Accumulation of biopolymers in activated sludge biomass

In this study, activated sludge bacteria from a conventional wastewater treatment process were induced to accumulate polyhydroxyalkanoates (PHAs) under different carbon-nitrogen (C:N) ratios. As the C:N ratio increased from 20 to 140, specific polymer yield increased to a maximum of 0.38 g of polymer/g of dry cell mass while specific growth yield decreased. The highest overall polymer production yield of 0.11 g of polymer/g of carbonaceous substrate consumed was achieved using a C:N ratio of 100. Moreover, the composition of polymer accumulated was dependent on the valeric acid content in the feed. Copolymer poly (3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] was produced in the presence of valeric acid. The 3-hydroxyvalerate (3HV) mole fraction in the copolymer was linearly related tovaleric content in the feed, which reached a maximum of 54% when valeric acid was used as sole carbon source. When the 3HV U in the polymer increased from 0–54 mol%, the melting temperature decreased from 178° to 99°C. Thus, the composition, and hence the mechanical properties, of the copolymer produced from activated sludge can be controlled by adjusting the mole fraction of valeric acid in the feed medium.     

生物质和废塑料混合热解协同特性研究

选取聚丙烯(PP)和竹屑作为废塑料与生物质的典型代表,在热重分析仪和固定床台架上研究了塑料掺混比例对混合热解失重特性、动力学机理、产物分布行为等特性的影响,并分析了混合热解时生物质和废塑料间的协同作用机制。结果表明,随着塑料掺混比例的增加,混合热解终止温度由501℃降低至471℃,主要热解温度区间缩短;混合热解所需活化能呈现先减小后增大的趋势,在塑料掺混比例为0.25时取得最小值。通过对比实验数据和理论数据发现,生物质与废塑料混合热解具有很强的协同作用:该协同作用降低了生物质反应所需能量,增加了废塑料反应所需能量,降低了混合热解过程的总活化能;此外,协同作用促进大分子挥发分转化为小分子气体,促进芳烃、烷烃等烃类生成,抑制CO₂、苯酚、羧酸、呋喃和酮类等含氧物质生成。     

Fast co-pyrolysis of coal and biomass in a fluidized-bed reactor

Co-pyrolysis is one of the most promising options for the utilization of coal and biomass. Coal/biomass blends were prepared using Yilan subbituminous (YL) and corncob and the mass ratios of coal in mixtures varied between 0 and 100 %. Co-pyrolysis characteristics were investigated in a thermogravimetric analyzer from 303 to 973 K under the nitrogen flow of 100 mL min^?1. The co-pyrolysis residues were less than the sum simply added of the solid yields of individuals. With heating rate increased from 10 to 40 K min^?1, the residues decreased more severely compared to the expected under various blending ratios. For fast pyrolysis in fluidized-bed reactor, gas volumes and char yields of co-pyrolysis showed a significant linearity. But pyrolysis-oil yields were higher than the expected from the additive model when the YL blending ratios were less than 60 %. The co-pyrolysis evolved more H₂, CH₄, C₂ + C₃, and less CO than an additive pyrolysis process of individual fuel. The GC/MS results indicated that co-pyrolysis-oil contained more alcohols, ketones, aldehydes, or acids than that of individual fuel. All of that suggested the H/OH in volatiles produced from rapid pyrolysis of biomass transferred to the radicals of coal pyrolysis. The possible reaction mechanism also was provided in the paper.     

烟煤与生物质快速共热解产物特性分析

研究了烟煤(YL)分别与富含半纤维素的玉米芯(CB)和富含木质素的松木屑(SD)快速共热解产物产率和气体组成的变化规律。结果表明,烟煤与生物质共热解组分互相作用,造成共热解气、液、固相产率和气体组成的明显变化,且与生物质种类有关。相对于独立热解过程,玉米芯丰富的半纤维素造成热解水蒸气和CO₂浓度较高,且玉米芯中富含的K元素挥发迁移至煤焦表面,对热解半焦与水蒸气、CO₂的气化反应起到催化作用,反应生成的H₂和富氢组分易与热解生成的自由基结合,抑制自由基之间的缩聚反应,使得共热解气体和液体产率增加,而半焦产率减小。烟煤/松木屑共热解过程中,松木屑中富含的Ca元素在煤焦表面迁移,促进了松木屑热解液体在半焦表面裂解反应,生成CO₂、CO和富氢自由基等轻质组分,造成共热解半焦和液体产率降低而气体产率增加。热解产物半焦、焦油、水蒸气、CO₂之间的气化和裂解反应均产生富氢的次生组分,从而提高了共热解气体中CO和烃类气体产率,降低了H₂产率。     

H2 enriched fuels from co-pyrolysis of crude glycerol with biomass

Pyrolysis of glycerol has been identified as a possible route for producing high added value fuels like renewable hydrogen (H₂). Crude glycerol (CG) is the main byproduct of biodiesel industry and without purification it is a low added value material due to the presence of impurities. Co-pyrolysis of CG with biomass may improve the efficiency of the process and as a primary step of gasification give important information concerning the maximization of H₂ concentration in the produced gas. Moreover, the thermochemical treatment of crude glycerol–biomass mixtures may offer several economic and environmental advantages in biodiesel industry and reduce the cost of biodiesel production. A mixture of CG with olive kernel (OK) was used as pyrolysis feed material. Pyrolysis of a 25 wt% mixture of CG with OK at high temperature (T = 720 °C) seemed to promote steam reforming reactions leading to an increase of H₂ concentration of 11.6 vv% in the pyrolysis gas in comparison to H₂ in gas obtained by low temperature pyrolysis (T = 520 °C).     

生物质与废轮胎共热解催化热解油蒸发过程及其动力学研究

采用热重微商(TG-DTG)法考察生物质稻壳与废轮胎共热解经催化与非催化热解油的热失重行为,并同0#柴油的热失重行为进行了比较;同时采用Achar微分法和Coats-Redfern积分法对热解油热失重蒸发过程的蒸发热进行了计算,并结合Satava和Bagchi法确定了热失重蒸发过程的机理函数, 建立了0#柴油和在催化与非催化条件下得到的热解油蒸发过程的动力学方程,得出了在催化与非催化条件下热解油热失重过程的机理函数,其动力学方程为dα/dt=Ae-△vapH/RT(1-TBX〗α)2;而0#柴油的热失重蒸发过程动力学方程为dα/dt=1.5Ae-△vapH/RT(1-α)2/3\[1-(1-α)1/3\]-1。蒸发热的顺序由大到小依次为,柴油＞非催化热解油＞SBA-15热解油＞MCM-41热解油。结果表明,通过建立的模型函数得到的蒸发热与实验值非常接近。催化剂SBA-15和MCM-41的存在对降低高沸点馏分的物质具有一定作用,而SBA-15催化作用强于MCM-41。     

NOx and N2O precursors from co-pyrolysis of biomass and sludge

Heterobimetallic oxalate complex precursor, Ca₃[La(C₂O₄)₃(H₂O)₄]₂·5H₂O (CaOLa) was synthesized in aqueous medium and characterized by elemental analysis, IR, electronic spectral, and powder X-ray diffraction studies. It is found to be fined crystalline in nature with triclinic symmetry. Thermal studies (TG, DTG, and DTA) in air showed that the departure of aqua ligands completed at ca. 240 °C. A mixture of mainly CaO, La₂O₃, and La₂CaO _x along with a trace of carbides of calcium and lanthanum were identified in the end products at 1,000 °C. The nature of decomposition in nitrogen was explored from DSC study and discussed the evaluated kinetic parameters.     

Low-temperature co-pyrolysis of a low-rank coal and biomass to prepare smokeless fuel briquettes

Smokeless fuel briquettes have been prepared with low-rank coal and biomass. These raw materials have been mixed in different ratios and have been pyrolysed at 600 °C with the aim to reduce both the volatile matter and the sulphur content, and to increase the high calorific value (HCV). The co-pyrolysis of coal and biomass has shown a synergetic effect. The biomass favours the release of hydrogen sulphide during the thermal treatment. This fact can be explained in terms of the hydrogen-donor character of the biomass. Moreover, the optimisation of the amount of binder and the influence of different types of biomass in the blend have been studied with respect to the mechanical properties of the briquettes (impact resistance, compression strength and abrasion). Briquettes prepared with sawdust (S) present better mechanical properties than those with olive stones (O) because of its fibrous texture.     

共热解过程对褐煤焦和生物质焦氧化特性的影响

以锡盟褐煤和玉米秸秆为原料,利用固定床程序升温热解的方法制备了褐煤焦、生物质焦以及褐煤和生物质不同混合比例的共热解焦样,并进行了孔结构和化学结构的表征以及其灰成分分析。采用等温热重法在450 ℃下考察褐煤焦和生物质焦的混合样与其相同比例的共热解焦样的氧化活性,对比分析共热解过程对焦样反应活性的影响。实验结果表明,共热解过程中的二次反应对焦样结构有着明显的影响,进一步导致其反应活性下降。尤其是生物质添加量低于50%时,由于共热解过程生物质中大量挥发分的释放增强了其与半焦的二次反应,促使新生焦中部分小于五环的有机结构向更大的结构转化。但生物质添加量大于50%时,生物质焦的反应活性起主导作用,焦样中碱金属和碱土金属催化作用较明显,特别是钾的影响,使得共热解过程中挥发分与半焦的二次反应对其结构及反应性的影响减弱。     

The influence of side chains on the properties of simple model biopolymers: Monte Carlo simulations

A model for the simulation of proteins is introduced which is based on a new set of bond vectors and a new method for modeling the side chains of proteins. The drawbacks of united atoms models are summarized and the motivation for this new model is given. Some preliminary results are shown which shall demonstrate the suitability of the model proposed.     

原料对自由落下床中生物质与煤共热解行为的影响

在500～700℃和生物质混合比0～100％(质量分数)条件下,利用自由落下床反应器考察原料对生物质与煤共热解行为的影响.所用煤原料为大雁褐煤(DY)和铁法烟煤(TF),而生物质原料为农业废弃物秸秆(LS)和木材加工余料白松木屑(SD).结果表明,即使在自由落下床中停留时间短的条件下,生物质与煤共热解的协同效应仍然发生...     

高密度聚乙烯与两种典型生物质在Y型分子筛上的催化共热解研究

采用固定床反应器,在氢气气氛下研究了高密度聚乙烯(HDPE)与两种典型生物质(杉木、毛竹)(8:2wt%)的共热解及在Y型分子筛上的催化共热解。结果表明,与HDPE单独热解相比,共热解生成的油相液体的碳数分布变窄,使C5-C11汽油馏分的含量显著增加,而C12-C20以及C20 组分相应降低。共热解最高的总液体收率出现在NaY催化剂上,毛竹与HDPE共热解中达到58·9%。在Y型分子筛加入后,共热解水相产物中乙酸含量明显增加,苯酚类产物含量则显著下降。乙酸生成量最多的是USY催化剂,其次是HY、NaY。在USY催化剂作用下,毛竹与HDPE共热解水相液体所含有机物中,乙酸含量达到38·3%。     

The influence of exchangeable cations on the carbonization of biomass

Cations of calcium and potassium added to wood through ion exchange have unique effects on the thermal decomposition of the wood. Addition of calcium ions increases the decomposition temperature of the wood and affects the char yield only slightly, while addition of potassium ions reduces the decomposition temperature and significantly increases the char yield. These effects are distinct from the effects of salts of the same elements added to the same or similar materials through absorption of a solution of the salt. For instance, potassium carbonate absorbed on cellulose significantly increases its decomposition temperature, although it has the opposite effect when added to wood through ion exchange. The primary sites for ion exchange are believed to be glucuronic acids in the hemicellulose fraction, and it is therefore likely that the effects of exchanged cations are due primarily to their influence on the decomposition of this component. When naturally occuring inorganic species are removed from wood by acid washing, the char yield is reduced and the cellular structure of the wood can be lost during carbonization, particularly at high heating rates.     

Effect of alkali and alkaline earth metals on co-pyrolysis characteristics of municipal solid waste and biomass briquettes

Journal of Thermal Analysis and Calorimetry - To investigate the influence of alkali and alkaline earth metals (AAEMs: K, Na, Ca, and Mg) on the co-pyrolysis of municipal solid waste (MSW) and...     

自由落下床中生物质与煤共热解的协同效应对焦油组成的影响

利用溶剂萃取-柱层析方法,将自由落下床中豆秸与大雁褐煤共热解以及单种原料热解的液体产品分为沥青烯、酚类、脂肪烃类、芳香烃类和极性物等组分。结果表明,共热解的沥青烯产率为11.4%,低于根据煤和生物质单独热解的质量加权平均计算值19.0%,且芳香性增大;与计算值相比,低分子量的酚类、甲基苯酚、二甲基苯酚及其衍生物的含量提高了5%;而且长侧链的脂肪烃含量减少。共热解焦油的芳香类组分中十氢萘的质量分数是43.37%,但其在单一原料热解焦油中并没有被检测到。热解油分析结果表明,自由落下床生物质与煤快速共热解过程中存在协同效应,其主要原因是,发生氢解和加氢反应。煤与生物质共热解有利于产生低分子量的化合物,改善油品的质量。     

Applications of biopolymers I: chitosan

Abstract  

Chitosan is prepared from chitin, the second most abundant natural polymer in the world. It is primarily composed of glucosamine and N-acetyl glucosamine residues with a 1,4-β-linkage. It can be obtained by deacetylation of chitin, which is produced from shells of crustaceans, insects, and other sources. Chitosan is a nontoxic, biodegradable, and biocompatible natural polymer and can be used in a wide range of applications such as in the areas of biomedicine, membranes, drug delivery systems, hydrogels, water treatment, food packaging, etc. In this paper, some novel applications of this biopolymer in different fields are reviewed.     

The co-pyrolysis of flame retarded high impact polystyrene and polyolefins

The co-pyrolysis of brominated high impact polystyrene (Br-HIPS) with polyolefins using a fixed bed reactor has been investigated, in particular, the effect that different types of brominated aryl compounds and antimony trioxide have on the pyrolysis products. The pyrolysis products were analysed using FT-IR, GC–FID, GC–MS, and GC–ECD. Liquid chromatography was used to separate the oils/waxes so that a more detailed analysis of the aliphatic, aromatic, and polar fractions could be carried out. It was found that interaction occurs between Br-HIPS and polyolefins during co-pyrolysis and that the presence of antimony trioxide influences the pyrolysis mass balance. Analysis of the Br-HIPS + polyolefin co-pyrolysis products showed that the presence of polyolefins led to an increase in the concentration of alkyl and vinyl mono-substituted benzene rings in the pyrolysis oil/wax resulting from Br-HIPS pyrolysis. The presence of Br-HIPS also had an impact on the oil/wax products of polyolefin pyrolysis, particularly on the polyethylene oil/wax composition which converted from being a mixture of 1-alkenes and n-alkanes to mostly n-alkanes. Antimony trioxide had very little impact on the polyolefin wax/oil composition but it did suppress the formation of styrene and alpha-methyl styrene and increase the formation of ethylbenzene and cumene during the pyrolysis of the Br-HIPS.     

The co-pyrolysis of flame retarded high impact polystyrene and polyolefins

The co-pyrolysis of brominated high impact polystyrene (Br-HIPS) with polyolefins using a fixed bed reactor has been investigated, in particular, the effect that different types of brominated aryl compounds and antimony trioxide have on the pyrolysis products. The pyrolysis products were analysed using FT-IR, GC–FID, GC–MS, and GC–ECD. Liquid chromatography was used to separate the oils/waxes so that a more detailed analysis of the aliphatic, aromatic, and polar fractions could be carried out. It was found that interaction occurs between Br-HIPS and polyolefins during co-pyrolysis and that the presence of antimony trioxide influences the pyrolysis mass balance. Analysis of the Br-HIPS + polyolefin co-pyrolysis products showed that the presence of polyolefins led to an increase in the concentration of alkyl and vinyl mono-substituted benzene rings in the pyrolysis oil/wax resulting from Br-HIPS pyrolysis. The presence of Br-HIPS also had an impact on the oil/wax products of polyolefin pyrolysis, particularly on the polyethylene oil/wax composition which converted from being a mixture of 1-alkenes and n-alkanes to mostly n-alkanes. Antimony trioxide had very little impact on the polyolefin wax/oil composition but it did suppress the formation of styrene and alpha-methyl styrene and increase the formation of ethylbenzene and cumene during the pyrolysis of the Br-HIPS.