化学添加剂在制备煤基活性炭中的作用与比较

采用添加化学药品ＫＯＨ和ＺｎＣｌ２的方法控制煤炭化过程和炭化物结构性状,以生成各向同性的炭素前驱体,并制备出优质活性炭     

低钠保健皮蛋加工技术研究

在传统加工方法的基础上,利用KOH代替NaOH,并用KCl部分代替NaCl,加工低钠保健松花蛋,钠含量由465.8mg/100g降至287.6mg/100g,降幅为38.27%.本课题初步摸清了低钠无铅松花蛋的工艺要点,并测试了蛋中Na+、K+、Cu2+、Zn2+和碱浓度的变化情况.     

KOH作用下稻壳制备高比表面积活性炭的研究

以稻壳为原料、KOH为活化剂,制备了高比表面积活性炭,研究了活化剂用量、活化温度和活化时间对活性炭吸附性能的影响.研究结果表明,活化剂与稻壳的质量比为3:1,在800℃活化1h,制得的活性炭碘吸附值为1520.32mg/g,亚甲蓝吸附值为3442.50mg/g,比表面积为2027.42m2/g.SEM和XRD观察发现,干馏过程及活化过程的共同作用使活性炭产生多孔结构.     

胶体碳微球的活化及其亚甲基蓝液相吸附性能的研究

以葡萄糖为前驱体,采用液相碳化法,制备颗粒约为100～200nm胶体碳微球.采用KOH作活化剂对胶体碳微球进行活化处理.考察了碱炭比、活化温度和保温时间等工艺因素对孔径和比表面积的影响.通过XRD、SEM等分析手段对胶体碳微球活化前后的表面形貌、孔径分布、显微结构进行分析.经热处理和活化后,胶体碳微球的BET比表面积从26.6m2/g增加到1383.4m2/g.相同实验条件下,在亚甲基蓝液相吸附试验中,经活化处理后的样品所表现出的吸附量是商业活性炭Calgon-F300的两倍.     

利用稻草制浆黑液制备活性炭的研究

利用稻草制浆黑液中提取的木质素/二氧化硅复合材料为前驱体制备了活性炭.研究了活化剂KOH用量、活化反应的温度和活化反应的时间对活性炭吸附性能的影响.最佳的反应条件为:浸渍比(KOH于复合材料的质量比)为3:1,活化反应的温度为750℃,活化反应的时间为1h,此时制备的活性炭碘吸附值最大.制备的活性炭碘吸附值达到816.26 mg/g,BET比表面积为532.6 m2/g.活性炭大部分为介孔结构,含有少量微孔结构,平均孔径在6 nm.     

碱炭比及活化温度对稻壳活性炭极微孔的影响

采用N₂吸附、CO₂吸附和热重红外联用等技术手段, 考察了在KOH活化稻壳炭的过程中碱炭比和活化温度对活性炭极微孔的影响。结果表明: 在不同碱炭比(0.6︰1~3︰1)和活化温度(640~780℃)下制备的稻壳活性炭, 极微孔主要分布在0.42~0.70 nm。当碱炭比增加时, 极微孔孔容先增大后减小; 而当活化温度升高时, 极微孔孔容呈降低趋势。极微孔率随碱炭比或活化温度的升高而单调递减。在活化温度为640℃、碱炭比为1: 1时, 可得极微孔孔容为0.149 mL/g、极微孔率达36.3%的微孔活性炭。活性炭的极微孔孔容与其在10⁴ Pa时的CO₂吸附量高度线性相关。     

Surface passivation of cadmium zinc telluride radiation detectors by potassium hydroxide solution

The spectral resolution of cadmium zinc telluride (CZT) room temperature nuclear radiation detectors is often limited by the presence of conducting surface species that increase the surface leakage current. Surface passivation plays an important role in reducing this surface leakage current and thereby decreasing the noise of the detectors and improving the spectral energy resolution. Chemical etching with a Br-MeOH solution leaves CZT surfaces rich in Te and is considered as one of the primary causes of the increased surface leakage current. Previous studies have shown that hydrogen peroxide (H₂O₂) forms oxides of tellurium on the CZT surface and thus acts as a good passivating agent. In this study we will present results on the use of potassium hydroxide (KOH) as an alternative passivating agent. The KOH aqueous solution leaves a more stoichiometric (evaluated from the trends in the surface Cd:Te ratio) and smoother CZT surface. The passivation effects of KOH solution on the surface of the CZT have been characterized by current-voltage measurements for different KOH concentrations and etching times for both parallel strip electrodes as well as a metal-semiconductor-metal configuration. The surface chemical composition and its morphology were studied by scanning x-ray photoelectron spectroscopy and atomic force microscopy. The comparison and demonstration of improvements in the spectral resolution of the CZT detectors (based on ²⁴¹Am spectra) with and without the KOH treatment are presented.     

强碱性固体凝胶电解质电性能研究

采用自由基溶液聚合方法,将KOH嵌入由聚丙烯酸/聚丙烯酰胺(PAA/PAAM)构成的固体凝胶中,制成具有较高机械强度的强碱性固体凝胶电解质。研究发现,固体凝胶电解质电导率接近KOH水溶液电导率,在KOH质量分数为20%时其电导率达最大值0.28 S/cm;电导率随温度的变化遵循Arrhenius原理。     

The influence of bismuth oxide doping on the rechargeability of aqueous cells using MnO2 cathode and LiOH electrolyte

Bi-doped manganese dioxide (MnO₂) has been prepared from γ-MnO₂ by physical admixture of bismuth oxide (Bi₂O₃). The doping improved the cycling ability of the aqueous cell. These results are discussed and compared with the electrochemical behavior of bismuth-free MnO₂. Batteries using the traditional potassium hydroxide (KOH) electrolyte are non-rechargeable. However, with lithium hydroxide (LiOH) as an electrolyte, the cell becomes rechargeable. Furthermore, the incorporation of bismuth into MnO₂ in the LiOH cell was found to result in significantly longer cycle life, compared with cells using undoped MnO₂. The Bi-doped cell exhibited a greater capacity after 100 discharge cycles, than the undoped cell after just 40 cycles. X-ray diffraction and the microscopic analysis suggest that the presence of Bi³⁺ ions reduces the magnitude of structural changes occurring in MnO₂ during cycling. Comparison with additives assessed in our previous studies (titanium disulfide (TiS₂); titanium boride (TiB₂)) shows that the best rechargeability behavior is obtained for the current Bi-doped MnO₂. As the size of Bi³⁺ ions (0.96 Å) is much larger than Mn³⁺ (0.73 Å) or Mn²⁺ (0.67 Å) they have effectively prevented the formation of non-rechargeable products.