稻草秸秆基吸附剂的制备及其对硫代钼离子吸附选择性的实验研究

以稻草秸秆为原料,经酸碱处理去除其中金属及Si等杂质,再用预干燥法将3-氯-2-羟丙基-三甲基氯化铵(CHPTMA)与其反应制备出具有选择吸附性能的改性稻草,并对其进行了氮含量的测定和红外光谱表征。以某厂含钼2～3 g/L、WO3为100 g/L左右的反萃液为原料液,经硫代化后,用改性稻草进行除钼试验,考察了固液比、反应时间、反应温度、料液pH以及料液浓度对钨钼分离效果的影响。结果表明,在弱碱性条件下固液比为1g∶30 mL,吸附时间为0.5 h,吸附温度为20℃时,吸附除钼效果最好,且吸附量随料液浓度的上升而增加。在最佳条件下,除钼率可达48%,WO3回收率为99%,分离系数稳定在1.7左右。     

Germination Conditions Affect Physicochemical Properties of Germinated Brown Rice Flour

ABSTRACT:  Germinated brown rice has been reported to be nutritious due to increased free gamma-aminobutyric acid (GABA). The physicochemical properties of brown rice (BR) and glutinous brown rice (GNBR) after germination as affected by different steeping times (24, 36, 48, and 72 h depending on the rice variety) and pHs of steeping water (3, 5, 7, and as-is) were determined and compared to those of the nongerminated one (control). As the steeping time increased or pH of steeping water decreased, germinated brown rice flours (GBRF) from both BR and GNBR had greater reducing sugar, free GABA and α-amylase activity; while the total starch and viscosity were lower than their respective controls. GBRFs from both BR and GNBR prepared after 24-h steeping time at pH 3 contained a high content of free GABA at 32.70 and 30.69 mg/100 g flour, respectively. The peak viscosity of GBRF obtained from both BR and GNBR (7.42 to 228.22 and 4.42 to 58.67 RVU, respectively) was significantly lower than that of their controls (255.46 and 190.17 RVU, respectively). The principal component analysis indicated that the important variables for discriminating among GBRFs, explained by the first 2 components at 89.82% of total explained variance, were the pasting profiles, α-amylase activity, and free GABA.     

Adsorption of Photographic Sulphur Sensitizers to Silver Bromide and Silver Sulphide

Heats of adsorption of thiosulphate, thiosulphatoargentate and p-toluenethiosulphonate to silver bromide, silver bromo"dide, silver chloride and silver sulphide were measured using a slow microcalorimeter. The results did not confirm previous evidence for the cluster mechanism for silver sulphide formation during sulphur sensitization. The possibility of this model was discussed. Heats of adsorption of silver and sulphide ions were also measured.     

Characterization of platinum–iron catalysts supported on MCM-41 synthesized with rice husk silica and their performance for phenol hydroxylation

Abstract

Mesoporous material RH-MCM-41 was synthesized with rice husk silica by a hydrothermal method. It was used as a support for bimetallic platinum?iron catalysts Pt–Fe/RH-MCM-41 for phenol hydroxylation. The catalysts were prepared by co-impregnation with Pt and Fe at amounts of 0.5 and 5.0 wt.%, respectively. The RH-MCM-41 structure in the catalysts was studied with x-ray diffraction, and their surface areas were determined by nitrogen adsorption. The oxidation number of Fe supported on RH-MCM-41 was + 3, as determined by x-ray absorption near edge structure (XANES) analysis. Transmission electron microscopy (TEM) images of all the catalysts displayed well-ordered structures, and metal nanoparticles were observed in some catalysts. All the catalysts were active for phenol hydroxylation using H₂O₂ as the oxidant at phenol : H₂O₂ mole ratios of 2 : 1, 2 : 2, 2 : 3 and 2 : 4. The first three ratios produced only catechol and hydroquinone, whereas the 2 : 4 ratio also produced benzoquinone. The 2 : 3 ratio gave the highest phenol conversion of 47% at 70 °C. The catalyst prepared by co-impregnation with Pt and Fe was more active than that prepared using a physical mixture of Pt/RH-MCM-41 and Fe/RH-MCM-41.     

稻壳混合贫煤燃烧对SO2排放的影响

本文利用循环流化床实验平台,分析稻壳混煤燃烧对SO2排放的影响.将稻壳与贫煤按不同质量比制成混合燃料,在流化床锅炉中燃烧,采集炉温及烟气中SO2浓度等数据进行分析.结果表明,当燃烧温度恒定时,SO2的排放量随着燃料中稻壳所占比重增加而降低;当燃料中稻壳所占比重恒定时,SO2的排放量随着燃烧温度的升高而增加.     

Diverse Monitoring Approaches Reveal 14C Dispersion Pattern and Its Impact on the Environment around the Tokai Reprocessing Plant

Carbon-14 (¹⁴C) is of great interest in the assessment of dose due to the nuclear industry because of the biological importance of carbon. We collected atmospheric CO₂, rice grain, leafy vegetable, and Japanese mugwort samples at various locations at different time intervals, and measured their ¹⁴C concentrations to show the spatiotemporal distribution of ¹⁴C around the Tokai reprocessing plant (TRP). The results consistently gave the picture of a ¹⁴C dispersion pattern brought about by the prevailing wind in this area, which conveys the ¹⁴C plume, and as a result, caused elevated ¹⁴C concentrations in the area 2–3 km southwest of the main stack of the TRP. The increases in ¹⁴C concentration were, however, quite temporary, and the baseline concentration remained at the background level even in the elevated area. The ¹⁴C concentrations in vegetations generally followed those in atmospheric CO₂, but seemed different in ¹⁴C uptake response between vegetation types, emphasizing the importance of this nature not only in its application as bioindicators in environmental monitoring but also in establishing a more realistic dose evaluation model for ¹⁴C. Through a series of investigations, we found the highest ¹⁴C concentrations of 374, 287, and 361 Bq kg-C^?1 in atmospheric CO₂, rice grains, and leafy vegetables, respectively. They corresponded to a maximum of ~110 Bq kg-C^?1 excess above the background. The annual effective dose delivered from the concentrations was estimated to be around 0.7 μSv yr^?1, only 0.07% of the annual effective dose limit for the public. Thus, we conclude that the ¹⁴C releases from the TRP have a very slight impact both on the environment and on the public.     

Characterization of Biogenic Silica Generated by Thermo Chemical Treatment of Rice Husk

This study presents two routes to produce amorphous silica from an Egyptian rice husk under conditions optimized for least environmental impact and low cost. The first route includes thoroughly washing of the husk sample with water, dry milling and leaching with citric acid. The leaching process was applied in two stages, that is, at 323 K for 180 min and then at 353 K for 60 min. After washing and drying, the leached sample was subjected to a heat treatment in a muffles furnace at four sequential steps. The second route includes all the previously mentioned steps, except the citric acid leaching. The final products were characterized using x-ray fluorescence analysis, carbon content analysis, x-ray diffraction, differential thermal analysis, nitrogen adsorption, mercury intrusion, and scanning electron microscopy. The results show that the citric acid leaching has many advantages with respect to silica yield and porosity as well.     

稻壳纤维素制备阴离子交换剂及其性能的研究

采用稻壳纤维素,通过硝化、碱化、老化、交联、胺化等制备工艺,制得了表面具有甲胺基团的阴离子交换剂。直接耐晒翠蓝阴离子交换的性能实验表明,选择三甲胺盐酸盐作为胺化剂,胺化温度为65℃时,制备的离子交换剂的交换率最高。通过正交实验得出在pH值为4,反应温度为60℃,反应时间为120 min的条件下,稻壳基离子交换剂对直接耐晒翠蓝阴离子交换效果较好。离子交换过程的动力学研究表明,在反应前期(前80 min),离子交换行为为膜扩散所控制;在反应后期(80 min后),为内部扩散所控制。     

丘陵山区水稻生产全程机械化工程研究

水稻生产的主要环节有耕整地、种植(育秧、栽插、直播)、田间管理(植保、除草)和收获,丘陵山区水稻生产主要环节对机械装备的要求有其特殊要求.文中给出了丘陵山区水稻生产全程机械化机械装备研究的技术路线,同时提出了丘陵山区水稻生产全程机械化的对策.     

煤与稻壳共热解热重分析及动力学

利用热重分析仪对长焰煤和稻壳分别单独及按不同掺混比例进行热质量损失实验研究。通过比较煤与稻壳共热解热质量损失曲线和计算得到的理论曲线发现,添加稻壳对共热解过程有促进作用,在不同的稻壳掺混比例下,共热解过程质量损失率和最大质量损失速率均较理论值有不同程度的增大,推测稻壳掺混对共热解存在促进作用,促进作用与稻壳掺混比例不成线性关系。对煤与稻壳及共热解过程进行动力学分析,获得了反应活化能和频率因子,分析计算热解动力学参数表明共热解过程存在动力学补偿效应。