Effect of reduction roasting by using bio-char derived from empty fruit bunch on the magnetic properties of Malaysian iron ore

Beneficiation of Malaysian iron ore is becoming necessary as iron resources are depleting. However, the upgrading process is challenging because of the weak magnetic properties of Malaysian iron ore. In this study, bio-char derived from oil palm empty fruit bunch （EFB） was utilized as an energy source for reduction roasting. Mixtures of Malaysian iron ore and the bio-char were pressed into briquettes and subjected to reduction roasting processes at 873-1173 K. The extent of reduction was estimated on the basis of mass loss, and the mag-netization of samples was measured using a vibrating sample magnetometer （VSM）. When reduced at 873 K, the original goethite-rich ore was converted into hematite. An increase in temperature to 1073 K caused a significant conversion of hematite into magnetite and enhanced the magnetic susceptibility and saturation magnetization of samples. The magnetic properties diminished at 1173 K as the iron ore was par-tially reduced to wustite. This reduction roasting by using the bio-char can assist in upgrading the iron ore by improving its magnetic proper-ties

Catalytic Pyrolysis of Soybean Oil with CaO/Bio-Char Based Catalyst to Produce High Quality Biofuel

In this paper,CaO/bio-char was synthesized by directly co-pyrolysis of Ca(OH)_(2) and rice straw,and used as catalyst to catalytic pyrolysis of soybean oil to produce high quality biofuel.In this co-pyrolysis process,CaO particles has been successfully embedded on the bio-char surface.During the catalytic pyrolysis process,CaO/biochar showed a good catalytic performance on the deoxygenation of soybean oil.Pyrolysis temperature affected the pyrolysis reactions and pyrolytic products distributions dramatically,higher pyrolysis temperature lead to seriously cracking reactions,lower bio-oil yield and higher gases yield,and lower pyrolysis temperature lead to higher bio-oil yield with higher oxygenated compounds content and lower hydrocarbons contents,the suitable pyrolysis temperature was around 650℃.Under the optimal conditions(650℃ with WHSV at 6.4 h^(−1) and carrier gas flow rate at 100 ml/min),the selectivity(%)of hydrocarbons in the bio-oil was more than 90%.CaO/bio-char catalyst still shows good catalytic deoxygenation activity after 4 cycles.1 g of CaO/bio-char catalyst can catalyze pyrolysis of 32 g of soybean oil to produce high-quality liquid fuel.Bio-char based catalyst has been proved to be a promising catalyst for catalytic conversion of triglyceride-based lipids into high quality liquid biofuel.

Adsorption of Lead (II) and Copper (II) Ions from Mono Synthetic Aqueous Solutions Using Bio-Char from <i>Ficus natalensis</i>Fruits

Many science-based institutions in most developing countries use heavy metal containing salts in practical teaching sessions. The commonly used chemicals are the salts of lead (II) and copper (II) and the wastes generated end up into the environment when untreated. Thus, a study was done to remove lead (II) and copper (II) ions from mono synthetic aqueous solution using bio-char from Ficus natalensis fruits (FNF). This was done at varied pH, contact time, temperature, bio-char dosage level, salinity and metal ion concentration using the batch approach. The residual metal concentrations were determined using the atomic absorption spectrophotometer. The optimum pH for the adsorption of copper (II) and lead (II) ions was found to be 4.0 and 5.0 respectively. The maximum percentage adsorption of copper (II) and lead (II) by the FNF bio-char was established at 60 minutes contact time, 47.5°C and 0.4 g adsorbent dose. Increase in the metal ion concentration and the presence of interfering ions in the aqueous solution lead to decrease in the percentage adsorption. The highest adsorption capacity was found to be 161.29 mg/g and 1250 mg/g for copper (II) and lead (II) ions respectively. The thermodynamic parameters indicated the feasibility of the adsorption of copper (II) and lead (II) on the bio-char of FNF. Thus, bio-char from FNF may be used as an adsorbent in waste management where copper (II) and lead (II) ions are present at a concentration range of between 5 and 100 mg/l.

Effect of Tannin in Green Tea By-Product in Combination with Bio-Char Supplemented into Basal Beef Cattle Diet on Nutrient Digestibility, Methane Production and Animal Performance

The experiment was conducted by using 20 bulls of Lai Sind cattle (a cross breed between Red Sindhi and local Vietnam yellow cattle) from 15 - 16 months of age, weighed approximately 154 - 156 kg, housed individually with provision of adequate feed trough and free access to water to evaluate the effect of tannin sourced from green tea by-product and addition of bio-char on methane production and animal performance. The experimental diets were formulated by replacing elephant grass in basal diet by bio-char and green tea by-product with the replacement of 0.5 - 1 bio-char and 3% - 5% green tea by-products, respectively to make the content of tannin in the diet of 7.3 g and 12.5 g tannin per kg dry matter. Results from this study revealed that bio-char and green tea by-product included into the diet with different levels had significantly affected on the feed intake, as the increasing level of tannin in the diet tended to increase the feed intake. The inclusion of green tea by-product in the diet which resulted in the content of tannin in the diet of 12.5 g/kg DM had significantly reduced methane emission without altering animal performance, thus the inclusion of 0.5% bio-char and 5% of green tea by-product can be applied in order to mitigate methane emission, thus contributed to environment protection.

Rice Husk Bio-Chars as Adsorbent for Methylene Blue and Ethinylestradiol from Water

Biobased adsorbents are eco-friendly materials used for water and wastewater treatment and air cleaning.This research work explores the potential use of rice husk chars as a low-cost adsorbent for pollutants from water,such as methylene blue and ethinylestradiol.Rice husk chars are prepared by combustion of rice husks(RH-Char)or pre-treated rice husks(PT-Char).A third char(M-Char)supplied by a local company which uses rice husks as combustion material is also studied.The chars are characterized by field emission scanning electron microscopy(FE-SEM)in conjunction with energy dispersive X-ray spectroscopy(EDX),X-ray powder diffraction(XRD),and zeta-potential measurements.The three bio-chars are tested as adsorbent for the removal of two wastewater contaminants:methylene blue(MB)and ethinylestradiol(EE2).According to the results,RH-Char and PT-Char present zeta-potential values near−52 mV,whereas M-Char shows a zeta-potential value of−32 mV.Both RH-Char and PTChar are rich in amorphous SiO_(2) and M-Char has crystalline SiO_(2)(cristobalite).The bio-chars remove MB and EE2 efficiently showing the following results for the adsorption capacity of MB(inμmol g^(−1)):769.2(RH-Char),41.2(PT-Char),and 31.7(M-Char).The adsorption capacity values for EE2(inμmol g^(−1))are:33.1(RH-Char),19.1(PT-Char),and 16.9(M-Char).The information gathered in the present work evidences the potential of rice husks bio-chars for bio-remediation and may in future contribute to the conversion of a side-stream from the rice industry into value-added materials.

Study on cationic dye adsorption of bio-chars prepared from thermal-alkaline-pretreated sludge

Sludge bio-char(SC)and thermal-alkaline treated sludge bio-char(TSC)were prepared from municipal sewage sludge(RS)and thermal-alkaline treated sludge sediments(STAS)through fast pyrolysis under nitrogen existence condition to remove cationic red X-GRL(A)and cationic yellow X-6G(B)from aqueous solutions.Results of adsorption experiment show that the adsorption capacities of TSC are better than the adsorption capacities of SC.The highest adsorption capacity of 47.65 mg/g for A and 45.41mg/g for B are obtained by TSC in an isotherm experiment at 2.0 g/L dosage and 25°C temperature.TSC adsorption for the two kinds of cationic dyes can be well fitted by pseudo-second-order kinetics model and Langmuir isotherm model.

水热及水热氧化预处理对棉秆基成型炭和活性炭性能的影响

水热及水热氧化预处理可以调整生物质内部组分占比,有效促进生物质资源多元化利用。以棉秆为实验原料,经160℃~260℃水热及水热氧化预处理后制备成型炭和活性炭,并使用范式法、热重分析和X射线光电子能谱等测试手段,分析了水热及水热氧化预处理后生物质内部组分的演变对棉秆基成型炭和活性炭的产率、理化性能的影响。结果表明:水热及水热氧化预处理后棉秆中半纤维素和纤维素的分解有利于成型炭的产率和能量密度的增加;与水热预处理相比,水热氧化预处理进一步提高了成型炭的产率及热值,可在一定程度上降低预处理强度;棉秆基活性炭的总产率受预处理产率和活化产率的综合影响;随着水热及水热氧化预处理温度的升高,活性炭总产率呈现先升高后降低趋势,并在预处理温度为200℃获得的最大产率分别为36.95%和29.17%;与原料活性炭相比,水热及水热氧化预处理棉秆基活性炭的前驱体表面含氧官能团含量显著提升,有利于后续的氯化锌活化,得到的活性炭比表面积显著增加,吸附性能更优;此外,在180℃和200℃下水热氧化后的棉秆基活性炭碘吸附值均达到GB/T 13803.2-1999制净水用活性炭的二级品标准。

生物质炭对烟气脱硝脱汞的实验研究

文章从低成本角度对烧结烟气进行脱硝脱汞研究,选用木屑在低温慢速热解条件下(室温至600℃,5℃/min)制备生物质炭,然后利用硝酸对生物质炭进行改性,最后在固定床反应器上进行脱硝和脱汞实验。通过比表面积分析和傅里叶红外光谱分析,改性生物质炭具有更大的比表面积和微孔体积,其含氧官能团和碱性原子团明显增多,两者综合作用,使得改性生物质炭的脱硝脱汞能力明显优于生物质炭的。

活性生物炭材料对水中Cr(Ⅵ)的吸附特性

以棉花秸秆和玉米秸秆为原料、水蒸气为活化剂,制备不同的活性生物炭材料,探讨不同的活化时间对生物炭材料吸附性能的影响。利用氮气吸附-脱附全自动比表面积和孔隙度分析仪(BET)、扫描电镜(SEM)对活性生物炭材料的孔道和表面结构进行了分析和表征。结果表明:当炭化温度500℃、炭化时间1 h,每克炭化料的水蒸气流量0.04 g·min^(-1)、活化温度800℃、棉花秸秆活化时间30 min、玉米秸秆活化时间45 min,制备的活性生物炭材料吸附性能较好。将最优条件下制得的活性生物炭材料应用于含铬水溶液的处理,研究结果表明,随着溶液Cr(Ⅵ)离子浓度的提高,吸附时间越长,吸附效果越好。

气化温度对生物质气化的可燃气、炭和焦油特性的影响

【目的】生物质气化技术是一种清洁可再生的能源利用技术。研究气化温度对气化产物特性的影响机制,构建气化产物特性的演变规律,对中国实现碳达峰与碳中和目标具有重大意义。【方法】以玉米Zea mays秸秆、棕榈Trachycarpus fortunei壳和马尾松Pinus massoniana等3种农林生物质废弃物为原料,以空气为气化剂,采用自制的微型固定床气化装置,开展3种生物质的气化多联产研究,系统研究了不同气化温度(700、800、900℃)对气化性能的影响,以及对气化三相产物(可燃气、生物质炭与焦油)特性的影响机制。【结果】随着气化温度从700℃增加至900℃,可燃气的质量产率逐渐增加,而生物质炭和焦油的质量产率逐渐减小。较高的气化温度有利于提升可燃气的热值。在3种原料中,马尾松可燃气的热值最高,一氧化碳、氢气和甲烷体积分数分别为40.03%、18.27%和18.29%,低位热值达13.58 MJ·m^(-3)。随着气化温度的增加,生物质炭中的碳元素质量分数增加,氢元素质量分数下降,灰分质量分数大幅增加,其中马尾松炭的热值最高,达29.70 MJ·kg^(-1)。随着气化温度的增加,3种原料的气化液体产物中酸类、醇类、醛酮类、呋喃类化合物相对含量逐渐减小,而芳烃类化合物相对含量大幅增加,其中马尾松的芳烃类化合物相对含量最高,达到61.12%。【结论】气化温度对生物质气化三相产物的产量及特性有显著的影响,选择合适的气化温度对提高生物质可燃气热值及气化效率至关重要。

改性生物质炭负载铁类Fenton体系降解亚甲基蓝研究

以棉花秸秆作为前驱体,用K_(2)CO_(3)活化后制备出改性生物质炭K_(2)CO_(3)@BC,置于FeSO_(4)溶液中形成悬浮液,干燥并煅烧,制得改性生物质炭负载铁催化剂Fe/K_(2)CO_(3)@BC。采用XRD、FT-IR、SEM等对Fe/K_(2)CO_(3)@BC进行表征,并研究其耐酸耐碱性。以亚甲基蓝作为目标污染物,将Fe/K_(2)CO_(3)@BC催化剂和H_(2)O_(2)组成非均相类Fenton体系降解水中的亚甲基蓝,探究了溶液pH、Fe/K_(2)CO_(3)@BC投加量、H_(2)O_(2)用量、温度等因素对亚甲基蓝降解效果的影响。结果表明,催化剂Fe/K_(2)CO_(3)@BC中的Fe物种主要以Fe3O4形式存在,具有一定的耐酸耐碱性,稳定性好。Fe/K_(2)CO_(3)@BC-H_(2)O_(2)类Fenton系统可高效催化降解水中的亚甲基蓝,且H_(2)O_(2)用量少,体系pH适应范围广。催化剂循环使用5次后,对亚甲基蓝的去除率仍达到85%以上。动力学研究表明该降解过程符合准二级动力学方程,证明亚甲基蓝的去除是由Fe/K_(2)CO_(3)@BC-H_(2)O_(2)体系中的氧化还原反应决定的。催化剂活化H_(2)O_(2)分子,产生羟基自由基,是高效降解亚甲基蓝的主要原因。

污泥共混燃烧发电工艺及其最新应用研究进展

介绍了当前污泥处置的传统工艺,阐述了具有潜在应用价值的污泥共混燃烧发电工艺,同时也对最新的污泥热化学解聚制备高附加值生物碳材料的应用研究进行了总结,并对污泥处置处理工艺在未来的发展方向进行了展望,以期为污泥的资源化以及工业化进程提供依据。

落叶松不同器官化学组分及其生物炭理化性质研究

为实现落叶松采伐剩余物的多级、高值利用及炭化还林、改良土壤提供理论依据,探究了落叶松不同器官(树干边材、树枝、树皮、树叶和松果)材料的主要化学组分,分析了其热解特性及其生物炭的基本理化性质,分离并测定落叶松各器官纤维素、半纤维素、木质素、苯醇抽提物和灰分含量,并表征各器官材料的热稳定性。将落叶松不同器官材料分别在500、700、900℃下炭化并表征各生物炭的理化性质。落叶松树干边材中综纤维素含量最高、松针中木质素和灰分含量最高、树枝中苯醇抽提物含量最高。落叶松的热解过程分为干燥、快速热降解和煅烧3个阶段,主热解反应发生在200~400℃,热重结果及炭得率分析均表明,松针的残炭率最高。同一组织器官的生物炭产率和表面官能团种类均随炭化温度的升高而逐渐减少;而同一组织器官生物炭的pH值随炭化温度上升而逐渐升高。5种生物炭的比表面积情况为:树皮炭>树干炭>松果炭>松针炭>树枝炭。落叶松边材的纤维素含量最高,适宜用作造纸制浆等原材料,松针的木质素含量较高,适宜用于提取化学品。树干边材、树皮和树枝适合炭化还林,其中树皮炭的炭得率较高、比表面积较大,pH值呈强碱性且化学性质比较稳定,可用于改良酸性土壤。

生物质炭燃烧特性与动力学分析

利用小型固定床反应器对棉杆和木屑进行了炭化制焦实验,利用热重分析仪对制得的生物质炭进行氧化实验。基于综合反应速率方程推导了生物质炭氧化过程气固反应机理,并对热重实验结果进行拟合计算。实验结果表明,随着制焦炭化温度的升高,生物质炭的着火温度和燃尽温度升高,燃烧特性指数S减小;棉杆炭综合燃烧性能优于木屑炭。棉杆炭在低温段和高温段燃烧的反应机理不同,低温段燃烧反应的机理是片状内扩散反应机理,高温段燃烧反应的机理是球形界面化学反应机理。木屑炭的反应机理是球形界面化学反应机理。拟合计算求得的活化能并不能反映出生物质炭进行燃烧反应的难易程度。

氯化锌活化生物质炭制备活性炭及其表征

以生物质炭为原料,采用氯化锌活化制备高比表面积微孔生物质活性炭,研究了浸渍比、活化剂浓度、活化温度与活化时间等条件对生物质活性炭吸附性能的影响,利用氮气吸附脱附、扫描电子显微镜、傅里叶红外光谱、X射线衍射等技术对生物质活性炭表面微观结构、形貌特征及化学结构进行了分析。结果表明,制备生物质活性炭的适宜工艺条件为:浸渍比为3,活化剂质量分数为40%,活化温度为600℃,活化时间为90min。在该条件下制备的生物质活性炭对亚甲基蓝的吸附值为213mg/g,超过国家水处理用活性炭一级品标准。经测试生物质活性炭的BET比表面积高达631.2m2/g,平均孔径2.23nm,总孔容为0.352cm3/g;孔隙结构发达,孔径分布狭窄,孔形状为排列整齐的蜂窝状结构,含有大量的微孔,84.4%的孔集中在2nm以内;表面存在醇羟基、羰基、醚、酚等含氧官能团。

生物质焦及其特性

生物质焦是生物质热解的固体产物。文章综述了生物质焦的产生机理,热解反应条件及生物质的种类、颗粒大小、灰分含量、无机物含量等原料特性对生物质焦产量的影响规律,介绍了生物质焦的物理吸附特性,燃烧、气化的化学特性以及生物质焦的应用,其目的是为今后生物质焦的研究提供参考依据。

生物质气化技术的再认识

近现代,生物技术在工业、农业和能源领域得到广泛应用,对世界科技和经济发展起到重大的变革和促进作用。由于化石燃料资源性枯竭问题和环境污染问题,寻找一种清洁、可再生的替代燃料和燃料生产技术已迫在眉睫。生物质气化技术作为一种清洁的可再生能源利用技术得到了快速发展,然而由于气化设备自身不够成熟以及未对气化副产物(生物质炭和生物质提取液)加以有效利用等问题,严重阻碍了生物质气化技术的商业化推广和运行。生物质气化多联产技术是指基于生物质下吸式固定床气化的气、固、液三相产品多联产及其产品分相回收、利用技术。该技术的提出,以及相关核心设备的开发成功与应用,为生物质气化技术的进一步发展提供了新的思路。笔者详细介绍了气化技术发展的历史和困境、生物质气化多联产技术的路线和核心设备以及多联产技术产品的开发和应用情况。

生物质炭对土壤性状和作物产量的影响

综述了生物质炭(biomass charcoal)对土壤性状和作物产量的影响。生物质炭化后与木炭相似,耐降解,可提高土壤碳库容量,减少温室气体排放。同时炭具有很大的表面积,持水性、吸附性均较强。在一定量下,施炭可增加土壤阴、阳离子交换量、吸附氮、磷及矿物离子,减少养分损失,在一定范围内,普遍能增加作物生物量和产量,因此认为生物质炭还田是提高土壤肥力、增加碳封存时间的有效途径。

生物质制备燃料炭实验研究

利用管式固定床炭化装置对棉秆、木屑和竹屑进行炭化实验,利用工业分析仪、快速量热仪和热重分析仪对炭化实验制得的生物质炭进行分析,用木炭和烧烤炭质量指标评价生物质炭质量,用着火温度、燃尽温度和综合燃烧特性指数S评价生物质炭燃烧特性。结果表明:随着炭化温度的升高,生物质炭产率和干基挥发分产率减小、干基固定碳产率增大,相应的变化速率减小;着火温度和燃尽温度随着炭化温度的升高而升高,S值减小;相比木屑炭和竹屑炭,棉秆炭的燃烧特性最好。对比生物质炭与木炭和烧烤炭的燃烧特性和炭质量发现,木屑和竹屑可用于生产木炭替代品,棉秆可用于制作烧烤炭,500℃为棉秆制备烧烤炭的最佳炭化温度。

KOH活化木屑生物炭制备活性炭及其表征

以木屑热裂解的生物质炭为原料,氢氧化钾为活化剂,采用化学活化法制备活性炭,探讨了碱炭比、活化温度和活化时间对活性炭吸附亚甲基蓝吸附值的影响。利用N2吸附实验、XRD和FTIR等实验技术,对原料与制备活性炭的结构与性能进行了表征。结果表明,在碱炭质量比为1.5、活化温度750℃、活化时间2 h的条件下,所制备的活性炭对亚甲基蓝吸附值为255 mg/g,BET总比表面积为1514 m2/g,中孔比表面积为110 m2/g,吸附总孔容为0.821 cm3/g,中孔孔容为0.117 cm3/g,吸附平均孔径为2.170 nm。