An efficient and mild recycling of waste melamine formaldehyde foams by alkaline hydrolysis

Melamine formaldehyde foam(MFF)generates many poisonous chemicals through the traditional recycling methods for organic resin wastes.Herein,a high MFF degradation ratio of ca.97 wt.%was achieved under the mild conditions(160℃)in a NaOH–H2O system with ammelide and ammeline as the main degradation products.The alkaline solvent had an obvious corrosion effect for MFF,as indicated by scanning electron microscopy(SEM).The reaction process and products distribution were studied by Fourier-transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS),and ^(13)C nuclear magnetic resonance(NMR).Besides,the MFF degradation products that have the similar chemical structures and bonding performances to those of melamine can be directly used as the raw material for synthesis of melamine urea-formaldehyde resins(MUFs).Moreover,the degradation system demonstrated here showed the high degradation efficiency after reusing for 7 times.The degradation process generated few harmful pollutants and no pre-or post-treatments were required,which proves its feasibility in the safe removal or recovery of waste MFF.

Study on enzymatic hydrolysis of soybean β-conglycinin using alkaline protease from Bacillus subtilis ACCC 01746 and antigenicity of its hydrolysates

Due to its beneficial health effects,the use of soybean protein has shown a continuous increase,but concerns regarding the allergenicity of soybean antigenic protein have also increased.This study aimed to evaluate the hydrolytic effects of a non-commercial alkaline protease isolated from the Bacillus subtilis ACCC 01746 on soybeanβ-conglycinin and the allergenicity of its hydrolysates.Alkaline protease of the strain was separated by precipitation method of organic solvents,and theβ-conglycinin was separated by alkali-solution and acid-isolation and purified by use of gel column.Using the degree of hydrolysis(DH)and inhibition rate as evaluation indexes,the enzymatic hydrolysis parameters ofβ-conglycinin was optimized by single factor and L_(9)(3^(4))orthogonal tests,so as to explore the effect of the protease on the hydrolysis degree and the antigenicity ofβ-conglycinin hydrolysates.The results showed that the native enzyme existed as an 18.3 kDa monomer with a 430 U/g maximum activity.The purity ofβ-conglycinin was 84.8%.The single-factor test results showed that DH showed the oppostie trendency with the inhibition rate,and the increase of protein concentration causedmonotone increasing and monotone decreasing of the inhibition rate and the DH,and the optimal protein concentration was 30 mg/mL.The optimization results showed that pH had the largest impacts on both DH and the inhibition rate,followed by enzyme dosage,hydrolysis temperature and hydrolysis time.Under the optimum hydrolysis conditions of protein concentration 30mg/mL,enzymedosage0.7%,hydrolysis time40min,temperature 55°C and pH8.5,the DH reached the highest of 76.28%,and the inhibition rate was the lowest of 27.03%,which was reduced greatly compared with that before optimization.These results suggested that alkaline protease appeared to show a relatively high effeciency in lowering soybean allergenicity,making it possible to produce low-allergenicity soybean protein.

Kinetic study of alkaline protease 894 for the hydrolysis of the pearl oyster Pinctada martensii

A new enzyme (alkaline protease 894) obtained from the marine extremophile Flavobacterium yellowsea (YS-80-122) has exhibited strong substrate-binding and catalytic activity, even at low temperature, but the characteristics of the hydrolysis with this enzyme are still unclear. The pearl oyster Pinctada martensii was used in this study as the raw material to illustrate the kinetic properties of protease 894. After investigating the intrinsic relationship between the degree of hydrolysis and several factors, including initial reaction pH, temperature, substrate concentration, enzyme concentration, and hydrolysis time, the kinetics model was established. This study showed that the optimal conditions for the enzymatic hydrolysis were an initial reaction pH of 5.0, temperature of 30°C, substrate concentration of 10% (w/v), enzyme concentration of 2 500 U/g, and hydrolysis time of 160 min. The kinetic characteristics of the protease for the hydrolysis of P. martensii were obtained. The inactivation constant was found to be 15.16/min, and the average relative error between the derived kinetics model and the actual measurement was only 3.04%, which indicated a high degree of fitness. Therefore, this study provides a basis for the investigation of the concrete kinetic characteristics of the new protease, which has potential applications in the food industry.

KINETICS AND MECHANISM RELATING ALKALINE HYDROLYSIS OF POLYESTER BLEND FIBER

Cation Dyeable Polyester(CDP)was made by copolymerizing dimethyl terephthalate(DMT),S-sodium sulfonate dimethyl isophthalate(SIPM) with a weight fraction of 4.5% and ethyleneglycol (EG).Blend of PET and CDP was spun into hollow fiber.The fiber was then treated withaqueous NaOH.In this paper,kinetics and mechanism of alkaline hydrolysis of PET,CDP andtheir blend PET/CDP fiber were studied by means of specific area measurement,scantling elec-tron microscopy and other chemical analyses.It was showed that the rate of alkaline hydrolysis isCDP】PET/CDP】PET.Because of blending effect,the alkaline hydrolysis of PET/CDP is dif-ferent from that of PET.CDP phase in the PET/CDP fiber is predominantly hydrolyzed,andhence some pieces of fiber(micro-fiber) fall off the fiber because of etching.

Alkaline Hydrolysis to Reduce the AOX Concentrations in Effluents from Chlorination Treatment of Wool

Organic halogens generated in the chlorlnatlon treatment of wool are proven to be acutely toxic to human beings. Legislation on environmental pollution has become more and more stringent in recent years. So the chlorlnation treatment is faced with disuse. Alkaline hydrolysis is adopted to reduce the AOX (Absorbable Organic Halogen) concentrations in the effluents from the chlorlnatlontreatment under 40℃ and pH values 9, 10, 11 and 12. After treatment the reduction of AOX appears approximately 65%.

Hydrolysis of Fish Protein by Analkaline Protease

Cod muscle protein was hydrolyzed by an alkaline protease in our study. The influences of hydrolysis temperature,fish protein concentration,and ratio of protease addition to protein amount on its degree of hy- drolysis (DH) of protein were studied in details by applying dual quadratic rotary combinational design. The final results showed that more than 84% cod muscle protein could be hydrolyzed and recovered. Cod protein hydrolysate thus obtained had a balanced amino acid composition and mainly consisted of small peptides with molecule weight less than 6900 dalton.

Alkaline Hydrolysis of PP/EHDPET Blend Fibers

Polypropylene superfine fibers or cell porous fibers were prepared from the bi-component blend fibers of polypropylene/easlly hydro-degraded polyester(PP/EHDPET)by alkaline hydrolysis process. EHDPET is a kind of copolyester that can be rapidly hydro-degraded in the hot alkaline solution. This paper discussed the kinetics of alkaline hydrolysis of EHDPET, and the effect of catalyst, bulk ratio and the content of polypropylene grafted maleic anhydride (PP-g-MAH) on the alkaline hydrolysis process. Meanwhile, the morphological change of the outer surface of blend fibers during this process was also investigated by the technology of scanning electron microscope (SEM).

Preliminary Study on the Treatment Efficiency of Pasteurized Lime Thermal Alkaline Hydrolysis for Excess Activated Sludge and Reduction of Tetracycline Resistance Genes

Thermal alkaline hydrolysis is a common pretreatment method for the utilization of excess activated sludge(EAS).Owing to strict environment laws and need for better energy utilization,new methods were developed in this study to improve the efficiency of pretreatment method.Direct thermal hydrolysis(TH),pasteurized thermal hydrolysis(PTH),and alkaline pasteurized thermal hydrolysis(PTH+CaO and PTH+NaOH)methods were used to treat EAS.Each method was compared and analyzed in terms of dissolution in ammonium nitrogen(NH_(4)^(+)-N)and soluble COD(SCOD)in EAS.Furthermore,the removal of tetracycline resistance genes(TRGs)and class 1 transposon gene intI1 from EAS was investigated.The NH_(4)^(+)-N and SCOD concentrations in EAS treated by PTH were 1.24 and 2.58 times higher than those of TH.However,the removal efficiency of total TRGs and intI1 between the groups was comparable.The SCOD concentration of the PTH+NaOH group was 4.37 times higher than that of the PTH group,and the removal efficiency of total TRGs was increased by 9.52%compared with that by PTH.The NH_(4)^(+)-N and SCOD concentrations of the PTH+CaO group could reach 85.04%and 92.14%of the PTH+NaOH group,but the removal efficiency of total TRGs by PTH+CaO was 19.78%lower than that by PTH+NaOH.Thus,to reduce the financial cost in actual operation,lime(CaO)can be used instead of a strong alkali(NaOH),and pasteurized steam at 70℃ instead of conventional high-temperature heating to treat EAS.This study provides a reference for the development of alkaline hydrolysis under moderate temperatures along with the removal of TRGs in EAS.

Kinetic analysis of waste activated sludge hydrolysis and short-chain fatty acids production at pH 10

The accumulation of short-chain fatty acids （SCFAs）, a preferred carbon source for enhanced biological phosphorus removal microbes, was significantly improved when waste activated sludge （WAS） was fermented at pH 10. The kinetics of WAS hydrolysis and SCFAs production at pH 10 was investigated. It was observed that during WAS anaerobic fermentation the accumulation of SCFAs was limited by the hydrolysis process, and both the hydrolysis of WAS particulate COD and the accumulation of SCFAs followed first-order kinetics. The hydrolysis and SCFAs accumulation rate constants increased with increasing temperature from 10 to 35℃, which could be described by the Arrhenius equation. The kinetic data further indicated that SCFAs production at pH 10 was a biological process. Compared with the experiment of pH uncontrolled （blank test）, both the rate constants of WAS hydrolysis and SCFAs accumulation at 20℃ were improved significantly when WAS was fermented at pH 10.

Extraction of Amino Acids from Excess Activated Sludge by Enzymatic Hydrolysis

A study was undertaken to investigate the production of amino acids from excess activated sludge (EAS) by enzymatic hydrolysis. Firstly, the protein was extracted from EAS. Secondly, the protein solution was further hydrolyzed under free enzyme or immobilized enzyme. The reversed phase high performance liquid chromatography (RP-HPLC) and inductively coupled plasma emission spectrometer (ICP) were applied to determine the contents of amino acids and heavy metals, respectively. The effects of enzyme/substrate(E/S), pH, temperature, and reaction time were investigated in detail. The results indicated that, the optimum conditions for protein hydrolysis were temperature 55℃, pH 10, E/S 9 g/L, and reaction time 8 h, and the highest yield of amino acids was more than 10 g/100 g dry sludge (DS) under free enzyme. Moreover, the security and nutrition were taken into consideration. There were seven kinds of essential amino acids and ten non-essential amino acids in the raw amino acid (RAA) solution, and the contents of heavy metals were lower, living up to Hygienical standard for feeds (China). This technology widens the source of amino acids and makes the extraction of amino acids from EAS more economic and effective.

Effect of Limited Enzymatic Hydrolysis on Structure Characterization of Glycinin

[ Objective] This study aimed to characterize the structure of soybean glycinin affected by limited enzymatic hydrolysis. [ Method ] The glycinin was limitedly hydrolyzed by alkaline protease; then the SDS-polyacrylamide gel electrophoresis （SDS-PAGE）, scanning electron microscopy （SEM）, Fourier transform infrared spectroscopy （fTIR） and other means were performed to characterize the glyeinin structure changing during the hydrolysis process. [ Result] SDS-PAGE analysis showed that the subunit contem of glycinin significantly decreased after hydrolysis, and acidic subunits were more susceptible to hydrolysis than alkaline subunits. The scanning electron microscopy revealed that the structure of glycinin powder changed greatly after hydrolysis. The I^TIR results showed that the propor- tions of all conformations of glycinin changed greatly during hydrolysis process. In addition, the protein hydrophobicity and sulfhydryl content were also significantly influenced by hydrolysis. [ Conclusion] The enzymatic hydrolysis greatly changed the conformations of glyeinin, and the change was dependent on the degree of hy- drolysis.

Study on Saccharification of Saccharum spontaneum L. by Sulphuric Acid Hydrolysis

In order to improve the saccharification rate by acid hydrolysis in the technique for production of ethanol from biomass, in this study, Saccharum spontaneum L. was used as the experimental material to investigate the rules and technological conditions for two-step acid-hydrolysis saccharification by single factor experiment and orthogonal experiment. According to the results, concentrated sulfttric acid hydrolysis was the first step, with the liquid-solid ratio of 42： 1, sulfuric acid concentration of 70%, hydrolysis time of 20 rain, and hydrolysis temperature of 55 ℃ ; dilute sulphuric acid hydrolysis was the second step, with the liquidsolid ratio of 115： 1, sulfuric acid concentration of 5.5%, hydrolysis time of 155 min, and hydrolysis temperature of 100℃. In two-step acid hydrolysis process, the yield of reducing sugar was 48.78%. The results indicated that two-step acid-hydrolysis saccharification required mild conditions, simple operation and low cost, and led to high reducing sugar yield, exhibiting a broad application prospect.

Effect of various aromatic compounds with different functional groups on enzymatic hydrolysis of microcrystalline cellulose and alkaline pretreated wheat straw

Low molecular aromatic compounds are detrimental to the enzymatic hydrolysis of lignocellu-lose.However,the specific role of their functional groups remains unclear.Here,a series of nine aromatic compounds as additives were tested to understand their effect on the hydrolysis yield of microcrystalline cellulose(MCC)and alkaline pretreated wheat straw.Based on the results,the inhibition of aldehyde groups on MCC was greater than that of carboxyl groups,whereas for the alkaline pretreated wheat straw case,the inhibitory effect of aldehyde groups was lower than that of carboxyl groups.Increased methoxyl groups of aromatic compounds reduced the inhibitory ef-fect on enzymatic hydrolysis of both substrates.Stronger inhibition of aromatic compounds on MCC hydrolysis was detected in comparison with the alkaline pretreated wheat straw,indicating that the substrate lignin can offset the inhibition to a certain extent.Among all aromatic com-pounds,syringaldehyde with one aldehyde group and two methoxyl groups improved the glucan conversion of the alkaline pretreated wheat straw.

Optimization of sugar production from Durian seeds via alkaline hydrolysis for second-generation bioethanol production

As one way to eliminate the issues found in the preceding generation,feedstock exploration in second-generation bioethanol production remains an issue,especially for a tropical country such as Indonesia.From exotic fruit by-products,durian holds a promising perspective that rests on its abundance,superb carbohydrate content and limited usage until now.This work presents the first-ever utilization of durian seeds for sugar production under optimized conditions through alkaline hydrolysis.A simple form of sugar was extracted by varying four parameters,namely substrate loading,NaOH concentration,hydrolysis time and hydrolysis temperature.Response surface methodology based on the Box-Behnken design was employed to outline the most optimum parameter values.Analysis of variance revealed that the quadratic model fit the data appropriately with the order of significance as substrate loading>hydrolysis time>NaOH concentration>hydrolysis temperature.The optimized conditions for reducing sugar yield,as high as 2.140 g/L,corresponded to<50 g/L substrate loading,0.522 M NaOH,60 minutes of hydrolysis time and 80oC hydrolysis temperature.The possible ethanol content of 1.094 g/L was also expected under optimized conditions,demonstrating great potential in second-generation bioethanol production.

超声碱解提取-超高效液相色谱-串联质谱法测定土壤中14种酚酸含量

建立了一种测定土壤中14种酚酸类物质的分析方法。样品用1.0 mol/L NaOH溶液超声辅助提取,提取液经盐酸酸化,沉淀胡敏酸,上清液用乙酸乙酯萃取富集,在电喷雾负离子模式下,以多反应监测模式采集数据进行定性和定量分析。结果表明,土壤中14种酚酸组分在5.0~5000μg/L范围内有良好的线性关系(R>0.995),检出限为0.3~12.5μg/kg,定量限为1.0~39.2μg/kg。在高低浓度基体加标测试中,14种酚酸的加标回收率分别为78.6%~97.3%和65.8%~89.7%,相对标准偏差分别为1.2%~4.3%和3.1%~9.6%。该方法前处理简单、快速,灵敏度高,重现性好,适用于大批量土壤样品中酚酸类化合物检测,为研究土壤中酚酸类化合物引起的连作障碍提供技术支持。

改良碱水解法测定特殊医学用途婴儿配方奶粉中脂肪含量

文章选定最佳水浴加热时间、混合醚使用量和抽提次数,对GB 5009.6—2016《食品安全国家标准食品中脂肪的测定》中碱水解法进行改良。通过质控样品测定、加标回收试验、精密度试验和实际样品检测,探讨改良碱水解法测定特殊医学用途婴儿配方奶粉中脂肪适用性。结果表明,质控样脂肪含量理论值为22.0 g/100g,测定值为21.9 g/100g,测定结果在允许误差范围内,试验结果可靠;特殊医学用途婴儿配方奶粉和质控样加标回收率为95.9%~98.6%,相对标准偏差为1.10%~1.16%,改良碱水解法准确度高,精密度好;23批次市售特殊医学用途婴儿配方奶粉的脂肪含量均符合国家标准,改良碱水解法适合检测特殊医学用途婴儿配方奶粉中脂肪。

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。

镧掺杂棒状二氧化铈催化剂低温水解羰基硫的性能

在低温下实现高炉煤气中羰基硫(COS)的高精度脱除对环境保护意义重大,催化水解法可以在较低的操作温度下将COS转化成更易脱除的H2S.通过制备三种不同形貌的二氧化铈(CeO_(2)),以及在棒状二氧化铈(CeO_(2)-R)中掺杂不同质量分数的金属镧(La),对催化剂表面氧空位和碱性位点进行调控,探讨氧空位和碱性位点对催化活性的影响,并提出催化剂失活机理.研究发现,CeO_(2)-R具有较多的表面羟基和氧空位含量,在反应温度为75℃,相对湿度为17%时表现出了优异的COS脱除能力,进一步掺杂不同含量La后催化剂的氧空位和表面碱性强度都明显提高,其中,掺杂质量分数为10%的金属La的催化剂100%脱除COS的持续时间较CeO_(2)-R提高了120%,达到570 min.X射线衍射(XRD)、X射线电子光谱(XPS)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)表征表明,金属La掺杂进入到CeO_(2)-R的晶格内,形成固溶体结构.电子顺磁共振(EPR)和二氧化碳程序升温脱附(CO_(2)-TPD)分析表明La与CeO_(2)的协同作用形成了更多不对称的氧空位,并提高了催化剂碱性强度,氧空位与碱性位点的共同作用提高了催化剂对COS的脱除能力.在反应过程中生成硫酸盐等副产物沉积在催化剂表面,堵塞孔隙,覆盖活性中心导致催化剂硫中毒.综上所述,通过探讨催化剂表面的结构和化学性质,为低温催化水解COS提供了新的认识,对开发高效、稳定的COS水解催化剂具有指导意义.

不同工艺制备的聚酯纤维在碱性条件下的结构性能变化规律

为了解不同工艺制备的聚酯纤维在碱性条件下应用性能的变化规律,分别选择工业丝路线制备的高强(HT)聚酯工业丝和高速纺丝制备的全拉伸聚酯纤维(FDY)作为研究对象,采用人工加速的碱性热水环境(85℃)开展老化试验,研究纤维力学性能的变化规律,同时分别利用广角X射线衍射、小角X射线散射和特性黏度等方法对结晶、片晶堆砌以及化学结构等形态结构变化进行研究。结果表明,两种聚酯纤维在碱性水环境下的结构和性能变化可区分为三个阶段:初期受水和热的共同作用,纤维的断裂强度较明显减小,结晶度不变,取向度明显下降,归因于部分处于冻结的非晶区取向分子链段发生解取向而收缩;随后纤维断裂强度缓慢下降,非晶区分子链断裂,同时有少量新的结晶生成;后期断裂强度下降程度更加明显,且结晶度开始减小,特性黏度明显降低,分子链断裂成为主导因素。由于HT工业丝具有更高的结晶度与晶粒尺寸,水分子和OH-的侵蚀作用受到抑制,这使其碱解反应速率变慢,力学性能变化程度低于FDY纤维,表明HT工业丝的抗碱解性能优于FDY纤维。