DO) was beneficial for PMLA production, while the mechanisms of DO in PMLA biosynthesis by Aureobasidium pullulans are still poorly understood. In this work, the amount of PMLA was first compared when A. pullulans ipe‐1 were cultured under a high DO level (70% saturation) and a low DO level (10% saturation). Meanwhile, the key enzymes involved in different pathways of the precursor L‐malic acid biosynthesis were studied. The results revealed that the activities of glucose‐6‐phosphate dehydrogenase (G6PDH) and phosphoenolpyruvate carboxylase (PEPC) were positively correlated with cell growth and PMLA production, while the activities of phosphofructokinases (PFK), pyruvic carboxylase (PC) and citrate synthetase (CS) did no show such correlations. It indicated that the Pentose Phosphate Pathway (PPP) may play a vital role in cell growth and PMLA biosynthesis. Moreover, the precursor L‐malic acid for PMLA biosynthesis was mainly biosynthesized through phosphoenolpyruvic acid (PEP) via oxaloacetate catalyzed by PEPC. It was also found that low concentration of sodium fluoride (NaF) might impel carbon flux flow to the oxaloacetate through PEP, but inhibit the flux to the oxaloacetate via pyruvic acid. [ABSTRACT FROM AUTHOR]

Recovery of sugars from cane molasses is a promising approach to increase the added value of molasses and reduce its environmental pollution. In this work, for the first time, nanofiltration (NF) was used for the separation of sucrose and reducing sugar in cane molasses by a cascade diafiltration-concentration process. The retention difference between sucrose and reducing sugar by all the tested NF membranes was not distinct at 25 °C, while due to the thermal-induced pore size change and enhanced solute diffusivity, the NF retention behavior changed significantly at 60 °C, and the DL membrane with a sucrose retention of 96% and a reducing sugar retention 5% was selected for the process optimization and modeling. High temperature (55-60 °C), low permeate flux (below 15 Lm−2 h−1), and high sugar concentration resulted in a low retention of reducing sugar due to the dominant diffusive mass transfer, which was desirable for the molasses separation by NF. Mathematical modeling could well predict the diafiltration and concentration processes if using right sugar retention data. The deviations between prediction lines and experimental data in the cross-flow filtration of real solution were mainly caused by the permeate flux variation rather than membrane fouling. After diafiltration, the ratio of sucrose in total molasses sugar increased from 76.1 to 87.9%, while in the permeate of the second concentration step, the ratio of sucrose was only 2.4%. Thus, the retentate of diafiltration could be directly used for sucrose crystallization to avoid the accumulation of reducing sugar and salts, and the permeate of the second concentration step could be concentrated by NF270 at room temperature to produce syrup drinking. [ABSTRACT FROM AUTHOR]

Alginate dialdehyde (ADA), a biocompatible polymer, was used as an intermediate layer on a nylon membrane to readily fabricate cation exchange (CEX), metal-affinity (Me-affinity), histidine-affinity (His-affinity) and peptide-affinity (Pep-affinity) membrane adsorbers without any organic solvent usage. All the membrane adsorbers exhibited a high selectivity in the fractionation of a IgG (immunoglobulin)/HSA (human serum albumin) mixture. Along with a high purity of 100%, a high IgG binding capacity of 30, 24, 21 and 28 mg mL−1 (membrane volume) was achieved by the CEX, Me-affinity, His-affinity and Pep-affinity membrane adsorbers in flow-through mode respectively, which is superior to those of the reported membrane adsorbers. Furthermore, the CEX and Pep-affinity adsorbers were tested for the separation of IgG from human plasma solution. The carboxylic groups along with the peptides on the Pep-affinity adsorber captured IgG synergistically with a higher recovery and purity (99% and 98.6%). This synergetic adsorber showed a qmax and dynamic binding capacity (DBC) of 138.4 and 38.7 mg mL−1 respectively for IgG binding which was somewhat higher than that of the reported protein A agarose (having qmax and DBC of 84 and 24.4 mg g−1 respectively). The present work indicated that the ADA layer not only activated the membrane surface to attach various adsorptive ligands under mild conditions, but also reduced non-specific adsorption. Due to the versatile linking function and green reaction conditions, the ADA coating on the nylon membrane is promising for the preparation of diverse membrane adsorbers. [ABSTRACT FROM AUTHOR]

Abstract: α, ω‐Dodecanedioic acid (DC12) usually serves as a monomer of polyamides or some special nylons. During the biosynthesis, oxygenation cascaded in conversion of hydrophobic n‐dodecane to DC12, while the oxidation of n‐dodecane took place in the intracellular space. Therefore, it was important to investigate the role of oxygen supply on the cell growth and DC12 biosynthesis. It was found that stirring speed and aeration influenced the dissolved oxygen (DO) concentration which in turn affected cell growth as well as DC12 biosynthesis. However, the effect of culture redox potential (Orp) level on DC12 biosynthesis was more significant than that of DO level. For DC12 biosynthesis, the first step was to form the emulsion droplets through the interaction of n‐dodecane and the cell. When the stirring speed was enhanced, slits in the surface layer of the emulsion droplets would be increased. Thus, the substances transportation by water through the slits would be intensified, leading to an enhanced DC12 production. Compared with the batch culture at a lower stirring speed (400 rpm) without culture redox potential (Orp) control, the DC12 concentration was increased by 5 times up to 201.3 g/L with Orp controlled above 0 mV at a higher stirring speed (800 rpm). [ABSTRACT FROM AUTHOR]

Rice straw was pretreated with sulfuric acid combined with five organic acids (oxalic acid, acetic acid, tartaric acid, succinic acid, and fumaric acid) at 121°C for 90 min with five different blending ratios. The concentrations of glucose, xylose, arabinose and inhibitors such as acetic acid, furfural and HMF (5‐hydroxymethylfurfural) in the prehydrolysate were analyzed. It demonstrated that the concentrations of both sugars and inhibitors in prehydrolysate decreased with increasing organic acids blending ratio. The different solid residues from pretreatments were subjected to enzymatic hydrolysis process. The results showed that pretreating rice straw using combined sulfuric acid with oxalic acid or fumaric acid resulted in the maximum glucose yield (∼66%) after 72 h enzymatic hydrolysis in sharp contrast to ∼58% glucose yield obtained from pretreatment only with sulfuric acid under the same conditions. Furthermore, the structure of the raw material and the pretreated rice straw were characterized by scanning electron microscopy (SEM) and Fourier transformer infrared (FTIR) spectrum to clarify the effects of the combined sulfuric acid with oxalic or fumaric acid pretreatment on disrupting the fibers, removing hemicellulose and making the cellulose structure loose. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 808–814, 2018 [ABSTRACT FROM AUTHOR]

Nanofiltration (NF) is considered a competitive technique for acidic stream treatments. However, poorly reactive acid-resistant monomers normally cause thick and uneven separation layers with ultra-low permeability. Herein, catalyst-anchored secondary polymerization is employed after the interfacial polymerization (IP) reaction between trimesoyl chloride (TMC) and 3-aminobenzenesulfonamide (ABSA) to fabricate an extremely acid-resistant NF membrane. Acylation catalysts in ethanol are grafted on the nascent layer by reacting with residual acyl chloride groups to enhance the monomer reactivity, while the ethanol-induced nascent layer structure regulation greatly improves the surface uniformity. Benefiting from the improved self-inhibition effect and optimized phase integrity of the modified IP process, the resulting acid-resistant membrane has unprecedented water permeance (up to 31.4 Lm−2h−1bar−1), desirable Na 2 SO 4 rejection (92.8%), high dye/H+ selectivity and impressive acid stability (20 wt% of H 2 SO 4 for 50 days), outperforming almost all advanced acid-resistant NF membranes. Our work provides a versatile approach for the synthesis of high-performance specialty membranes. [Display omitted] • An acid-resistant NF membrane is fabricated by a catalyst-anchored secondary polymerization. • Anchored catalysts catalyze the secondary polymerization of low-reactive monomers. • Ethanol-induced swelling rearrangement greatly improves the phase interface uniformity. • The NF membrane has unprecedented water permeance up to 31.4 Lm−2h−1bar−1. • The membrane exhibits excellent acid-resistance in 20 wt% H 2 SO 4 for 50 days. [ABSTRACT FROM AUTHOR]

α,ω-Dicarboxylic acids (DC) are versatile chemical intermediates with different chain lengths, which are well-known as polymer building block. In this work, a new strain with high productivity of DC was isolated from oil-contaminated soil. Based on the morphology and phylogenetic analyses of the internal transcribed spacer sequences, it was characterized as Candida viswanathii. It was found that the contribution of carbon flux to the cell growth and DC production from n-dodecane could be regulated by the sucrose and yeast extract concentrations in the medium, and besides the broth pH, a suitable proportioning of sucrose and yeast extract was the key to achieve the optimal transition from cell growth phase to DC production phase. By optimizing culture conditions in a 7.5-L bioreactor, a higher DC productivity of 1.59 g·L h with a corresponding concentration of 181.6 g/L was obtained. After the purification of DC from the culture, the results from gas chromatography-mass spectrometry, infrared spectroscopy and H-NMR showed that α,ω-dodecanedioic acid (DC) was the major product of C. viswanathii ipe-1 using pure n-dodecane as substrate. For the first time, we reported that a high productivity of DC could be produced by C. viswanathii. [ABSTRACT FROM AUTHOR]

Recovery of volatile organic compounds (VOCs) from industrial wastewaters is important for the prevention of environmental pollution. This study investigated pervaporative recovery of VOCs by vinyltriethoxysilane (VTES)-grafted-silicalite-1/PDMS mixed matrix membrane (MMM) from the methanol-containing binary, ternary and quaternary wastewater solutions. The separation of methanol/water binary mixtures was first conducted. The influence of feed concentration and temperature on the membrane performance, such as permeation fluxes and VOC/water separation factor, was investigated. It was observed that with the increase of VOC concentration in the feed, the total permeation flux increased and the selectivity changed slightly first, then decreased. At a feed methanol concentration of 10.51 wt% at 65 °C, the maximum PSI of 5346 g/m 2 h with a separation factor of over 10 were obtained with the VTES-g-silicalite-1/PDMS MMM, which makes it among the best in the literature and is very competitive for methanol recovery from aqueous solutions. The apparent activation energies of water and VOC during the pervaporation process was calculated based on Arrhenius equation. Then the mixed matrix membrane was applied to ternary and quaternary wastewater model solutions. Compared with binary methanol/water mixture, the addition of ethanol and/or acetone led to a decrease of the total flux, methanol flux, and methanol/water separation factor, but increased the total VOCs flux and the permeate VOCs concentration. Separation factors of individual VOC towards water follow the order of acetone > ethanol > methanol, which is consistent with those in binary aqueous mixtures. [ABSTRACT FROM AUTHOR]

BACKGROUND β-Poly (L-malic acid) ( PMLA) can be used as a pro-drug or for a drug-delivery system, while the separation of PMLA producer cells of Aureobasidium pullulans from its fermentation broth is a challenge. This paper reports the separation of A. pullulans from PMLA fermentation broth by membranes technology. RESULTS The best separation efficiency was obtained by the membrane with a molecular weight cut off of 300 kDa, an initial feed volume of 1300 mL, a volume reduction ratio ( VRR) of 7.2, a cross-flow velocity of 6 m s−1, a trans-membrane pressure ( TMP) of 0.2 MPa, and a temperature of 40°C. The average flux reached 55.97 L m−2 h−1 with a VRR of 7.2. The main fouling mechanism during the filtration of cell suspension solution was cake layer formation, while it was pore blocking for fermentation broth and cell free broth. Since the cake layer induced by cells would reject some macromolecular substances (i.e. reduce the pore blocking and enhance the fluxes), one step separation of A. pullulans with a 300 kDa membrane was better than that with centrifugation followed by membrane filtration. CONCLUSION One step separation of A. pullulans by membranes technology would be beneficial for PMLA bio-refinery. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

[Display omitted] • NF membranes with particular charge spatial distribution are defined as mix-charged membranes. • Mix-charged NF membrane has higher separation selectivity and better antifouling ability. • Characterization methods with higher resolution and more quantitative index are required. • Polarizing charge distribution by process regulation during interfacial polymerization is promising. • New architectures of mix-charged layer can be designed based on biological ion channel structure. Steric and charge exclusions are mainly responsible for the separation selectivity of nanofiltration (NF) membranes, thereinto membrane charge spatial distribution plays an important role in filtration behavior of charged solutes, yet doesn't get enough attention. In this review, we suggest that NF membranes with particular charge spatial distribution can be called mix-charged membranes. First, the roles of Donnan effect on NF separation selectivity as well as antifouling ability for mix-charged membranes are discussed from practical application point of view. Second, the effect of horizontal/longitudinal charge distribution on the NF performance and corresponding six characterization methods are critically reviewed from the perspective of fundamental research. Third, three fabrication technologies for mix-charged NF membranes including interfacial polymerization (five strategies), sequential coating and self-assemble are summarized, focusing on the strategies to regulate charge proportion and polarize charge distribution. We find that there are still many unclear issues in the separation mechanisms of mix-charged NF membranes, such as micro-electric filed, electrostatic neutralization and ion dehydration, and deeper understanding on the structure-performance relationship and more precise control the charge spatial distribution need a quantitative index of charge distribution and higher-resolution characterization methods. This review not only intends to emphasize the importance of charge spatial distribution of NF membranes, but also offers guidance for designing and developing advanced mix-charged membranes for specialty separations. [ABSTRACT FROM AUTHOR]