Methanol oxidation in acidic and alkaline electrolytes using PtRuIn/C electrocatalysts prepared by borohydride reduction process

PtRuIn/C electrocatalysts( 20% metal loading by weight) were prepared by sodium borohydride reduction process using H_2PtCl6·6H_2O,RuCl_3·xH_2O and InCl_3·xH_2O as metal sources,borohydride as reducing agent and Carbon Vulcan XC72 as support. The synthetized PtRuIn/C electrocatalysts were characterized by X-ray diffraction( XRD),energy dispersive analysis( EDX),transmission electron microscopy( TEM),cyclic voltammetry( CV),chronoamperommetry( CA) and polarization curves in alkaline and acidic electrolytes( single cell experiments). The XRD patterns showPtpeaks are attributed to the face-centered cubic( fcc) structure,and a shift of Pt( fcc) peaks indicates that Ru or In is incorporated into Ptlattice. TEMmicrographs showmetal nanoparticles with an average nanoparticle size between 2.7 and 3.5 nm. Methanol oxidation in acidic and alkaline electrolytes was investigated at room temperature,by CV and CA. PtRu/C( 50 ∶ 50) shows the highest activity among all electrocatalysts in study considering methanol oxidation for acidic and alkaline electrolyte. Polarization curves at 80 ℃ showPtRuIn/C( 50 ∶ 25 ∶ 25)with superior performance for methanol oxidation,when compared to Pt/C,PtIn/C and PtRu/C for both electrolytes. The best performance obtained by PtRuIn/C( 50 ∶ 25 ∶ 25) in real conditions could be associated with the increased kinetics reaction and/or with the occurrence simultaneously of the bifunctional mechanism and electronic effect resulting from the presence of Ptalloy.

Alkaline digestion behavior and alumina extraction from sodium aluminosilicate generated in pyrometallurgical process

In pyrometallurgical process, Al-and Si-bearing minerals in iron and aluminum ores are easily transformed into sodium aluminosilicates in the presence of Na_2O constituents, which alters the leaching behaviors of Al_2O_3 and SiO_2. It was confirmed that sodium aluminosilicates with different phase compositions synthesized at various roasting conditions were effectively digested in the alkaline digestion process. Under the optimum conditions at temperature of 100–120°C, liquid-to-solid ratio(L/S) of 10:2 mL/g, caustic ratio of 4, and Na_2O concentration of 240 g/L, the actual and relative digestion ratio of Al_2O_3 from the synthesized sodium aluminosilicates reached maximums of about 65% and 95%, respectively, while SiO_2 was barely leached out. To validate the superior digestion property of sodium aluminosilicate generated via an actual process, the Bayer digestion of an Al_2O_3-rich material derived from reductive roasting of bauxite and comprising Na_(1.75) Al_(1.75) Si_(0.25)O_4 was conducted; the relative digestion ratio of Al_2O_3 attained 90% at 200°C.

Acid equilibrium during bioleaching of alkaline low-grade sulfide copper ore

This article reports the study on acid equilibrium during bioleaching of alkaline low-grade copper sulfide ore. Adding auxiliary agents 1# （sulfur） and 2# （pyrite） makes bacterial leaching of copper and acid production carried out simultaneously because the auxiliary agents can be oxidized by bacteria and the oxidation products involve acid. The acid required for dissolving alkaline gangue during bacterial leaching is produced, and acid equilibrium is reached during the ore bio-leaching. The recovery of copper reaches more than 95%.

Curing mechanism of alkaline phenolic resin with organic ester

To study the curing mechanism of alkaline phenolic resin with organic ester, three esters were chosen to react with three systems - alkaline phenolic resin, potassium hydroxide aqueous solution containing phenol, and potassium hydroxide aqueous solution. The variations of pH, heat release and gel pH during the reactions were monitored and measured. Infrared spectroscopy （IR） and thermal gravity analysis （TG） techniques were used to characterize the curing reaction. It was found that organic ester is only partial y hydrolyzed and resin can be cured through organic ester hydrolysis process as wel as the reaction with redundant organic ester. The sequential curing mechanism of alkaline phenolic resin cured by organic ester was identified as fol ows： a portion of organic ester is firstly hydrolyzed owing to the effect of the strong alkaline; the gel is then formed after the pH decreases to about 10.8-10.88, meanwhile, the redundant organic ester （i.e. non-hydrolysis ester） starts the curing reaction with the resin. It has also been found that the curing rate depends on the hydrolysis velocity of organic ester. The faster the hydrolysis speed of the ester, the faster the curing rate of the resin.

Preparations of Pure Alkaline Earth Molybdate Phases from Single Molecular Precursors

The pure phases of alkaline earth molybdates MMoO 4, where M=Mg, Ca, Sr or Ba, were synthesized via the calcination of the related citrato oxomolybdate complexes. The mixed metal oxides can be highly dispersed at the atomic level due to the existence of uniform citrato oxomolybdenum precursors in definite composition. The complexing effect helps to produce the fine-grained oxides with particle size in the ultrafine scale(<100 nm) at heat-treatment temperatures below 500 ℃. The structures of the precursor complexes and the finally heat-treated particles were studied by means of IR, XRD, DSC, DTA and TG techniques. The morphologies of the particles were observed by using the SEM technique. The average particle sizes were calculated to be in the range of 30_50 nm based on X-ray diffraction line-broadening and SEM images, indicating the poor conglomeration of crystallite at low temperatures.

EFFECTSOFVASOACTIVEINTESTINALPEPTIDEONACTIVITIESOFSUCCINICDEHYDROGENASEANDALKALINEPHOSPHATASEINRATHEPATOMACELLS

Using cytochemical method,microspectrophotometry and image analysis,effects of va-soactive intestinal peptide(VIP)on activities of succinic dehydrogenase(SDH)and alkalinephosphatase(ALP)in rat hepatoma cells were studied in vitro.The results showed that thehepatoma cell expressed potent positive reactions of SDH and ALP,the positive positionswere located at the cell membranes and/or cytoplasm.Having been treated with VIP,ALPdecreased obviously in activity(P【0. 01,compared with hepatoma cells untreated by VIP).The sites of ALP activty were chiefly located at the cell membranes,particularly at the cell-cell contacts.Cultured rat hepatoma cells had intensive SDH activity in their cytoplasm.Compared with untreated eclls,there was no marked difference in the intensity of SDH activ-ity in VIP-treated hepatoma cells(P】0.05).

Isolation of enriched-yielders and fed-batch production of alkaline protease from the newly isolated <i>Bacillus</i>sp. BHA

An alkalophilc and thermophilic Bacillus sp. BHA that produced a thermostable alkaline protease was isolated from decaying protein substrates. The isolate was found to grow in pH range 7 - 11 with an optimum pH 9.0 and temperature up to 55℃. The activity of alkaline protease of Bacillus sp. BHA (68.98 APU/ml) was found higher than the standard strains of Bacillus amyloliquefaciens MTCC 610 (8.98 APU/ml) and Bacillus subtilis MTCC 8349 (12.14 APU/ml, used in this study, and was comparable (68.98 APU/ml, equivalent to 30.38 APU/mg) to the activity of the commercially produced standard protease procured from Novo Nordisk, Denmark (30.35 APU/mg). Hence, the proteolytic activity produced by this isolate was further investigated in batch and fed-batch process. Sucrose was the best carbon source for the production of protease activity by that isolate. Different organic nitrogen sources (casein, peptone and beef extract) at 1% (w/v) with varying levels of sucrose (1% - 4% w/v) initially repress enzyme synthesis. The duration and extent of repression decreased with increased concentration of sucrose. Maximum protease activity was found in basal medium with 4% (w/v) sucrose and 1% (w/v) yeast extract. Yeast-extract was thought to be an inducer of enzyme synthesis. Further, the basal medium was unique with respect to the enzyme production, as protease production was growth associated with the peak enzyme production being detected at the time of maximum growth. Interestingly, a rise in 34.2% (104.86 APU/ml) of protease activity was detected at incubation temperature of 50℃ and when culture filtrate was assayed at 60℃, signifying a high temperature stability of the produced protease by this isolate. Additional studies on the enzyme characterization were resulted in recognition of highly significant properties of the activity towards casein at pH 9.0 and stability at high temperature with retention of 96% the enzyme activity at 60℃. The parametric study under feed intervals had enabled improvement in the maximum protease activities attainable from batch cultures in excess of 21.78% and 26.32% via two feeding strategies. A small continual increase in enzyme activity (132.46 APU/ml during 24 h - 120 h) and enhancement in protease production in excess of 36.84% was observed by fed-batch process than the batch experiment.

国内常用脱酸工艺、特点与脱酸对象的选择

本文论述了脱酸对象的选择原则与脱酸过程中存在的风险,并结合中国国情给出了需优先脱酸的对象、脱酸过程中可能存在风险而需要谨慎处置的对象,以及不宜脱酸的对象。对国内使用较为广泛的脱酸技术进行了分析,包括同类比较与差异性分析,并以咨询的方式给出了脱酸用户所关切的信息。

乏燃料后处理碱性流程的研究进展

乏燃料后处理碱性流程是用碳酸盐、氢氧化物等碱性物质的溶液作为介质进行乏燃料的溶解及铀、钚等元素的分离与纯化的方法。碱性条件下,乏燃料中的大部分裂变产物和次锕系元素并不溶解或者在溶解过程中转变为碳酸盐、氢氧化物沉淀。与已经实现工业化的PUREX(plutonium uranium redox extraction)酸性流程相比,碱性流程具有腐蚀性更小、流程更简单等潜在的优点。鉴于碱性流程的优点及其在乏燃料后处理中的潜在应用,日本、美国、俄罗斯、韩国等国家的科研人员已经围绕该流程开展了一些研究工作。本文首先介绍了各国建议的碱性流程的技术路线;然后逐一介绍了与主要工艺环节相关的基础研究的进展,包括乏燃料的氧化溶解、核素分离、试剂的回收等;最后对该领域面临的挑战和前景进行了讨论。

酶解法制备阿胶蛋白肽工艺条件优化及抗氧化活性分析

目的:研究酶解法制备阿胶蛋白肽的工艺条件及阿胶蛋白肽的抗氧化活性。方法:以阿胶为原料,通过酶解实验优化碱性蛋白酶Alcalase 2.4L制备阿胶蛋白肽的酶解工艺条件。以酶解pH、酶与底物比、酶解温度作为考察因素,以阿胶的水解度为指标,在单因素实验的基础上,通过正交试验确定最佳工艺条件;利用高效凝胶色谱法测定酶解前后阿胶溶液的分子量分布情况,并通过检测对ABTS+和DPPH自由基的清除率,考察酶解前后阿胶溶液的抗氧化活性,从而综合分析酶解效果;采用4种不同大小孔径的超滤膜分离阿胶蛋白肽液,研究经超滤膜分离后不同分子量阿胶蛋白肽的抗氧化活性。结果:阿胶溶液的最佳酶解条件为:pH10.5、酶与底物比9%、酶解温度63℃,此条件下测得阿胶酶解液的水解度为15.93%±1.32%;酶解后阿胶溶液的分子量大部分分布在5000 Da以下;当浓度为10 mg/mL时,未酶解和酶解后的阿胶蛋白肽溶液ABTS+自由基清除率分别为75.83%±0.32%和93.16%±0.21%,DPPH自由基清除率为16.93%±2.41%和39.95%±1.27%;经超滤处理获得五组不同分子量的阿胶蛋白肽(>30 kDa、10~30 kDa、3~10 kDa、1~3 kDa和<1 kDa),分析比较发现低分子量的阿胶蛋白肽抗氧化效果较好。结论:碱性蛋白酶Alcalase 2.4L能够有效制备阿胶蛋白肽,且阿胶蛋白肽具有良好的抗氧化活性。试验结果为后续开展阿胶蛋白肽的抗氧化机制研究提供科学依据。

枸杞子结合多酚碱水解与酸水解提取工艺的比较和产物分析

为了全面评估枸杞子中的酚类成分,本研究分别利用碱水解和酸水解法制备了其中的结合多酚(non-extractable phenolic compounds, NEPC)。选取Box-Behnken实验设计建立了酸或碱的浓度、水解时间和料液比等与NEPC得率之间的数学模型,并优化了水解工艺参数。碱水解过程中的时间对NEPC得率影响显著,而料液比对酸水解的结果影响较大;最佳工艺条件下,碱水解和酸水解获得的NEPC分别为0.65±0.05 mg/100 g和0.52±0.03 mg/100 g。利用UPLC-Q-TOF-MS,从水解产物中解析了11种化合物,主要是苯丙素衍生物。11种化合物都可在酸水解产物中被检出,而碱水解产物中仅鉴定出4种物质。研究结果表明,碱水解能得到更多的NEPC,酸水解产物则表现出良好的化合物多样性,因此制备NEPC时,应根据不同的研究目的选择水解方法。

超声辅助碱法破碎溶出小球藻蛋白质工艺的优化

本文通过采用响应曲面法优化小球藻蛋白质溶出工艺,并对其二级结构进行表征。以小球藻蛋白质的溶出率为指标,考察超声功率、超声时间、NaOH质量分数及水浴时间对提取率的影响。在Plackett-Burman试验的基础上,采用4因素3水平的响应面分析法确定小球藻蛋白溶出工艺。结果表明,小球藻蛋白质最佳溶出工艺条件为超声功率460.08 W、超声时间16.05 min、NaOH质量分数14.03%、水浴时间37.18 min,溶出率达87.64%。在最优条件下溶出的小球藻蛋白经等电点法提取且纯化后进行傅立叶变换红外光谱分析、微观结构分析以及氨基酸分析,结果表明,小球藻蛋白二级结构中主要为β-折叠,含量为30.00%;微观结构显示,小球藻蛋白表面光滑且有孔洞结构;含有5种必需氨基酸,占总量的42.71%。综上,超声辅助碱法破碎小球藻蛋白的破壁程度显著,蛋白溶出率高,且操作简单、成本低,具有较好的工业化应用前景。该研究为小球藻蛋白的食品应用提供了相关参考。

优化碱酸法提纯石墨的研究

【目的】优化天然石墨提纯效果,降低酸在提纯过程中的过多使用对环境造成的影响,满足各行各业对高品质石墨的需求,实现更环保、高效的石墨提纯。【方法】以鳞片石墨为原料,采取NaOH-HCl-HF联合处理的工艺对石墨进行提纯研究,提高石墨的固定碳含量(质量分数,下同),降低石墨中的主要杂质元素如Si、Fe、Al、Cu等的含量,详细考察NaOH的用量以及焙烧温度2个关键因素对该工艺提纯效果的影响;通过扫描电子显微镜(SEM)观察石墨形貌特征,X射线荧光光谱仪(XRF)和电感耦合等离子体原子发射光谱仪(ICP)测定提纯处理前后石墨的杂质含量,X射线衍射仪(XRD)确定石墨及其灰分的晶体结构。【结果】当焙烧温度为500℃、焙烧时间为2.5h,HCl的体积与石墨的质量比为2∶1,氢氟酸的体积与石墨的质量比为2∶1时,石墨的平均固定碳含量从原来的95.3%提高到99.93%;当NaOH与石墨的质量比分别为0.5∶1和0.6∶1时,石墨的平均固定碳含量为99.91%和99.93%;考虑到成本效益等因素,确定当NaOH与石墨的质量比设定为0.5∶1时为理想工艺条件;经过提纯处理后的石墨层结构并不会出现明显的变化,基本性能不变,提纯处理后的石墨相比于提纯处理前的石墨,杂质含量明显地降低。【结论】该碱酸工艺不仅能有效地去除石墨中的杂质,盐酸和氢氟酸的组合还可以显著地提升提纯效果,可有望应用在石墨提纯处理和新能源材料领域。

中国毛虾酶解工艺优化及其酶解条件对风味的影响

【目的】筛选一种可直接使用、效果明显的蛋白酶酶解中国毛虾(Acetes chinensis),并分析不同酶解条件变化对风味的影响,以达到不需控制pH值且可降低工艺成本、改善风味效果,为毛虾酶解方面的利用提供理论依据。【方法】以福林-酚法、甲醛滴定法筛选酶活力最优的蛋白酶,以氨基酸态氮(AAN)质量分数、水解度(DH)、感官评分为指标进行工艺单因素实验,并利用正交实验法[L9(34)]优化酶解工艺。借助气象色谱-离子迁移谱仪(GCIMS)结合OPLS-DA法分析其单因数实验过程挥发性物质变化。【结果与结论】维持毛虾原始pH值条件下,碱性蛋白酶活力为28 435 U/g,确定为最适酶,最佳工艺为55℃、4 h、加水量20%、加酶量0.8%(227.48 U/g),所得毛虾AAN质量分数为1.11 g/100 g。GC-IMS结果表明,酶解过程显著改变毛虾气味表现,时间、温度的梯度变化是毛虾酶解液气味差异化的主要原因。其中变量投影重要性因子分析表明,温度主要影响醛类、醇类变化,时间主要影响酯类、酮类变化,加酶量、加水量主要影响醇类变化。结果表明,碱性蛋白酶酶解毛虾效果明显,工艺简单,其对酶解液风味改善作用显著。

粉煤灰提取氧化铝工艺的研究进展

粉煤灰是在燃煤电厂发电过程中产生的主要固体废弃物,除Si元素外,还存在着较多的Al元素,是良好的氧化铝提取来源。文中采用酸法、碱法以及酸碱联合的工艺,对从粉煤灰中提取氧化铝工艺做出了归纳与概括,系统研究了三种技术的优缺点,并对未来粉煤灰综合利用中氧化铝的萃取技术给出了研究思路,为提升粉煤灰的使用价值提供借鉴。

粉煤灰吸收剂固碳降碱工艺研究

粉煤灰吸收剂固碳降碱工艺在减少二氧化碳(CO_(2))排放、资源综合利用和碱性废水处理等方面具有重要意义。以陕西榆林三道沟府谷电厂固体废弃物粉煤灰为原料,通过改性处理制备了粉煤灰CO_(2)吸收剂(简称“吸收剂”),研究了不同预处理剂(分别为乙酸(CA)、氯化钠(NaCl)和氢氧化钠(NaOH)溶液,质量分数均为85%)对吸收剂的固碳降碱性能和返碱、浸出性质的影响,并分析了温度和CO_(2)进气速率对固碳降碱工艺的影响。结果表明,NaOH能够有效破坏粉煤灰的球形玻璃体结构,释放活性组分。提高温度可以增大粉煤灰中的离子浸出速率,使反应向正向移动。增大CO_(2)进气速率能够提高CO_(2)在吸收剂中的溶解速率,但过高的CO_(2)进气速率会缩短气液接触时间,导致吸收效率降低。以NaOH溶液作预处理剂,在温度为60℃、CO_(2)进气速率为40 mL/min和吸收时间为5 h的条件下,该固碳降碱工艺的效果最佳,吸收剂的吸收效率可达27.89%,固碳性能为30.16 kg/t。

混合电解槽制氢系统选型及评估方法

电解槽是光伏电解水制氢技术的关键设备,其性能的优劣是影响制氢技术发展的关键因素。目前已被投入工程应用的电解槽有碱性电解槽(alkaline electrolyzer,AEL)和质子交换膜电解槽(protonexchange membrane electrolyzer,PEMEL),两类电解槽在经济性和技术性方面各有优劣。因此,提出混合电解槽应用技术。首先,提出层次分析-熵权法综合评估方法,按照所提方法求得混合电解槽系统最优选型;其次,将混合电解槽系统应用在光储耦合制氢系统中,并搭建其仿真模型;在此基础之上,进行3类电解槽多个性能指标对比分析。结果表明,混合电解槽成本为同容量PEMEL设备成本的56%,且混合电解槽电解效率可达91.5%,验证了所提方案的适用性。

锌冶炼渣中有价金属回收工艺研究

回收利用锌冶炼渣中有价金属,对冶金行业可持续发展具有重要意义。某锌冶炼渣中锌、铅、金、银含量较高,试验采用酸浸—碱浸—氰化浸出湿法梯级浸出工艺回收锌、铅、金、银。试验结果表明:在硫酸质量分数20%,液固比2∶1,浸出温度80℃,浸出时间2 h的条件下,锌浸出率为90.31%;在氢氧化钠质量分数10%,液固比2∶1,浸出温度80℃,浸出时间2 h的条件下,铅浸出率为93.37%;在氰化钠质量分数0.20%,液固比2∶1,浸出时间16 h的条件下,金、银浸出率分别为82.61%、92.39%。该湿法梯级浸出工艺实现了锌冶炼渣的综合回收。

高温组织降解设备在高等级生物安全实验室的应用与风险管控

对高温组织降解设备在高等级生物安全实验室中的应用进行了分析,重点介绍了该设备的原理和技术性能,并以实际运行的121个批次(共计约203 t)的动物残体的无害化处理过程数据为基础,整理、总结了高温组织降解设备在实际使用过程中的性能和特点,针对高温组织降解设备在实际运行维护过程中的关键风险点进行了识别并给出了具体的管控措施。

酸碱性工业废水处理设备易损分析与养护措施

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