水热生物炭燃烧特性与动力学分析

采用热重法对锯末、玉米秸秆水热生物炭燃烧特性及动力学进行了研究,考察了不同升温速率(10、20、40℃/min)对燃烧特性的影响,分析了它们的燃烧特性及动力学参数。结果表明:1)水热炭化前后生物质燃烧质量损失集中在挥发分和固定碳燃烧阶段,升温速率快,着火温度、燃尽温度高,整体向高温区转移,综合燃烧特性指数越大;2)40℃/min时,锯末水热生物炭综合燃烧特性指数远大于玉米秸秆,在其余升温速率下区别不明显;3)以20℃/min相同升温速率时,锯末、玉米秸秆水热生物综合炭燃烧特性相对于未炭化生物质下降27%、13%;4)采用一级反应动力学模型和积分法对水热生物炭燃烧动力学进行了研究,一级反应动力学能很好的描述2种生物炭的燃烧动力学,相关系数(R2)均高于0.9,挥发分阶段活化能大于固定碳阶段的活化能。研究结果可为水热生物炭的燃烧应用能提供理论指导。

水热生物炭基材料催化活化过氧单硫酸盐去除水中难降解有机物的研究进展

基于过氧单硫酸盐(PMS)的高级氧化工艺(AOPs)在高效去除难降解有机污染物的领域中具有广阔的应用前景。生物炭是可再生或废弃生物质碳化的固体产物,水热碳化是生物质资源化的低耗能过程,它的主要产物是水热生物炭(HC)。由于HC具有丰富的表面官能团,同时在制备过程中其表面组成和结构较易进行优化调控,HC作为一类新兴碳基功能材料用于催化活化PMS的AOPs过程对于难降解有机污染的高效去除提供了新的途径。文中从HC的生物质来源、合成方法及其活化PMS的机制、影响因素和应用等方面,阐述了HC/PMS体系去除水环境中难降解有机污染物的研究进展,并提出了该研究领域中亟需解决的问题和HC催化活化PMS研究的未来发展方向。

不同生物质原料水热生物炭特性的研究

以木屑、小麦秸秆和玉米秸秆为原料,采用水热法制备生物炭,研究不同生物质水热生物炭特性,分析了水热生物炭的产率、元素组成、表面特性、多环芳烃含量及表面官能团的变化。结果表明:以木屑为原料制备的水热生物炭产率最高(54.66%),C含量(52.59%)较水热小麦和玉米秸秆生物炭(分别为43.73%和43.93%)高,但O含量(41.56%)明显低于水热小麦和玉米秸秆生物炭(分别为49.94%和50.95%)。扫描电镜显示水热木屑生物炭表面光滑,孔状结构较多且排列整齐,水热小麦生物炭表面粗糙孔隙较少,而水热玉米生物炭孔隙结构不明显。傅里叶红外光谱分析显示原料经水热炭化后官能团种类差异不大,但相对含量发生了变化:水热小麦和玉米秸秆生物炭有机官能团含量相对增加,而无机矿物(如SiO2)含量略有减少;水热木屑生物炭有机官能团和无机矿物的含量均明显增加。采用气质联用仪(GC-MS)分析水热生物炭多环芳烃含量,结果表明三种水热生物炭总多环芳烃含量依次为水热小麦秸秆生物炭>水热木屑生物炭>水热玉米秸秆生物炭,并以菲和萘为主。

不同反应条件下番茄秸秆水热生物炭的理化性质和微观结构变化

为探究炭化温度和裂解时间对番茄秸秆水热生物炭(TSHB)微观结构、理化性质、主要成分及炭化效率的影响,并获得高效的炭化条件,采用低耗能的水热炭化法将番茄秸秆裂解为番茄秸秆水热生物炭。设置3个炭化温度(180、220、260℃)和4个裂解时间(2、4、6、8 h),共12个处理,研究不同组合的炭化温度和裂解时间对番茄秸秆水热生物炭形貌结构、功能基团、pH值、电导率(EC值)、生物炭成分的影响,并分析番茄秸秆水热生物炭主要成分的变化。结果表明,番茄秸秆多孔且中空的维管束结构有利于水分和热量在番茄秸秆内部的快速传递,增加水热炭化温度能加速破坏番茄秸秆维管束结构和将条状番茄秸秆炭化为颗粒状水热生物炭。番茄秸秆水热生物炭的功能基团主要是脂肪醚C-O、烷烃C-H、饱和脂肪酸酯C-O、胺C-N以及细胞壁基团C-O、C=O、C-N、C-O-C。提高炭化温度可增加番茄秸秆水热生物炭功能基团数量,但炭化温度达到260℃时,明显破坏且大幅度减少番茄秸秆水热生物炭功能基团数量。水热炭化法制备的番茄秸秆水热生物炭为酸性生物炭(pH值5.13~5.33)。在相同的裂解时间下,相较于180℃和260℃炭化温度,220℃炭化温度制备的番茄秸秆水热生物炭均获得最高的EC值(6 213~7 899μs/cm),但裂解时间从2 h延长到8 h,番茄秸秆水热生物炭EC值大幅下降18.19%~26.92%。提高炭化温度和延长裂解时间均显著增加番茄秸秆水热生物炭固定碳含量(2.23~27.99个百分点),但降低番茄秸秆水热生物炭挥发分含量(2.46~30.97个百分点)。提高炭化温度能增加番茄秸秆水热生物炭的总有机碳含量及全氮、灰分含量,增加幅度分别为10.63~29.91、0.58~0.87、1.82~3.09个百分点。综上,相对于延长裂解时间,提高水热炭化温度能更有效地提高番茄秸秆的炭化效率,增加番茄秸秆水热生物炭的氮氧功能基团数量及固定碳、全氮含量。水热炭化温度是决定番茄秸秆水热生物炭微观结构、功能基团、pH值、主要成分的关键因素,220℃炭化温度和4~6 h裂解时间是水热炭化法制备番茄秸秆水热生物炭较为合适的炭化条件。

秸秆水热生物炭燃烧特性评价

为推动水热生物炭燃料化利用,以不同水热炭化温度(200、240、280、320、360℃)下得到的小麦秸秆水热生物炭为原料,利用生物炭化学组成、动力学参数、燃烧指数对水热生物炭燃烧特性进行了评价,并研究了水热炭化温度对燃烧特性的影响。研究结果表明,随着水热炭化温度由200℃增加到360℃,由于脱水、脱羧反应的发生,水热生物炭的燃料比由0. 34增加到1. 2,O/C和H/C物质的量比分别由0. 5、1. 17降至0. 07、0. 67,水热生物炭的煤化程度升高;水热生物炭在低温段、高温段的活化能分别由14、67 k J/mol增加到41. 4、76. 5 k J/mol,水热生物炭燃烧反应活性降低;无量纲燃烧指数Z由3. 49×10-2降至6. 64×10-3,表明燃烧反应活性降低,这与化学组分和表观活化能的评价结果一致,指数Z可用于衡量水热生物炭的燃烧活性。

水热生物化学

从水热生物化学角度阐述了水热条件下生命起源的可能性,并综述了化学合成,微生物学,分子系统树,海洋考察等方面的证据以及水热生命起源模型.通过模拟原始环境,由无机小分子出发合成一系列有机生物分子,实现了有机生物分子的非生物合成,并探讨了此过程中的手性起源问题.

Prediction of Structure-H Gas Hydrate Formation Conditions for Reservoir Fluids

In this work, a thermodynamic model is developed for prediction of structure H hydrate formation. The model combines the Peng-Robinson equation of state for the vapor, liquid and aqueous phases with the extended Ng-Robinson hydrate model for gas hydrate formation of all three structures. The parameters of 14 structure- H hydrate formers are determined based on the experimental data of structure-H hydrates in the literature. The expression of fugacity of water in the empty hydrate phase is correlated for calculating structure-H hydrate formation conditions in the absence of free water. The model is tested by predicting hydrate formation conditions of a number of structure-H hydrate forming systems which are in good agreement with the experimental data. The proposed model is also applied to the prediction of hydrate formation conditions for various reservoir fluids such as natural gas and gas condensate.

Antioxidant and isozyme features of two strains of Laminaria japonica (Phaeophyceae)

Healthy sporophytes of two gametophyte mutants of Laminariajaponica with different heat resistances： kelp 901 （901, with comparatively stronger heat-resistance） and Rongcheng No. I （RC, sensitive to heat stress）, were respectively collected during October to December 2002 from Yantai and Rongcheng Sea Farm in the Shandong Peninsula of China. The contents of some biochemical materials and antioxidant capacity were analyzed under controlled laboratory conditions to identify if there is any relation between the overall antioxidant capacity and the heat-resistance in L. japonica and to understand possible mechanism of heat-resistance. Results show that： （1） the overall antioxidant capacity in healthy sporophyte of 901, such as vitamin E, polyphenol, and ascorbic acid contents and the enzymatic activity of SOD, POD, CAT, Gpx, PPO, and PAL, were not always higher than that of RC under controlled laboratory conditions, and no significance （P〉0.05） was shown in total antioxidant capacity （T-AOC） in 901 and RC. Result suggested that the difference in antioxidant capacity was not a decisive factor for different heat-resistances in L. japonica; （2） the simultaneous assay on isozymes was carried out using vertical polyacrylamide gel electrophoresis （PAGE）. Considerable differences in peroxide （PRX）, malate dehydrogenase （MDH）, malic enzyme （ME）, polyphenol oxidase （PPO） and glutamate dehydrogenase （GDH） were obtained in 901 and RC from either the band number, relative mobility （Rf）, or staining intensity, and ME could be used as an indicator to distinguish healthy sporophyte of 901 and RC under controlled laboratory conditions.

Life cycle cost analysis of new FRP based solar parabolic trough collector hot water generation system

Parabolic trough collectors （PTCs） are employed for a variety of applications including steam generation and hot water generation. This paper deals with the experimental results and an economic analysis of a new fibre reinforced plastic （FRP） based solar PTC with an embedded electronic controlled tracking system designed and developed for hot water generation in a restaurant in Madurai, India. The new collector performance has been tested according to ASHRAE Standard 93 （1986）. The performance of a new PTC hot water generation system with a well mixed hot water storage tank is investigated by a series of extensive tests over ten months period. The average maximum storage tank water temperature observed was 74.91℃, when no energy is withdrawn from the tank to the load during the collection period. The total cost of the new economic FRP based solar PTC for hot water generation with an embedded electronic controlled tracking system is Rs. 25000 （US$ 573） only. In the present work, life cycle savings （LCS） method is employed for a detailed economic analysis of the PTC system. A computer program is used as a tool for the economic analysis. The present worth of life cycle solar savings is evaluated for the new solar PTC hot water generation system that replaces an existing electric water heating system in the restaurant and attains a value of Rs. 23171.66 after 15 years, which is a significant saving. The LCS method and the MATLAB computer simulation program presented in this paper can be used to estimate the LCS of other renewable energy systems.

Characterization of Thailand Rice Husk Ash from Biomass Power Plant and Synthesized Zeolite

Thailand rice husk ash was used to synthesize zeolite by hydrothermal treatment. Raw rice husk ash material and zeolitic products were characterized in terms of specific surface area （BET method）, morphological analysis （SEM）, mineralogical composition （XRD） and CEC （cation exchange capacity）. LOI （Loss of ignition） of rice husk ash was also evaluated. Result indicated that the rice husk ash sample from Roi-Et Green power plant in the Northeastern of Thailand with combustion temperature of 650 ℃ has a high content of SiO2 （above 90 wt.%）. Zeolite-X from rice husk ash with high content of Si was successfully synthesized using hydrothermal treatment. The zeolitic material synthesized with the optimal condition possessed a maximum value of CEC of 503 meq/100g, and it has potentiality to be used as ion exchangers.

Capturing Heat from a Batch Biochar Production System for Use in Greenhouses and Hoop Houses

Biochar is charcoal produced at comparatively high temperature and used as an agricultural amendment, which also sequesters carbon. Most of the research on biochar manufacture in the United States has either focused on large-scale continuous systems with multiple products or small batch systems with biochar as the only product. At James Madison University in Harrisonburg, Virginia, we have worked on a batch system to make high quality biochar while capturing the heat for use either as a backup system for hot water heating, or to heat a greenhouse in winter. The system is now in its third iteration. In the first, we used a small intramural grant to experiment with low cost material using a minimalist design. While the unit captured some heat, operation of the design was smoky and hazardous to handle. The second design, funded by a larger intramural research grant, captured considerable heat, made 8-10 kg of biochar per burn and captured up to 250 MJ per batch of biochar made, but remained smoky. The third generation pyrolysis unit was constructed on Avalon Acres Farm in Broadway, Virginia, funded by a 25 × 25 grant through James Madison University （JMU）. This unit makes the same amount of biochar, with less smoke, and sends the captured heat to a storage tank to help heat a greenhouse and home on the site. Our average efficiency of heat transfer is 12.5% of the total heat value of the starting woody biomass, a number we believe can at least double.

Studies on Partial Molar Volumes of Some Amino Acids and Their Groups in Aqueous Solutions from 293.15K to 333.15K

Densities of aqueous solutions of eight amino acids, glycine, L-alanine, L-valine, L-isoleucine, L-serine, L-threonine, L-arginine and L-phenylalanine, are measured as a function of amino acid concentration from 293.15K to 333.15K. These data are used to calculate the apparent molar volume Vφ and infinite dilution apparent molar volume Vφo (partial molar volume). Data of five amino acids are used to correlate partial molar volume Vφo usinggroup contribution method to estimate the contributions of the zwitterionic end groups (NH3+,COO-) and CH2 group, OH group, CNHNHNH2 group and C6H5(phenyl) group of amino acids. The results show that Vφo values for all kinds of groups of amino acids studied increase with increase of temperature except those for CH2 group, which are almost constant within the studied temperature range. Data of other amino acids, L-valine, L-isoleucine and L-threonine, are chosen for comparison with the predicted partial molar volume Vφo using the group additivity parameters obtained. The results confirm that this group additivity method has excellent predictive utility.

Depth distribution and ecological preferences of periphytic algae in Kenyir Lake,the largest tropical reservoir of Malaysia

We studied the depth distribution of periphyton,growing on inundated dead trees in Kenyir Lake,Malaysia in June 1995.The algal floral composition and structure manifested changes down the depth gradient in terms of species richness,abundance,diversity and cell density.In regression analysis,all these algal attributes were negatively correlated with the depth gradients at P<0.05.In terms of species richness,the bacillariophytes showed dominance over the cyanophytes and chlorophytes;whereas with respect to standing crop,the cyanophytes showed dominance over the bacillariophytes and chlorophytes.The chlorophyll a was higher at the mid and bottom-depths than the surface-depth in both the downstream and upstream sites,which showed that vertical productivity or biomass accumulation was greater in low light irradiance.The product-moment correlation analysis showed that conductivity,turbidity,dissolved oxygen,reactive phosphate and ammonium-nitrogen were highly correlated with the algal assemblage data.However,photosynthetic active radiation(PAR) showed poor correlation with the community data.These observations have cast some light on the autoecological characteristics,habitat preferences and environmental responses of tropical periphytic communities.

Effect Mechanism of Structure-Changed Water on Heat Stability of Lysozyme

Based on the mechanism of the effect of hydration on the heat stability of lysozyme and the theory of water molecule clusters, the effect of structure-changed water on heat stability of lysozyme has been studied. The results obtained by differential scanning calorimetry (DSC) showed that the thermal denaturation temperature of lysozyme had been elevated 8.47 K through hydration of lysozyme with processed water whose structure had been changed so it was called "structured water" compared to ordinary water. The reason is that structured water changed the dipole moment of water molecules and easily formed cyclic water hexamer or cage-like water hexamer, so that the interacting force of maintaining three-dimensional conformation of lysozyme could be reinforced.

水热体系中的凝聚态及化学反应

水是一种清洁、安全、环境友好的化学反应介质,认识水介质体系中水的性质及水热化学反应对凝聚态化学的研究至关重要。水热条件下的水处于高温高压状态,其物理化学性质往往与常态下的水完全不同;因此,水热体系中可进行的化学反应范畴大为拓宽。本文介绍了水分子及其团簇的结构,水性质随条件变化的规律和特点以及水热体系中的凝聚态问题,综述了水热体系中典型的材料合成、水热有机化学反应、生物水热合成等内容,梳理了凝聚态和水热化学之间的关系,期望从凝聚态化学的角度为理解水热化学及反应体系提供一些新的思路。

Water-Extractable Carbon Pools and Microbial Biomass Carbon in Sodic Water-Irrigated Soils Amended with Gypsum and Organic Manures

Microbial biomass carbon (MBC), a small fraction of soil organic matter, has a rapid turnover rate and is a reservoir of labile nutrients. The water-extractable carbon pools provide a fairly good estimate of labile C present in soil and can be easily quantified. Changes in soil MBC and water-extractable organic carbon pools were studied in a 14-year long-term experiment in plots of rice-wheat rotation irrigated with canal water (CW), sodic water (SW, 10-12.5 mmol c L-1 residual sodium carbonate), and SW amended with gypsum with or without application of organic amendments including farmyard manure (FYM), green manure (GM), and wheat straw (WS). Irrigation with SW increased soil exchangeable sodium percentage by more than 13 times compared to irrigation with CW. Sodic water irrigation significantly decreased hot water-extractable organic carbon (HWOC) from 330 to 286 mg kg-1 soil and cold water-extractable organic carbon (CWOC) from 53 to 22 mg kg-1 soil in the top 0-7.5 cm soil layer. In the lower soil layer (7.5-15 cm), reduction in HWOC was not significant. Application of gypsum alone resulted in a decrease in HWOC in the SW plots, whereas an increase was recorded in the SW plots with application of both gypsum and organic amendments in both the soil layers. Nevertheless, application of gypsum and organic amendments increased the mean CWOC as compared with application of gypsum alone. CWOC was significantly correlated with MBC but did not truly reflect the changes in MBC in the treatments with gypsum and organic amendments applied. For the treatments without organic amendments, HWOC was negatively correlated with MBC (r = 0.57*) in the 0-7.5 cm soil layer, whereas for the treatments with organic amendments, both were positively correlated. Irrigation with SW significantly reduced the rice yield by 3 t ha-1 and the yield of rice and wheat by 5 t ha-1 as compared to irrigation with canal water. Application of amendments significantly increased rice and wheat yields. Both the rice yield and the yield of rice and wheat were significantly correlated with MBC (r = 0.49**-0.56**, n = 60). HWOC did not exhibit any relation with the crop yields under the treatments without organic amendments; however, CWOC showed a positive but weak correlation with the crop yields. Therefore, we found that under sodic water irrigation, HWOC or CWOC in the soils was not related to MBC.

Biocompatibility and bone regeneration of PEO/Mg-Al LDH-coated pure Mg:an in vitro and in vivo study

Forming a stable anti-corrosion surface layer on magnesium(Mg)and its alloys has become a major challenge in developing a desirable degradable medical implant in bone.In this study,a porous MgO layer was first formed on Mg by plasma electrolytic oxidation(PEO),and then a Mg-Al layered double hydroxide(LDH)layer was prepared to seal the porous structure of the PEO layer(LDH-2h and LDH-12h)via hydrothermal treatment.The bilayer structure composite coating,which can effectively resist the penetration of surrounding media,is similar to plain Chinese tiles.The in vitro results revealed that compared with other coatings,the LDH-12h composite coating can reduce the release of Mg ions and induce a milder change in pH when immersed in phosphate-buffered saline(PBS).In vitro rat bone marrow stem cell(rBMSC)culture suggested that the LDH-12h composite coating is favorable for cell activity,proliferation and could improve the osteogenic activity of rBMSCs.A subcutaneous implantation test revealed that the as-prepared sample showed enhanced corrosion resistance and histocompatibility in vivo,especially in the LDH-12h group.Moreover,LDH-12h had the lowest rate of degradation and the closest combination with the new bone after being inserted into a rat femur for 12 weeks with no major organ dysfunction.In summary,the asprepared PEO/Mg-Al LDH composite coating is able to improve the corrosion resistance and biocompatibility of Mg and to enhance osteogenic activity in vivo,suggesting its promising prospects for orthopedic applications.

Rice Straw-Derived Biochar Properties and Functions as Cu(Ⅱ) and Cyromazine Sorbents as Influenced by Pyrolysis Temperature

In this study, biochars from rice straw （Oryza sativa L.） were prepared at 200-600 ℃ by oxygen-limited pyrolysis to investigate the changes in properties of rice straw biochars produced at different temperatures, and to examine the adsorption capacities of the biochars for a heavy metal, copper（II） （Cu（II））, and an organic insecticide of cyromazine, as well as to further reveal the adsorption mechanisms. The results obtained with batch experiments showed that the amount of Cu（II） adsorbed varied with the pyrolysis temperatures of rice straw biochar. The biochar produced at 400 ~C had the largest adsorption capacity for Cu（II） （0.37 mol kg-1） among the biochars, with the non-electrostatic adsorption as the main adsorption mechanism. The highest adsorption capacity for cyromazine （156.42 g kg-1） was found in the rice straw biochar produced at 600 ℃, and cyromazine adsorption was exclusively predominated by surface adsorption. An obvious competitive adsorption was found between 5 mmol L-1 Cu（II） and 2 g L-1 cyromazine when they were in the binary solute system. Biochar may be used to remediate heavy metal- and organic insecticide-contaminated water, while the pyrolysis temperature of feedstocks for producing biochar should be considered for the restoration of multi-contamination.

Green synthesis of fluorescent carbon quantum dots and carbon spheres from pericarp

An economical idea was developed to synthesize fluorescent carbon quantum dots （CQDs） directly fl-om the refluxing extraction of orange pericarp via a hydrothermal technique. Hydrothermal temperatures and times were adjusted to control the particle sizes and the quantum yields of the obtained CQDs. The as-prepared carbon quantum dots showed narrow particle size distribution, good water solubility, and acceptable fluorescence lifetimes. Due to their high stability, these obtained carbon quantum dots have great application potential in nano-biotechnology. Furthermore, carbon spheres with uniform morphology and size can be easily obtained as the reaction byproducts of this green synthesis process.