Suppression effects of powder suppressants on the explosions of oxyhydrogen gas

Suppression tests of oxyhydrogen gas explosions were performed in an explosion tube with five types of dry powder used as the suppressants. The experimental results showed that the powder with large dust cloud density and small radius has better suppression effect, which agrees well with previous correlative results. Moreover, our results also showed that particles with chemical activity and light material density, their suppression effect are more prominent than that of the inert particles with heavy density. To discover the detailed suppression process of dust powder, governing equations were developed based on the homogeneous reactive two-phase flow. The TVD scheme and the Lax–Wendroff–Rubin scheme were adopted to solve the reactive gas phase and particle phase, respectively. The time splitting technique was employed to handle the stiffness of the coupled equations. Our calculated results showed that the dust cloud has the suppression effect on the explosion of oxyhydrogen gas, and with the increase of dust cloud density or the decrease of particle diameter, its suppression effect become more evident, which is in good agreement with our experimental results, in addition, the numerical results showed that with the same particle diameter, the suppression performance is enhanced with the reduction in particle material density.     

粉料无尘装车技术及其在电除尘器、大布袋除尘器输灰系统中的应用

传统电除尘器、大布袋除尘器输灰系统存在工艺繁杂、能耗大、输送速度慢、系统难于维护及二次扬尘问题,电除尘器、大布袋除尘器输灰系统采用粉料无尘装车技术可有效简化工艺、提高生产速度和系统运行、维护可靠性,很大程度减少能耗并彻底根除二次扬尘。     

MBR与SMBR脱氮除磷特性及膜污染控制

为提高污水深度处理效能和工艺运行的稳定性,研究以序批式膜生物反应器(SMBR)与传统膜生物反应器(MBR)为对象,对比研究其脱氮除磷特性、缺氧时间对工艺效率的影响及膜污染控制策略,同时应用分子生物学技术对两种工艺中微生物群落结构和组成进行分析.结果表明,间歇曝气能强化系统脱氮,使SMBR工艺去除总氮效果优于MBR,而在氨氮、总磷、COD、浊度去除方面两者无明显差异,去除率分别为94%、78%、80%、97%.延长SMBR工艺缺氧时间对COD、氨氮去除无显著影响,降低了总氮、总磷的去除率,总氮去除率由61%下降到46%,总磷由74%下降到52%.采用间歇曝气和投加一定浓度的粉末活性炭(PAC)均有利于减缓膜污染.微生物群落分析发现,两种工艺中微生物群落结构和组成无显著差异,硝化螺菌属(Nitrospira)和脱氯单胞菌属(Dechloromonas)为系统中的高丰度功能菌群,为工艺高效运行提供了生物学基础.     

改性凹凸棒土及粉末活性炭助凝聚硅硫酸铝消除微污染水中有机氯

以硅酸钠和硫酸铝为原料制备了聚硅硫酸铝絮凝剂(PASS),采用强化混凝的处理方法,对微污染水中有机氯(OCPs)的消除进行了研究.同时,考察了混凝剂投加量、pH值、原水浊度、粉末活性炭和改性凹凸棒土助凝剂等因素对OCPs消除效果的影响.结果表明:PASS投加量为5 mg·L-1时,OCPs的去除率可以达到57%~87%,浊度去除率可以达到99.1%,其效果好于聚合氯化铝(PAC);PASS混凝处理OCPs的最佳pH值范围是6~7;OCPs的去除与浊度的去除具有显著相关性,原水浊度的大小会影响OCPs的去除,低浊条件下OCPs和浊度的去除率明显低于中浊和高浊条件;粉末活性炭和改性凹凸棒土作为助凝剂与PASS复配均可显著提高OCPs的去除率,分别达到78%~100%和72%~95%.相较而言,凹凸棒土储量丰富,廉价易得,因此,以改性凹凸棒土替代粉末活性炭更有优势.     

制备方法对二氧化钛粉末薄膜光电极性能的影响研究

目的研究光电功能涂层制备方法对粉末薄膜光电极的光电转换效率的影响。方法采用喷涂法制备光电材料的FTO薄膜光电极,观察其表面形貌,通过研究光电流和光电位的变化评价光电材料的光电转换效率,并与点涂法和电泳法制备的光电极进行对比分析。结果喷涂法制备的二氧化钛FTO薄膜光电极性能优于其他两种方法制备的电极,在3.5%氯化钠溶液中,光电位变化更稳定,压降大于500 m V,光电流变化大于60μA/cm~2。结论喷涂法制备光电极能够提高半导体粉末材料的光电化学效率,是一种可推行的薄膜光电极制备方法。     

改性松果粉对罗丹明B染料废水的吸附性能研究

将天然松果粉分别用乙二胺四乙酸(EDTA)、硫酸、氢氧化钠进行改性,以改性松果粉为吸附剂,探究了不同pH、投加量、吸附时间对罗丹明B吸附性能的影响.实验结果表明,经硫酸改性的松果粉对罗丹明B染料废水的最佳吸附条件为:硫酸质量浓度为2 mol·L-1,pH为6,罗丹明B初始质量浓度50 mg·L-1,吸附剂投加量4 g·L-1,吸附时间150 min,此条件下脱色率达到97.72%,吸附量达到12.22 mg·g-1.吸附动力学研究表明,此吸附过程符合准二级动力学方程,属于化学吸附.     

Sequestration of toxic Pb（II） ions by chemically treated rubber （Hevea brasiliensis ） leaf powder

Rubber leaf powder (an agricultural waste) was treated with potassium permanganate followed by sodium carbonate and its performance in the removal of Pb(II) ions from aqueous solution was evaluated. The interactions between Pb(II) ions and functional groups on the adsorbent surface were confirmed by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) coupled with X-ray energy dispersive spectroscopy (EDX). The effects of several important parameters which can affect adsorption capacity such as pH, adsorbent dosage, initial lead concentration and contact time were studied. The optimum pH range for lead adsorption was 4–5. Even at very low adsorbent dosage of 0.02 g, almost 100% of Pb(II) ions (23 mg/L) could be removed. The adsorption capacity was also dependent on lead concentration and contact time, and relatively a short period of time (60–90 min) was required to reach equilibrium. The equilibrium data were analyzed with Langmuir, Freundlich and Dubinin-Radushkevich isotherms. Based on Langmuir model, the maximum adsorption capacity of lead was 95.3 mg/g. Three kinetic models including pseudo first-order, pseudo second-order and Boyd were used to analyze the lead adsorption process, and the results showed that the pseudo second-order fitted well with correlation coefficients greater than 0.99.     

硫粉投加量与污泥含固率之比对生物淋滤过程的影响

通过接种污泥硫细菌混合菌液,研究了S粉投加量与污泥含固率之比(SA/TS)对城市污泥中重金属生物淋滤效果的影响.结果表明,增大SA/TS值能显著缩短淋滤时间,提高淋滤效果.当SA/TS为2.5,经过8 d生物淋滤,Cu和Zn的淋滤效果可达到最佳,溶出率分别为66.2%和63.9%.淋滤进行16 d后,Pb的溶出率为30.8%.对于Cu,不论淋滤前后有机态都是较强的结合态.Zn的溶出主要是由于结合能力强的铁锰氧化态在淋滤过程中被大量浸出.Pb经过16 d的淋滤,铁锰氧化态所占比例有所下降而有机态比例上升.加大SA/TS有利于提高S粉的利用率,对N的保存影响不大,但增加了P的流失.     

玉米秸秆发酵浸出液模拟废水发酵产氢的放大实验研究

在20 L的半连续流发酵罐中,以牛粪堆肥为产氢菌源,按照玉米秸秆发酵浸出液的主要成分配制模拟废水,考察和分析了几个关键环境因素对发酵产氢的影响.结果表明,HRT、C/N、Fe²⁺浓度和模拟废水浓度对发酵产氢均有不同程度的影响.在本实验条件下,秸秆模拟废水的氢产量、氢浓度和产氢速率分别为11.80 mol/kg、56%和8.81 L/(L·d),底物转化率大于90%,废水中COD去除率为39.40%.在整个发酵产氢过程,液相主要发酵副产物为丁酸、乙酸和丙酸以及少量的乙醇和丁醇.     

不同耕作措施对旱作夏玉米田土壤呼吸及根呼吸的影响

为了探明不同耕作措施对旱作夏玉米田土壤呼吸及根呼吸的影响,采用定位试验,对比研究了深松耕(ST)、免耕(NT)、旋耕(RT)和翻耕(CT)这4种耕作方式下土壤呼吸速率的动态变化特征;并利用根去除法研究了根呼吸对土壤呼吸的贡献.结果表明,夏玉米生长季,4种耕作方式下土壤呼吸速率随生育期均呈单峰型变化趋势,在抽雄期达到最大,各生育期土壤呼吸速率大小顺序依次表现为:抽雄期开花期灌浆期成熟期拔节期苗期.不同耕作措施对平均土壤呼吸速率的影响表现为CTSTRTNT;土壤呼吸速率与土壤温度的相关系数达到显著性水平(P0.05),不同耕作措施下5 cm地温可以解释土壤呼吸速率变异的35%~75%.而土壤呼吸速率与土壤水分的相关系数却未达到显著性水平.夏玉米生长季中,不同耕作措施下根呼吸作用占土壤呼吸作用的比例在45.13%~56.86%之间波动,均值为51.72%.因此,利用根去除法可以用来了解作物生长对土壤碳排放的贡献及比较不同耕作措施对根系呼吸贡献的影响,从而为筛选出减缓农田土壤有机碳分解的耕作措施提供依据.