Sorption and desorption of lindane by wood charcoal in fixed‐bed reactor

Abstract

Sorption and desorption of lindane (y‐HCH) by wood charcoal (WC) and wood charcoal treated by 1N HNO₃ (WCT) in fixed‐bed reactor (FBR) were investigated in this study. WCT revealed a better performance than WC, in removing lindane in FBR. The breakthrough of lindane was significantly affected by the size of WCT, flow rate to the FBR, and depth of WCT bed. The removal of lindane in the presence of mixture of other pesticides was considerably reduced. The design parameters for FBR were calculated based on the bed‐depth service time (BDST) approach. Many parameters Viz. depth of sorption zone, velocity of sorption, sorbent use rate, critical bed‐depth, bed efficiency, and service time, were determined for design of the fixed‐bed. Using the material balance principle, the characteristics of the wave‐front were evaluated and found that the wave‐front velocity is approximately equal to the sorption velocity determined from the BDST approach. Desorption studies were performed in dilute organic solvent media and they gave an excellent performance in regeneration process.     

火龙果果酒酿造工艺技术

研究了以火龙果为原料生产发酵型火龙果果酒的工艺.在单因素试验中,分别以温度、糖度、柠檬酸的添加量及接种量对火龙果果酒发酵特性的影响作了试验.为了进一步优化发酵工艺,选择影响成品酒风味的诸多因素中最大的三个因素--糖度、酸度、接种量做三因素三水平的正交试验.结果表明,柠檬酸添加量对火龙果果酒的发酵影响最大,其次是接种量,最后是糖度.最适控制条件为柠檬酸添加量5g/L、接种量0.20g/L、糖度25%.经过发酵而成的火龙果果酒的酒色诱人、口感醇和、风味独特,具有丰富的营养价值.     

辅料添加对厨余垃圾生物干化产品燃烧热特性的影响

为达到降低厨余垃圾含水率,使其可作为垃圾衍生燃料进行燃烧的目的,选择玉米秸秆和木本泥炭2种辅料与厨余垃圾进行联合生物干化,研究了辅料添加对厨余垃圾生物干化产品燃烧热特性的影响,以不添加任何辅料的厨余垃圾单独进行生物干化作为对照处理,生物干化周期为21 d。结果表明：单独进行厨余垃圾生物干化时挥发性固体(VS)降解率最高,添加木本泥炭处理时VS降解率最低;对照处理对VS降解损失主要的贡献组分为淀粉、纤维素和脂肪,然而,对于添加玉米秸秆和木本泥炭的处理,纤维素、半纤维素和淀粉是VS降解损失主要的贡献组分。随着生物干化反应的进行,物料的燃烧速率和燃烧率均降低,同时燃烬点推后,但燃点基本保持不变。其中,添加木本泥炭的处理燃点最高,燃烬点最低,燃烧率最高。各处理物料燃烧一级动力学方程拟合效果较好(R² =0.86~0.97)。生物干化过程使厨余垃圾单独处理第2失重段反应变难,第3失重段反应变易。然而,对于添加辅料的处理,生物干化过程使第2失重段反应变易,第3失重段反应变更难。总体而言,生物干化过程使各处理的表观活化能(E_m)降低了15.9%~29.4%,使得厨余垃圾的燃烧更加容易。以上研究结果可为厨余垃圾燃料化处理提供参考。     

High efficiency of the NH4H2PO4/Mg(OH)2 composite for guaranteeing safety of wood production

Currently, China's timber industry is in high demand with the development of real estate. However, there is a certain fire hazard in the production process of wood manufacturing. Once a fire occurs, the fire is violent and the spread is rapid. Therefore, to improve the safety of its production process, ammonium dihydrogen phosphate and magnesium hydroxide were selected to prepare a new composite superfine dry powder, which was denoted as the NH₄H₂PO₄/Mg(OH)₂ composite. Furthermore, to figure out dry powders' extinction effect on Class A fire, the wood-crib fire suppression effect of the NH₄H₂PO₄/Mg(OH)₂ composite was test, and then compared with that of ultrafine dry powder (UDP) and commercial ABC dry powder (C-ABC) in a 1 m³ chamber. Three parameters of the fire extinguishing process, namely flame extinction time, powder consumption and temperature drop were adopted to measure the fire suppression performance. The results demonstrated that UDP and C-ABC both had a larger flame extinction time and powder consumption than the NH₄H₂PO₄/Mg(OH)₂ composite. Besides, a fire (wood cribs) can be extinguished by the NH₄H₂PO₄/Mg(OH)₂ composite with the fastest temperature drop and a much-improved toxic gas suppression ability. In short, the NH₄H₂PO₄/Mg(OH)₂ composite can better guarantee the safety of the wood processing production process. Moreover, the reasons for performance advantages of the NH₄H₂PO₄/Mg(OH)₂ composite were discussed.     

全球气候变化下中国林产品的减排贡献：基于木质林产品固碳功能核算

森林及其产品的固碳功能对减缓气候变化具有重要作用。木质林产品（下简称HWP）的碳储存是全球气候变化的重要议题,研究HWP碳储量并对其进行功能管理,对我国政府提高温室气体减排潜力并参与气候谈判、提交国家温室气体排放清单具有重要的现实意义。论文依据政府间气候变化专门委员会（IPCC）建议的HWP碳量核算模型,研究了1961—2011年中国HWP的固碳功能,继而比较分析了中国HWP碳储量的减排潜力。研究表明：从总量看,储量变化法、大气流动法基础上核算的中国2011 年度碳储量值分别为6.76×10⁸ t 碳和2.58×10⁸ t 碳;从年增长量看,储量变化法、大气流动法基础核算的中国HWP碳储量增长平均值为1 063×10⁴ t 碳和262×10⁴ t 碳。基于中国是世界HWP进口大国,储量变化法的选择应用将对我国有利。HWP碳储量减排贡献的研究发现：中国HWP碳储量为森林立木总量的4.75%~8.42%,平均约为6%;对比中国能源消费的年碳排放量值,中国HWP的年碳储量可以减排约1.6%,中国HWP具有显著的碳汇功能及进一步提升的减排潜力。     

Mycogenic decomposition of wood and carbon emission in forest ecosystems

Problems related to biological decomposition of wood and volumes of mycogenic emission of carbon dioxide and carbon in forests of Western Siberia are considered. Annual C-CO₂ emission in the region reaches 31 million tons of carbon, which is equivalent to 116 million tons of carbon dioxide. With respect to the volume of emission, natural zones may be arranged in the following descending series: southern taiga (38%), middle taiga (29%), subtaiga (16%), forest-steppe (10%), northern taiga (6%), and forest-tundra (1%).     

Effects of Acidification and its Mitigation with Lime and Wood Ash on Forest Soil Processes in Southern Sweden. A Joint Multidisciplinary Study

A joint multidisciplinary investigation was undertaken to studythe effects of lime and wood ash applications on two Norway spruce forest Spodosolic soils. The two sites, typical for southern Sweden, were treated in 1994 with either 3.25 t ha^-1 dolomite or 4.28 t ha^-1 wood ash (Horröd site) or in 1984 with either 3.45 or 8.75 t ha^-1 dolomite (Hasslöv site). Both sites show signs of acidification by atmospheric anthropogenic deposition and possessed low soil pH(4.3) and high concentrations of inorganic Al (35 M) in theupper illuvial soil solution. The prevailing soil conditions indicated perturbed soil processes. Following treatment with lime or wood ash, the soil conditions were dramatically altered. Cation exchange capacity (CEC) and base saturation (BS) was considerable increased after addition. Four years after application most of the added Ca and Mg was still present in the mor layer. Fifteen years after application,Mg in particular, became integrated deeper in the soil profile with a greater proportion lost by leaching incomparison to Ca. The concentrations of these ions were greatestin the mor layer soil solutions and Mg had higher mobility givinghigher concentrations also deeper in the profile. Four years after treatment, the application of wood ash and limeresulted in lower pH values and higher inorganic Al in mineral subsoil solutions compared to the untreated soil. We hypothesize that this was probably due to an increased flow of hydrogen ionsfrom the upper soil as a result of displacement by Ca and Mg ionsin the enlarged exchangeable pool. In contrast, fifteen years after lime and wood ash application, the mineral subsoil horizonspossessed a higher pH and lower soil solution Al content than theuntreated plots.Liming promoted soil microbial activity increasing soil respiration 10 to 36%. This is in the same range as net carbon exchange for forests in northern Sweden and could potentially have a climatological impact. The turnover of low molecularweight organic acids (LMWOA) by the soil microbial biomass werecalculated to contribute 6 to 20% to this CO₂ evolution.At Horröd, citrate and fumarate were the predominant LMWOAs with lowest concentrations found in the treated areas. In contrast, at the Hasslöv site, propionate and malonate were the most abundant LMWOAs. Higher microbial activity in the upper soil horizons was also theprobable cause of the considerably higher DOC concentrations observed in the soil solution of ash and lime treated areas. Thelime-induced increase in DOC levels at Hasslöv could be attributed to increases in the 3–10 kDa hydrophobic size fraction. Liming also promoted nitrification with high liming doses leading to extreme concentrations of NO₃ ^- (1 mM) in soil solution.At Hasslöv the community of mycorrhizal fungi was dramatically changed by the addition of lime, with only four of 24 species recorded being common to both control and treated areas.Many of the observed effects of lime and ash treatment can be viewed as negative in terms of forest sustainability. After fouryears of treatment, there was a decrease in the pH of the soil solution and higher concentrations of inorganic Al and DOC. Increased organic matter turnover, nitrification and NO₃ ^-leakage were found at Hasslöv. Considering that the weathering rate and the mineral nutrient uptake by trees is mostprobably governed by mycorrhizal hyphae etchingmineral grains in the soil, it is important to maintain this ability of the mycorrhizal fungi. The lime and ash-induced changed mycorrhizal community structure may significantly affect this capability. In light of this investigation and others, as reviewed by Lundström et al. (2003), the implications ofliming on forest health are multifaceted with complex relationships occurring over both space and time.     

Kickback risk of portable chainsaws while cutting wood of different properties: laboratory tests and deductions

Portable chainsaws are associated with substantial risk and can cause serious injury to operators, especially during kickback. This paper presents new results from research and analyses conducted regarding the impact between the different properties of wood on this occurrence. In an open area, such differences may include: wood species, humidity, temperature and the facing angle of the wood fibres in relation to the kerf and shape of the wood surface that comes in contact with the tip of the guide bar. This paper investigates chainsaw kickback including the research results on kickback and wood-cutting energy, saw chain speed and the efficiency of the chainsaw engine. It also presents conclusions drawn from the tests that can be useful for chainsaw users, showing the dependencies between the different properties of wood and the risk of injury.     

四川射洪硅化木国家地质公园景观特征及成因

四川射洪硅化木国家地质公园不仅硅化木化石数量多，分布集中，且与恐龙化石一起出现，十分罕见，具有重要的科考和旅游价值。硅化木的形成条件是必须有丰富的森林资源和高浓度的含可溶性二氧化硅的矿物质热液。     

薪柴燃烧溶解性棕色碳排放特征及光学性质

对农村薪柴（杨木和毛竹）燃烧排放的4类溶解性棕色碳（BrC）组分,包括水溶性有机物（WSOM）、水溶性类腐殖质（HULIS_WS）、碱溶性有机物（ASOM）和碱溶性类腐殖质（HULIS_AS）的组成特征和光学性质进行了初步研究.结果显示,薪柴燃烧排放出大量的BrC,其中BrC_T（WSOM+ASOM）占烟气PM_2.5质量的46%~56%,排放因子为（7.5~16）g/kg.HULIS是薪柴燃烧排放BrC的重要组分,占BrC_T的44%~46%.4类BrC的特征吸收指数（SUVA₂₅₄）、光吸收效率（MAE₃₆₅）和Ångström指数（AAE）值分别为1.9~4.0m²/g、0.4~2.1m²/g和6.2~11.1,说明薪柴燃烧排放BrC具有较高的芳香度、较强的光吸收能力且其光吸收具有较强的波长依赖性.三维荧光光谱分析结果显示,薪柴燃烧排放BrC主要以类蛋白荧光物质组成为主,这与雨水和大气气溶胶中水溶性BrC以类腐殖质荧光物质组成为主的特征存在显著差异.相关性分析结果显示,BrC的MAE₃₆₅与HIX和SUVA₂₅₄呈现显著的正相关性,与E₂/E₃、FI、BIX和β：α呈现显著的负相关性,说明薪柴燃烧排放BrC的光吸收特性与其芳香性、腐殖化程度、自生源贡献和新鲜度等紧密相关.本研究结果有助于进一步认识生物质燃烧BrC的排放特征,为探索大气BrC的来源和环境效应提供数据基础和科学依据.