Minimization of artifacts in sulfuric acid mist measurement using NIOSH Method 7903

NIOSH Method 7903 employs a silica gel tube for sulfuric acid mist measurement in workplaces. However, SO2 gas present in the sample volume can be transformed into sulfate in the sampling process causing an artifact that is reported as sulfuric acid. A sampling train incorporating a honeycomb denuder system was applied for field sampling at seven phosphate fertilizer plants to evaluate its use for reducing the artifact sulfate concentration while preserving the actual sulfuric acid mist concentration. The denuder system was designed to remove SO2 gas before the air entered the silica gel tube and to monitor SO2 concentration at the same time. A deactivation model was also applied to correct for the presence of the artifact. The denuder system had 95.7 +/- 6.8% collection efficiency for SO2 gas, and the impact of sulfate aerosol on SO2 collection was negligible. SO2 concentrations at the seven plants ranged from 34 ppb to 5.6 ppm. The honeycomb denuder system and the deactivation model were shown to reduce the artifact sulfate concentration by 70% and 39%, respectively. However, they were still higher than the sulfate aerosol concentration measured by a cascade impactor. One possible reason is the residual sulfate in the glass fiber filter and the silica gel.     

介质阻挡放电氦等离子体-气相色谱测定绿豆中脂肪酸含量

基于介质阻挡放电氦等离子体-气相色谱结合微型样品前处理方式,建立绿豆中脂肪酸含量的快速测定方法,采用石英毛细管柱HP-88（100 m×0.25 mm,0.25 μm）（88%-氰丙基/芳基-聚硅氧烷固定液）,载气为超纯氦气（纯度99.999 9%）,载气流量为1.5 mL/min,柱温为程序升温,进样口温度250 ℃,隔垫吹扫流量为3mL/min,分流比为1∶60,检测器温度为280 ℃,等离子体放电气体流量为40 mL/min,进样体积为1 μL;样品中目标物采用异辛烷萃取,氢氧化钾-甲醇甲酯化后上机分析。实验结果表明,绿豆样品中8 种脂肪酸甲酯检测灵敏度在0.105～0.196 μg/mL之间,相对标准偏差在1.04%～1.35%之间。所建方法所需样品量及化学试剂少,样品前处理简单快速,重现性好,能够精确测定绿豆中脂肪酸含量。     

Studies of 2.45 GHz microwave induced plasma abatement of CF4

Microwave plasmas at 2.45 GHz frequency operated at atmospheric pressure in synthetic gas mixtures containing N2 and CF4 are investigated experimentally for various operating conditions, with respect to their ability to destroy perfluorocompounds. It was found that the destruction and removal efficiency of the process is highly dependent on the total gas flow and concentration of CF4. Destruction and removal efficiencies of CF4 up to 98% have been achieved using 1.9 kW of microwave power at 16 L/min total flow rate.     

Versatile gas/particle ion chromatograph

A new, compact gas/particle ion chromatograph has been developed for measuring ionic constituents in PM2.5 (particulate matter of aerodynamic diameter < or = 2.5 microm) and water-soluble ionogenic gases. The instrument has separate sampling channels for gases and particles. In one, a membrane denuder collects soluble gases for preconcentration and analysis. In the other, a cyclone removes larger particles, a membrane denuder removes soluble gases, and a continuously wetted hydrophilic filter collects particles. A single, multiport, syringe pump handles liquid transport, and one conductivity detector measures anions and ammonium for both channels. Electrodialytically generated gradient hydroxide eluent permits 20 min chromatographic runs. Gas/particle samples are each collected for 40 min, butthe sampling intervals are staggered by 20 min. Liquid samples from the gas denuder and particle collector are aspirated and preconcentrated on sequential cation and anion concentrators and transferred respectively to an ammonia transfer device and an anion separation column. The flow configuration results in an ammonium peak before anion peaks in the chromatogram. The system measures ammonia, organic acids (such as acetic, formic, and oxalic acids), HCl, HONO, SO2, HNO3, and the corresponding ions in the aerosol phase. Low ng/m3 to sub-ng/m3 limits of detection (LODs) are attained for most common gases and particulate constituents, the LODs for gaseous SO2 to NH3 range, for example, from sub parts per trillion by volume (sub-pptv) to approximately 5 pptv.     

Effects of gas flow rate, inlet concentration and temperature on biofiltration of volatile organic compounds in a peat-packed biofilter

The effects of incoming gas concentration, empty bed residence time (EBRT), and column temperature on the removal efficiency of volatile organic compounds (isoprene, dimethyl sulfide, chloroform, benzene, trichloroethylene, toluene, m-xylene, o-xylene and styrene) were studied for 101 d in a biofilter comprising two glass columns (I.D. 5.0 cm x height 62 cm) packed with peat. At an EBRT of 3 min the removal efficiency increased up to 90% 34 d after start up at both 25 degrees C and 45 degrees C when the incoming gas concentration was raised stepwise to 65 g.m(-3). When the incoming gas concentration increased to 83 g.m(-3), the removal efficiency was 93% at 25 degrees C, but dropped to 74% at 45 degrees C. At an incoming gas concentration of 92 g.m(-3) and an EBRT of 1.5 min, the removal efficiencies were 91% and 94% at 25 degrees C and 32 degrees C, respectively. However, at 1 min of EBRT, the removal efficiencies decreased to 68% and 81% at 25 degrees C and 32 degrees C, respectively. The removal rate per unit time and per unit volume of the biofilter was proportional to the incoming gas rate up to 3483 g VOC.m(-3).h(-1). Further increase of the incoming gas rate lowered the removal rate as compared to that predicted by the proportionality. The maximum removal rate was 3977 g.m(-3).h(-1) at 32 degrees C. At an EBRT of 1.5 min, the removal efficiency was highest for isoprene (93%), and lowest for chloroform (84%). Aromatic compounds (benzene, toluene, and xylene) were removed by 93-94%. The cell concentration increased 100-fold from the initial value, and reached 1.12 x 10(8) cells.(g of dry peat)(-1). At 32 degrees C, 67% of the incoming VOC was removed in the first quarter of the column.     

实验室浮选柱脱墨系统的初步研究

介绍了一种用于废纸脱墨的实验室浮选柱装置。利用这套系统初步考察了浮选柱用于浮选时的一些特点和性能,如不同的空气流量以及浆料流量下脱除胶黏物和灰分的能力。实验发现,即使在空气贮藏量较低、浮选柱气体流量0.4m3/h时,胶黏物去除率也能够达到83.4%、灰分去除率在50%以上。实验证明这套浮选系统对胶黏物去除具有较好的选择性。     

粮食中马拉硫磷检测最优化色谱条件的探讨

本文通过使用AC10毛细管柱进行实验研究,探讨了设置GC色谱分离条件：柱温、载气流速（柱流量）、检测器温度、汽化室温度、汽化室分流出口吹扫流量及吹扫时间、检测器的燃气与助燃气流量、尾吹气流量对峰高、峰面积、保留时间的影响,找到了最佳的色谱条件,该色谱嗓件检测马拉磺磷的最小检出浓度为0．005mg／kg,测定保留时间的相对标准偏差为0．27％,峰面积的相对标准偏差为0．38％,结果显示该色谱条件的灵敏度、精密度良好,证明了我们选择的最佳色谱条件完全满足粮食卫生标准规定的原粮中马拉硫磷残留限量标准的检测要托     

AB-8大孔树脂纯化绿豆皮黄酮工艺优化及纯化前后抗氧化能力比较

采用AB-8大孔树脂初步分离纯化绿豆皮黄酮。分别对上样条件和洗脱条件进行优化,考察上样液质量浓度、上样液pH值、上样流速、以及洗脱剂体积分数、洗脱剂用量、洗脱流速对吸附解吸性能的影响,最终确定AB-8大孔树脂的分离纯化绿豆皮黄酮工艺为上样液质量浓度1.5?mg/mL、上样液pH5.0、上样流速1.0?mL/min;洗脱液乙醇体积分数70%、洗脱剂用量225?mL、洗脱流速2.0?mL/min,在此条件下分离纯化,绿豆皮黄酮纯度由27.95%提高到62.38%。经紫外-可见光谱扫描,出现黄酮类化合物特征峰带,经红外光谱扫描,光谱具备黄酮类物质特征官能团,验证了黄酮类物质的存在;利用扫描电镜对纯化前后黄酮类物质进行微观分析,得出被包裹的片状和粉粒状颗粒大部分被释放出来,这可能是导致纯化后黄酮类化合物纯度增高的原因。纯化后的绿豆皮黄酮与粗提物相比具有较高的抗氧化能力。     

吹扫捕集-气相色谱/质谱法测定纺织品中多种异味物质

建立了气相色谱/质谱联用法测定纺织品中多种异味物质的方法.样品经吹扫、捕集及热脱附后,用气相色谱/质谱联用仪(GC/MS)测定,采用外标法定量.对GC/MS的仪器条件、吹扫捕集器(P&T)影响因素(吹扫时间和温度、吹扫流速、脱附条件等)、基质效应、样品量等条件进行优化.在最佳实验条件下,10种异味物质的质量分数与峰面积...     

Sampling atmospheric carbonaceous aerosols using an integrated organic gas and particle sampler

Measurement of particle-bound organic carbon (OC) may be complicated by sampling artifacts such as adsorption of gas-phase species onto particles or filters or evaporation of semivolatile compounds off the particles. A denuder-based integrated organic gas and particle sampler (IOGAPS), specifically designed to minimize sampling artifacts, has been developed to sample atmospheric carbonaceous aerosols. IOGAPS is designed to first remove gas-phase chemicals via sorption to the XAD-coated denuder, and subsequently particles are trapped on a quartz filter. A backup sorbent system consisting of sorbent- (XAD-4 resin) impregnated filters (SIFs) was used to capture the semivolatile OC that evaporates from the particles accumulated on the upstream quartz filter. A traditional filter pack (FP) air sampler, which uses a single quartz filter to collect the particles, was employed for comparison in this study. Elemental and organic carbon were determined from filter punches by a thermal optical transmittance aerosol carbon analyzer. Field measurements show that there was no significant difference between the elemental carbon concentrations determined by the FP and IOGAPS, indicating that particle loss during the transit through the denuder tube was negligible. Compared with the OC determined by FP (3.9-12.6 microg of C/m3), the lower OC observed on the quartz filter in the IOGAPS (2.2-6.0 microg of C/m3) was expected because of the removal of gas-phase organics by the denuder. Higher semivolatile organic carbon (SVOC) on the backup SIFs during the night (1.24-8.43 microg of C/m3) suggests that more SVOC, emitted from primary sources or formed as secondary organic compounds, partitions onto the particles during the night because of the decreased ambient temperature. These data illustrate the utility of an IOGAPS system to more accurately determine the particle-bound OC in comparison to FP-based systems.     

Simultaneous desulfurization and denitrification from flue gas by Ferrate(VI)

An innovative semidry process has been developed to simultaneously remove NO and SO? from flue gas. According to the conditions of the flue gas circulating fluidized bed (CFB) system, ferrate(VI) absorbent was prepared and added to humidified water, and the effects of the various influencing factors, such as ferrate(VI) concentration, humidified water pH, inlet flue gas temperature, residence time, molar ratio of Ca/(S+N), and concentrations of SO? and NO on removal efficiencies of SO? and NO were studied experimentally. Removal efficiencies of 96.1% for SO? and 67.2% for NO were obtained, respectively, under the optimal experimental conditions, in which the concentration of ferrate(VI) was 0.03 M, the humidified water pH was 9.32, the inlet flue gas temperature was 130 °C, the residence time was 2.2 s, and the molar ratio of Ca/(S+N) was 1.2. In addition, the reaction mechanism of simultaneous desulfurization and denitrification using ferrate(VI) was proposed.     

大孔树脂吸附桦褐孔菌多糖色素的机理及工艺优化

为探究大孔树脂吸附桦褐孔菌多糖色素动力学与热力学特征及最佳工艺条件,本实验通过水提醇沉、Sevag法除蛋白、透析制备桦褐孔菌多糖,采用静态吸附实验筛选色素吸附率及多糖保留率评分最高的大孔树脂,研究其吸附动力学与热力学特性,并优化该大孔树脂在动态吸附桦褐孔菌多糖色素中的径高比、吸附时间、上样量以及洗脱流速,确定最佳工艺条件。结果表明,实验筛选的17个不同型号大孔树脂中,大孔树脂HPD-500最为适宜,其吸附色素的过程符合准二级动力学模型,反应过程中受颗粒内扩散与液膜扩散的影响;并且吸附过程符合热力学Freundlich模型,为多分子层吸附,其中吸附焓变>0为吸热反应,吉布斯自由能<0为自发反应,吸附熵变>0为熵增反应。HPD-500吸附色素的最佳条件为径高比1:10,吸附时间1 h,上样量10 mg,洗脱流速1.5 mL/min。在此条件下,桦褐孔菌的色素吸附率为83.15%,多糖保留率为78.89%,多糖纯度由20.40%提升至56.52%。HPD-500大孔树脂具有吸附桦褐孔菌多糖中色素、提高多糖纯度的能力,本文为桦褐孔菌资源高效利用提供了理论及实验基础。     

Improved characterization of gas-particle partitioning for per- and polyfluoroalkyl substances in the atmosphere using annular diffusion denuder samplers

Gas-phase perfluoroalkyl carboxylic acids (PFCAs) sorb strongly on filter material (i.e., GFF, QFF) used in conventional high volume air samplers, which results in an overestimation of the particle-phase concentration. In this study, we investigated an improved technique for measuring the gas-particle partitioning of per- and polyfluoroalkyl substances (PFASs) using an annular diffusion denuder sampler. Samples were analyzed for 7 PFAS classes [i.e., PFCAs, perfluoroalkane sulfonic acids (PFSAs), fluorotelomer alcohols (FTOHs), fluorotelomer methacrylates (FTMACs), fluorotelomer acrylates (FTACs), perfluorooctane sulfonamides (FOSAs), and perfluorooctane sulfonamidoethanols (FOSEs)]. The measured particulate associated fraction (Φ') using the diffusion denuder sampler generally followed the trend FTACs (0%) < FTOHs (~8%) < FOSAs (~21%) < PFSAs (~29%) < FOSEs (~66%), whereas the Φ' of the C(8)-C(18) PFCAs increased with carbon chain length, and ranged from 6% to 100%. The ionizability of some PFASs, when associated with particles, is an important consideration when calculating the gas-particle partitioning coefficient as both ionic and neutral forms can be present in the particles. Here we differentiate between a gas-particle partitioning coefficient for neutral species, K(p), and one that accounts for both ionic and neutral species of a compound, K(p)'. The measured K(p)' for PFSAs and PFCAs was 4-5 log units higher compared to the interpolated K(p) for the neutral form only. The measured K(p)' can be corrected (to apply to the neutral form only) with knowledge of the pK(a) of the chemical and the pH of the condensed medium ("wet" particle or aqueous aerosol). The denuder-based sampling of PFASs has yielded a robust data set that demonstrates the importance of atmospheric pH and chemical pK(a) values in determining gas-particle partitioning of PFASs.     

Removal of chlorophenols from wastewater using red mud: an aluminum industry waste

Removal of toxic substances from wastewaters using low-cost alternatives to activated carbon is an important area in environmental sciences. Efforts have been made to convert red mud, an aluminum industry waste, into a low-cost potential adsorbent, and the final material has been used for the removal of phenol, 2-chlorophenol, 4-chlorophenol, and 2,4-dichlorophenol from wastewater. It is pertinent to mention that phenol and chlorophenols are highly carcinogenic and an priority class of pollutants which needs to be removed from effluents before discharge into water bodies. 2,4-Dichlorophenol and 4-chlorophenol are sorbed by the developed adsorbent up to 94-97%, while the removal of 2-chlorophenol and phenol was up to 50-81%. The removal of phenols and its derivatives was achieved up to 98% by column experiments at a flow rate of 0.5 mL/min. The order of removal was 2,4-dichlorophenol > 4-chlorophenol > 2-chlorophenol > phenol, and the removal takes place through a particle diffusion mechanism. The adsorption was found to be endothermic in nature and follows both Langmuir and Freundlich models. Estimation of the phenols was carried out by capillary electrophoresis, and the adsorbent has been successfully tried for the removal of chlorophenols from a wastewater. The developed process is very useful, economic, rapid, and reproducible for the removal of phenols.     

径向流耦合超滤分离纯化铜藻多糖及其烟丝保润的应用

研究铜藻提取液通过径向流色谱快速脱除蛋白质的工艺参数,以蛋白质脱出率和多糖保留率为考查指标,考察进样浓度、进样量、进样速度以及洗脱速度参数的影响。结果表明:当上样流速5 mL/min,洗脱速度40mL/min,上样量100 mL,上样浓度5mg/mL时,蛋白质脱除率为74.35%,多糖保留率为80.75%。利用超滤技术将通过径向流后和未通过径向流的铜藻多糖分离为10 ku以下、10～100 ku和100 ku以上各3个组分,通过对比多糖组分的蛋白质脱除率,得出径向流耦合超滤较单一法蛋白质脱除率上都有提高,耦合法脱除率达95%以上。对铜藻多糖各组分的保润性能进行测定,结果显示,铜藻多糖无论在防止解吸还是防止吸湿方面都有提高。     

Removal of pharmaceuticals and personal care products (PPCPs) from urban wastewater in a pilot vertical flow constructed wetland and a sand filter

Removal efficiencies and elimination kinetics of 13 pharmaceuticals and personal care products (PPCPs) and BOD5, TSS, and ammonium were evaluated in a pilot vertical subsurface-flow constructed wetland (VFCW) and compared with those obtained by a sand filter. On the basis of the observed removals, the PPCPs studied were grouped in relation to their removal efficiency into (i) PPCPs very efficiently removed, that is, >95% removal in one of the systems (caffeine, salicylic acid, methyl dihydrojasmonate, CA-ibuprofen, hydrocinnamic acid, oxybenzone, ibuprofen, OH-ibuprofen); (ii) PPCPs moderately removed, with removals between 70 and 90% in the two systems (naproxen, diclofenac, galaxolide, and tonalide); and finally (iii) PPCPs poorly removed, with elimination rates of <30% (carbamazepine). At design hydraulic loading rate (HLR) the planted VFCW and the nonplanted SF exhibited similar PPCP removal efficiencies, but the VFCWwas less sensitive to removal decline in overloading conditions (up to 2 times the design HLR). Moreover, under a clogging simulation, the HLR and the presence of vegetation were some of the key aspects affecting the PPCPs, BOD5, and ammonium removal from domestic wastewater. The VFCW evaluated was more efficient in terms of removal efficiency and loading rate for most of the PPCPs studied in comparison to constructed wetlands of other configurations (i.e., horizontal subsurface flow) and SF (nonplanted). The shorter hydraulic residence time (a few hours) in VFCW compared to that in other CW configurations ranging from days to weeks makes VFCWs a very appropriate wastewater treatment option in space-limited areas.     

三维电极床反应器去除甲苯废气的研究

介绍了用三维电极反应器去除有害废气甲苯的情况。实验研究了电流、气体停留时间等不同因素对甲苯去除率的影响。当电流为3 A、气体流量为2000 mL/min时,反应器对浓度为1300 mg/m3的甲苯废气的去除率达40%以上。     

酸催化乙醇制浆废液综合利用的前处理工艺

制浆废液中的多酚化合物是影响其后续利用和污染环境的主要因素,采用XDA-1、D301、XDA-7树脂分别对造纸废液进行脱酚处理。结果表明：XDA-1脱酚效果较好,在最佳条件下,即流速1.5ml/min,样品中酚类浓度为0.3mg/ml左右,上样pH为2.0时,酚类的脱除率达到97.7%,还原糖损失率为5.8%。采用80%乙醇洗脱柱,88.9%的多酚得到回收。     

水酶法水解液中大豆多肽的吸附纯化及其氨基酸组成分析

考察大孔吸附树脂对水酶法水解液中大豆多肽的吸附性能和纯化效果,通过静态吸附和解吸实验对8种树脂进行了初步筛选,并进一步研究了上样体积、上样流速、解吸剂体积分数等条件对大孔吸附树脂纯化能力的影响。结果表明：DA201-C大孔吸附树脂对水酶法大豆多肽的吸附性能优于其他7 种树脂,其最佳动态吸附工艺为：上样体积140 mL、上样流速1.5 mL/min、水洗体积350 mL,体积分数25%、50%、75%、100%乙醇溶液分级洗脱,每次80 mL,流速2 mL/min。经纯化后各大豆多肽组分纯度均在80%以上,总回收率为95.65%,树脂吸附量为13.32 mg/g,糖类及盐类杂质分别降低51%及90%以上;乙醇分级洗脱可分离4 个大豆多肽组分,其中75%体积分数组分SP-DA75氧自由基清除能力最强,肽段的抗氧化性与其疏水性氨基酸含量及酸性氨基酸含量具有一定相关性。     

硬糖类产品中桉叶素的含量测定

目的 建立适用于硬糖类产品中桉叶素的检测方法.方法 采用气相色谱法测定硬糖中桉叶素的含量.采用Agilent HP-INNOWAX毛细管色谱柱(柱长为30 m,内径为0.32 mm,膜厚为0.25μm),采用顶空进样,进样量为5 mL,炉温为85℃,平衡时间为30 min,进样口温度为150℃,柱温为程序升温:初始温度...