正渗透过程参数对渗透性能的影响

正渗透是新的非热能驱动膜过程。采用界面聚合的方法制备了中空纤维复合膜。以Na2SO4、MgSO4、NaCl和Mg-Cl2水溶液作为驱动液进行了正渗透实验。实验表明,正渗透通量随着驱动液浓度的增加而增加,其中Na2SO4、MgCl2水溶液的渗透通量大于MgSO4、NaCl水溶液的。驱动液中无机盐向原水中扩散的渗透速率随无机盐浓度的增加而增加,且MgCl2>NaCl>Na2SO4>MgSO4。原水流速对正渗透通量的影响极小,而驱动液流速对正渗透通量的影响较大。     

新型界面聚合法制备高性能聚酰胺反渗透膜

目的 为减缓界面聚合反应速率,使聚合过程可控,以制备结构和性能稳定的反渗透膜.方法 提出一种新的含缓冲层的自由界面聚合工艺(Buffer Layer Free Interfacial Polymerization,BLIP)来实现聚合速率的控制,研究单体浓度和反应时间对BLIP膜结构和性能的影响,选用硫酸钠(Na2SO4)和氯化钠(NaCl)测试BLIP膜的脱盐性和耐氯性.结果 当间苯二甲胺(m-xylylenediamine,m-XDA)与均苯三甲酰氯(trimesoyl chloride,TMC)质量分数分别为0.6％,0.3％时,BLIP膜对硫酸钠(Na2SO4)和氯化钠(NaCl)的脱盐率最佳,分别为92.55％,83.99％,水通量分别为8.30,9.15 L/(m2·h).当膜在活性氯浓度为l g/L的NaClO溶液中浸泡12h后,Na2SO4和NaCl的脱盐率均保持在72％以上.结论 添加缓冲层提高了TMC在油相的分散均匀性,减缓了界面聚合速率,显著提高了BLIP膜的性能.文中提出了一种新颖、节能、简单的反渗透膜制备工艺,为促进界面聚合工艺的发展提供了新的思路.     

Kinetics of gas-liquid reaction between NO and Co(NH3)6(2+)

Wet ammonia desulphurization process can be retrofitted for combined removal of SO2 and NO from the flue gas by adding soluble cobalt(II) salts into the aqueous ammonia solutions. The Co(NH3)6(2+) formed by ammonia binding with Co2+ is the active constituent of scrubbing NO from the flue gas streams. A stirred vessel with a plane gas-liquid interface was used to measure the chemical absorption rates of nitric oxide into the Co(NH3)6(2+) solution under anaerobic and aerobic conditions separately. The experiments manifest that the nitric oxide absorption reaction can be regarded as instantaneous when nitric oxide concentration levels are parts per million ranges. The gas-liquid reaction becomes gas film controlling as Co(NH3)6(2+) concentration exceeds 0.02 mol/l. The NO absorption rate is proportional to the nitric oxide inlet concentration. Oxygen in the gas phase is favorable to the absorption of nitric oxide. But it is of little significance to increase the oxygen concentration above 5.2%. The NO absorption rate decreases with temperature. The kinetic equation of NO absorption into the Co(NH3)6(2+) solution under aerobic condition can be written as.     

Chromium recovery from chrome shaving generated in tanning process

In this study, the chromium recovery conditions in the form of soluble chromate from chrome shaving (chromium-containing solid waste) by oxidation with air, oxygen and Na2O2 were investigated and basic Cr(III) sulphate solution using in the tanning was prepared from the chromate obtained. It has been determined that the oxidation agent is the most effective parameter affecting the chromate formation. While maximum oxidation yields in air and oxygen atmosphere at 850 degrees C were found to be 23.02 and 30.41%, respectively, the highest chromium recovery efficiency in the form of chromate (99.45%) occurred in the presence of eight times Na2O2 with respect to stoichiometric amount of chromium. The chromate generated in Na2O2 oxidation process where 99.45% of chromium in the chrome shaving can be recovered was leached with distilled water and pregnant chromate solution was prepared. The chromate ions in this solution were reduced by using Na2SO3 and Cr(III) sulphate solution was obtained.     

中空纤维含浸液膜渗透器烟气脱硫的研究

使用中空纤维含浸液膜渗透器,以水、亚硫酸钠溶液以及柠檬酸钠溶液为膜液,分别考察了室温下,不同原料气/吹扫气进气速率和不同膜液浓度对SO2、O2、N2等组成的混合气体中SO2的去除效果以及吹扫气出口处SO2浓度的影响.结果表明:该反应器在适宜的操作条件下不仅能较好地去除SO2,而且对SO2的富集效果也十分明显.     

室内外细粒子PM_(2.5)和总悬浮颗粒物污染水平的对比研究

为了解室内外空气颗粒物PM2.5和总悬浮颗粒物(TSP)的污染状况,自2008年3月24日～4月3日在西安交通大学学生办公室、教师办公室、化学实验室和室外同时采集PM2.5和TSP样品,对其质量浓度及无机水溶性离子组分(Na+、NH4+、K+、Mg2+、Ca2+、Cl-、NO3-和SO42-)进行了分析。结果表明,室内外PM2.5和TSP浓度都远远高于美国空气质量标准规定的35μg/m3。室内外颗粒物浓度具有相同的变化趋势,且室内总体上低于室外。室内PM2.5在TSP中所占比例在65%～85%,室外在40%左右。室内外TSP和PM2.5中二次污染离子SO42-、NO3-和NH4+占总离子质量的50%以上,主要富集在细颗粒中。NH4+、K+和Cl-在总离子中的比例均为室内大于室外,PM2.5中大于TSP。Ca2+、Mg2+主要富集在粗颗粒上,室外含量远远高于室内。     

Electrocoagulation of synthetically prepared waters containing high concentration of NOM using iron cast electrodes

The aim of this investigation is to evaluate the treatability of synthetically prepared water with high concentration of humic substances by electrocoagulation in batch mode using iron cast electrodes. Effects of applied potential, initial humic substance concentration and supporting electrolyte type on humic substance removal efficiency were investigated. NaNO3, Na2SO4 and NaCl were used as supporting electrolyte. Among these supporting electrolytes, Na2SO4 and NaCl have provided high removal efficiencies, whereas in the experiments using NaNO3 as supporting electrolyte have been observed no flock formation. The highest removal rate is obtainable with NaCl as supporting electrolyte. Removal efficiencies for initial humic substance concentration of 500 mg L-1 with NaCl and Na2SO4 equal to 97.95% for 35 min and 92.69% for 70 min, respectively. This behavior of the system has been derived from oxidation products, available in the bulk solution, of chloride ions. When NaCl is used as supporting electrolyte, there is an advantage of providing the disinfection of water, but humic substances and chloride ions are available in the bulk solution with risk of formation undesirable organo-chlorine compounds, so the Na2SO4 is the most favorable supporting electrolyte.     

Morphological modifications of selenium by recrystallization of its aqueous complex solutions

Recrystallization of elemental selenium (Se) from aqueous solution in presence of sodium sulphite (Na2SO3) and sodium sulphide (Na2S) acting as complexing agents has resulted in the formation of nano and microstructures of Se having five different morphological modifications. (1) An aqueous solution of sodium selenosulphate (Na2SO3Se) obtained by dissolving Se in Na2SO3 under refluxing condition yields hemispherical microcrystals. (2) The filtrate of the above reaction mixture on aging produces hexagonal prismatic microrods of Se. Addition of Na2SO3Se solution to formalin (HCHO) at room temperature and refluxing conditions generates (3) Se nanorods, and (4) spherical microcrystals, respectively. (5) Recrystallization of Se from aqueous solution of Na2S develops flower shaped microcrystals.     

室内挥发性有害有机物限量标准研究

室内挥发性有害有机物的种类繁多，我国现有室内空气质量标准中有机物的限量指标只有甲醛、苯、甲苯、二甲苯、TVOC5种。我们通过研究发现室内空气中17种有机挥发性有害物质出现的频率较高，浓度较大，且对人体健康有很大的危害，世界各国和各地区的空气质量标准分别对这17种物质中的部分组分给出了安全限量。通过科学分析我们建议了涵盖甲醛、烷烃类、卤代烃类、苯系物等的室内挥发性有害有机物限量标准，使我国的室内空气质量控制指标更具有效性和针对性。     

Recovery of H2SO4 from waste acid solution by a diffusion dialysis method

A diffusion dialysis method using anion exchange membrane was used to recover H2SO4 from waste sulfuric acid solution produced at the diamond manufacturing process. Effects of flow rate, operation temperature, and metal ion concentration on the recovery of H2SO4 were investigated. The recovery of H2SO4 increased with the concentration of H2SO4 and operation temperature. It also increased with the flow rate ratio of water/H2SO4 solution up to 1, above which no further increase was observed. The flow rate did not affect the rejection of Fe and Ni ions. About 80% of H2SO4 could be recovered from waste sulfuric acid which contained 4.5M free-H2SO4 at the flow rate of 0.26x10(-3) m3/hm3. The concentration of recovered H2SO4 was 4.3M and the total impurity was 2000 ppm. Preliminary economic evaluation has revealed that the dialysis system is highly attractive one that has payback period of only few months.     

Simultaneous removal of SO2 and NO by wet scrubbing using aqueous chlorine dioxide solution

The present study attempts to generate chlorine dioxide (ClO(2)) gas continuously by chlorate-chloride process and to utilize it further to clean up SO(2) and NO(x) gases simultaneously from the flue gas in the lab-scale bubbling reactor. Experiments were carried out to examine the effect of various operating parameters like input SO(2) concentration, input NO concentration, pH of the reaction medium, and ClO(2) feeding rate on the SO(2) and NO(x) removal efficiencies at 45 degrees C. Complete oxidation of NO into NO(2) occurred on passing sufficient ClO(2) gas into the scrubbing solution. SO(2) removal efficiency of about 100% and NO(x) removal efficiency of 66-72% were achieved under optimized conditions. NO(x) removal efficiency decreased slightly with increasing pH and NO concentration. Input SO(2) concentration had marginal catalytic effect on NO(2) absorption. No improvement in the NO(x) removal efficiency was observed on passing excess of chlorine dioxide in the scrubbing solution.     

原子吸收测定酸雨钾,钠,钙,镁干扰因素探讨及其消除

主要讨论了用原子吸收分光光度法测定酸雨K、Na、Ca、Mg中主要阴离子AC-、NO3-、CIO4-、C1-、SO42-、PO43-F-对测定的干扰和采用硝酸锶做为干扰抑制剂的最佳使用浓度。结果表明:AC-<10.0mg/L、CIO4-<10.0mg/L、C1-<15.0mg/L、F-<10.0mg/L对K、Na、Ca、Mg测定无干扰;酸雨中含有大于0.50mg/L的PO34-、NO3-就可降低钙的吸光度,但含量达10.0mg/L也不影响K、Na、Mg的测定;含有大于0.50mg/L的SO24-对钙镁的测定都有抑制作用,且随着干扰物浓度的提高吸光值有变小的趋势,选择0.5%硝酸锶可消除以上干扰。     

Ozone monitoring based on a biosensor concept utilizing a reagentless alcohol oxidase electrode

An electrochemical method based on the concept of a biosensor for the monitoring of ozone is described for first time. The proposed method includes two parts: a selective sorbent for ozone, that is, eugenol, and a formaldehyde amperometric biosensor mounted into a flow-through cell. Ozone adds rapidly to the double bond of the allyl group of eugenol, which has been immobilized onto a hydrophobic C-18 reactor and the so produced formaldehyde is collected into the working buffer solution (sampler) and pumped to the detector. A multimembrane assembly consisting of an alcohol oxidase-modified nylon membrane sandwiched between an outer polycarbonate and an inner cellulose acetate membrane was fitted onto a Pt electrode and the enzymatically produced H2O2 was monitored at +0.65 V (vs Ag/AgCl/KCl 3 M). Under optimum conditions, a linear calibration curve over the concentration range 3-200 microg x mL(-1) ozone was constructed. The detection limit (S/N = 3) was calculated at 1.1 microg x mL(-1) ozone. The proposed method is interference-free from other gases such as O2, Ar, N2, N2O, NOCl, SO2, NH3, and CO2, which were tested at concentrations >200-fold higher than that of 100 microg x mL(-1) ozone used for comparison. Besides selectivity, the method is easy to perform and reproducible; its applicability in synthetic gaseous samples is also demonstrated.     

负离子空气净化灯对室内空气中甲醛的治理作用

为有效解决室内空气中甲醛治理问题,采用模拟室内环境污染状况,通过负离子空气净化灯在开灯前后室内空气中甲醛含量变化的实验方法进行论证,得出负离子空气净化灯在开灯后,能产生大量的负氧离子,对净化空气质量,特别是降低空气中的甲醛含量,有较好的治理效果,对改善人类生活环境有积极的作用。     

学校室内空气质量研究

本文采用国内外先进的仪器,进行了学校各种不同类型房间的室内空气质量的测试;其主要测试参数为:室内空气温度、湿度、气流速度、噪声、照度、CO浓度、CO2浓度、甲醛浓度、粉尘浓度和挥发性有机物(TVOC)等;在此基础上,提出了一些有效的改善室内空气质量的方法和措施.     

室内甲醛污染控制效果的探讨

针对室内空气中甲醛污染的现状,本文分析了控制室内小气候、建材甲醛的去除和室内空气净化对甲醛污染的控制效果,认为可以通过高温烘赶、加强通风、人造板中的甲醛去除和各种净化空气措施来减少室内甲醛污染。     

Chemiluminescent method for continuous monitoring of nitrous acid in ambient air

A continuous-flow method for measuring atmospheric HNO2 concentration in real time has been developed that uses a chemiluminescent NOx monitor. A Na2CO3 solution strips gaseous HNO2 from the atmosphere by means of pulling an air sample and the solution through a glass coil and mixing continuously with ascorbic acid solution which reduces nitrite to NO. The mixture is led into a gas-liquid separating coil consisting of microporous PTFE tubing. The NO evolved from the separating coil is swept out by a stream of clean air and detected with a chemiluminescent NOx monitor. The technique utilizes a dual flow system and dual channel NOx monitor to correct positive interferences from NO2 and peroxyacetyinitrate (PAN). The concentration of HNO2 is determined by difference between the two measurements. Sensitivity of the method is a function of the ratio of sampling flow rate to carrier gas flow rate, which permits readily a highly sensitive measurement.     

Sodium and potassium released from burning particles of brown coal and pine wood in a laminar premixed methane flame using quantitative laser-induced breakdown spectroscopy

A quantitative point measurement of total sodium ([Na](total)) and potassium ([K](total)) in the plume of a burning particle of Australian Loy Yang brown coal (23 ± 3 mg) and of pine wood pellets (63 ± 3 mg) was performed using laser-induced breakdown spectroscopy (LIBS) in a laminar premixed methane flame at equivalence ratios ( U ) of 1.149 and 1.336. Calibration was performed using atomic sodium or potassium generated by evaporation of droplets of sodium sulfite (Na(2)SO(3)) or potassium sulfate (K(2)SO(4)) solutions seeded into the flame. The calibration compensated for the absorption by atomic alkalis in the seeded flame, which is significant at high concentrations of solution. This allowed quantitative measurements of sodium (Na) and potassium (K) released into the flame during the three phases of combustion, namely devolatilization, char, and ash cooking. The [Na](total) in the plume released from the combustion of pine wood pellets during the devolatilization was found to reach up to 13 ppm. The maximum concentration of total sodium ([Na](max)M(total)) and potassium ([K](max)(total)) released during the char phase of burning coal particles for φ = 1.149 was found to be 9.27 and 5.90 ppm, respectively. The [Na](max)(total) and [K](max)(total) released during the char phase of burning wood particles for φ = 1.149 was found to be 15.1 and 45.3 ppm, respectively. For the case of φ = 1.336, the [Na](max)(total) and [K](max)(total) were found to be 13.9 and 6.67 ppm during the char phase from burning coal particles, respectively, and 21.1 and 39.7 ppm, respectively, from burning wood particles. The concentration of alkali species was higher during the ash phase. The limit of detection (LOD) of sodium and potassium with LIBS in the present arrangement was estimated to be 29 and 72 ppb, respectively.     

二氧化硫低浓度状况的甲醛法测定探讨

本文就环境空气中二氧化硫在低浓度状况下,短时间采样采用甲醛缓冲溶液吸收法测定进行探讨。结果表明,采用5mL吸收液吸收的方法在二氧化硫低浓度状况下是可行的。此方法可降低检出限。     

聚合物P(NIPAM-AM-NPA)的合成及溶液性能

以丙烯酸壬基酚聚氧乙烯酯(NPA)、丙烯酰胺、N-异丙基丙烯酰胺为单体,采用自由基水溶液聚合方法制备了水溶性共聚物P(NIPAM-AM-NPA)。采用FT-IR、1H-NMR对该共聚物以表征;研究了共聚物浓度、温度以及不同电解质对共聚物溶液性能的影响。结果表明,随着盐浓度的增加,聚合物溶液表观黏度有较大幅度上升。在相同情况下,NaCl的增粘效果最为显著,而MgCl2和CaCl2则影响不大。该共聚物的盐水溶液在升温条件下可保持良好的增粘作用,适当条件下还会出现黏度随温度升高而上升的独特现象。