Characteristics of as-prepared biochar derived from catalytic pyrolysis within moderate-temperature ionic liquid for CO2 uptake

A promising biochar as solid adsorbent for CO₂ uptake was prepared by the catalytic pyrolysis of coconut shell in moderate-temperature ionic liquid (IL). Then, it was characterized by means of SEM, EDS, BPEA, BET, NLDFT, FTIR, and TG-DSC, and a mechanism interpretation of the porous biochar formation was conducted. In addition, the adsorption characteristics of CO₂ on the as-prepared biochar, such as adsorption capacity, adsorption potential, isosteric heat, and static selectivity at different adsorption temperatures and pressures, were systematically evaluated. The results indicated that the as-prepared biochar exhibited an adequate CO₂ adsorption with a capacity of 4.5 mmol/g at 273 K and 100 kPa. Then, a significant number of slit-like pores were revealed to exist on the as-prepared biochar with a peak pore size between a range of 0.6 nm-2 nm. The porous structure formation was ascribed to the release of carbon-, hydrogen-, oxygen-, sulphur-, and nitrogen-containing compounds during biochar preparation. Meanwhile, both the adsorption potential and isosteric heat of the CO₂ uptake under the tested conditions decreased with an increase in the adsorption capacity, which ranged from 33 kJ/mol-21 kJ/mol and 23 kJ/mol-7 kJ/mol, respectively. Therefore, the isosteric heat could be considered as a piecewise function of adsorption capacity. In addition, the molar ratios of CO₂ over N₂ adsorbed under the tested conditions were above 11 and were accompanied by molar ratio peaks of 26 at 273 K and 19 at 298 K, respectively. Moreover, an interesting phenomenon occurred: the static adsorptive selectivity of CO₂ over N₂ first increased and then decreased and there was an increase in the adsorption pressure at the tested adsorption temperatures.     

The study of optimal parameters of oxygen-enriched combustion in fluidized bed with optimal torrefied woody waste

The study explored the oxygen-enriched combustion behavior of torrefied waste wood pellets in a fluidized bed. For biomass torrefaction, three indexes, namely energy yield index (EY), proximate analysis-based index (PA), and effective comprehensive combustion index (S_mix), are used to present the optimal conditions from each viewpoint. Four operating parameters, incorporating torrefaction temperature, residence time and nitrogen flow rate, were taken into consideration in this study. The signal-to-noise ratios of each parameter were evaluated to examine the influencing impact of different factors. The optimal results were employed in the investigation of biochar combustion using a laboratory-scale fluidized-bed reactor with oxygen lancing. Oxygen was injected into different zones of the fluidized bed to investigate its influence on combustion efficiency. The parameters of biochar combustion optimization include torrefied materials, fluidized-bed temperature, oxygen inlet position, and oxygen concentration. The total fluidized-bed efficiency and the volatile combustion ratio were evaluated.     

Preparation and electrochemical properties of biochar from pyrolysis of pomelo peel via different methods

Dried pomelo peel waste was employed as raw material and heated separately via three different thermal treatment methods which are vacuum tube furnace (700?°C, 300?～?1 × 10^?5?Pa), muffle furnace (300?°C in air) and hydrothermal treatment in an oven (200?°C, sealed). Therefore, three kinds of amorphous porous carbon were obtained and named as S1, S2 and S3, respectively. XRD, SEM, EDS, specific surface area and pore size analyzer have been used to characterize the morphology, composition and porosity of the biochar materials which show 3 dimensional porous framework morphologies, but only S1 possesses highest specific surface area (464.96m²/g) among the 3 biochar materials. The electrochemical properties were characterized via galvanostatic charge/discharge method, cyclic voltammetry (CV) and AC impedance. After 100 cycles of charge and discharge process, the specific capacity of the biochar S1 maintained 297.0mAh/g. The specific capacity of S2 was 103.3mAh/g and the specific capacity of S3 is 106.0mAh/g. Thus, S1 exhibits a high specific surface area and excellent electrochemical performance which may have potential application due to low cost of the biochar prepared from pomelo peel wastes.     

生物炭-膨润土共改性及其铅离子吸附与稳定化研究

重金属污染具有高毒性、持久存留和生物积累等特性, 严重危害人体健康和生态安全。本研究通过氯化钙对玉米芯残渣和膨润土混合物进行碱改性, 在无氧条件下高温煅烧制备了一种碱改性生物炭-膨润土复合物(CaO-Bent-CB)。该复合物的比表面积高, 达到441.1 m²/g, 明显高于直接煅烧制备的生物碳(132.7 m²/g)和碱改性生物炭(177.2 m²/g)。进一步评价了该复合物对水中铅离子吸附性能, 结果表明在水中铅离子浓度为120 mg/L, 膨润土与玉米芯残渣质量比为1:5, 用量为1 g/L条件下, 吸附6 h后铅离子去除率达98%, 吸附量为109.6 mg/g, 均高于生物炭(13.4 mg/g)、膨润土(72.9 mg/g)和碱改性生物炭(86.9 mg/g)。此外, 采用CaO-Bent-CB对铅离子污染土壤进行稳定化处理, 当土壤中铅离子浓度为2200 mg/kg, CaO-Bent-CB用量为土壤干重的8%时, 在pH=3.2的硫酸-硝酸浸提液中浸出12 h, 酸浸出铅离子浓度低至4.5 mg/L, 低于危险废物鉴别标准值(5 mg/L)。上述研究结果表明这种生物炭-膨润土共改性复合物在重金属污染水体和土壤修复中具有很好的应用前景。     

大型水生植物的资源化利用

为了更好地利用大型水生植物,防止二次污染,在分析大型水生植物传统资源化利用途径的基础上,提出了大型水生植物资源化利用的新途径,即利用大型水生植物厌氧发酵生产有机酸和制备生物质炭,用于污水处理的脱氮除磷,以利于碳素循环。     

球磨改性生物炭在环境修复中的应用进展

利用球磨机械力化学技术制备的改性生物炭具有成本低、产能高、绿色无溶剂等优点,近年来受到研究人员的广泛关注.球磨改性增加生物炭表面官能团、扩大其比表面积以及提高吸附容量,使球磨改性生物炭对环境污染物具有优异的去除性能,在环境修复领域应用前景广阔.介绍了球磨改性生物炭的制备与理化性质,总结了球磨改性生物炭在环境修复中对污染物质去除的最新进展,同时明确其对各类污染物的去除机制.在此基础上,探讨球磨改性生物炭在环境修复中目前存在的问题与限制因素,从明确技术和经济可行性、扩展材料应用范围以及厘清潜在生态环境风险等方面提出未来研究方向.     

Preparation of magnetic biochar derived from cyclosorus interruptus for the removal of phenolic compounds: Characterization and mechanism

A novel magnetic biochar was prepared via pyrolysis method and modification. The influence factors of contact time, initial concentration, temperature, and pH on the adsorption were investigated. The experimental results exhibited that the adsorption ability of methyl salicylate onto biochar was higher than that of phenol and para-chlorophenol under the same condition, which may be owing to the effect of hydrogen bonding, hydrophobicity, and π–π interaction. The maximum adsorption capacities of phenol, para-chlorophenol and methyl salicylate were 62.6, 131.6, and 169.7 mg/g at 298 K, respectively. This magnetic biochar exhibited high reusability (retained 82.1% after five cycles) and sharply magnetic performance (21.4emu/g).     

Use of three types of magnetic biochar in the removal of copper(II) ions from wastewaters

Three types of magnetic biochars (MBC1, MBC2, and MBC3) were synthesized from biochar using NaBH₄ as a reducing agent of Fe(II) to Fe(0) to remove copper(II) ions from different wastewaters. Based on the research it was found that removal of copper(II) ions by MBC1 occurs with a yield of 99.8% for the concentration 50 mg/dm³ and decreases to 71.7% at 200 mg/dm³. The maximum pH sorption was found at pH 5. The highest correlation coefficient values (65.55 mg/g) were obtained for the Langmuir isotherm model. Application of 0.5 mol/dm³ HNO₃ as a desorbing agent gives the highest desorption percentage 98.92%.     

烘焙温度和停留时间对生物炭特性的影响

以杨树枝、柳树枝、稻壳、玉米秸秆、成型稻壳和成型木屑6种生物质为对象,在烘焙温度为200~300℃和停留时间为20~40 min的条件下,利用固定床烘焙实验装置开展了生物质烘焙实验,结合生物炭的工业分析、元素分析和热值测定结果,分析了烘焙温度和停留时间对生物炭H/C,O/C,能量得率,能量密度的影响。结果表明:随着烘焙温度和停留时间的增加,生物炭的挥发分,质量得率,H/C,O/C,能量得率不断下降,固定碳、低位发热量和能量密度不断升高;烘焙温度对生物炭的影响显著强于停留时间,烘焙处理对木质类和农业类生物质影响显著强于成型生物质;在烘焙温度为300℃和停留时间为40 min的条件下,成型生物质的能量密度最高仅为1.10,而木质类生物质的能量密度最高可达到1.40。