Polyamide hydrolysis accelerated by small weak organic acids

It is well known that acidity, pH, of a solution accelerates the hydrolysis of soluble amides. Here we describe the unexpected result that weak small organic acids at low concentrations hydrolyze a polyamide at rates approximately twice that of a water HCl solution of the same pH. The effect of three small organic acids in dilute solutions, acetic, propanoic, and butanoic was studied. It is observed that the effect on the hydrolysis rate increases as the organic acid gets weaker. Butanoic, the weakest acid, has the strongest effect on increasing the hydrolysis rate. Measurements on the concentration of these acids in the polyamide reveal that there is a selective desire for these weak organic acids to diffuse into the polyamide. The concentration of these acids in the polyamide is found to be several multiples of the concentration in the water environment. And the acid concentration is highest for butanoic. The hydrolysis rate is shown to be governed by solubility, not pH of the water environment. The longer hydrocarbon tail on the carboxylic group increases its compatibility with the polyamide's monomer structure. Results are reported on the hydrolysis of polyamide-11 polymerized from aminoundecanoic acid, both neat and a commercial plasticized composition, placed in water at 100 °C and 120 °C under anaerobic conditions in high pressure glass tubes.     

微波-过氧化氢协同降黏辅助酶法制备壳寡糖

利用微波-过氧化氢协同处理壳聚糖,通过降低壳聚糖的黏度辅助促进其酶解制备壳寡糖。通过单因素实验与正交实验,确定了影响壳聚糖微波-过氧化氢降黏效果的因素主次顺序是微波时间、H2O2的用量、微波功率。优化后的降黏条件是:H2O2添加量为0.1 mL,微波功率为120 W,微波时间为0.5 min,所得壳聚糖黏度比原料黏度降低了96.9%,且并未发生结构的改变。对其酶解的结果表明,经微波-过氧化氢协同降黏再酶解的壳寡糖得率为80.1%,比未经降黏处理的提高了11.8%,产物壳寡糖数均相对分子质量为2 027,平均聚合度为10,明显低于未经降黏处理而直接酶解所得的壳寡糖。     

高真空扩散泵油275^#生产工艺改进

简述了高真空扩散泵油275^#的生产工艺,分析了水解釜材质和精馏系统存在的问题,提出了改造意见,并比较了改造效果。结果表明,将水解釜材质由搪瓷更换成不锈钢后,既节约原材料消耗,又减少水洗过程中的物料损失和排污量,从而大幅度降低了产品的生产成本;精馏系统装置经过改造后,产品中的三甲基五苯基三硅氧烷含量比改造前生产的产品高出15个百分点,提高到84%以上;且产能翻一番。     

纺织工业印染废水处理实例

江西某纺织企业采用初沉+水解酸化+CASS+混凝沉淀吸附+过滤组合工艺处理纺织工业印染废水,处理水量为8 000 m3/d。调试运行结果表明,当进水COD、BOD5、SS分别为2 000、450、300 mg/L,色度为800倍时,出水COD、BOD5、SS分别为54、10、30 mg/L,色度为30倍,平均COD、BOD5、SS和色度去除率分别为97.3%、97.8%、90.0%和96.3%,出水水质稳定,达到《纺织染整工业水污染物排放标准》(GB 4287—2012)中新建企业水污染物排放限值的要求。     

烟气脱硝中尿素法制氨工艺比较

介绍了烟气脱硝的工艺,包括选择性非催化还原法（SNCR）、选择性催化还原法（SCR）及SNCR/SCR混合烟气脱硝技术,还原剂为液氨和尿素。燃烧后的烟气必须进行脱硝处理,对尿素水解和热解技术进行了比较,总结了尿素水解的技术优势和经济性。认为采用尿素水解法进行烟气脱硝安全性好、运行成本低,应用前景较好。     

Kinetic modeling of hemicellulose hydrolysis in the presence of homogeneous and heterogeneous catalysts

Kinetic models were developed for the hydrolysis of O‐acetyl‐galactoglucomannan (GGM), a hemicellulose appearing in coniferous trees. Homogeneous and heterogeneous acid catalysts hydrolyze GGM at about 90°C to the monomeric sugars galactose, glucose, and mannose. In the presence of homogeneous catalysts, such as HCl, H₂SO₄, oxalic acid, and trifluoroacetic acid, the hydrolysis process shows a regular kinetic behavior, while a prominent autocatalytic effect was observed in the presence of heterogeneous cation‐exchange catalysts, Amberlyst 15 and Smopex 101. The kinetic models proposed were based on the reactivities of the nonhydrolyzed sugar units and the increase of the rate constant (for heterogeneous catalysts) as the reaction progresses and the degree of polymerization decreases. General kinetic models were derived and special cases of them were considered in detail, by deriving analytical solutions for product distributions. The kinetic parameters, describing the autocatalytic effect were determined by nonlinear regression analysis. The kinetic model described very well the overall kinetics, as well as the product distribution in the hydrolysis of water soluble GGM by homogeneous and heterogeneous catalysts. The modelling principles developed in the work can be in principle applied to hydrolysis of similar hemicelluloses as well as starch and cellulose. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1066–1077, 2014     

酯化水解法提取L-乳酸工艺研究

L-乳酸是一种重要的发酵有机酸,又是生产生物可降解材料聚乳酸的原料。采用酯化水解法精制提取L-乳酸,得出成熟的工艺条件：乳酸与甲醇用量比为1∶3.5,乳酸浓度为85%左右,硫酸加入量为总投料量的2.5%左右,酯化时间为2.5 h。在最佳工艺条件下,酯化水解工序总收率由70%提高到85%,且产品质量稳定,经济效益明显提高。     

酶法制备猪肺抗氧化肽

为了分离制备猪肺抗氧化肽,该文研究了中心组合设计和响应面分析优化猪肺抗氧化肽的提取工艺,以DPPH自由基清除率为响应值,分析了料液比、水解时间和酶浓度对制备抗氧化肽的影响,再通过葡聚糖凝胶Sephadex G-50、G-25和G-10对抗氧化肽进行分离纯化,得到了具有抗氧化活性的肽段,测定其清除DPPH自由基、超氧阴离子、ABTS自由基、羟基自由基以及金属螯合的能力。猪肺抗氧化肽的最佳提取工艺参数为:新鲜猪肺质量与水质量的比例(料液比)为1∶3,水解6 h,酶浓度为6 500 U/g,此时DPPH自由基清除率为66.89%;抗氧化活性最强的组分A5清除DPPH自由基、超氧阴离子、ABTS自由基和羟基自由基的IC50分别为0.073、0.989、0.192和1.261 g/L,金属螯合能力的IC50为6.505 g/L;其相对分子质量为175。     

二氢月桂烯醇型三硅氧烷表面活性剂的合成及性能

在自制的Pt-聚甲基乙烯基硅氧烷(PMVS)催化剂作用下,1,1,1,3,5,5,5-七甲基三硅氧烷与二氢月桂烯醇型聚醚在甲苯中经硅氢加成合成系列三硅氧烷表面活性剂(Sxy)。通过FTIR和1HNMR验证了Sxy系列产物的结构,并测试了产物的表面与界面性能,与市售三硅氧烷表面活性剂BD-3077进行比较。结果表明,Sxy可将水的表面张力降低至23 mN/m以下,略高于BD-3077(21 mN/m);质量分数为0.5%的S36、S39和S312溶液在室温下澄清,浊点高于85℃;Sxy均具有优良的水解稳定性,远优于BD-3077。     

汽爆甘蔗渣转化乙醇的实验研究

研究了甘蔗渣的汽爆条件,并利用高效液相色谱（HPLC）对甘蔗渣汽爆产物进行了分析。在相同汽爆蒸汽压力下,随着汽爆保压时间的延长,降解产生的对后续酶解和发酵有害的物质甲酸、乙酸和糠醛等也随之增加。研究了汽爆甘蔗渣的酶解和发酵性能,在实验室小试的基础上,进一步利用50 L发酵罐进行放大的酶解和发酵实验,在酶解液固形物浓度27.09%（ω）条件下,48 h发酵液乙醇浓度6.17%（φ）,显示汽爆甘蔗渣能够较好地被转化用于生产乙醇。