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1.
To clarify the effect of the pyrolysis operating conditions of the biomass on the physicochemical properties of the char and its combustion reactivity, palm kernel shell was pyrolyzed at different temperatures (400–700 °C). Analyses such as proximate and ultimate analysis, XRD, FTIR, N2 adsorption, and SEM were used to investigate the physicochemical properties of biochar samples. The results show that an increase in pyrolysis temperature led to a development of pore structure and specific surface area of the produced biochar, which was beneficial for improving the biochar combustion reactivity. Besides, with increase in pyrolysis temperature, the carbon content exhibits a raise trend, but the oxygen and hydrogen contents exhibit the opposite behavior, and the aromaticity and graphitization degree of biochar produced at high temperature also increase. The combustion reactivity of biochar was found to be highly dependent on the pyrolysis temperature, and the aromatic structure and graphitization degree have greater effects on biochar combustion reactivity than those of the specific surface area and pore structure.  相似文献   

2.
The effects of pyrolysis temperature and heating rate on the porous structure characteristics of rice straw chars were investigated. The pyrolysis was done at atmospheric pressure and at temperatures ranging from 600 to 1000 °C under low heating rate (LHR) and high heating rates (HHR) conditions. The chars were characterized by ultimate analysis, field emission scanning electron microscope (FESEM), helium density measurement and N2 physisorption method. The results showed that temperature had obvious influence on the char porous characteristics. The char yield decreased by approximately 16% with increasing temperature from 600 to 1000 °C. The carbon structure shrinkage and pore narrowing occurred above 600 °C. The shrinkage of carbon skeleton increased by more than 22% with temperatures rising from 600 to 1000 °C. At HHR condition, progressive increases in porosity development with increasing pyrolysis temperature occurred, whereas a maximum porosity development appeared at 900 °C. The total surface area (Stotal) and micropore surface area (Smicro) reached maximum values of 30.94 and 21.81 m2/g at 900 °C and decreased slightly at higher temperatures. The influence of heating rate on Stotal and Smicro was less significant than that of pyrolysis temperature. The pore surface fractal dimension and average pore diameter showed a good linear relationship.  相似文献   

3.
A novel composite, biochar derived from spent coffee grounds with immobilized TiO2 (biochar–TiO2) was prepared, characterized, and applied as an alternative, effective, and sustainable photocatalyst for degrading diclofenac from aqueous solution. Composites with different mass ratios between TiO2 and biochar were prepared by mechanical mixing and subsequent pyrolysis in an inert atmosphere of N2 at 650°C. The sample with biochar–TiO2 ratio of 1:1 presented a degradation efficiency of 90% at just 120 min versus 40% for TiO2 used as reference. This fact is associated with a set of intrinsic characteristics obtained during the formation of the composite, such as superior pore size, avoiding the recombination of the ē/h+ pair, bandgap reduction, and promotion of reactive oxygen species due to phenolic groups present on the biochar surface. The dominant reactive species involved during the photocatalytic degradation of diclofenac were h+ and OH. The diclofenac degradation pathways were determined based on the identification of intermediates and nonpurgeable organic carbon (NPOC) analysis. The novel biochar–TiO2 composite prepared in this work showed high physical–chemical stability and efficiency over five consecutive cycles of reuse, proving to be a highly promising photocatalyst for degrading diclofenac in water.  相似文献   

4.
Thermal Analysis of Casein   总被引:3,自引:0,他引:3  
Case in was analyzed during thermal treatment and pyrolysis. The thermal degradation process of casein was interpreted and thermostability indices, rate, order and activation energy of thermode-structive reaction of casein were determined on the basis of thermogravimetric analysis. The thermodestruction of casein has the characteristics of a first order reaction with activation energy E a=3.87 kcal mol–1 (16.2 kJ mol–1).The pyrolysis of casein was investigated and we determined optimal heating temperature — 550°C and yields of biochar, pitch, pyrolysis water and gases.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

5.
Using bamboo powder biochar as raw material, high-quality meso/microporous controlled hierarchical porous carbon was prepared—through the catalysis of Fe3+ ions loading, in addition to a chemical activation method—and then used to adsorb copper ions in an aqueous solution. The preparation process mainly included two steps: load-alkali leaching and chemical activation. The porosity characteristics (specific surface area and mesopore ratio) were controlled by changing the K2CO3 impregnation ratio, activation temperature, and Fe3+ ions loading during the activation process. Additionally, three FBPC samples with different pore structures and characteristics were studied for copper adsorption. The results indicate that the adsorption performance of the bamboo powder biochar FBPC material was greatly affected by the meso/micropore ratio. FBPC 2.5-900-2%, impregnated at a K2CO3: biochar ratio of 2.5 and a Fe3+: biochar mass ratio of 2%, and activated at 900 °C for 2 h in N2 atmosphere, has a very high specific surface area of 1996 m2 g−1 with a 58.1% mesoporous ratio. Moreover, it exhibits an excellent adsorption capacity of 256 mg g−1 and rapid adsorption kinetics for copper ions. The experimental results show that it is feasible to control the hierarchical pore structure of bamboo biochar-derived carbons as a high-performance adsorbent to remove copper ions from water.  相似文献   

6.
Pyrolysis of rice straw (RS), a popular method for producing biochar, effectively treats heavy metal(loid)-contaminated RS. Here, we carried out this process at different temperatures and investigated the deportment of heavy metal(loid)s and the property evolution of biochars. Also, the optimal pyrolysis temperature for Pb adsorption and immobilization was studied. We observed that increasing the temperature could volatilize the heavy metal(loid)s. Cd was the most volatile metal therein, followed by As, while Ni, Cu, and Pb were relatively refractory. More than 75% of the remaining heavy metal(loid)s were non-exchangeable fractions at 700 °C, significantly reducing the environmental risk during subsequent application. Meanwhile, higher pyrolysis temperature resulted in higher pH values, higher surface areas, and stronger Pb adsorption capacity of RS biochars. The maximum adsorption capacity (Qm) of biochars was in the order of BC300 (77.2 mg·g?1) < BC500 (137.2 mg·g?1) < BC700 (222.6 mg·g?1). Besides, high-temperature biochar could significantly reduce the vertical Pb migration. And BC700 increased the fraction of residual Pb from 39.7% to 44.0% in the soil under the acid rain leaching condition. Therefore, we propose that the heavy metal(loid)-contaminated RS biochar produced at 700 °C might be more suitable for the remediation of soil heavily polluted in the Pb-smelting area.  相似文献   

7.
Producing biochar and biofuels from poultry litter (PL) through slow pyrolysis is a farm-based, value-added approach to recycle the organic waste. Experiments were conducted to examine the effect of pyrolysis temperature on the quality PL biochar and to identify the optimal pyrolysis temperature for converting PL to agricultural-use biochar. As peak pyrolysis temperature increased incrementally from 300 to 600 °C, biochar yield, total N content, organic carbon (OC) content, and cation exchange capacity (CEC) decreased while pH, ash content, OC stability, and BET surface area increased. The generated biochars showed yields 45.7–60.1% of feed mass, OC 325–380 g kg−1, pH 9.5–11.5, BET surface area 2.0–3.2 m2 g−1, and CEC 21.6–36.3 cmolc kg−1. The maximal transformation of feed OC into biochar recalcitrant OC occurred at 500 °C, yet 81.2% of the feed N was lost in volatiles at this temperature. To produce agricultural-use PL biochar, 300 °C should be selected in pyrolysis; for carbon sequestration and other environmental applications, 500 °C is recommended.  相似文献   

8.
Formation of NOX precursors during pyrolysis of three typical kinds of biomass (wheat straw, rice straw and corn cob) was studied using a thermogravimetric analyzer (TGA) coupled with a Fourier transform infrared (FTIR) spectrometer in argon atmosphere. Two pretreatment methods, including deionized water washing and acid washing were utilized to investigate the effect of included minerals on the distribution of nitrogen containing species during wheat straw pyrolysis. KOH and CaO were loaded onto the demineralized (dem) wheat straw to study the effect of excluded minerals on nitrogen release. The residues of the samples after pyrolysis were characterized by X-ray diffraction (XRD) analysis. The results show that different kinds of biomass have distinctive formation characteristics of N-containing species. HCN and HNCO are the main N-containing species for rice straw, while NH3 and HCN are the main N-containing species for wheat straw and corn cob.The existence of minerals influences the formation of N-containing species during biomass pyrolysis. Both the included potassium and excluded potassium promote N-conversion to NH3, HCN, NO and HNCO at lower temperature, but decrease the total yields of N-containing species. The included calcium decreases N-conversion to HCN, NH3 and HNCO at lower temperature (<about 330 °C), while favors the total yields of N-containing species. However, the presence of added calcium restrains N-conversion to HCN, NH3, NO and HNCO.  相似文献   

9.
The purpose of this study was to clarify the effects of biochar on the diversity of bacteria and fungi in the rice root zone and to reveal the changes in soil microbial community structure in the root zone after biochar application to provide a scientific basis for the improvement of albic soil. Rice and corn stalk biochar were mixed with albic soil in a pot experiment. Soil samples were collected at the rice maturity stage, soil nutrients were determined, and genomic DNA was extracted. The library was established using polymerase chain reaction (PCR) amplification. The abundance, diversity index, and community structure of the soil bacterial 16SrRNA gene V3 + V4 region and the fungal internal transcribed spacer-1 (ITS1) region were analyzed using Illumina second-generation high-throughput sequencing technology on the MiSeq platform with related bioinformatics. The results revealed that the biochar increased the soil nutrient content of albic soil. The bacteria ACE indexes of treatments of rice straw biochar (SD) and corn straw biochar (SY) were increased by 3.10% and 2.06%, respectively, and the fungi ACE and Chao indices of SD were increased by 7.86% and 14.16%, respectively, compared to conventional control treatment with no biochar (SBCK). The numbers of bacterial and fungal operational taxonomic units (OUT) in SD and SY were increased, respectively, compared to that of SBCK. The relationship between soil bacteria and fungi in the biochar-treated groups was stronger than that in the SBCK. The bacterial and fungal populations were correlated with soil nutrients, which suggested that the impacts of biochar on the soil bacteria and fungi community were indirectly driven by alternation of soil nutrient characteristics. The addition of two types of biochar altered the soil microbial community structure and the effect of rice straw biochar treatment on SD was more pronounced. This study aimed to provide a reference and basic understanding for albic soil improvement by biochar, with good application prospects.  相似文献   

10.
以麦秆和稻壳生物质为研究对象,在不同的热解温度、热解速率以及蒸汽活化温度条件下制备了生物质焦,采用比表面积与孔隙度分析仪测定生物质焦的比表面积和孔隙结构参数。利用固定床吸附装置,研究了热解温度、热解速率、活化温度和模拟烟气中SO2和NO浓度等因素对生物质焦吸附SO2和NO性能的影响。结果表明,蒸汽活化可以显著提高生物质焦的BET比表面积、D-R比表面积、D-R微孔容积和总孔容,降低其平均孔径,并显著增加蒸汽活化生物质焦对SO2与NO吸附的起始穿透时间和吸附量。快速热解下制得的蒸汽活化焦对SO2和NO的吸附效果优于慢速热解,热解温度为873 K的蒸汽活化焦的吸附性能明显好于热解温度为673与1 073 K的蒸汽活化焦。在973~1 173 K下,随着蒸汽活化温度的提高,蒸汽活化生物质焦对SO2和NO的吸附量呈现先上升后下降的趋势。随着模拟烟气中SO2与NO浓度的降低,蒸汽活化生物质焦对SO2与NO吸附的起始穿透时间延长,但相应的SO2和NO吸附量下降。在873 K、快速热解和1 073 K条件下制得的蒸汽活化麦秆焦对SO2和NO吸附量最大,其值分别为109.02和21.77 mg/g。  相似文献   

11.
The effects of two types of biochar on corn production in the Mediterranean climate during the growing season were analyzed. The two types of biochar were obtained from pyrolysis of Pinus pinaster. B1 was fully pyrolyzed with 55.90% organic carbon, and B2 was medium pyrolyzed with 23.50% organic carbon. B1 and B2 were supplemented in the soil of 20 plots (1 m2) at a dose of 4 kg/m2. C1 and C2 (10 plots each) served as control plots. The plots were automatically irrigated and fertilizer was not applied. The B1-supplemented plots exhibited a significant 84.58% increase in dry corn production per square meter and a 93.16% increase in corn wet weight (p << 0.001). Corn production was no different between B2-supplemented, C1, and C2 plots (p > 0.01). The weight of cobs from B1-supplemented plots was 62.3%, which was significantly higher than that of cobs from C1 and C2 plots (p < 0.01). The grain weight increased significantly by 23% in B1-supplemented plots (p < 0.01) and there were no differences between B2-supplemented, C1, and C2 plots. At the end of the treatment, the soil of the B1-supplemented plots exhibited increased levels of sulfate, nitrate, magnesium, conductivity, and saturation percentage. Based on these results, the economic sustainability of this application in agriculture was studied at a standard price of €190 per ton of biochar. Amortization of this investment can be achieved in 5.52 years according to this cost. Considering the fertilizer cost savings of 50% and the water cost savings of 25%, the amortization can be achieved in 4.15 years. If the price of biochar could be reduced through the CO2 emission market at €30 per ton of non-emitted CO2, the amortization can be achieved in 2.80 years. Biochar markedly improves corn production in the Mediterranean climate. However, the amortization time must be further reduced, and enhanced production must be guaranteed over the years with long term field trials so that the product is marketable or other high value-added crops must be identified.  相似文献   

12.
Chlorine content in agricultural straw is high, and HCl formation during straw combustion is a challenging problem. The relationship between HCl and the formation of NOx and N2O is important and unclear. Effect of HCl in atmosphere on nitrogen transfer during wheat straw and cotton stalk pyrolysis was performed using a thermogravimetric analyzer coupled with a Fourier transform infrared spectrometer. Pyrolysis of polyvinyl chloride supplies HCl. The pathway of nitrogen transfer in the presence of HCl was studied. The results show that in the presence of HCl, the temperature corresponding to NH3 starting release during wheat straw pyrolysis increases, and those of HCN and HNCO reduce. HCl inhibits the conversion of straw–N into NH3, however, favors the transformation of straw nitrogen into HCN and HNCO.  相似文献   

13.
There is limited information on changes cause by nitrogen (N) fertilizers and biochar (BC) application in soil carbon and nitrogen availability, leaching and microbial activity at different growth stages in rice. This is first comprehensive study conducted in early and late seasons during 2019 to evaluate efficiency of various traditional N fertilizers (i) Urea (ii) Ammonium nitrate and (iii) Ammonium sulfate (315 kg N ha−1) with or without biochar (30 t ha−1). Results illustrated that all N fertilizers sources applied with biochar significantly increased soil organic carbon (SOC) content by an average 48.44% and 50.63%, soil total nitrogen (Nt) by 4.56% and 4.94%, reduction in total nitrogen leaching by 42.63% and 76.16%, while dissolved organic carbon leaching (DOC) augmented by 39.87% and 38.38% than non-applied treatments in early and late season, respectively. Additionally, soil microbial biomass C and N progressively increased with growth stages and was found higher than non-applied treatments in both seasons. Furthermore, combined application of N fertilizers and biochar, facilitated soil N transformation and the net concentration of NH4+–N and NO3–N was relatively higher than non-charred treatments. Similarly, in both early and late seasons, urease enzyme activity increased by an average 13.52% and 13.55%, β-glucosidase by 15.99% and 19.27% however, catalase activity decreased by 14.58% and 12.38%, correspondingly. Moreover, no significant difference (p < 0.05) was recorded among N fertilizers sources in both seasons.  相似文献   

14.
The physical state of the material obtained during the various stages of preparation of a typical MgCl2-supported, high-mileage propylene polymerization catalyst was studied by BET, mercury porosimetry, and x-ray diffraction techniques. The starting MgCl2 and the substance after HCl treatment have negligible BET surface areas. Mercury porosimetry showed that they have large pores with radii > 200 nm which are probably crevices between MgCl2 crystallites. The most pronounced physical changes occur during dry porcelain ball milling in the presence of ethyl benzoate. After 60 h or more of ball milling the material had a 5.1–7.3 m2 g?1 BET surface area, twice the pore surface area, and a smaller pore radius than before ball milling and a large reduction in crystallite sizes to almost ultimate dimensions. The crystallites were probably held together by complexation with ethyl benzoate in the form of large agglomerates. Subsequent reactions with p-cresol and triethyl aluminum had minor effects in further reduction of the MgCl2 crystallite size but efficiently brokeup the agglomerates. The final refluxing with TiCl4 increased the BET surface area to 110–150 m2 g?1 but may have increased the crystallite size somewhat due to cocrystallization of TiCl3 and AlCl3 with MgCl2. There may have been only 8–10 crystallites in each catalyst particle. The surface structure of the catalyst resembled those of the classical Ziegler-Natta γ-TiCl3·0.33 AlCl3 catalyst.  相似文献   

15.
This research encompasses the use of noxious weed Parthenium hysterophorus as feedstock for pyrolysis carried out at varying temperatures of 300, 450 and 600°C. Temperature significantly affected the yield and properties of the pyrolysis products including char, syngas and bio-oil. Biochar yield decreased from 61% to 37% from 300 °C to 600 °C, whereas yield of gas and oil increased with increasing temperature. The pyrolysis products were physico-chemically characterized. In biochar, pH, conductivity, fixed carbon, ash content, bulk density and specific surface area of the biochar increased whereas cation exchange capacity, calorific value, volatile matter, hydrogen, nitrogen and oxygen content decreased with increasing temperature. Thermogravimetric analysis showed that the biochar prepared at higher temperature was more stable. Gas Chromatography-Mass Spectrometry analysis of biochar indicated the presence of alkanes, alkenes, nitriles, fatty acids, esters, amides and aromatic compounds. Number of compounds decreased with increasing temperature, but aromatic compounds increased with increasing temperature. Scanning electron micrographs of biochar prepared at different temperatures indicated micropore formation at lower temperature while increase in the size of pores and disorganization of vessels occurred at increasing temperature. The chemical composition was found to be richer at lower pyrolysis temperature. GC–MS analysis of the bio-oil indicated the presence of phenols, ketones, acids, alkanes, alkenes, nitrogenated compounds, heterocyclics and benzene derivatives.  相似文献   

16.
The compressed wheat and corn straw bale were pyrolyzed on a microwave heating device self-designed and built with respect to the time-resolved temperature distribution, mass loss and product properties. Considering scale up and technology promotion of microwave pyrolysis (MWP), the investigations on electricity consumption and energy balance of MWP were carried out emphatically. The results indicated that MWP had obvious advantages over conventional pyrolysis, such as heating rapid and more valuable products obtained. The distribution of pyrolysis products such as gas, liquid and char was close to 1:1:1 due to the medium pyrolysis temperature and the slow heating rate, which was not favorable for the formation of gas and/or liquid products. The content of H2 attained the highest value of 35 vol.% and syngas (H2 and CO) was greater than 50 vol.%. The electricity consumption of MWP was between 0.58 and 0.65 kW h (kg straw)−1 and with the increase of microwave power, the electricity consumption required for pyrolysis of unit mass of straw increased. The minimum microwave power for MWP was about 0.371 kW (kg straw)−1 and the proportion of heat loss and conversion loss of electricity to microwave energy occupied in the total input energy was 42%. Data and information obtained are useful for the design and operation of pyrolysis of large-sized biomass via microwave heating technology.  相似文献   

17.
Co-pyrolysis of straw and Ca(OH)2 is a feasible modification method to improve the adsorption capacity of biochar for Cd. However, few studies have quantitatively analyzed the contribution of different adsorption mechanisms of alkali-modified biochar. In this study, the alkali-modified (Ca) biochar were prepared by co-pyrolyzing lime (Ca(OH)2) and soybean straw (SBB) or rape straw (RSB) at 450 °C. The adsorption mechanism was investigated by a series of experiments and was provided by quantitative analysis. The maximum adsorption capacities of Cd2+ by Ca-SBB and Ca-RSB were calculated to be 78.49 mg g?1 and 49.96 mg g?1, which were 1.56 and 1.48 times higher than SBB (50.40 mg g?1) and RSB (33.79 mg g?1), respectively. Compared with the original biochar (SBB, RSB), alkali-modified biochar (Ca-SBB and Ca-RSB) were found to have faster adsorption kinetics and lower desorption efficiencies. The mechanism study indicated that Ca(OH)2 modification effectively enhanced the contribution of ion exchange and decreased the contribution of functional groups complexation. After Ca(OH)2 modification, precipitation and ion exchange mechanisms dominated Cd2 + absorption on Ca-SBB, accounting for 49.85% and 34.94% of the total adsorption, respectively. Similarily ion exchange and precipitation were the main adsorption mechanism on Ca-RSB, accounting however for 61.91% and 18.47% of total adsorption, respectively. These results suggested that alkali-modified biochar has great potential to adsorp cadmium in wastewater.  相似文献   

18.
选用四种生物质即稻杆(RS)、稻壳(RH)、松木屑(WC)和棉花杆(CS)制备了生物质焦,利用N2吸附/脱附和傅里叶变换红外光谱(FT-IR)仪,对制备的生物质焦的孔隙结构和表面化学性质进行了表征,分析生物质种类和制焦条件对生物质焦性质的影响。在固定床汞吸附实验台上研究了生物质焦的脱汞性能。结果表明,随着热解温度的升高,生物质焦的比表面积、微孔容积、分形维数等参数有先增大后减小的趋势。WC600、RS600、RH600均有较好的孔结构特性;热解温度升高,生物质焦表面官能团的数量和种类随之减少。不同生物质制备的焦样表面官能团的数量和种类差异较大。其中,RH600和RS600的表面官能团的种类比较丰富,而且含量相对较多。但WC600和CS600表面的官能团种类和数量都很少。生物质焦的单位汞吸附容量与其分形维数以及微孔容积之间并非简单的依附关系,其吸附能力还受含氧官能团等其他因素的影响。  相似文献   

19.
Biochar was prepared from corncob-to-xylose residue (CCXR) by KOH activation and anaerobic pyrolysis method. The effect of activation temperature on the microstructure of the biochar was studied. Results showed that the biochar prepared at 850°C (850NBC) possessed high specific surface area and exhibited excellent adsorption property. The maximum adsorption capacity of 2249 mg g−1 was obtained when 850NBC was used for treating methylene blue (MB) solution. Adsorption isotherm fittings revealed that Langmuir and Freundlich models were applicable to 850NBC adsorption process, and the adsorption process was limited by adsorption site and the biochar surface functional groups. Furthermore, 850NBC showed good adsorption property when it was used to treat the other organic dyes of Congo red (751 mg g−1), Orange II (735 mg g−1), Indigo carmine (662 mg g−1) and Methyl Orange (465 mg g−1). Biochar 850NBC also possessed an acceptable recyclability which maintained 68.7% absorption capacity after 6 cycles when it was used to treat MB solution. These results proposed that 850NBC is expected to be a promising potential adsorbent for treating organic dyes waste water.  相似文献   

20.
以废弃汽车外轮胎热解后的副产物轮胎热解焦(Tyre pyrolysis char,TPC)为原料,利用均匀沉淀法制备以轮胎焦为载体的负载型Ni/TPC催化剂,采用EDX、SEM、XRD、TG、BET手段对催化剂进行了表征与分析,同时使用管式炉测试了Ni/TPC催化剂在秸秆热解燃气重整中的催化性能,并考察了热解温度、保温时间、镍负载量及催化时间对秸秆热解燃气重整效果的影响。研究结果表明,TPC富含焦和金属,Ni/TPC催化剂分散均匀,热稳定性好,比表面积为62 m2/g。催化剂活性测试显示,Ni/TPC催化剂用于作物秸秆热解燃气重整具有很强的催化活性,可显著提高燃气中可燃气体含量;热解温度在750℃、保温时间10 min、30%的Ni负载量时Ni/TPC催化剂的催化效率最高,连续使用850 min后,燃气中的H2含量仍相对提高到50%以上,长时间使用后活性结构由Ni3ZnC0.7转变成FeNi3,催化活性依然较强且趋于稳定,TPC可以作为良好的新型镍基催化剂载体。  相似文献   

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