Emission of organic carbon,elemental carbon and water-soluble ions from crop straw burning under flaming and smoldering conditions

Emissions from major agricultural residues were measured using a self-designed combustion system. Emission factors (EFs) of organic carbon (OC), elemental carbon (EC), and water-soluble ions (WSIs) (K⁺, NH₄⁺, Na⁺, Mg²⁺, Ca²⁺, Cl⁻, NO₃⁻, SO₄^2–) in smoke from wheat and rice straw were measured under flaming and smoldering conditions. The OC₁/TC (total carbon) was highest (45.8% flaming, 57.7% smoldering) among carbon fractions. The mean EFs for OC (EF_OC) and EC (EF_EC) were 9.2 ± 3.9 and 2.2 ± 0.7 g/kg for wheat straw and 6.4 ± 1.9 and 1.1 ± 0.3 g/kg for rice straw under flaming conditions, while they were 40.8 ± 5.6 and 5.8 ± 1.0 g/kg and 37.6 ± 6.3 and 5.0 ± 1.4 g/kg under smoldering conditions, respectively. Higher EC ratios were observed in particulate matter (PM) mass under flaming conditions. The OC and EC for the two combustion patterns were significantly correlated (p < 0.01, R = 0.95 for wheat straw; p < 0.01, R = 0.97 for rice straw), and a higher positive correlation between OC₃ and EC was observed under both combustion conditions. WSIs emitted from flaming smoke were dominated by Cl⁻ and K⁺, which contributed 3.4% and 2.4% of the PM mass for rice straw and 2.2% and 1.0% for wheat straw, respectively. The EFs of Cl⁻ and K⁺ were 0.73 ± 0.16 and 0.51 ± 0.14 g/kg for wheat straw and 0.25 ± 0.15 and 0.12 ± 0.05 g/kg for rice straw under flaming conditions, while they were 0.42 ± 0.28 and 0.12 ± 0.06 g/kg and 0.30 ± 0.27 and 0.05 ± 0.03 g/kg under smoldering conditions, respectively. Na⁺, Mg²⁺, and NH₄⁺ were vital components in PM, comprising from 0.8% (smoldering) to 3.1% (flaming) of the mass. Strong correlations of Cl⁻ with K⁺, NH₄⁺, and Na⁺ ions were observed in rice straw and the calculated diagnostic ratios of OC/EC, K⁺/Na⁺ and Cl⁻/Na⁺ could be useful to distinguishing crop straw burning from other sources of atmospheric pollution.     

基于TSAVI的OLI模拟数据翅碱蓬生物量反演研究

翅碱蓬是辽东湾北部滨海湿地一种典型的植被,其生物量的评估对了解滨海湿地生态系统生产力,生态系统机构和功能的形成具有十分重要的作用。而翅碱蓬覆盖度不均一,特别是自然状态下的覆盖度较低,土壤背景影响严重。将基于模拟Landsat 8 OLI数据的转换型土壤调整指数(transformed soil adjusted vegetation index,TSAVI)作为自变量,与地面实测生物量进行回归分析,构建了翅碱蓬群落生物量反演模型。结果表明：TSAVI(红光600～687 nm,近红外820～880 nm)与生物量的相关性显著,相关系数在0.9左右,最高相关系数可达0.92;线性、二次多项式优于对数、指数和幂模型,模型拟合优度r2都为0.83,再结合模型的F值和运算效率,认为线性模型是反演成熟翅碱蓬生物量的最优模型。最后,实现了研究区域Landsat 8 OLI卫星遥感数据翅碱蓬群落生物量反演及模型验证,估算值和实测值的相关系数r为0.962,平均相对误差为0.106,翅碱蓬覆盖度越大,相对误差越低,覆盖度低的翅碱蓬生物量反演的相对误差在0.18左右,表明所建立的线性反演模型在高、低覆盖度时均具有良好的反演精度;此外,还人为地将模型中土壤线系数a和b引入±5%扰动,扰动后的反演结果平均相对误差比较稳定,相关系数有所降低,但都在0.9以上,表明所建立反演模型具有较好的稳定性。     

Simultaneous Multielement Study of the Binding of Metals in Solution by an Algal Biomass,Chlorella Vulgaris

Abstract

The adsorption process of four metals in solution (Pb, Cu, Zn, Cd) to Chlorella Vulgaris will be described and compared to a previous study using three metals (Pb,Cu,Zn) in solution. The binding capacity of Chlorella Vulgaris to four elements simultaneously increases with time, mass of algae, and up to a temperature of about 20.0°C. The equilibrium points for binding three metals simultaneously are at pH=4.55, with 7 mg of algae, and after 2.0 hrs. in a 5 ml aliquot of the solution. In the four metal system, the optimum values are significantly higher while the binding capacity is reduced. The competition between metals for binding sites in the algal cells is governed by kinetic properties as related to the pH, mass of algae, time, and concentration of solution. The binding process is also dependent upon thermodynamics with respect to the temperature of the solution.     

生物质气化技术的研究进展

生物质能是一种可再生能源,它来源于生物体(如植物、动物、微生物等)通过光合作用将太阳能转化为化学能,并以有机物的形式储存。生物质能可以在适当的条件下被转化为热能、电能、生物燃料等,是一种重要的替代传统化石能源的可持续能源。生物质气化作为生物质的开发路径之一,是利用生物质生产合成气的有效方式。本文综述了生物质气化技术的研究,包括传统气化技术、共气化技术、化学链气化技术以及超临界气化技术等。介绍了每个气化技术的实验研究,阐述了各个气化技术的特点;详细介绍了化学链气化中载氧体与共气化中掺杂剂的使用。本文旨在探索使生物质气化效率达到最优的方案,并列举了目前存在的局限性,为进一步发展生物质气化技术以及生物质气化研究提供有益参考。     

Ultrasonication-promoted synthesis of Ni/mayenite for catalytic reforming of biomass tar

Ultrasound-assisted approach was successfully applied for the synthesis of mayenite from calcium and aluminum hydroxides and then subsequently impregnated with Ni by the wet impregnation method. The synthesis was performed with a 13 mm probe-type ultrasound, operating under an acoustic power of 30.5 W and a frequency of 20 kHz. Ultrasound application was studied in detail from a 3^k experimental design, where the variables studied were ultrasound time (10–50 min) and calcination temperature (900–1200 °C). Ultrasound promoted an effective dispersion of the precursors in a short time of 10 min leading to a high conversion to mayenite after calcination at 1200 °C. Ultrasound treatment also had a positive effect on Ni impregnation, increasing the dispersion of the metal in the support and leading to a stronger interaction of nickel-containing species with mayenite support. The use of ultrasound application has proved to be attractive both for catalyst properties and for facilitating catalyst synthesis.     

Hydrogenolysis of benzofuran using aqueous ethanol solution over graphite-supported platinum catalyst

Graphite-supported platinum catalysts (Pt/G) were highly active for the hydrogenolysis of benzofuran to o-ethylphenol in aqueous ethanol solution at 523 K without using any external hydrogen gas. The hydrogenolysis activities and selectivity to o-ethylphenol in ethanol solution over Pt/G were higher than those with a conventional method using externally supplied hydrogen gas. Both water and ethanol were indispensable for the hydrogenolysis in aqueous ethanol solution at 523 K.     

Apparent Kinetics of Co-Gasification of Biomass and Vacuum Gas Oil (VGO)

This communication reports the beneficial effects of co-gasification of biomass and residual oil to produce syngas. In this regard, various blends of glucose (a biomass surrogate) to vacuum gas oil (VGO) have been employed to investigate the synergic effects on the gasification process. The non-isothermal co-gasification experiments were conducted in a thermogravimetric analyzer at different heating rates and gasifying agents. The analysis showed that the co-gasification rate increased with the increase of glucose content in the feedstock. The presence of the oxygen in the biomass molecules helped the overall gasification process. The maximum gasification rate of 42.70 wt/min (DTG_max) was observed with 25 wt% glucose containing sample. The use of gasifying agents appeared to have some influence, especially during high temperature gasification of the glucose-VGO blends. At a same gasification temperature, the co-gasification rate of glucose-VGO blends were found to be 125.7 wt/min and 98.59 wt%/min for N₂ and CO₂, respectively. The kinetics of the co-gasification of glucose-VGO blends was conducted based on modified random pore model using TGA experimental data and implemented in MATLAB. The estimated activation energy and rate constants were found to be consistent to the observed co-gasification rates. The apparent activation energies of co-gasification of VGO/biomass blends with different weight percentages shows values ranging 60.56–48.25 kJ/mol. The kinetics analysis suggested that the addition of biomass helped to increase the reaction rate by lowering the activation energy required for accomplishing the reactions compared with petroleum carbonaceous feedstocks. The reaction rate constants isotherms are plotted to show that the k-values are exhibiting similar trends at moderate heating rates between 20 and 60 °C/min. This remark arises due to the nature of the reactions involved which are considered to be inherently similar in this range of heating rate.     

A new class of plants for a biofuel feedstock energy crop

Directly burnable biomass to be used primarily in steam boilers for power production has been researched and demonstrated in a variety of projects in the United states. The biomass typically comes from wood wastes, such as tree trimmings or the byproducts of lumber production, or from a cash crop, grown by farmers. Of this latter group, the main emphasis has been utilizing corn stover, or a prairie grass called switchgrass, or using tree seedlings such as willow. In this article, I propose an alternative to these energy crops that consists of several different herbaceous plants with the one consistent property that they annually generate and appreciable bulk of dried-down burnable mass. The fact that they are a set of plants (nine are offered as candidates) gives this energy crop a great deal of flexibility as far as growing condition and annual harvest time line. Their predicted yield is impressive and leads to speculation that they can be economically feasible.     

生物质定向气化制合成气—气化热力学模型与模拟

通过对气化炉内反应的热力学模型构建和模拟,探讨了实现生物质定向气化为合成气(H2∶CO=2∶1) 的条件,以便使用该合成气直接合成液体燃料—甲醇.在考虑气化过程中物质平衡、能量平衡和化学反应平衡的 基础上,建立了生物质气化模型,并使用PASICAL语言及其外挂DELPHI程序,编写了FBGB程序,用于模拟生物 质、水蒸气输入量与产气中各种气体组分含量之间的关系.通过模拟,发现水蒸气与生物质输入速率的比值 (S/B)是影响H2/CO值的关键参数.模拟结果显示当其它反应条件确定时,S/B与H2/CO呈线性递增关系,通 过调节S/B,H2与CO的比例可以得到控制.     

Rapid screening of inorganic and organic anions in liquid by‐products from hydrothermal treatment of biomass by capillary electrophoresis

A simple and rapid capillary electrophoresis method with capacitively coupled contactless conductivity detection (CE‐C⁴D) for the simultaneous determination of inorganic and organic anions in liquid product obtained from the hydrothermal treatment of biomass residues is presented. Under the optimal analytical conditions, limits of detection ranged from 1.8 to 9.4 μM for most target solutes and 53 μM for citrate. Relative standard deviations were below 0.5% for migration times and within 0.6–6.5% for peak areas for all solutes. The proposed method was successfully applied for the rapid determination and screening of inorganic and organic anions in liquid product produced following differing hydrothermal treatment temperatures for banana and pineapple biomass, and the contribution of organic acid formation to acidity in the liquid was evaluated. CE‐C⁴D could be a suitable method for the optimization or tailoring of HTT conditions for desired liquid product composition, and additionally for determination of the best variety(s) of biomass to use in such processes.