Microscopic Visualization of the Enzymatic Degradation of Poly(3HB-co-3HV) and Poly(3HV) Single Crystals by PHA Depolymerases From Pseudomonas lemoignei

As a complement to previous studies of the enzymatic degradation of folded chain lamellar single crystals of polyhydroxyalkanoates, single crystals of a number of polyhydroxyalkanoates were partially degraded with depolymerases from Pseudomonas lemoignei and examined by transmission electron microscopy. Single crystals of bacterial poly(3-hydroxybutyrate-co-3-hydroxyvalerate), bacterial poly(3-hydroxyvalerate), and synthetic poly(3-hydroxybutyrate) with 88% isotactic diads were degraded using purified extracellular PHA-depolymerases from P. lemoignei: PHB-depolymerase A, PHB-depolymerase B, and depolymerases from recombinant E. coli: PHB-depolymerase PhaZ4 (PHB-depolymerase E), PHB-depolymerase PhaZl (PHB-depolymerase C), and PHB-depolymerase PhaZ5 (PHB-depolymerase A). In contrast to previous results with single crystals of bacterial PHB, the predominant effect observed with all crystals was a significant narrowing of the lamellae. This suggests an edge attack mechanism which because of lateral disorder of the crystals leads to a narrowing of the crystalline lamellae as opposed to the splintering effect previously observed. The model suggested for the degradation of single crystals of bacterial PHB by PHB-depolymerases is refined to include the effects of lateral disorder caused by the introduction of valerate or repeat units of opposite stereochemistry into the single crystal.     

Improved enzymatic hydrolysis of waste paper by ozone pretreatment

Waste paper samples made from newsprint, copier paper, and magazine paper, as well as samples of kraft pulp and thermomechanical pulp, were pretreated with ozone to improve enzymatic hydrolysis. The ozone treatment of pulps of newsprint and of magazine paper increased the specific surface areas and total pore volumes while decreasing the lignin content so that these values became similar to those of thermomechanical pulps. These morphological and chemical changes in the pulps resulted in the increased access of cellulase to the pulp fiber surface and increased enzymatic hydrolysis. For copier paper, in which the lignin content was very low, additives on the pulp fiber surface were oxidized and removed by ozone treatment and extraction, and this allowed improved enzymatic hydrolysis. In contrast, surface areas and total pore volumes of kraft pulp and bleached kraft pulp were decreased by the ozone treatment, resulting in morphological changes in the pulps that decreased enzymatic hydrolysis.     

Effects of higher-order structure of poly(3-hydroxybutyrate) on its biodegradation. II. Effects of crystal structure on microbial degradation

As one of a series of studies concerning the relationship between the higher-order structure and the biodegradability of a biodegradable plastic, the effects of the crystal structure of the plastic on microbial degradation were investigated. Bacterial poly(d-(–)-3-hydroxybutyrate) (PHB) films which had a wide range of crystallinity were prepared by the melt-quenching method. Results of the microbial degradation indicated that the development of crystallinity evidently depressed the microbial degradability. From scanning electron microscopy (SEM) observations, it is suggested that the microbial degradation proceeded in at least two manners. One was preferential degradation of the amorphous region leaving the crystalline lamellae intact, which was considered to be a homogeneous enzymatic degradation over the surface. The other was nonpreferential spherical degradation on the surface. The SEMs indicate that the spherical holes were the result of colonization by degrading bacteria. The holes varied in size and number with the change of crystal structure. Therefore, it is considered that the crystal structure of PHB also influenced the physiological behavior of the degrading bacteria on the PHB surface.     

Enzymatic Degradation and Aminolysis of Microbial Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) Single Crystals

Solution-grown single crystals of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] were hydrolyzed by polyhydroxybutyrate (PHB) depolymerase from Ralstonia pickettii T1. Enzymatic degradation proceeded from the edges of lamellar crystals, yielding serrated contour and small crystal fragments. Gel permeation chromatography analysis revealed that the molecular weights of the crystals decreased during enzymatic degradation, suggesting that the enzymatic hydrolysis of chain-folding regions at the crystal surfaces occurred in addition to the enzymatic degradation at crystal laterals or edges. After P(3HB-co-4HB) single crystals were aminolysed in 20% aqueous methylamine solution to remove the folded-chain regions and enzymatic degradation by lipase from Rhizopus oryzae to remove 4HB components at crystal surfaces of single crystal aminolyzed, it was found that a small amount (up to ca. 2 mol%) of 4HB component can be incorporated into the P(3HB) mother crystal lattice irrespective of the 4HB content.     

Processing and Thermal Behaviors of Poly (Butylene Succinate) Blends with Highly-Filled Starch and Glycerol

Fully-biodegradable and highly-filled thermoplastic starch plasticized with glycerol (GTPS)/poly (butylene succinate) (PBS) blends were prepared by Haake Mixer. Processing properties, thermal behaviors including melting and crystallization behavior, crystal structure, and compatibility of the blends were investigated using differential scanning calorimeter (DSC), wide angle X-ray diffractometer (WAXD), scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA). The maximum and equilibrium torques decreased with the rising of glycerol contents and the dropping of PBS contents. GTPS30/PBS blends exhibited double melting endothermic peaks in the DSC thermograms, which related to the crystallization behavior and compatibility of the blends, but no double peaks for GTPS40/PBS. The addition of starch and glycerol could lead to higher crystallinity and lower crystallization rate of PBS, but would not change the crystal types and crystallite sizes of PBS according to DSC and WAXD analysis. SEM and DMA results gave the evidence to confirm the better compatibility of GTPS40/PBS. Besides, higher storage modulus in glassy state of GTPS/PBS blends than PBS could be seen from DMA analysis, which was the contrary in rubbery state.     

Degradation Behaviour and Field Performance of Experimental Biodegradable Drip Irrigation Systems

The field performance of experimental biodegradable drip irrigation thin wall and regular pipes was investigated through three sets of full-scale experiments and in the laboratory. These experimental biodegradable drip irrigation systems were produced through the processing of biodegradable under real soil conditions polymers, Mater-Bi and Bioflex. The mechanical behaviour of the biodegradable thin wall pipes during the irrigation period was more unstable when compared to the corresponding behaviour of the rigid pipes. The tensile strength of the Mater-Bi and Bioflex thin wall pipes remained almost constant during the total exposure time, except from the folding areas. During the first 7–23 days of exposure in the field, the thin wall pipes had already lost more than the 50% of their initial elongation at break value due to degradation. However, their hydraulic performance began to decline only after a period of 100–120 days with the simultaneous formation of the first cracks. Likewise, the majority of the series of biodegradable rigid pipes exhibited a remarkable reduction in their elongation at break values in the transverse direction within the first 2 weeks. Despite the significant drop of the elongation at break, all biodegradable rigid pipes generally retained their tensile strength as well as a satisfactory hydraulic performance during almost the whole duration of their exposure. A few premature leakages in some points adjoining the drippers were observed after 8–10 weeks of exposure.     

A mathematical model for the anaerobic treatment of Baker's yeast effluents

Baker's yeast fermentation produces high strength wastewaters containing high concentrations of organic materials that cannot easily be degraded by biological processes. A two-stage (anaerobic-aerobic) treatment system has been used in order to treat this effluent efficiently. Most of the COD reduction takes place during the anaerobic degradation. The objective of this study was to generate a simple mathematical model for the anaerobic stage. The model, which is based on the elimination of COD, assumes that only three consecutive reactions namely hydrolysis, acidogenesis and methanogenesis are significant. In the laboratory-scale experiments, feed strength was increased from 3600 to 14,000 mg O2 l-1 in a batch reactor. Three reaction rate constants were found as 0.08, 0.004, 0.06 h-1 by analyzing data from the laboratory experiments. The model was tested and found to be congruent with the daily operation data, which were collected from the Pakmaya Baker's Yeast Kocaeli Factory Plant. This plant contains three Upflow Anaerobic Sludge Blanket reactors, which are run in series. The rate constants of the hydrolysis and methanogenesis were similar to the batch experiment case.     

A New and Sound Technology for Biogas from Solid Waste and Biomass

Organic waste, as a main constituent of municipal solid waste, has as well as solid biomass a high potential for biogas generation. Despite the importance of biogas generation from these materials, the availability of large-scale biogas processes lacks behind the demand. A newly developed double-stage solid–liquid biogas process, consisting of an open hydrolysis stage and a fixed-bed methane reactor, allows the biogas production from almost all biodegradable solid waste and renewable resources like maize, grass, sugar cane, etc. Furthermore, residues from industrial processes, like the glycerine waste water from biodiesel production, can also be converted into biogas successfully. Due to the strong separation of hydrolysis and methanation, the process is extremely stable. No malfunction has been detected so far. The open hydrolysis releases CO₂ and allows oxidation of sulfur. Consequently, the biogas has a high methane (>72%) and low H₂S concentration (<100 ppm). Stirrers or other agitation equipment are not necessary; only liquids are pumped. The biogas generation becomes controllable for the first time; thus, the actual generation can be easily adapted to the consumption.     

Effect of the milling solution on lead stabilization in municipal solid waste incinerator fly ash during the milling processes

The wet milling process had been found to effectively stabilize lead in fly ash. This study adopts this method and looks at the effect of different milling solutions to improve the efficiency of lead stabilization. Different milling solutions (water, phosphoric acid and ethanol) and different milling times (1, 24, 48 and 96 h) were selected as parameters. Since lead oxide can be identified by XRD in this experiment’s samples, 5% lead oxide was added to the extracted mixed fly ash to make instrumental analysis easier. The experimental results indicate that the effect of stabilization of lead after milling could exceed 96%. During milling with water, considerable lead leached into the water in the initial stage (1 h) of the process, but a stable level was reached as the milling time increased. After milling with ethanol and 0.2 M phosphoric acids, the efficiency could exceed 93% after 1 h of milling time. The results of the sequential extraction procedure (SEP) results show that the residual fraction could be increased from 8.93% to 56.16% when a 0.2 M phosphoric acid solution was used. Clearly the choice of an appropriate milling solution can enhance lead stabilization in the fly ash.     

零价铁-克雷伯氏菌联合体系对亚甲基蓝溶液的脱色性能

以零价铁(ZVI)和一株高效脱色菌克雷伯氏菌yl-1作为联合体系,研究其对亚甲基蓝溶液的脱色性能,并采用单因素实验及中心组合设计-响应面分析法(CCD-RSM法)对该过程的脱色条件进行优化。实验结果表明:相比于单独ZVI体系和单独yl-1脱色菌体系,ZVI-脱色菌联合体系的脱色率分别提高了40%和10%;在初始pH为8、初始亚甲基蓝质量浓度为250 mg/L、ZVI投加量为4.0 g/L、反应温度为33℃的最优条件下,ZVI-脱色菌联合体系对亚甲基蓝脱色反应液的脱色率为91.33%。     

Corrosion behavior of glass and glass-ceramics made of municipal solid waste incinerator fly ash

Glasses and glass-ceramics were prepared by melting municipal solid waste (MSW) incinerator fly ash and their corrosion properties were evaluated. Corrosion of both materials proceeded in two different steps. At the initial stage, the corrosion process is a diffusion-controlled process. After approximately 10 h at the initial stage, weight losses increased linearly with time due to the total dissolution of glasses or glass-ceramics. Leaching of heavy metals from glasses and glass-ceramics were well within international environmental regulations. Corrosion proceeded uniformly in fly ash glass while Na2CaSiO4 crystalline phase was preferentially dissolved in the glass-ceramics.     

Thermal Properties and Crystallization Behavior of Novel Biodegradable Poly(hexamethylene succinate-<Emphasis Type="Italic">co</Emphasis>-6 mol% butylene succinate) and Poly(hexamethylene succinate)

In this research, the thermal properties and crystallization behavior of novel poly(hexamethylene succinate-co-6 mol% butylene succinate) (PHBS) and its homopolymer poly(hexamethylene succinate) (PHS) were extensively studied. With respect to PHS, the introduction of a small content of butylene succinate (BS) unit slightly reduces the melting point and equilibrium melting point but hardly influences the glass transition temperature of PHBS. Despite crystallization temperature, PHS and PHBS crystallize through the same crystallization mechanism. At the same crystallization temperature, PHBS crystallizes more slowly than PHS; furthermore, lowering crystallization temperature enhances the crystallization rates of PHBS and PHS. The spherulites morphologies were observed for both of them, with the spherulites nucleation density of the copolymer being smaller than that of the homopolymer. PHBS and PHS share the same crystal structures, indicative of the location of BS unit in the amorphous region.     

模拟氯化钠盐渣的高温处理

采用高温处理法对模拟氯化钠盐渣（简称盐渣）进行处理，研究了加热过程中气体有机物产生量随加热时间的变化规律以及加热温度对气体有机物产生量的影响，并分析了盐渣的高温处理效果。实验结果表明：含苯盐渣、含异丁醇盐渣、含氯苯盐渣、含二甲苯盐渣和混合盐渣在高于盐渣中所含有机物沸点30 ℃的条件下加热120 min，盐渣中的有机物去除率均大于99.99%;混合盐渣的加热温度越高，气体有机物的产生速率越快，相同时间内有机物的去除率也越大;盐渣中有机物的气化分离可分为3个阶段，初始阶段有机物气化速率较小，中间阶段气体有机物产生量迅速增加，最后阶段大部分有机物从盐渣中气化分离;盐渣中的有机物在高温气化时，会发生一定的化学反应，有微量的新物质生成。     

Bioremediation of Stranded Oil on an Arctic Shoreline

The application of slow-release and soluble fertilizers proved to be an effective and environmentally benign way of stimulating oil biodegradation on an Arctic shoreline. Fertilizer application to the surface of the beach delivered nutrients to the oiled sediment beneath the beach surface. There was no significant run-off of this fertilizer to either the nearshore water or to unfertilized plots, and there were no adverse toxicological effects of the fertilizer application. The fertilizer application was followed by an increase in oxygen consumption and carbon dioxide evolution from the beach, increased microbial biomass, and significantly greater biodegradation of oil on the plots that had received fertilizer. The rate of oil biodegradation was approximately doubled over the course of a year by fertilizer applications in the first two months after the spill.Simple test kits proved adequate to monitor the fertilizer-application process in the field in a time frame that would allow the application process to be fine-tuned during treatment on a real spill. Simple test kits and portable instrumentation were useful in demonstrating the initial success of the bioremediation strategy.     

Natural Weathering Studies of Polypropylene

Polypropylene (PP) has achieved a dominating position and hence, their consumption increases thereby littering, which lead to environmental pollution. Photodegradation seems to be a better choice because of naturally available sunlight as energy source for degradation. The present work involves the study of the variation of degradation behavior of PP film during tropical summer and winter seasons. The photodegradation is followed by Fourier transform infrared (FTIR) spectroscopic technique. Various indices like hydroxyl, carbonyl, vinylidene, lactones, ester, carboxylic acid and crystallinity are calculated and these values increased after a brief induction period. The variation in the mechanical properties like tensile strength and elongation at break percentages are determined. The scanning electron microscopic (SEM) images of weathered PP showed surface cracks when carbonyl index value increases sharply and the mechanical properties show a sudden decrease. Attempted life time prediction using mathematical models showed that the carbonyl growth is more affected by ultraviolet (UV) and cumulative total solar radiation for PP weathered during summer. The loss in tensile strength of PP weathered during summer is more dependent on the average temperature and the UV portion of the total solar radiation whereas, intensity of UV radiation has profound effect on the tensile strength of PP weathered during winter.     

甲胺磷生产废水处理试验研究

提出三条处理甲胺磷生产废水的工艺路线：（１）胺化废水脱氨处理,甲基氯化物废水水解处理,然后混合生化处理;（２）胺化废水脱氨处理后与甲基氯化物原水混合一段生化处理;（３）胺化废水脱氨处理后与甲基氯化物原水混合二段生化处理。对影响废水脱氨、有机磷水解率和生化处理效果的各种因素进行了试验研究,分析了甲胺磷废水水解生成物,筛选出生化处理甲胺磷废水的优势菌种。     

Isolation and Characterization of Nanocrystalline Cellulose from Totally Chlorine Free Oil Palm Empty Fruit Bunch Pulp

Nanocrystalline cellulose (NCC) was isolated from a totally chlorine free (TCF) bleached oil palm empty fruit bunch (OPEFB) pulp via acid hydrolysis using a 58 % sulfuric acid concentration and ultrasonic treatment. The effects of acid concentration and hydrolysis time were investigated. Characterization of OPEFB–NCC was carried out using TEM, FTIR, ¹³C-NMR, XRD, zeta potential and TGA. The optimal hydrolysis time was 80 min as indicated by the leveling off of the OPEFB–NCC dimensions (length 150 nm and diameter 6.5 nm) with no significant loss of crystallinity at this point. The presence of a shoulder peak at 1231 cm^?1 (assigned to a sulfate group) in the FTIR spectrum of NCC is indicative of a successful esterification. This is further corroborated by the ¹³C-NMR analysis whereby the distinct C4 amorphous and crystalline peaks present in OPEFB–TCF pulp had almost disappeared and the cluster of signals for C2, C3, C5, and a well separated signal of C6 had merged into one single peak in the OPEFB–NCC sample. These observations allude to most of the amorphous region having been removed and to the strong possibility of sulfonation having not only occurred on the C6, but also on C2 and C3. OPEFB–NCC isolated over shorter hydrolysis time was more thermally stable; however, the char fraction decreases with hydrolysis time despite having a higher zeta potential. The results of this investigation demonstrate that NCC can be produced from pulp made by chlorine free environmentally benign processes with ensuing savings in energy and chemicals.     

微波诱导水解法制备纳米TiO_2及光催化降解盐酸四环素

采用微波诱导水解法快速制备了纳米TiO_2光催化剂,通过XRD、TEM、SEM、BET和EDS技术对其进行了表征。该方法可在10 min内制备出平均粒径约7.5 nm的锐钛矿相纳米TiO_2。采用该催化剂(加入量0.5 g/L)对盐酸四环素(TC,100 mg/L)进行紫外光催化降解,40 min时降解率高达92.9%,60 min时TOC去除率为81.7%,明显优于市售P25纳米TiO_2。这主要归功于所制备纳米TiO_2表面残留的有机物提高了光生电子-空穴对的分离能力,以及纳米粒子的小尺寸效应和较大的比表面积。溶液p H为9时TC的降解率更高。该催化剂具有较好的光催化稳定性。活性基团捕获实验表明,纳米TiO_2光催化降解TC过程中空穴起主要作用。     

薄膜负载型TiO_2光催化降解乙酸

利用TiCl_4水解法在玻璃表面制备纳米TiO_2光催化膜,考察了TiO_2光催化膜对乙酸光催化降解过程的影响因素.实验结果表明:使用活化温度为460℃、镀膜4次、表面积168 cm~2的TiO_2光催化膜处理500 mL0.667 mmoL/L的乙酸350 min时,乙酸降解率为80.0%,与等量TiO_2粉末相比光催化膜活性显著增加;当乙酸初始浓度c_0小于0.667 mmoL/L时,光催化降解过程可用Langmuir-Hinshelwood动力学方程来描述;TiO_2膜连续使用5次(30 h)时的光催化活性基本不变;用质量分数为5%的HCl溶液浸泡失去活性的光催化膜1 h,TiO_2光催化膜的活性可完全恢复.     

采用络合萃取法从维生素B12发酵废液中回收丙酸

采用络合萃取法回收维生素B12发酵废液中的丙酸,确定了络合萃取的最佳工艺条件：以0．5mol／L的磷酸三丁酯(TBP)为络合剂,油水比(体积比)为1：2,常温下萃取30min。在最佳工艺条件下单级萃取率为56％左右,四级萃取率可达98％以上。络合萃取过程中使用的有机溶剂可反复使用,使成本大大降低。