Models for the formation of poly(butylene terephthalate): effect of water on the kinetics of the titanium tetrabutylate-catalysed reactions: 3

In an effort to investigate the mechanism of catalysis of titanium tetrabutoxide on the polycondensation of poly(butylene terephthalate), alcoholysis and hydrolysis reactions were studied with the aid of model molecules. The retarding effect of water has also been taken into account. Appropriate kinetic equations are derived and discussed and the results compared with experimental data obtained at different molar ratios of reactants.     

HPLC法研究C.I.Reactive Red 24水解反应动力学

采用反相离子对高效液相色谱法(HPLC)研究了C.I.Reactive Red 24 水解反应动力学.当染料溶液中羟基过量时, 可视为一级反应; -d[A]/dt=k[A].在pH=13时, ln(A0/A)与反应时间t呈线性关系; 95℃时的水解反应速率常数K(0.0599)比70℃时的k(0.0101)高约4倍; pH为13时, 反应速率常数K(5.99×10-2)比8.5时的k(4.8×10-3)高约11.5倍; pH值每升高1, 染料的水解速率相应提高1.5倍.     

NaOH预处理对植物纤维素酶解特性的影响

对NaOH预处理对植物纤维素酶解特性的影响进行了研究,利用红外光谱(IR)对处理前后物料组成变化进行了对比分析。研究结果表明,NaOH预处理对纤维素物料化学组成比例有很大影响;NaOH预处理后,物料中纤维素明显得到润胀,纤维素结晶指数降低,纤维素结晶区受到破坏,再经纤维素酶处理后,结晶指数有所增强;NaOH预处理是一种有效的植物纤维素原料预处理方法,经NaOH预处理后的物料更易于酶解。     

铌酸催化水解葡萄糖的研究

研究了铌酸催化水解葡萄糖溶液的反应,考察了不同热处理温度对铌酸催化剂活性的影响。研究发现,当热处理温度为400 ℃时,此类催化剂对葡萄糖催化水解生成乙酰丙酸（LA）的活性和选择性较好。对不同制备方法得到的铌酸催化剂活性进行比较,结果表明,直接水洗法制备得到的铌酸较有利于LA的生成。对用磷酸处理的铌酸催化剂进行考察发现,对于本反应体系,催化剂酸性的增加反而使活性下降。用XRD对催化剂的结构表征结果表明,催化剂活性与其表面是否结晶无明显关系。     

高浓度成衣水洗染色废水的处理

采用混凝沉淀-水解-接触氧化-气浮-沉淀工艺处理高浓度成衣水洗染色废水,设计规模为6000m^3／d。处理后,CODcr、BOD5、SS和色度的去除率分别达到92．6％、94．2％、90．4％、94．6％,总排放口水质：pH=7．07,CODcr=93mg／L,BOD5=22．8mg／L,SS=50mg／L,色度为16倍。     

凝胶色谱法测定产出液中聚合物水解度的研究

常规水解度检测方法不适用于产出液中聚合物水解度的检测。本文建立了水解度的标准曲线,确定了凝胶色谱法测试产出液中聚合物水解度的方法,解决了目前产出液中聚合物水解度无法测定的难题,该方法简洁、快速、准确。     

不同pH对焦磷酸铵水解的影响

以主成分为焦磷酸铵的水溶性聚磷酸铵为实验原料,设置8.2、6.0、4.0、3.5、3.0、2.5、2.0等7组pH梯度,系统研究了酸度对焦磷酸铵水解的影响。结合一级反应动力学方程与阿累尼乌斯方程进行焦磷酸铵的水解动力学计算,结果表明：经过310 d（第二批260 d）的放置,pH从8.2降低到2.0时焦磷酸铵质量分数从初始态的92.6%依次减少为85.4%、51.2%、50.6%、50.2%、24.3%、12.9%和6.0%。焦磷酸铵在自然温度下的水解速率随着pH的降低而不同程度地加快,服从一级反应机理。pH从8.2降低到2.0时焦磷酸铵的水解速率常数从2.92×10-4~3.43×10-4增加至3.41×10-3~1.47×10-2,二者相差10~40余倍,对应半衰期为50~2 000 d。秋冬与春夏两时段的水解速率差异很大,二者水解速率常数相差1.17~4.32倍,焦磷酸铵的水解活化能为7.5~68.5 kJ/mol。     

Effect of LHW,HCl, and NaOH pretreatment on enzymatic hydrolysis of sugarcane bagasse: sugar recovery and fractal-like kinetics

Conversion of lignocellulose to sugars involves two main processes, namely pretreatment and enzymatic hydrolysis. Lignocellulose pretreatment leads to the degradation of enzymatic recalcitrance of substrate for achieving efficient saccharification. In this study, liquid hot water (LHW), hydrochloric acid (HCl), and sodium hydroxide (NaOH) were as reagents used to pretreat sugarcane bagasse (SB). Results showed that LHW, HCl, and NaOH pretreatment could solubilize 95.3%, 94.7% xylan and 88.7% lignin, respectively. Enzymatic hydrolysis of pretreated SB showed that the maximum glucose (26.0?g/L) and xylose (12.7?g/L) concentration were produced by NaOH pretreatment, and slightly more glucose and less xylose were produced after HCl pretreatment compared to LHW pretreatment. Addition of Tween 80 or xylanase could significantly improve both glucose and xylose production. At 48?h, the glucose increase for LHW, HC1 and NaOH pretreatment was 38.3%, 26.4% and 8.0%, respectively, and the xylose increase for them was 35.0%, 24.9% and 1.7%, respectively. Fractal-like kinetics showed that the value of rate constant increased after the addition of Tween 80 or xylanase, and the efficiency of enzymatic hydrolysis mainly depended on rate constant other than fractal dimension of substrate. Totally, substrate accessibility was dominated for efficient of lignocellulose to sugar compared to enzyme loading. The application of fractal-like theory on the heterogeneous enzymatic hydrolysis of lignocellulose was quite successful.     

Optimization of enzymatic hydrolysis parameters for antioxidant capacity of peptide from goat placenta

The goat placenta protein was hydrolyzed by pepsin and the optimal hydrolysis parameters of strongest antioxidant capacity of peptides were obtained using response surface methodology (RSM). The effects of reaction temperature, pH value and enzyme to substrate (E:S) ratio on the reducing power (RP) of the peptides and degree of hydrolysis (DH) of protein were well fitted to a quadric equation with high determination coefficients. The hydrolysate with optimal RP was predicted to be obtained at: temperature of 36.5 °C, pH value of 1.05, and E:S ratio of 2.03% and 3–10 kDa fraction (10 mg/mL), rich in GLY, GLU, ASP and TYR, was proved to exhibit highest RP, which is equivalent to the RP of 0.189 mg/mL ascorbic acid. The fraction of peptide also showed peroxidation inhibition in linoleic acid oxidation system and had a free radical scavenging ability similar to ascorbic acid (10 μg/mL) in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) system after 17 min.