Efficient reductive dechlorination of monochloroacetic acid by sulfite/UV process

Most halogenated organic compounds (HOCs) are toxic and persistent, and their efficient destruction is currently a challenge. Here, we proposed a sulfite/UV (253.7 nm) process to eliminate HOCs. Monochloroacetic acid (MCAA) was selected as the target compound and was degraded rapidly in the sulfite/UV process. The degradation kinetics were accelerated proportionally to the increased sulfite concentration, while the significant enhancement by increasing pH only occurred in a pH range of 6.0-8.7. The degradation proceeded via a reductive dechlorination mechanism induced by hydrated electron (e(aq)(-)), and complete dechlorination was readily achieved with almost all the chlorine atoms in MCAA released as chloride ions. Mass balance (C and Cl) studies showed that acetate, succinate, sulfoacetate, and chloride ions were the major products, and a degradation pathway was proposed. The dual roles of pH were not only to regulate the S(IV) species distribution but also to control the interconversion between e(aq)(-) and H(?). Effective quantum efficiency (Φ) for the formation of e(aq)(-) in the process was determined to be 0.116 ± 0.002 mol/einstein. The present study may provide a promising alternative for complete dehalogenation of most HOCs and reductive detoxification of numerous toxicants.     

Degradation of tert-butyl alcohol in dilute aqueous solution by an O3/UV process

This paper describes the degradation of tert-butyl alcohol (TBA) in dilute aqueous solution by an O3/UV process. The degradation process was investigated experimentally in a semi-batch reactor under various operational conditions, i.e., ozone gas (O3) dosage, UV light intensity, and water quality in terms of varying bicarbonate concentration. TBA was oxidized rapidly in the O3/UV system, and acetone, hydroxy-iso-butyraldehyde, and formaldehyde were identified as primary intermediates, whereas pyruvaldehyde and acetic, formic, pyruvic, and oxalic acids were generated as a result of further oxidation process. A good organic carbon balance was obtained, indicating that most reaction intermediates have been identified and quantified.     

紫外/过氧化氢法制备葡萄糖酸的研究

研究了紫外辐射下利用过氧化氢氧化葡萄糖转化为葡萄糖酸的工艺。结果表明:采用紫外灯照射葡萄糖溶液,并通空气和流加过氧化氢,可快速将葡萄糖转化成葡萄糖酸。研究发现,葡萄糖与过氧化氢摩尔比、反应温度、反应时间、葡萄糖溶液质量体积分数等影响葡萄糖酸产率。通过正交实验,得到最佳工艺条件为:葡萄糖与过氧化氢摩尔比1:3,反应温度50℃,反应时间6h,葡萄糖溶液质量体积分数0.25g/mL;在此反应条件下,葡萄糖酸产率为78.26%。     

纸浆漂白过程中草酸的形成、危害及控制

随着制浆造纸工业的不断发展以及人们环保意识的不断提高,传统的含氯漂白工艺开始逐渐被无元素氯漂白（ECF）、全无氯漂白（TCF）等绿色漂白工艺取代。但是在绿色漂白过程中产生的草酸一直困扰着企业科技人员。本文介绍了纸浆漂白过程中草酸的形成、来源,草酸结垢对漂白设备的危害,以及对草酸及其危害的有效控制。     

以三苯甲烷染料酸性品红作探针检测罐头肉中的痕量Hg

建立了检测肉罐头中有毒重金属元素Hg的酸性品红共振光散射法,研究了共振光散射的光谱特征、适宜反应条件、共存物质的影响及反应机理。在pH 6.56的Tris-盐酸缓冲介质中,溴代十六烷基吡啶增敏酸性品红并与Hg(Ⅱ)结合生成三元复合物,使体系的共振光散射(RLS)显著增强并产生新的RLS光谱,在最大共振散射峰附近,Hg(Ⅱ)的质量浓度在0.005~0.40 mg/L与体系的共振光散射增强强度的绝对值│ΔIRLS│呈线性关系,定量限为0.032 mg/kg。方法简便、灵敏,加标回收率为98.5%~102%,相对标准偏差RSD(n=5)为2.0%~2.5%。适于罐头类肉食中Hg的测定。     

印染废水的厌氧/好氧/混凝沉淀/臭氧处理

采用中试规模(3 m3/d)悬浮生物滤池A/O/混凝沉淀/O3组合工艺,对纱线印染企业二沉池出水进行深度处理,考察稳定运行条件下,COD、色度和铁离子的去除效果以及处理出水对产品质量的影响。试验结果表明:进水COD、色度、铁离子分别为127 mg/L,532倍和0.24 mg/L时,相应的出水指标为51 mg/L,4倍和0.055 mg/L。在不影响产品质量的条件下,回用率可达50%左右。     

Catalytic determination of traces of oxalic acid in vegetables and water samples using a novel optode

A new optode has been introduced for determination of oxalic acid. The optode sensing reagent is Victoria blue 4R which is immobilized on triacetylcellulose membrane. This reagent could be oxidized by dichromate in acidic media resulting in decoloration of the membrane. Oxalic acid has a strong catalytic effect on this reaction. The difference in absorbance of the immobilized form of Victoria blue 4R at 615 nm between uncatalyzed and catalyzed reactions (ΔA) is directly proportional to the concentration of oxalic acid. Oxalic acid can be determined in the concentration range of 2–180 μg ml⁻¹. The effect of different possible interfering species has been examined and was shown that the optode has a very good selectivity. The optode has been applied for the determination of oxalic acid in different real samples such as spinach, beet root, mushroom and river water with excellent recoveries.     

Decontamination of chilli flakes in a fluidized bed using combined technologies: Infrared,UV and ozone

An initial study of the combination of IR, UV and ozone on treating raw and artificially inoculated chilli flakes (CF, Capsicum annum L) was assessed using a specially designed fluidised bed system, in a fused quartz tube, using a distributor plate and filtered air, to keep the CF in an air suspension. The untreated samples, as bought, were contaminated with ~1 × 10⁶ cfu/g, they were subsequently autoclaved, and inoculated with Escherichia coli (MG1655). The individual treatments were all effective in reducing the bioburden with log reduction and treatment times ~6 logs (cfu/g) in ≤20 min for ozone (300 mgO₃hr^−>1); ~7 logs (cfu/g) in ≤40 min, for UV (4 W); and ~7 logs (cfu/g) in ≤20 min, for IR (100 W); for stationary air with ozone, and an airflow of 108 Lmin^−>1 with UV and IR treatment. The IR was modulated so that the external tube temperature was 58–60 °C. The treatment order was more effective for the IR and UV followed by ozone, than ozone followed by UV and IR (ozone, 10 min, UV and IR 10 min combined), this was due to the higher intial reduction of the UV and IR (0.80 log (cfu/g)) than with ozone first (0.13 log (cfu/g)). Such decontamination systems could be used efficiently when conveying the spices, just prior to aseptic packaging.     

Inactivation of Escherichia coli in orange juice using ozone

This research investigated the efficacy of gaseous ozone for the inactivation of Escherichia coli ATCC 25922 and NCTC 12900 strains in orange juice. Orange juice inoculated with E. coli (10⁶ CFU mL^− 1) as a challenge microorganism was treated with ozone at 75–78 µg mL^− 1 for different time periods (0–18 min). The efficacy of ozone for inactivation of both strains of E. coli was evaluated as a function of different juice types: model orange juice, fresh unfiltered juice, juice without pulp, and juice filtered through 500 µm or 1 mm sieves. Fast inactivation rates for total reduction of E. coli were achieved in model orange juice (60 s) and in juice with low pulp content (6 min). However, in unfiltered juice inactivation was achieved after 15–18 min. This indicated that juice organic matter interferes with antibacterial activity of gaseous ozone. The effect of prior acid (pH 5.0) exposure of E. coli strains on the inactivation efficacy of ozone treatment was also investigated. There was a strain effect observed, where prior acid exposure resulted in higher inactivation times in some cases by comparison with the control cells. However, the overarching influence on inactivation efficacy of ozone was related to the pulp content. Generally, the applied gaseous ozone treatment of orange juice resulted in a population reduction of 5 log cycles.

Industrial relevance

To facilitate the preservation of unstable nutrients many juice processors have investigated alternatives to thermal pasteurisation, including un-pasteurised short shelf life juices with high retail value. This trend has continued within the European Union. However within the US recent regulations by the FDA have required processors to achieve a 5-log reduction in the numbers of the most resistant pathogens in their finished products. Pathogenic E. coli may survive in acid environments such as fruit juices for long periods. This study demonstrates that the use of ozone as a non-thermal technology is effective for inactivation of E. coli and acid exposed E. coli in orange juice. Information on the design of the ozone treatment for inactivation of E. coli which results into safe juice products is also among the main outputs of this work. Ozone auto-decomposition makes this technology safe for fruit juice processing.     

破乳-混凝-光催化化学氧化法处理废切削液新工艺

先硝酸破乳,再用聚合硫酸铁(PFS)和阳离子聚丙烯酰胺(PAM)复合处理废切削液,当pH为8.0,PFS和PAM的用量分别是1 800mg.L-1和8mg.L-1时混凝效果较好.混凝上清液用UV/H2O2/Fe2 系统氧化,当pH=3,分4次加入H2O2,紫外照射6.5h,结果令人满意.采用该工艺处理废切削液,其COD去除率为99.5%,脱色率100%,出水达到了国家《污水综合排放标准》(GB-8987-1996)一级标准.     

Improving fatty acid methyl ester production yield in a lipase-catalyzed process using waste frying oils as feedstock

The application of waste frying oil (WFO) mixed with rapeseed oil as a feedstock for the effective production of fatty acid methyl esters (FAME) in a lipase-catalyzed process was investigated. The response surface methodology (RSM) was used to optimize the interaction of four variables: the percentage of WFO in the mixed feedstock, the methanol-to-oil ratio, the dosage of Novozym 435 as a catalyst and the temperature. Furthermore, the addition of methanol to the reaction mixture in a second step after 8 h was shown to effectively diminish enzyme inhibition. Using this technique, the model predicted the optimal conditions that would reach 100% FAME, including a methanol-to-oil molar ratio of 3.8:1, 100% (wt) WFO, 15% (wt) Novozym 435 and incubation at 44.5 °C for 12 h with agitation at 200 rpm, and verification experiments confirmed the validity of the model. According to the model, the addition of WFO increased FAME production yield, which is largely due to its higher contents of monoacylglycerols, diacylglycerols and free fatty acids (in comparison to rapeseed oil), which are more available substrates for the enzymatic catalysis. Therefore, the replacement of rapeseed oil with WFO in Novozym 435-catalyzed processes could diminish biodiesel production costs since it is a less expensive feedstock that increases the production yield and could be a potential alternative for FAME production on an industrial scale.     

紫外亚硝基胍复合诱变选育高产酸乳酸菌

为获得产酸性能优良的乳酸菌用于发酵乳制品的生产,从实验室保藏菌株中筛选出产酸性能较强的菌株TM111-S作为出发菌株,采用0.3g/L亚硝基胍处理60min和紫外线照射150s复合诱变3轮,最终得到一株产酸能力为83.66°T的菌株,较出发菌株提高了44.19%,连续传代后产酸性能稳定。     

Decontamination of powdery and granular foods using Continuous Wave UV radiation in a dynamic process

The purpose of this study was to investigate the potential of Continuous Wave UV radiation, applied in a dynamic process, to reduce Enterobacteriaceae counts in powdery and granular foods. Several food matrices were inoculated with a test strain (Escherichia coli LMG 8063) and radiated for 1 h with UV (254 nm, 2.88 mW/cm²). The particles were constantly homogenized under the UV source. Depending on the food matrix, reductions of 0.7–4.8 log cycles were obtained. For meringue chunks, a storage period of 20 h after inoculation prior to UV treatment caused a smaller reduction of the test strain (2.7 log cycles) than when radiation was applied immediately after inoculation (4.8 log cycles). Different initial contamination levels were tested. Higher inoculation levels tended to yield lower reductions. The results demonstrate that Continuous Wave UV radiation can be applied for microbial decontamination of specific powdery and granular food products under continuous homogenization.     

水酶法提取南瓜籽油过程中乳状液酶法联合化学法破乳工艺研究

为提高水酶法提取南瓜籽油的提油率,采用地衣芽孢杆菌碱性蛋白酶并联合化学破乳法对水酶法提取南瓜籽油过程中产生的乳状液进行破乳研究。通过单素试验并结合响应曲面优化试验,得出酶法破乳的最佳工艺为:液料比0.9:1.0(mL/g)、酶添加量3 078U/g、pH 10.4、酶解温度51℃、酶解时间2.5h,验证实验得破乳率为88.39%。酶解破乳后调节pH对乳状液稳定性及破乳率影响的研究发现当酶解破乳后调节pH至4.5时,破乳率增至95.47%。     

Citric acid crystallization process in dense phase using vibrated bed

This study evaluated mass yield, in crystallization of citric acid on a vibrated bed, using a large seed population (dense phase). A stainless steel crystallizer, jacketed and trunk-conical shaped was used in the crystallization experiments. The shaking system consisted of two perforated disks coupled to a mobile axle, which was connected to an eccentric. A central composite design (CCD) was used considering three independent variables: supersaturation level, dimensionless vibration number, and crystallization time, while the seed population (100,000 U) and operation temperature (55 °C) were fixed. Optimization of the experimental data obtained in the CCD was done finding the condition of maximum yield, 164.7%, which was experimentally tested and resulted in yield of 187.7%. An experimental simulation of serial crystallizers was studied, obtaining 166.9% yield, which was effective for obtaining crystals of greater final dimension.     

丝素/丙烯酰胺/丙烯酸吸水复合材料的紫外光辐照法制备

为制备生物相容性和生物降解性较好的丝素/ 丙烯酰胺/丙烯酸类吸水复合材料,在传统丙烯酰胺（AM）/丙烯酸（AA）吸水复合材料中引入丝素蛋白,借助于紫外光活化作用,通过光引发剂结合丝素蛋白中酪氨酸上酚羟基、丝氨酸中醇羟基的H元素,使丝素上产生活性自由基,与丙烯酰胺和丙烯酸单体进行接枝共聚。以冻干法制备了丝素/丙烯酰胺/丙烯酸复合材料。通过测定丝素材料的相对分子质量变化、结构特征、热性能和表面形态结构,分析不同条件下制得的丝素复合膜材料的结构与性质差异,评价复合材料吸水保水性和重复吸水性能。结果表明：在紫外光辐照下,丝素可与丙烯酰胺、丙烯酸接枝共聚,使丝素蛋白分子质量增加;其结构中乙烯基特征峰消 失,热稳定性提高,具有优良吸水保水性和重复吸水性。     

Preparative purification of rebaudioside A from aqueous extracts using chromatography: a process idea

An innovative chromatographic process idea for preparative purification of rebaudioside A from aqueous extracts of Stevia rebaudiana Bertoni leaves is developed. The process can handle high concentrated aqueous extracts, needs less equipment and has a lower solvent consumption compared to the state-of-the-art purification process of rebaudioside A. The innovative process consists of a cascade of three preparative chromatographic columns. The first column separates steviol glycosides from the plant matrix using water as eluent in reversed phase mode. The fraction of steviol glycosides is then concentrated on a second column which works as a capture column with a more non-polar adsorbent. The last column separates rebaudioside A from steviol glycoside under normal phase conditions using a mixture of acetonitrile and water as eluent. With a total yield of 97.5?±?1.5?% and a purity of 97.1?±?1.5?% the process fulfills the legal requirements for the purity of rebaudioside A.     

甲酸/过氧甲酸脱木素及制浆工艺研究进展

甲酸法制浆作为一种具有巨大发展潜力的有机溶剂制浆方法,引起了研究人员的广泛关注。本文主要阐述了甲酸法制浆的特点、反应机理及几种典型甲酸法制浆工艺的研究进展,并对甲酸法制浆在生物质精炼平台的构建方面作了展望。