Novel silicon-contained lignin-based carbon fibers derived from bamboo pulping black liquor with improved electrochemical performance for supercapacitors

Carbon fibers (CFs) are a promising candidate as electrode materials for flexible supercapacitors given its light weight and moderate cost. In this study, the lignin used was partially separated from kraft bamboo pulping black liquor and the higher molecular weight fraction, unavoidably contains a small amount of silicon compounds, so named silicon-contained lignin. Novel CFs were prepared using commercial polyacrylonitrile (PAN) and the lignin by electrospinning and further carbonization. Even in the presence of silicon compounds, the fibrous morphology of precursor fibers was significantly good, and the CFs with uniform fiber diameter and high specific surface area up to 182 m²/g were obtained with an increase in silicon-contained lignin. The CFs fabricated from silicon-contained lignin and commercial PAN had higher specific capacitance (22.20 mF/cm² at 10 mA/cm²) and superb cycling stability (94.21%) than that from silicon-free lignin or pure PAN separately.     

ICP-OES测定西藏铜矿浸出液中铜铅锌等8种矿物组分

电感耦合等离子体光谱法测定西藏铜矿浸出液中8种矿物组分,讨论了元素分析谱线选择、背景校正等因素。结果表明,在高海拔地区仪器参数优化条件下,元素间也没有干扰且该方法快速,准确可靠,各元素检出限5.6~42μg·m L-1之间,加标回收率为92.5%~106%,相对标准偏差RSD均小于1.0%,适用于高海拔条件下对铜矿浸出液的日常检测。     

钙化-酸浸提钒沉钒母液中锰的回收

对钙化?酸浸提钒沉钒母液中锰资源的回收，一方面可以提升提钒工艺的经济效益，另一方面可避免母液循环时锰浓度不断累积而影响氧化钒产品质量，从而有助于实现母液闭路循环而提升全流程的环境效益。本工作提出了采用草酸沉淀法高效回收沉钒母液中的Mn2+，考察溶液体系pH值、草酸加量系数、反应温度和时间对锰回收率及沉淀产物物相组成的影响，以及草酸沉淀分离锰后母液的循环次数对钒浸出过程的影响。结果表明，草酸沉淀法可高效分离沉钒母液中的Mn2+，在溶液体系pH=4.0、草酸加量系数为1.5、反应温度为50℃、反应时间为60 min的条件下，锰回收率达94.33%，所得产物为纯度大于98%的水合草酸锰，为片状晶体，并呈花簇状生长。将脱锰后的沉钒母液循环至酸浸段，对钒浸出率及浸出液中锰的浓度没有明显影响，表明该方法有助于实现钙化?酸浸提钒中废水的闭路循环。     

Fuel conversion characteristics of black liquor and pyrolysis oil mixtures: Efficient gasification with inherent catalyst

Alkali metals inherent in black liquor (BL) have strong catalytic activity during gasification. A catalytic co-gasification process based on BL with pyrolysis oil (PO) has the potential to be a part of efficient and fuel-flexible biofuel production systems. The objective of the paper is to investigate how adding PO into BL alters fuel conversion under gasification conditions. First, the conversion times of single fuel droplet were observed in a flat flame burner under different conditions. Fuel conversion times of PO/BL mixtures were significantly lower than PO and comparable to BL. Initial droplet size (300–1500 μm) was the main variable affecting devolatilization, indicating control by external heat transfer. Char oxidation was affected by droplet size and the surrounding gas composition. Then, the intrinsic reactivity of char gasification was measured in an isothermal thermogravimetric analyser at T = 993–1133 K under the flow of CO₂–N₂ mixtures. All the BL-based samples (100% BL, 20% PO/80% BL, and 30% PO/70% BL on mass basis) showed very high char conversion. Conversion rate of char gasification for PO/BL mixtures was comparable to that of pure BL although the fraction of alkali metal in char decreased because of mixing. The reactivities of BL and BL/PO chars were higher than the literature values for solid biomass and coal chars by several orders of magnitude. The combined results suggest that fuel mixtures containing up to 30% of PO on mass basis may be feasible in existing BL gasification technology.     

茅台镇酱香型白酒酿造环境中真菌菌群多样性分析

采用高通量测序技术结合数理统计软件分析方法，系统研究茅台镇酱香型白酒不同酿造轮次生产环境中的真菌菌群结构及特征。7 个轮次中共检测到4 个真菌门、212 个真菌属。根据各菌门、属的相对丰度，子囊菌门（Ascomycota）和担子菌门（Basidiomycota）是茅台镇酱香型白酒酿造环节中各酿造轮次的优势菌门，节担菌属（Wallemia）、复膜孢酵母属（Saccharomycopsis）为各轮次绝对优势真菌属。不同轮次环境样品中真菌组成结构的相似度较高，但其各轮次标志性真菌属存在差异。7 个酿造轮次共有相同真菌属56 个，在各轮次占主导地位，特征性真菌属在各轮次当中相对丰度和占比较小但种类丰富。Ascomycota最强节点为德巴利酵母属（Debaryomyces），Basidiomycota最强节点为红酵母属（Rhodotorula）。本研究揭示了茅台镇酱香型白酒不同酿造轮次环境中真菌菌群结构及其特征，为深入研究酱香型白酒酿造机理以及对酿造环境中微生物结构的解析提供了参考依据。     

杨木预水解液中化学组分质量浓度的P因子调控

为研究P因子对木质纤维原料预水解液中化学组分质量浓度的调控机制，分析了不同预水解温度（170~210℃）和预水解时间（30~120 min）条件下，杨木预水解液中固形物、木质素、木糖和葡萄糖质量浓度的变化规律。结果表明：升高预水解温度和延长预水解时间，固形物、木质素和葡萄糖质量浓度均逐渐增大。而木糖质量浓度随温度的升高而降低；190℃时，木糖质量浓度随预水解时间延长迅速减小。P因子对杨木预水解液中化学组分的质量浓度具有调控作用。固形物、木质素和葡萄糖质量浓度随P因子增加呈指数增大。而木糖质量浓度随P因子增加呈指数减小，P因子小于3 300时，木糖质量浓度随P因子增加迅速减小。     

Process performance in lignin separation from softwood black liquor by membrane filtration

Black liquor is a side-stream in the production of kraft pulp. The extraction of lignin and hemicelluloses from black liquor would reduce the load on the recovery boiler and give valuable by-products. Lignin was separated from black liquor by membrane filtration, using one ceramic and three polymeric nanofiltration membranes, with molecular weight cut-offs in the range of 200 Da to 1 kDa. Ultrafiltration was tested as a form of pretreatment prior to nanofiltration to separate hemicelluloses from lignin. The use of ultrafiltration prior to nanofiltration increased the flux drastically in the nanofiltration step with three of the membranes. The ceramic membrane exhibited a higher flux and lower lignin retention than the polymeric membranes. The two membranes with a molecular weight cut-off of 1 kDa were found to have the best performance in parametric studies, and were therefore used in concentration studies. The results were used for a preliminary economic evaluation of the process. These calculations showed that the most cost-effective alternative for the extraction of lignin was with the polymeric 1 kDa membrane without pretreatment, and that the production cost for a lignin solution with a concentration of 230 g L⁻¹ would be 46 € per ton of lignin.     

Simulation analysis of producing xylitol from hemicelluloses of pre-hydrolysis liquor

The pre-hydrolysis liquor (PHL) of the kraft-based dissolving pulp production process is currently sent to the recovery boiler and incinerated. However, PHL contains about 5–8% lignocelluloses that can be utilized in the production of value-added chemicals. In this study, a process for producing xylitol from hemicelluloses in PHL is developed. This process involves several acidification, neutralization, adsorption (along with reactivation) and evaporation stages. The mass balance indicates that 533 kg/h xylitol (with 99% purity), 187 kg/h lignin, 806 kg/h basic ferric acetate, and 1600 kg/h gypsum can be produced from 41,670 kg/h PHL. The energy balance shows that the evaporators are the largest consumers of energy, while the reactivation kiln, acidification, neutralization, and precipitation processes generate some heat. Overall, 41% conversion of xylose to xylitol is achieved.