柠檬酸改性核桃壳粉负载纳米零价铁的制备及EDTA优化去除四环素

为解决纳米零价铁(NZVI)因团聚而导致的反应活性降低问题,通过液相还原法合成新型柠檬酸改性核桃壳粉负载纳米零价铁(CA-WNS-NZVI)的复合材料,添加EDTA条件下对四环素(TC)进行去除研究。柠檬酸改性可以增加核桃壳粉表面的羧基基团,有助于提高NZVI的负载量和分散性;在反应体系中存在EDTA的情况下,CA-WNS-NZVI对TC去除率达到99.02%,而在无EDTA条件下,TC去除率仅为82.10%。系统地研究了TC初始浓度、pH、温度和EDTA浓度对TC去除效果的影响。CA-WNS-NZVI的SEM表征揭示了NZVI均匀地分布在CA-WNS-NZVI上。CA-WNS-NZVI复合材料的XRD和FT-IR谱图表明NZVI成功地负载在核桃壳表面。同时讨论了EDTA优化CA-WNS-NZVI复合材料对TC去除的反应机制。新型CA-WNS-NZVI复合材料有望为抗生素废水治理提供新思路和新技术方法。     

改性凹凸棒土负载纳米铁的制备及性能

以200目的天然凹凸棒土为原料,先对原土进行酸活化与微波改性,再以改性凹凸棒土为载体,采用液相还原法由Fe Cl3·6H2O和Na BH4制备改性凹凸棒土负载纳米铁。通过正交实验、扫描电镜(SEM)、能谱仪(EDS)及红外光谱(IR)对负载前后的凹凸棒土进行表征分析确定其最佳条件。并通过稳定性实验和去除实验对改性凹凸棒土负载纳米铁的性能分析。结果表明:改性凹凸棒土负载纳米铁的最佳条件是铁土比为2.5∶1,酸浓度为3 mol·L~(-1),微波时间为6 min,微波功率为600 W,改性时间为24 h。改性凹凸棒土负载纳米铁在常规水处理环境中能稳定存在。对水中的Cr(Ⅵ)有良好的去除效果,去除率可达97.67%。     

(B-NZVI)/CTMAB的制备及对水中铬(Ⅵ)的去除性能与机理

采用液相还原法制备膨润土负载纳米铁(B-NZVI),并用十六烷基三甲基溴化铵(CTMAB)对其进行表面改性,研究了不同n(FeSO4)/n(NaBH4)(记为N)制备的(B-NZVI)/CTMAB的除铬效果。结果表明,N=1时制备的(B-NZVI)/CTMAB除Cr(Ⅵ)效率最高,较未改性的膨润土负载纳米铁(B-NZVI)的除Cr(Ⅵ)效率(57.7%)提高了23.7%,反应速率提高1.31倍。X射线衍射发现,N=1时不仅有零价铁,还有Fe(Ⅱ),对加快反应速率和提升去除效果有一定作用。从反应后产物的光电子能谱(XPS)图看出Cr(Ⅵ)被吸附后大部分还原为Cr(Ⅲ),而铁被氧化为Fe(Ⅲ)。最后,结合反应前后材料的表面电性以及扫描电镜图,对(B-NZVI)/CTMAB改性机制、改性后纳米零价铁线的形成及去除Cr(Ⅵ)的机理和产物等进行了探究。     

电絮凝法去除水中四环素的效能及机理

为了探讨电絮凝法去除水中四环素的效能及机理,分别研究了电极材料、电流强度、电导率和四环素初始浓度等参数对电絮凝去除四环素的影响;并通过氧化性能评估实验、UV-vis光谱分析、X射线衍射(XRD)等方法探究电絮凝去除四环素的性能。结果表明:使用铁电极(面积300 mm×80 mm,厚2 mm),对初始浓度0.05 mmol·L-1的四环素模拟废水进行处理,在电流强度为0.3 A、电导率为1 000μS·cm-1、电解15 min时,四环素和总有机碳(TOC)的去除率分别可达99.6%和79.8%,并且约41.9%的四环素通过氧化降解作用从水中被去除。使用铁电极电絮凝技术能够快速高效地去除四环素,具有高氧化率、低成本的特点。     

酸碱改性生物质炭-纳米零价铁增强六价铬去除的机理

通过氢氟酸和氢氧化钠改性水稻秸秆生物质炭(BC),得到改性材料BC-HF和BC-NaOH,在此基础上负载纳米零价铁(Nanoscale zero-valent iron,nZVI)制得生物质炭负载纳米零价铁(nZVI@BC)、氢氟酸改性生物质炭负载纳米零价铁(nZVI@BC-HF)和氢氧化钠改性生物质炭负载纳米零价铁(...     

CMS包覆纳米零价铁去除2,4-二氯酚的条件优化

针对纳米零价铁(Fe~0)去除2,4-二氯酚(2,4-DCP)时易团聚、易氧化、去除效率差等问题,采用环境友好材料羧甲基淀粉钠(CMS)对纳米零价铁进行了包覆,制成包覆型纳米零价铁。探究了包覆比例(CMS:Fe0)、pH、包覆型纳米零价铁投加量等单因素对去除率的影响。在单因素实验的基础上,以包覆比例、pH、包覆型纳米零价铁的投加量为考察因素,以2,4-DCP的去除率为响应值,采用二次多项式响应面探究多因素交互作用对包覆型纳米零价铁去除2,4-DCP的影响。利用响应面优化模型对包覆型纳米零价铁去除2,4-DCP进行优化。模型优化结果显示:包覆型纳米零价铁去除2,4-DCP的最佳条件为pH 3.0,纳米零价铁包覆比例3.59:1,包覆型纳米零价铁的投加量7.96 g·L~(-1),模型预测2,4-DCP的最高去除率为90.03%,实验值为85.77%,两者相对误差为4.73%,证明了优化模型的可靠性。     

PBTCA稳定零价纳米铁的制备及其去除水中Cr(Ⅵ)

以2-膦酸丁烷-1,2,4三羧酸(PBTCA)为稳定剂,通过FeCl3.6H2O与NaBH4反应,利用液相还原法制备稳定纳米级零价铁颗粒(P-NZVI),并用透射电子显微镜(TEM)、扫描电子显微镜(SEM)及X射线衍射(XRD)进行表征,颗粒平均粒径为73 nm。考察了Cr(Ⅵ)溶液初始浓度、pH、NZVI投加量、温度等条件对Cr(Ⅵ)去除效果的影响,并与同等条件下不加稳定剂制备的纳米铁(N-NZVI)进行对比。结果表明:Cr(Ⅵ)的去除率随温度和纳米铁投加量增加而升高,随pH和Cr(Ⅵ)溶液初始浓度升高而降低。在相同实验条件下,P-NZVI对Cr(Ⅵ)的去除效果明显优于N-NZVI,表明改性后纳米铁在地表水原位修复领域具有较好的应用前景。     

改性沸石承载纳米Fe/Ni对水中2,4-二氯苯酚的去除

将通过液相还原法制备的纳米铁/镍(Fe/Ni)颗粒承载于改性沸石表面制得负载型复合材料,纳米Fe/Ni在改性沸石表面具有良好的分散性。复合材料对2,4-二氯苯酚(2,4-DCP)的去除包括吸附和降解两个过程,脱氯降解是主要过程。实验结果表明,25℃时,0.6 g的复合材料对20 mg·L~(-1)的2,4-DCP去除效果达到80%,在酸性条件下,复合材料的去除效果未见明显差异,碱性环境会影响2,4-DCP的去除效果。降解产物苯酚被吸附在材料表面,避免了对水环境的二次污染。     

新型光-类芬顿催化剂纳米FeVO_4的制备及其对盐酸四环素的降解性能

采用水热法制备新型光-类芬顿纳米钒酸铁,通过X射线衍射(XRD)、粒径和比表面积(BET)对产物进行表征。以盐酸四环素模拟废水,通过光-类芬顿体系下对盐酸四环素的催化降解效果评价钒酸铁的催化活性,研究分析光源、盐酸四环素初始浓度、pH值、FeVO_4的用量以及H_2O_2的用量对盐酸四环素催化降解性能的影响。结果表明,在可见光下,盐酸四环素初始浓度为50 mg·L~(-1),pH值为7,H2O2的用量为60μL时,1.5 g·L~(-1)纳米钒酸铁,经过120 min反应后降解率为97.63%。     

纳米零价铁颗粒去除污染土壤HCl浸提液中的Pb

主要研究了纳米零价铁颗粒对土壤HCl浸提液中重金属Pb的去除效果。通过批实验探讨HCl浓度、纳米零价铁投入量以及处理时间对Pb去除率的影响。实验结果表明,纳米零价铁颗粒对浸提液中Pb的去除反应符合langmuir和freundlich等温吸附方程;反应遵循准一级反应动力学方程,标准化后的反应速率常数KSA=0.018 mL/(m2.min);反应30 min时,0.5 g纳米零价铁对1.0 mol/L的HCl所提取Pb(51.7 mg/L)的去除率达到91.8%。研究结果表明,纳米零价铁对土壤HCl浸提液中Pb具有良好去除效果,但相对于处理水溶液中的Pb,反应速率偏低。     

Estimation of uncertainty of sampling for analysis of pesticide residues

Abstract

A computer model was used to take random samples from primary sample populations obtained from field trials to simulate the uncertainty of sampling for residue analysis of plant commodities and soil. The results indicate about 40%, 30% and 20% relative uncertainty when random samples of size 5, 10 and 25 are taken respectively, from a single lot. Therefore the sample size should be the same for establishing and enforcing legal limits.     

不同泥源对厌氧氨氧化反应器启动的影响

采用2套上流式生物膜反应器,分别接种少量厌氧氨氧化污泥和大量硝化污泥,考察其对厌氧氨氧化反应器启动的影响。污泥接种入反应器后,测得接种厌氧氨氧化污泥的反应器(R1)内MLSS为0.22 g/L,另一个反应器(R2)MLSS为2.7 g/L。与直接接种厌氧氨氧化污泥相比,R1经过72 d的运行才显现出厌氧氨氧化特性。经过114 d的培养,前者氮去除速率由0.23 kg/(m3.d)提升到5.29 kg/(m3.d),总氮去除率大于89%;R2的氮去除速率由0.01 kg/(m3.d)提升到1.1 kg/(m3.d),总氮去除率大于84.6%。说明普通污泥启动需要一个较长的筛选过程,直接接种少量的厌氧氨氧化污泥比接种普通的污泥能够更快启动厌氧氨氧化反应器。     

次氯酸钠发生器的研制

介绍了电解法生产次氯酸钠的原理 ,并在原有生产工艺的基础上进行了重新设计和对设备的重新选择、改造 ,得出了各个工艺参数的最佳值 ,生产出高品质的次氯酸钠     

An application of the theory of kinematics of mixing to the study of tropospheric dispersion

The most common technique used for numerical simulations of tracer mixing is that of the numerical solution of the advection–diffusion equation with the unresolved fluxes parameterized using the similarity theory. Despite correct predictions of the overall directions of transport, models based on a numerical solution of the advection–diffusion equation lack sufficient accuracy to correctly reproduce the coupling of mixing with small scale processes which are sensitive to the microstructure of the tracer distribution. The objective of this paper is to revisit the basic formalism employed in numerical models used to investigate atmospheric tracers. The main mathematical method proposed here is the theory of kinematics of mixing which could be applied effectively for simulations of atmospheric transport processes. At the beginning of the paper, we introduce simple mathematical transformations in order to demonstrate how complex topological structures are created by mixing processes. These idealistic flow systems are essential to explain transport properties of much more complex three-dimensional geophysical flows. An example of the application of the kinematics of mixing to the analysis of tracer transport on a planetary scale is presented in the following sections. The complex filamentary structures simulated in the numerical experiment are evaluated using some commonly applied statistical measures in order to compare the results with the data published in the literature. The results of the experiment are also analysed with the help of simple conceptual models of fluid filaments. The microstructure of the tracer distribution introduced in the paper is essential to increase our understanding of atmospheric transport and to develop more realistic parameterizations of small-scale mixing. The presented results could also be used to improve calculations of the coupling between microphysical processes and tracer mixing.     

造纸废水混凝处理中SFT助凝替代性研究

中小造纸厂废水处理常用PAC作混凝剂 ,PAM作助凝剂。由于PAM成本很高 ,影响了处理设备的投运率。用超细滑石粉 (SFT)替代PAM助凝 ,与混凝剂PAC配合 ,其混凝处理效果基本相当 ,但是处理成本降低 0 .10元 /m3 。由于SFT属环境无害材料 ,不会给排泥带来二次污染     

产油微藻培养与回收的关键技术研究进展

寻找廉价而高效的替代原料是实现生物柴油产业化的关键所在.微藻以含油量高、生长周期短、环境适应能力强、生物产量高等优点,有望成为一种极具潜力的生物柴油生产原料.然而,目前尚存在微藻培养低效成本高和微藻回收效率低两大难题.综述了微藻培养与回收过程中的关键技术,并对存在的两大难题及其改进技术进行了详细的探讨.最后,总结并展望了微藻培养、回收技术未来的发展趋势.     

红土吸附砷对其动电电位的影响

研究了遵义红土吸附砷对其动电电位的影响 ,从砷酸根浓度和体系pH对红土动电电位影响的角度作了探讨 ,结果表明 ,砷酸根离子浓度越大 ,Zata电位下降幅度越大 ,Zata电位也越低 ;随着体系pH的升高 ,氧化铁胶体动电电位逐渐下降 ,甚至改变了表面电位的符号。由此得出了红土吸附砷属于专性吸附的结论。     

活性炭三维电极法对印染废水的处理研究

对三维电极方法处理印染废水进行了实验研究,初步探讨了活性炭三维电极法处理印染废水的机理,对影响处理效果的各种要素,如反应时间、槽电压和pH值等进行了条件实验,得出了活性炭三维电极法处理印染废水的最佳运行条件为:停留时间120-180 min,槽电压25～30 V,进水pH值6.5～7.5。结果表明,该反应器能有效地降低废水色度,有较高的COD去除效率,并能提高印染废水的可生化性。     

生物质快速热裂解主要参数对生物油产率的影响

以松木木屑为原料,在自制的小型流化床上,开展了生物质热裂解温度、生物质粒径和进料速率对生物油产率的影响实验研究.结果表明,在热裂解温度分别为450、475、500、525和550℃条件下,当热裂解温度为500℃时,生物油产率最高,平均产率达到53.33%(质量百分比).反应温度越高,炭产量越低,不可冷凝气体产量越高,气体发热值越高;粒径＜1 mm的生物质其粒径对生物油产率影响不大;生物质进料速率增加时,生物油产率增加.本研究为生物能的利用提供了新的途径.     

Evaluation of the presence of drugs of abuse in tap waters

A total of seventy samples of drinking water were tested for non-controlled and illicit drugs. Of these, 43 were from Spanish cities, 15 from seven other European countries, three from Japan and nine from seven different Latin American countries. The most frequently detected compounds were caffeine, nicotine, cotinine, cocaine and its metabolite benzoylecgonine, methadone and its metabolite EDDP. The mean concentrations of non-controlled drugs were: for caffeine 50 and 19 ng L⁻¹, in Spanish and worldwide drinking water respectively and for nicotine 13 and 19 ng L⁻¹. Illicit drugs were sparsely present and usually at ultratrace level (<1 ng L⁻¹). For example, cocaine has mean values of 0.4 (Spain) and 0.3 ng L⁻¹ (worldwide), whereas for benzoylecgonine, these mean values were 0.4 and 1.8 ng L⁻¹, respectively. Higher concentrations of benzoylecgonine were found in Latin American samples (up to 15 ng L⁻¹). No opiates were identified in any sample but the presence of methadone and EDDP was frequently detected. Total mean values for EDDP were 0.4 ng L⁻¹ (Spain) and 0.3 ng L⁻¹ (worldwide). Very few samples tested positive for amphetamines, in line with the reactivity of chlorine with these compounds. No cannabinoids, LSD, ketamine, fentanyl and PCP were detected.