Comparison of the pyrolysis behavior of lignins from different tree species

Despite the increasing importance of biomass pyrolysis, little is known about the pyrolysis behavior of lignin—one of the main components of biomass—due to its structural complexity and the difficulty in its isolation. In the present study, we extracted lignins from Manchurian ash (Fraxinus mandschurica) and Mongolian Scots pine (Pinus sylvestris var. mongolica) using the Bjorkman procedure, which has little effect on the structure of lignin. Fourier transform infrared (FTIR) spectrometry was used to characterize the microstructure of the Bjorkman lignins, i.e., milled wood lignins (MWLs), from the different tree species. The pyrolysis characteristics of MWLs were investigated using a thermogravimetric analyzer, and the release of the main volatile and gaseous products of pyrolysis were detected by FTIR spectroscopy. During the pyrolysis process, MWLs underwent thermo-degradation over a wide temperature range. Manchurian ash MWL showed a much higher thermal degradation rate than Mongolian Scots pine MWL in the temperature range from 290–430 °C. High residue yields were achieved at 37 wt.% for Mongolian Scots pine MWL and 26 wt.% for Manchurian ash MWL. In order to further investigate the mechanisms of lignin pyrolysis, we also analyzed the FTIR profiles for the main pyrolysis products (CO₂, CO, methane, methanol, phenols and formaldehyde) and investigated the variation in pyrolysis products between the different MWLs.     

Does Wood Fuel Gathering for Household Use Follow an Optimality Model? A Study from Kakamega Forest,Western Kenya

Successful management of forests, especially in the context of subsistence wood fuel use, can be improved by the application of theoretic models that predict patterns of use. A first step in this approach is understanding the decision rules of people using forests. While optimal foraging theory is normally applied to foraging for food, it also makes sense to apply it in the context of “foraging” for wood fuel. In this study, we applied a time allocation model of optimal foraging theory to wood gathering decisions in communities around Kakamega Forest, a mid-altitude seasonal tropical rain forest. The model predicts that the amount of wood gathered should increase with the distance to the wood source. We found that the predictions of OFT are supported, but only for adults and more strongly on a weekly scale. Based upon the results, we then discuss future improvements of the model to better understand and predict human use.     

塔里木河中下游地区湿地景观格局变化

在RS和GIS技术的支持下,结合塔里木河中下游的区域特点,确定了塔里木河中下游湿地景观分类系统.通过采用景观多样性指数、优势度、景观破碎化指数、分布质心和平均斑块形状指数等景观的空间格局指数,较系统地分析了1980～2000年塔里木河中下游湿地景观空间格局变化.结果表明：塔里木河中下游湿地的分布面积呈显著下降趋势.1980～1990年湿地面积减少,斑块数量和密度增加.1990～2000年湿地面积有所增加,斑块数量和密度持续增加;随着人类干扰强度增加,景观多样性增加,优势度降低,湿地的破碎化程度越来越大;湿地景观要素中,河渠湿地、水库坑塘湿地面积有所增加,而湖泊、滩地、沼泽面积均在不断减少,其中沼泽湿地面积减少幅度最大.     

Biomass–oxygen gasification in a high-temperature entrained-flow gasifier

The technology associated with indirect biomass liquefaction is currently arousing increased attention, as it could ensure a supply of transportation fuels and reduce the use of petroleum. The characteristics of biomass–oxygen gasification in a bench-scale laminar entrained-flow gasifier were studied in the paper. Experiments were carried out to investigate the influence of some key factors, including reaction temperature, residence time and oxygen/biomass ratio, on the gasification. The results indicated that higher temperature favored H₂ and CO production. Cold gas efficiency was improved by > 10% when the temperature was increased from 1000 to 1400 °C. The carbon conversion increased and the syngas quality was improved with increasing residence time. A shorter residence resulted in incomplete gasification. An optimal residence time of 1.6 s was identified in this study. The introduction of oxygen to the gasifier strengthened the gasification and improved the carbon conversion, but lowered the lower heating value and the H₂/CO ratio of the syngas. The optimal oxygen/biomass ratio in this study was 0.4. The results of this study will help to improve our understanding of syngas production by biomass high-temperature gasification.     

Production of hydrogen and methane from potatoes by two-phase anaerobic fermentation

A two-phase anaerobic process to produce hydrogen and methane from potatoes was investigated. In the first phase, hydrogen was produced using heat-shocked sludge. About 12h lag-phase vanished, hydrogen yield increased from 200.4 ml/g-TVS to 217.5 ml/g-TVS and the maximum specific hydrogen production rate also increased from 703.4 ml/g-VSS d to 800.5 ml/g-VSS d when improved substrate was used, in which Cl(-) was substituted for SO(4)(2-). Better performances of 271.2 ml-H(2)/g-TVS and 944.7 ml-H(2)/g-VSS d were achieved when potatoes were pretreated by alpha amylase and glucoamylase. In the second phase, methane was produced from the residual of the first phase using methanogens. The maximum additional methane yield was 157.9 ml/g-TVS and the maximum specific methane production rate was 102.7 ml/g-VSS d. The results showed that the energy efficiency increased from about 20% (hydrogen production process) to about 60%, which indicated the energy efficiency can be improved by combined hydrogen and methane production process.     

Multifunctional Solar Waterways: Plasma‐Enabled Self‐Cleaning Nanoarchitectures for Energy‐Efficient Desalination

Evaporating seawater and separating salt from water is one of the most promising solutions for global water scarcity. State‐of‐the‐art water desalination devices combining solar harvesting and heat localization for evaporation using nanomaterials still suffer from several issues in energy efficiency, long‐term performance, salt fouling, light blocking, and clean water collection in real‐world applications. To address these issues, this work devises plasma‐enabled multifunctional all‐carbon nanoarchitectures with on‐surface waterways formed by nitrogen‐doped hydrophilic graphene nanopetals (N‐fGPs) seamlessly integrated onto the external surface of hydrophobic self‐assembled graphene foam (sGF). The N‐fGPs simultaneously transport water and salt ions, absorb sunlight, serve as evaporation surfaces, then capture the salts, followed by self‐cleaning. The sGF ensures effective thermal insulation and enhanced heat localization, contributing to high solar‐vapor efficiency of 88.6 ± 2.1%. Seamless connection between N‐fGPs and sGF and self‐cleaning of N‐fGP structures by redissolution of the captured salts in the waterways lead to long‐term stability over 240 h of continuous operation in real seawater without performance degradation, and a high daily evaporation yield of 15.76 kg m^?2. By eliminating sunlight blocking and guiding condensed vapor, a high clean water collection ratio of 83.5% is achieved. The multiple functionalities make the current nanoarchitectures promising as multipurpose advanced energy materials.     

A New Hyperspectral Index for Estimating Copper Content in an Indicative Plant for the Exploration of Copper Deposit

Journal of Plant Growth Regulation - With the rapid development of hyperspectral technology, estimating metal content in plants by establishing the relationship between vegetation indices and metal...