KOH对超临界水中褐煤连续制氢的影响

采用连续式超临界水反应装置,以20%的水煤浆为反应原料,考察了不同KOH/煤质量比、温度、压力对褐煤制氢过程的影响。实验结果表明,在水煤浆中添加KOH可以提高碳气化率及H2的体积分数和产率,在600℃、25 MPa、KOH/煤质量比为4.1%时,与未加KOH相比,气相产物收率由29.6%提高到49.5%,碳气化率由23.0%增大到31.5%;H2的产率由135.4 mL/(g daf coal)提高到239.1 mL/(g daf coal)。随着温度的升高,H2产率逐渐增大,650℃时达到287.8 mL/(g daf coal),是500℃时的5.4倍;高温、高压下,KOH对煤气化过程的催化作用更为明显。

芝加哥天蓝与KOH涂片镜检对马拉色菌诊断的比较

目的以培养作为诊断标准,比较芝加哥天蓝涂片镜检和KOH涂片镜检对马拉色菌诊断的阳性率、阅片耗时等方面差异。方法收集门诊可疑马拉色菌感染患者皮屑标本,同时做真菌培养、芝加哥天蓝涂片、KOH涂片,培养阳性的281份标本,对芝加哥天蓝涂片镜检和KOH涂片镜检阳性率、阅片时间进行统计学分析比较。结果芝加哥天蓝可将马拉色菌的孢子或菌丝染成蓝色而皮屑等被染成浅紫红色杂质背景,阅片时间(70.99±12.61)s,KOH阅片时间(79.56±15.67)s,差异有统计学意义(P<0.05)。培养阳性的281例马拉色菌标本中芝加哥天蓝染色涂片镜检阳性193例,阳性率68.68%,KOH涂片镜检阳性179例,阳性率63.70%,差异有统计学意义(P<0.05)。结论芝加哥天蓝涂片为马拉色菌的诊断提供了一种简单快速、阳性率高、稳定性强、性价比好、结果易读取的检查方法。

Removal of iron from ilmenite by KOH leaching-oxalate leaching method

Oxalic acid was used for the removal of iron from the intermediates of ilmenite leached by KOH liquor. Various parameters, such as pH, temperature, initial oxalate concentration, and illumination were investigated. Meanwhile, it was found that orthorhombic crystal Ti2O2（OH）2（C2O4）-H2O formed as the leaching proceeded. Scanning electronic microscope （SEM） images implied that the formation of Ti2O2（OH）2（C2O4）.H2O with good crystallinity proceeded through three stages. Calcining Ti2O2（OH）2（C2O4）·H2O, anatase （350℃） or mtile （550℃） type TiO2 was obtained, respectively. Element analysis found that the calcined product contained 94.9% TiO2 and 2.5% iron oxide, but only about 1600 ppm dissolvable iron oxide was left, which indicates that oxalic acid was comparatively effective on iron oxide removal from the intermediates. Finally, an improved route was proposed for the upgrading of ilmenite into mtile.

Effect of ultrasonic assisted KOH pretreatment on physiochemical characteristic and anaerobic digestion performance of wheat straw

In this study,ultrasonic field was applied during potassium hydroxide(KOH) pretreatment of wheat straw(WS).Three concentrations of KOH(2%,4%,and 6%) were tested during pretreatment.The results showed that there was a significant influence of the ultrasonic assisted KOH pretreatment(KOH(Upt)) on physiochemical characteristics of WS during pretreatment as well as on digester performance.The pretreatment time was optimized to 36 h for all KOH concentrations.The highest total volatile fatty acid(TVFA) productions(3189 mg·L^-1) from 6%KOHupt samples were observed.Similarly,the SEM analysis and FTIR observation revealed that KOH(Upt) effectively disrupted the physical morphology of WS and successful breaking of lignin and hemicellulose linkage between carboxyl groups.Moreover,the highest biogasification(555 ml·(g VS(loaded))^-1) and biomethane productions(282 ml·(g VS(loaded))^-1) from 4%KOH(Upt) digesters,with 69% of biodegradability,indicated significant availability of organic matter from KOH(Upt).The R^2 values(0.993-0.998) in Modified Gompertz Model indicated that the model was feasible to predict methane yield for this study.Similarly,the Bo values for 4%KOH(Upt)(283.30±2.74 ml·(gVS(loaded))^-1) were also in agreement to the experimental methane yield.These results suggested that ultrasonic addition during KOH pretreatment of WS can effectively increase the organic yield during pretreatment.Moreover,the increase in methane production from 4% KOH(Upt) suggested that digester performance can be improved with lower KOH concentrations using this pretreatment.

水蒸气和KOH二次活化对活性炭孔隙结构的影响研究

以商业活性炭为原料,采用水蒸气和KOH为活化剂,在不同活化条件下制备二次活化样品。用DFT方程考察活性炭孔径的变化;用FT-IR技术对活性炭表面官能团进行分析表征;采用XRD技术测试活性炭中的乱层结构。结果表明:无论何种活化方式,延长活化时间和提高活化温度,均有利于制备高比表面积且孔径发达的活性炭;化学二次活化较物理活化更易制得高比表面积且孔径发达的活性炭,且两种活化方式制备的活性炭的孔结构存在明显的差异;在适宜的条件下,KOH二次活化制备的活性炭在孔径<4.00 nm的范围内孔结构发达,孔径在4.00 nm~8.00 nm出现明显的分布峰,且石墨化结构破坏严重。

KOH活化制备加拿大一枝黄花微孔活性炭及表征

以入侵植物加拿大一枝黄花为原料,在氮气保护下,于400C直接碳化90 min后,选择KOH为活化剂制备高比表面积活性炭。研究了不同的KOH/C比值、活化温度及活化时间对活性炭吸附量及产率的影响。结果表明,最优活化条件为碱碳比3 g/g、活化温度800C及活化时间90 min,此时活性炭的亚甲基蓝吸附值、碘吸附值、活化产率和表面积分别为436 53 mg/g、2 1 53.6 mg/g、46.85%和2 21 4.6 m^2/g。采用热重分析研究加拿大一枝黄花的碳化过程,使用氨气吸附-脱附、傅立叶红外光谱法（FT-I R）、X射线衍射（XRD）及扫描电镜（SEM）对活性炭的空间结构特征、表面结构和表面官能团进行了表征。

Macroscopic superlubricity of potassium hydroxide solution achieved by incorporating in-situ released graphene from friction pairs

Graphene(G),as a typical two-dimensional material,is often used as an additive for liquid lubricants.However,graphene is mostly added to liquid lubricants in a one-time manner in friction;it mainly exists in the form of multilayer agglomerated structures due to theπ–πstacking between graphene sheets,making it unable to fully exert the synergistic lubrication function.Herein,we propose a new macroscopic superlubric system of graphene/potassium hydroxide(G/KOH)solution;and the graphene additive involved is exfoliated in-situ from graphene/epoxy(G/EP)friction pair by friction,continuously providing freshly-peeled graphene into KOH solution and minimizing the adverse effects of graphene agglomeration.Moreover,the in-situ produced graphene additive has thinner thickness and better anti-aggregation ability,which provide more graphene to accommodate OH−,form more stacked sandwich structures of OH−/graphene/OH−between friction pairs(i.e.,equivalent to a moving pulley block with more wheels),and finally realize superlubricity.This study develops a new liquid superlubric system suitable for alkaline environments,and at the same time proposes a new way to gradually release graphene additives in situ,rather than adding them all at once,deepening the understanding to liquid superlubricity mechanism,and paving the experimental foundation for the practical application of macroscopic superlubricity.

木质素纳米颗粒/天然纤维基活性碳纤维材料的制备及其电化学性能

以木质素纳米颗粒(LNPs)负载的天然纤维复合材料为研究对象,利用KOH活化的方法对其进行处理制备生物质基复合多孔活性碳纤维电极材料。随后在三电极体系中对合成的复合多孔活性碳纤维电极材料进行了电化学性能测试。研究表明,在0.5A/g的电流密度下,KOH活化的复合碳纤维电极材料的比电容为351.13F/g,远高于相同条件下未活化的复合碳纤维电极材料的比电容(7.88F/g)和未负载LNPs的天然纤维基活性碳纤维材料(306.50F/g)。而且在活化过程中,负载在纤维表面的LNPs会形成多孔的活性碳层结构,这会进一步提高复合活性碳纤维材料的循环稳定性,同时LNPs中丰富的羟基赋予复合材料额外的赝电容。在10A/g的电流密度下经过10000次循环后,复合活性碳纤维电极材料的电容保持率仍然为95%,高于未负载LNPs的活性碳纤维电极材料的电容保持率87%。结果表明,木质素纳米颗粒/天然纤维基活性碳纤维材料是一种理想的电极材料,本研究也为LNPs在生物质碳纤维作为储能电极材料的高值化应用提供了一条新途径。

KOH活化法聚丙烯腈基活性炭纤维的制备及表征

针对物理活化法制备聚丙烯腈基活性炭纤维(PAN-ACF)存在生产效率低、力学性能差、生产成本高等问题,以聚丙烯腈预氧化纤维(PANOF)为原料,氢氧化钾(KOH)为活化剂,用化学活化法代替物理活化法,通过改变活化工艺制得一系列不同的PAN-ACF样品。通过探讨浸渍浓度、浸渍时间、活化温度和活化时间四个因素对PAN-ACF得率和碘吸附值的影响规律,得到最佳活化工艺,并对最佳工艺下制得的PAN-ACF样品的微观结构、比表面积和孔结构进行表征分析,结果表明:最佳工艺下制得的PAN-ACF样品以微孔为主,存在少量的中孔和极少量的大孔,比表面积为2122.00 m^(2)·g^(-1),总孔容为1.00 cm^(3)·g^(-1),碘吸附值高达1740.20 mg·g^(-1),得率为40.07%。