聚天冬氨酸制造工艺研究进展

聚天冬氨酸具有高生物可降解性，是一种优良的“环境友好”型阻垢分散剂和缓蚀剂，它是一种新型水处理剂，本文系统地介绍了近年来聚天冬氨酸合成方法的最新研究成果，分析了各种合成方法和反应条件对产品转化率及其性能的影响，概括了控制成产品转化率与摩尔质量的主要因素和产品的分离提纯方法，提出了今后聚天冬氨酸制造工艺研究的发展方向。     

新型改性聚丙烯酰胺的合成及对污泥调理效果的研究

采用原位聚合法,在聚丙烯酰胺的聚合过程中引入金属离子进行改性,合成了一种新型改性聚丙烯酰胺.通过正交实验确定了改性聚丙烯酰胺的最佳合成条件.红外图谱显示,该聚丙烯酰胺是一种具有特殊结构的有机高分子化合物.以污泥脱水率和污泥比阻为考察指标,研究了改性聚丙烯酰胺对污水处理厂剩余活性污泥脱水性能的影响,结果表明,在每1000...     

高分子量高纯度阳离子聚丙烯酰胺的合成

以丙烯酰胺与丙烯酰氧乙基三甲基氯化铵为单体,在复合引发剂的作用下,选择水溶液共聚法合成高分子量与高纯度阳离子型聚丙烯酰胺(CPAM)。实验表明,有机偶氮引发剂A用量0.5‰、氧化还原引发剂用量0.45‰、还原剂与氧化剂摩尔比2∶1、反应体系pH为4与反应时间5 h条件下,CPAM分子量为1 042万,且溶解性好。通过对聚合物残单含量影响因素添加剂用量、反应时间的研究,结果表明,添加剂EDTA和增溶剂D对残留AM含量影响小,而苯甲酸钠对聚合物残留AM的含量影响显著;延长反应时间至7 h,残单含量可降低至0.27%,CPAM的纯度高。通过与国内外3种同类型产品进行对比,结果表明,自制产品的分子量明显高于其他产品,且残单含量比国内产品降低了50%～75%。     

阳离子聚丙烯酰胺类絮凝剂PAD的合成及优化

为了提高阳离子絮凝剂的絮凝性能,选用阳离子疏水表面活性单体DBC和亲水单体AM,以EDTA-2Na为络合剂,以AIBN和APS-NaHSO3为复合引发剂,采用水溶液聚合法制得一种新型阳离子聚丙烯酰胺类絮凝剂P(AM-DBC)(PAD)。此方法具有工艺操作简单、无需添加其他模板和表面活性剂、产物的相对分子质量高和转化率高等优势。单因素实验结果表明,当总单体质量分数为40%、单体摩尔比n(AM)∶n(DBC)=7∶3、pH=4.0、反应温度为60℃、EDTA-2Na的浓度为0.5%时,产物PAD的特性黏数为1 018.7 mL·g~(-1),转化率可达97.2%。采用响应曲面法的Box-Behnken模型对实验参数进行了优化,根据预测出的实验参数,修正后进行了平行实验。当总单体质量分数为42%、EDTA-2Na的浓度为0.56%、pH=4、反应温度为60℃时,合成的PAD的特性黏数为1 027.1 mL·g~(-1),预测值与实验值的误差仅为0.497%,可以较好地吻合,从而得到PAD的最优制备方法。制备的PAD性能优良,为工业化生产提供了依据,可以广泛应用于含油废水的处理。     

高分子絮凝剂SSXA的合成工艺及其在含Cu2+ 废水处理中的应用

以淀粉(ST)、丙烯酰胺(AM)、NaOH、CS2为原料,以硝酸铈铵(CAN)为引发剂合成一种新型的高分子絮凝剂--可溶性淀粉基黄原酸酯-聚丙烯酰胺接枝共聚物(SSXA).以SSXA去除Cu2+性能为依据确定最佳合成条件.结果表明,AM:ST=4:1(摩尔比),ST:NaOH:CS2=2:4:3(摩尔比),黄原酸酯化反...     

过硫酸钾-偶氮复合引发体系合成杂化高分子絮凝剂PACS-PAM及其表征

采用过硫酸钾(K_2S_2O_8)-偶氮二异丁咪唑啉盐酸盐(VA-044引发剂)复合引发体系合成了聚硫氯化铝-聚丙烯酰胺(PACS-PAM)杂化高分子絮凝剂。以特性黏度为指标,考察了引发剂配比、引发剂总用量、单体质量浓度、总铝浓度(AlT)、反应温度和反应时间等因素对杂化絮凝剂PASC-PAM的合成影响,结果表明,杂化絮凝剂PACS-PAM的最佳合成条件为引发剂K2S2O8与偶氮VA-044质量比为3∶1、引发剂总用量为单体总质量的0.2%、单体质量浓度为0.21 g/m L、总铝浓度(AlT)为0.15 mol/L、反应温度为50℃、反应时间为3 h,在最佳条件下合成的杂化高分子的特性黏度为14.70 d L/g。电导率分析、红外光谱(FTIR)分析和热重-差热(DTA-TGA)分析表明,杂化絮凝剂中有机组分同无机组分是通过PAM分子链端的硫酸根离子(—SO2-4)的桥连作用以离子键形式连接的。对黄泥悬浊液的絮凝效果研究表明,杂化絮凝剂PASCPAM的絮凝效果优于复配絮凝剂PASC-PAM。     

聚环氧琥珀酸合成及中试研究

聚环氧琥珀酸（PESA）是一种国际上公认的绿色阻垢剂。实验分析PESA合成过程中的主要工艺参数,如,反应体系pH、温度和时间,对产品阻垢性能的影响,借助中试实验平台,对正交实验结果进行验证和修正。实验结果表明,环氧化过程pH对中间体ESA产率影响显著;聚合反应过程中,体系的温度和反应时间存在关联性。根据自主开发的双反应釜及其反应控制技术,实现了中试规模的PESA化学合成过程温度等反应条件的精确控制,反应副产物减少,中间体ESA纯度高,可达90%以上,系统合成的最终产物PESA 20 mg/L时阻垢性能可达到90%以上,产品具备了较高的阻垢性能水平。     

限氮和限磷对活性污泥合成聚羟基烷酸的影响

聚羟基烷酸(PHA)是微生物在不平衡营养条件下贮存的一种胞内聚合物,限磷和限氮两种方式均有助于活性污泥中的混合菌群合成PHA,研究考察了两种不同方式下活性污泥合成PHA的情况。实验结果表明,当C∶N为125时,活性污泥中PHA的合成量达到细胞干重的59%;当C∶P为750时,活性污泥积累的最大PHA含量占细胞干重的37%,说明限氮和限磷两种方式对活性污泥合成PHA均有很大影响,且限氮方式更有效。     

草甘膦清洁生产研究与实践效果

草甘膦是目前国内外通用的一种高效、低毒、低残留的除草剂.通过对草甘膦生产工艺中主要产生污染物的双甘膦工段的改造,用三氯化磷一次合成双甘膦,可提高反应转化率,降低物料消耗,减少废水排放,达到实现减污增效的目的.     

艰氮和限磷对活性污泥合成聚羟基烷酸的影响

聚羟基烷酸（PHA）是微生物在不平衡营养条件下贮存的一种胞内聚合物，限磷和限氮两种方式均有助于活性污泥中的混合菌群合成PHA，研究考察了两种不同方式下活性污泥合成PHA的情况。实验结果表明，当C：N为125时，活性污泥中PHA的合成量达到细胞干重的59％；当c：P为750时，活性污泥积累的最大PHA含量占细胞干重的37％，说明限氮和限磷两种方式对活性污泥合成PHA均有很大影响，且限氮方式更有效。     

Synthesis of polychlorinated biphenyls (PCBs) using the Suzuki-coupling

An improved synthesis of polychlorinated biphenyls (PCBs) utilizing a palladium-catalyzed cross-coupling reaction (Suzuki-coupling) is described. The coupling of (chlorinated) aryl boronic acids 1-3 with bromochlorobenzenes 4 using the standard conditions of the Suzuki-coupling gave the desired PCB congeners 5-7 in good to excellent yields. The self-coupling product of the aryl boronic acids is the major impurity of this reaction. 3,4,5-trichlorophenyl derivatives such as 10 can be synthesized by coupling of an aryl boronic acid with the corresponding bromochloroaniline 8. The approach offers the advantage of high selectivity and good yields compared to conventional methods such as the Cadogan reaction and allows the use of less toxic starting materials.     

Ultraviolet degradation of methyltins: elucidating the mechanism by identification of a detected new intermediary product and investigating the kinetics at various environmental conditions

The photodegradation of methyltins, as environmental pollutants, has scarcely been studied so far because of the shortage of rapid and sensitive speciation methods, even though they have very simple structures. The photodegradation of monomethyltin trichloride (MMT), dimethyltin dichloride (DMT) and trimethyltin chloride (TMT) was studied with our new developed HPLC-FPD hyphenated system, which enables rapid and sensitive detection of methyltins. The half-life times and kinetic rate constants of their degradation at different pH were calculated. The results suggest that MMT, DMT and TMT can be degraded under the UV irradiation rapidly at different pH, with a degradation rate sequence of TMT相似文献   

添加剂升温烧蚀法在制备新型介孔水环境净化材料中的应用

首次探索了一种破坏式造孔与有机复合相结合的新方法以制备介孔复合水环境净化材料,使最终产品成为一种具有广谱孔结构分布的复合环境材料。详细介绍了该方法的第二步工艺即添加剂升温烧蚀法,在优化后的最佳条件下,产品的孔径得到了进一步扩大,其中部分孔道直径可达至介孔级,同时材料的表面得到了进一步活化。经此步工艺后,所制备的中间产品染料吸附量是原材料的194倍,是酸洗刻蚀后产品的122倍;24h吸湿率是原材料的38倍,是酸洗刻蚀后产品的19倍。     

Emission reduction of aluminium anodising industry by production of Mg2+-Al3+-SO4(2-) -hydrotalcite-type compound

The synthesis of Mg(2+)-Al(3+)-SO(4)(2-)-hydrotalcite-type compound from the acid wastewaters of the aluminium anodising industry has been studied as a possible way of reducing the emissions to the environment, recovering simultaneously resource materials as a valuable mineral. The process of synthesis was carried out using rinse wastewater solutions generated from the anodising treatment when a cascade rinsing system is employed. The method of co-precipitation at constant pH was employed for such a process, using MgO as a source of magnesium. The synthesis was studied as a function of precipitation pH (8-10) and flow rate of reagent mixture (5-30 ml min(-1)). High pH of precipitation and low flow rate of reagent mixture (5-15 ml min(-1)) were found optimal to improve the crystallinity of the synthesised product. The mineral characterisation was performed using X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis and differential thermal analysis, all of which indicated characteristics typical of the desired compound. Almost 100% of the aluminium initially present in the acid wastewater solutions was recovered in the form of Mg(2+)-Al(3+)-SO(4)(2-)-hydrotalcite-type compound.     

Synthesis of polychlorinated biphenyls and their metabolites with a modified Suzuki-coupling

A modified procedure for the synthesis of polychlorinated biphenyls (PCBs) utilizing the Suzuki-coupling, a palladium-catalyzed cross-coupling reaction, is described. The coupling of (chlorinated) benzene boronic acids with bromochlorobenzenes, using Pd(dppf)(2)Cl(2) (dppf = 1,1'-bis(diphenylphosphino)ferrocene) as the catalyst and aqueous sodium carbonate as the base, gave the desired PCB congeners in moderate to good yields. Eleven PCB congeners, including environmentally important PCB congeners and metabolites, were synthesized using this modified procedure. This new catalyst Pd(dppf)(2)Cl(2) offers the advantage of being less air-sensitive and has a longer shelf life compared to Pd(PPh(4))(4). Three new (di-)methoxylated PCB congeners were synthesized using the same procedure by either coupling a chlorinated benzene boronic acid with a bromo (di-)methoxybenzene or by coupling a (di-)methoxy benzene boronic acid with a chlorinated bromobenzene. The dimethoxylated PCB congeners were readily converted into the respective dihydroxylated PCB derivatives using boron tribromide in dichloromethane. This approach offers the advantage of high selectivity and moderate to good yields compared to conventional methods such as the Cadogan reaction and allows the use of less toxic starting materials.     

Effects of trichloroacetic acid on the nitrogen metabolism of Pinus sylvestris--a 13C/15N tracer study

Trichloroacetic acid (TCA) can be found in various environmental compartments like air, rain and plants all over the world. It is assumed that TCA is an atmospheric degradation product of volatile chloroorganic hydrocarbons. The herbicide effect of TCA in higher concentrations is well known, but not much is known about the phytotoxic effects in environmentally relevant concentrations. It can be shown in this study by using the 13C/15N stable isotope tracer technique that [13C]TCA is taken up by roots of two-year-old seedlings of Pinus sylvestris L. and transported into the needles. At the same time the effect of the substance on nitrogen metabolism can be analyzed by measuring the incorporation of 15NO3- into different nitrogen fractions of the plant. The more [13C]TCA incorporation, the higher the synthesis of 15N labelled amino acids and proteins is. These effects on the nitrogen metabolism are probably based on the activation of stress- and detoxification metabolism. It has to be assumed that there is an influence on N metabolism of Pinus sylvestris caused by the deposition of environmentally relevant TCA concentrations.     

Kinetics and pathways for the debromination of polybrominated diphenyl ethers by bimetallic and nanoscale zerovalent iron: effects of particle properties and catalyst

Polybrominated diphenyl ethers (PBDEs) are recognized as a new class of widely-distributed and persistent contaminants for which effective treatment and remediation technologies are needed. In this study, two kinds of commercially available nanoscale Fe⁰ slurries (Nanofer N25 and N25S), a freeze-dried laboratory-synthesized Fe⁰ nanoparticle (nZVI), and their palladized forms were used to investigate the effect of particle properties and catalyst on PBDE debromination kinetics and pathways. Nanofers and their palladized forms were found to debrominate PBDEs effectively. The laboratory-synthesized Fe⁰ nanoparticles also debrominated PBDEs, but were slower due to deactivation by the freeze-drying and stabilization processes in the laboratory synthesis. An organic modifier, polyacrylic acid (PAA), bound on N25S slowed PBDE debromination by a factor of three to four compared to N25. The activity of palladized nZVI (nZVI/Pd) was optimized at 0.3 Pd/Fe wt% in our system. N25 could debrominate selected environmentally-abundant PBDEs, including BDE 209, 183, 153, 99, and 47, to end products di-BDEs, mono-BDEs and diphenyl ether (DE) in one week, while nZVI/Pd (0.3 Pd/Fe wt%) mainly resulted in DE as a final product. Step-wise major PBDE debromination pathways by unamended and palladized Fe⁰ are described and compared. Surface precursor complex formation is an important limiting factor for palladized Fe⁰ reduction as demonstrated by PBDE pathways where steric hindrance and rapid sequential debromination of adjacent bromines play an important role.     

Environmental hazard — Assessment of chemicals and products

Part III: The Limits to Single Compound Assessment The principles and basic assumptions of single compound assessment are briefly reviewed. Limitations to this approach are shown, especially with regard to complex mixtures of similar substances, substitution products, and complicated (final) products containing chemicals and materials produced by the chemical industry. A new thinking in product lines and life cycles is emerging, leading to new assessment methods. In some cases, substitution has not improved the environmental performance of products, since very similar chemicals were used as substitutes.     

Conjoint analysis for environmental evaluation

BACKGROUND, AIM AND SCOPE: Conjoint analysis and the related choice-modelling methods have been used for many years in marketing research to evaluate consumer behaviour and preferences for different kinds of product attributes. Recently, the number of applications in environmental science and management has started to grow. Conjoint analysis is found in many different forms, and the environmental studies evaluated in this review display the same range of methods as in other fields. The key characteristic of all these methods is that trade-offs are evaluated by jointly considering a number of important attributes. MAIN FEATURES: This paper is a review of the literature on environmental applications of conjoint analysis and assesses in which environmental area conjoint analysis has been most successful. The method and the design of the studies are reviewed as well. RESULTS: A total of 84 studies were found, dealing with environmental issues that were evaluated by conjoint analysis. The studies concern agriculture, ecosystem management, energy, environmental evaluation, forestry, land management, pollution, products, recreation, environmental risk analysis and waste management. DISCUSSION: Choice experiments seem to have a comparatively stronger position in environmental studies than elsewhere. Most of the environmental applications are related to natural resource management. This is somewhat surprising, but a number of reports have appeared also on product evaluation, which could be a key application area in the future. CONCLUSIONS: Compared to marketing and transportation, the number of environmental conjoint studies is rather small but increasing, and the method has proven to work effectively in eliciting preferences on environmental issues. In environmental issues, experimenters often use choice experiments, especially concerning ecosystem management and environmental evaluations. When it comes to evaluating preferences concerning agriculture, forestry, energy and products, a more traditional approach of conjoint analysis is favoured. RECOMMENDATIONS AND PERSPECTIVES: Two new areas of application are identified in this review--environmental communication and expert elicitation. Conjoint analysis can thus be developed into a useful instrument for environmental risk analysis and communication, both of which are necessary for an efficient approach to risk governance.