利用大肠杆菌全细胞催化赖氨酸发酵液生产1,5-戊二胺

1,5-戊二胺是一种具有生物活性的生物胺。赖氨酸脱羧酶可以催化L-赖氨酸生产1,5-戊二胺。为了减少生产成本,本文利用大肠杆菌AST1以赖氨酸发酵液作为底物进行全细胞催化生产1,5-戊二胺。研究转化p H、菌体浓度、转化温度、磷酸吡哆醛(PLP)添加量以及不同酸种类对转化的影响,并对菌体的重复利用性进行了研究。在最优条件下:p H6.8、转化温度37℃、PLP添加量0.1mmol/L、菌体浓度(DCW)2.5g/L,用乙酸来调节转化过程p H,可以转化含有赖氨酸123.8g/L的发酵液,得到含有86.18g/L戊二胺的转化液,转化率可达到99.61%。并且菌体在赖氨酸发酵液中重复利用5次的情况下转化率可以达到50%以上,重复利用性明显比在赖氨酸溶液中转化时强,这极大程度地节约了生产成本,为1,5-戊二胺连续工业化生产打下了基础。     

生物法制备1,5-戊二胺的研究进展

生物法制备1,5-戊二胺是一种创新且具有潜在竞争力的生产方法,从生物法制备1,5-戊二胺研究现状、赖氨酸脱羧酶性质、1,5-戊二胺的生产菌种及代谢途径分析几方面进行了综述,并对其应用前景进行了展望.     

1,5-戊二胺的正辛醇/水分配系数测定

建立摇瓶法测定1,5-戊二胺的正辛醇/水分配系数分析方法。气相色谱法测定正辛醇中1,5-戊二胺含量,离子色谱法测定水相中1,5-戊二胺含量。当正辛醇与水体积比为2:1时,lgPow为-0.38;体积比为1:1时,lgPow为-0.26;体积比为1:2时,lgPow为-0.24;lgPow平均值为-0.3。该方法简单可靠,符合OECD 107要求,适用于1,5-戊二胺的正辛醇/水分配系数的测定。     

光气化法合成1,5-戊二异氰酸酯实验研究

以生物基1,5-戊二胺和光气等为主要原料,在溶剂邻二氯苯中,采用直接光气化法合成1,5-戊二异氰酸酯（PDI）,考察了溶剂用量、冷热光气化反应温度以及反应时间等因素对收率的影响。结果表明,当溶剂邻二氯苯与1,5-戊二胺质量比10∶1、冷光气化反应温度为15℃、热光气化反应温度为150℃、反应时间为12 h时,光气化反应合成PDI的收率最高,达到99.5%。     

聚1,5-萘二胺膜修饰电极电化学传感器的研究进展

聚萘二胺作为导电聚合物的一种,其性能在某些方面要优于传统的导电聚合物,有望成为一种新型的具有广阔应用前景的功能材料.本文综述了循环伏安法制备聚1,5-萘二胺的电化学行为以及电化学过程中可能产生的聚合物结构.阐述了聚1,5-萘二胺膜修饰电极的化学和生物探测应用.对聚1,5-萘二胺在传感器的应用和发展等方面进行了展望.     

半芳香共聚尼龙DT/6Ⅰ的制备及其性能研究

以2-甲基-1,5-戊二胺、1,6-己二胺、对苯二甲酸、间苯二甲酸为原料,采用溶液聚合法制备了一种透明共聚尼龙。采用核磁共振氢波谱、傅里叶红外光谱、差示扫描量热仪、热重分析仪、万能试验机等对透明共聚尼龙进行表征。结果表明,随着对苯二甲酸2-甲基-1,5-戊二胺尼龙盐(DT)含量的增加透明共聚尼龙的玻璃化转变温度和热分解温度不断提高,新合成的透明共聚尼龙较PA6T/6Ⅰ具有更好的耐热性和力学性能。     

纳米Fe~(3+)-TiO_2改性双极膜的制备、表征及其在海水中一、二价阳离子分离的应用

采用溶胶-凝胶法制备了Fe3+掺杂TiO2光催化剂。分析表明,制备的Fe3+-TiO2为锐钛矿型,其禁带宽度低于TiO2。将Fe3+-TiO2添加到聚乙烯醇-壳聚糖(PVA-CS)阴离子交换膜中,制备了PVA-CMC/Fe3+-TiO2-PVA-CS双极膜(BPM),(CMC:羧甲基纤维素钠)。研究结果表明,Fe3+-TiO2较TiO2具有更强的光催化双极膜中间界面层水解离能力,在太阳光照射下能大大提高水解离效率,降低双极膜膜阻抗和跨膜电压降。当电流密度为60 mA·cm-2时,PVA-CMC/Fe3+-TiO2-PVA-CS双极膜槽电压下降了0.8 V。此外,通过Fe3+-TiO2改性,CS膜亲水性和双极膜机械性能均获得提高。将改性后的双极膜用于分离模拟海水中一、二价阳离子,在太阳光照射下,K+离子和Na+离子双极膜透过率较无光照时有明显提高,电渗析2 h,K+离子和Na+离子的透过率分别为90.31%和82.93%,而二价阳离子的透过率均小于1.0%。     

基于电驱离子膜-分质结晶工艺的高盐废水资源化中试研究

以某化工企业高盐废水为处理对象后,设计构建了电驱离子膜-分质结晶试验装置进行耦合技术废水处理资源化研究。结果表明,高含盐工业废水通过该工艺处理钙镁离子去除96%以上,产品水水质各项指标均能够满足试验设计要求,产水率在71%左右。电驱离子膜系统可将TDS全部浓缩到200 000 mg/L以上,均可达到进水的6～8倍,盐回收率≥89%。试验期间硫酸钠产品盐均满足产品盐品质要求,氯化钠产品盐合格率偏低。该耦合技术可以实现零排放及资源化试验目的。     

生物质戊二胺己二酸盐改性共聚酯及其长丝的性能

生物基戊二胺己二酸盐改性共聚酯是将生物基戊二胺己二酸盐加入聚酯体系中合成的一种新的材料,用差示扫描量热分析法和热重分析研究生物基戊二胺己二酸盐改性共聚酯的热性能,制备了改性共聚酯长丝,研究了长丝的取向度、力学性能及亲水性能等。结果表明:改性共聚酯具有较好的热性能,纤维的取向度较常规聚酯纤维降低,纤维的手感和亲水性能显著改善,改性共聚酯长丝的断裂强度降低,断裂伸长率提高,戊二胺己二酸盐添加量不宜太大,控制在10%左右比较合适。     

1,3-丙二醇发酵液脱盐技术研究进展

1,3-丙二醇(PDO)是新型纤维PTT的关键原料,可通过化学法和生物发酵法生产,在生物发酵法生产PDO过程中,菌体代谢过程产生有机酸,发酵过程通过自控流加液碱调节发酵液pH值为中性,发酵结束时发酵液液中有2%~3%的盐,目前PDO发酵液脱盐的技术有离子交换、电渗析、双极膜电渗析、刮板蒸发等,本文对这几种脱盐技术进行了综述和比较,为该领域的从业人员提供参考。     

One-step conversion of sulfate lithium into high-purity lithium hydroxide crystals via bipolar membrane crystallization

To date, bipolar membrane electrodialysis (BMED) is being developed as a competitive technology for waste lithium-ion battery recovery. However, the purity and concentration of lithium hydroxide generated from a BMED plant could not meet the product criteria for ternary lithium batteries, thus requiring additional condensation, purification, evaporation, and crystallization procedures. Herein, bipolar membrane crystallization (BMC) was proposed for the one-step conversion of sulfate lithium into high-purity lithium hydroxide monohydrate crystals. By mediating a continuous saturated feedstock in the salt compartment, it is possible to convert Li₂SO₄ into 5+ mol/L LiOH at a current density higher than 500 A/m². Therefore, this unique design allows the production of 99.9% LiOH∙H₂O by taking the principle of water dissociation in the bipolar membrane and the simultaneous crystallization procedure. This proof-of-concept study proves the feasibility and competitiveness of the BMC for waste lithium recovery by abandoning the condensation and evaporation procedures.     

双极膜电渗析法由硫酸铵制备硫酸的工艺研究

利用两室双极膜电渗析法从硫酸铵溶液中制备硫酸。探讨了电渗析过程中的电流效率、能耗、产酸量等指标。实验结果表明,产酸量随时间的延长而增加,在恒定电流密度（0.09A.cm-2）的条件下,硫酸的电流效率达到90%,能耗为2.5～2.6kW.h.kg-1。     

Asymmetric bipolar membrane electrodialysis for acid and base production

Bipolar membrane electrodialysis (BMED) is a promising technique for upgrading traditional manufacturing procedures and achieving a circular economy. However, the industrial applications of BMED technology have been restricted by the large consumption of expensive bipolar membranes and the unmatching behavior between water splitting and ion migration. Herein, we proposed a novel asymmetric bipolar membrane electrodialysis (ABMED) to regulate the water splitting in the bipolar membrane and orientational ion migration in the electrodialysis (ED). It was found that the ABMED exhibited comparable performances to BMED for acid/base production when the area of the bipolar membrane was reduced to 50% of the monopolar membrane. The total process cost of ABMED was 0.78 $/kg NaOH, which is 21% lower than the BMED process. The asymmetric membrane design was capable to boost the water splitting in the bipolar membrane and to eliminate the concentration polarization in the ED process.     

Membrane fouling caused by amino acid and calcium during bipolar membrane electrodialysis

BACKGROUND: Bipolar membrane electrodialysis (BMED) has been widely applied in the recovery/production of organic acids and in the treatment of wastewater containing ammonium sulfate, sodium nitrate, sodium acetate and ammonium nitrate. However, membrane fouling is still one of the major problems in the electrodialysis process. Since calcium and amino acid are present naturally in fermentation wastewater, this study was carried out to determine the effects of calcium and amino acid on membrane fouling when simulated fermentation wastewater containing ammonium sulfate was treated by BMED. RESULTS: Calcium formed a scale on the cation exchange membrane (CEM) surface in contact with the base cell, but this had no significant adverse effect on the BMED performance. Amino acid, however, caused CEM fouling of the inner membrane, which hampered the BMED process. The coexistence of calcium and amino acid aggravated the membrane fouling, as observed morphologically on the CEM surface on the base cell side. Elemental mapping analysis showed that the membrane foulant was composed of calcium hydroxide and amino acid. CONCLUSION: The CEM fouling caused by calcium and that due to amino acid, which were distributed differently on the membrane, had different effects on the BMED performance. The coexistence of amino acid and calcium deteriorated the CEM fouling during BMED. Copyright © 2008 Society of Chemical Industry     

Bipolar membrane electrodialysis for clean production of L-10-camphorsulfonic acid: From laboratory to industrialization

In this study, bipolar membrane electrodialysis (BMED) was implemented for cleaner production of L-10-camphorsulfonic acid (L-CSA) to lower the environmental impact. Under the current density of 300–400 A/m² and feed salt concentration of 6–10 wt.%, the energy consumption and current efficiency were 2.24–2.70 kWh/kg and 20.89–29.5%, respectively. Positron annihilation lifetime spectroscopy, x-ray photoelectron spectroscopy with ion beam etching, and other characterizations were used to elucidate the transport behaviors of large-sized anions across the membranes. It was speculated that the large-sized camphor sulfonate ions were more likely to deposit on the surface of the anion-exchange membrane to form a deposition layer under a direct current electric field. The appearance of water splitting at this deposition layer would offset the water dissociation in the bipolar membrane. Nevertheless, the successful commissioning of industrial-scale stack proved the feasibility and sustainability of BMED technique for a closed loop L-CSA production.     

双极膜电渗析技术的研究进展

双极膜电渗析技术(BMED)是利用直流电场作用下双极膜界面层内发生水解离生成H+和OH-这一电化学特性,通过将双极膜与阴、阳离子交换膜适当组合,可实现不同的特种分离功能。与传统工艺相比,BMED具有高效节能、环境友好、操作便捷等突出技术优势。本文介绍了3种不同的BMED工作模型以及BMED在有机酸生产、水除盐、蛋白分离、超纯水制备等领域的最新研究进展,对BMED技术的进一步研究与发展进行了展望。     

乳酸发酵液电渗析过程中氨基酸的迁移现象

使用三室双极膜电渗析法处理乳酸发酵液时,杂质氨基酸的迁移会影响回收乳酸的纯度. 通过对乳酸发酵液电渗析过程中氨基酸迁移现象的研究,发现各种不同氨基酸的迁移速率主要受其初始浓度、pI值与料室pH值的差值、阴离子交换膜对其选择性及其自身电迁移率的影响. 根据此规律,建立了离子迁移速率计算模型,通过与实际过程比较,表明其可有效预测杂质氨基酸的迁移情况,估算特定体系达到预定收率时的纯度. 实验验证结果表明,氨基酸的迁移率为32.5%,与对照实验(82.6%)相比,降低率为60.7%. 通过调节氢渗漏控制料室pH值、提高阴膜对乳酸的专一选择性等可控制氨基酸向酸室迁移,以获取更高的乳酸纯度.     

Bipolar membrane electrodialysis for cleaner production of N-methylated glycine derivative amino acids

In this study, cleaner production of N-methylglycine (NMG), N,N-dimethylglycine (DMG), and N,N,N-trimethylglycine (TMG) with similar structures but different methylate groups was performed using bipolar membrane electrodialysis (BMED). The effects of the feed mass concentration and current density on the separation performance were intensively analysed in terms of the molecular size, molecular structure, ion concentration, and interaction between amino acids and membranes. The results indicated that the optimal recovery performance was achieved at a current density of 200 A/m² and feed mass concentration of 6%. Under the optimal conditions, the energy consumption and current efficiencies were 2.3 kWh/kg and 78% for NMG, 2.49 kWh/kg and 69.5% for DMG, and 3.52 kWh/kg and 39.6% for TMG, respectively. It was speculated a competition for water splitting occurs between the bipolar membranes and anion exchange membranes when BMED is used for the separation and purification of large-sized bioproducts.     

Clean post-processing of 2-amino-1-propanol sulphate by bipolar membrane electrodialysis for industrial processing of 2-amino-1-propanol

2-Amino-1-propanol (AMP) is a key intermediate compound in the production of antibiotics, with increasing demand in industry. In this study, we propose a newly designed bipolar membrane electrodialysis (BMED) system with a novel three-compartment configuration for the processing of AMP from the AMP sulphate solution. The operational parameters were investigated for optimizing the performance of this novel BMED stack, compared to the traditional two-compartment BMED stack in the pilot scale experiment. The experimental results indicate that this novel type of BMED stack offers a better performance for AMP processing than the conventional two-compartment BMED stack. The optimum performance was observed at the current density ranging from 40 to 60 mA cm⁻² and a spacer thickness of 0.70 mm. The corresponding current efficiency and energy consumption reached up to 53.4% and 3.135 kWh kg⁻¹, respectively. The two-compartment BMED stack was found to have a low current efficiency (39.8%) and a high energy consumption (3.864 kWh kg⁻¹). Pilot-scale experiments for an industrial application of this novel BMED stack have been applied, demonstrating that the BMED process is feasible and economically alternative for AMP purification in the industry.     

双极膜电渗析技术在工业高含盐废水中的应用

双极膜电渗析（BMED）作为新型膜分离技术,可将盐转变为相应的酸和碱,围绕BMED技术在工业高含盐废水领域的应用已逐渐成为热点,但在实际应用中还存在一些亟需解决的难点。本文主要介绍了近年来BMED技术在处理工业高含盐废水领域的研究现状,提出和探讨了限制BMED技术在该领域大规模工业化应用的3个关键性问题,即与酸碱浓度和纯度有关的技术问题、与过程成本有关的技术经济性问题以及与投资成本有关的经济性问题。针对这3个问题,指出BMED技术未来发展方向应致力于降低双极膜成本,减弱或消除离子交换膜同离子泄漏及水迁移过程。对于现阶段而言,将制备的酸碱回用于系统内部,是解决酸碱品质较低而未能商品化的主要途径,同时该过程可节省酸碱外购费用,弥补BMED技术投资成本过高问题。