炼焦过程排放挥发性有机物的排放特征和组成分布研究

为控制炼焦排放以及为预防城市大气污染提供可靠的污染源数据支持,利用不锈钢采样罐和全自动预浓缩/GC/MS系统,研究了58-Ⅱ型和JN43-80型焦炉在装煤时刻和炼焦过程(包括装煤时刻)中挥发有机物(VOCs)的排放特征及其组成分布,分析了焦化行业排放VOCs的反应活性。研究发现,在装煤时刻和炼焦过程中,58-Ⅱ型焦炉产生的总挥发性有机物(TVOCs)浓度分别为7022μg/m~3和6266μg/m~3;JN43-80型焦炉产生的TVOCs浓度分别为4185μg/m~3和3298μg/m~3。装煤时刻产生的TVOCs浓度明显高于炼焦过程产生的。炼焦过程无组织排放的VOCs包含烯烃、烷烃、芳香烃、卤代烃以及少量的醛和酮,其中乙烯、乙烷、丙烯、苯、甲苯等为主要成分。这些产生的VOCs反应活性各不相同,活性最大的是烯烃类物质,其活性占TVOCs反应活性比重为(86.2±2.1)%;其次是芳香烃类物质,其活性比重为(9.2±3.1)%;反应活性最大的5个物种分别是丙烯、乙烯、1,3-丁二烯、1-丁烯以及苯乙烯。     

水中挥发酚检测方法初探

酚类属高毒物质,水中挥发酚的含量直接影响人类健康。近10年来,我国研究人员对水中挥发酚的测定方法开展了很多研究,特别对于采用4-氨基安替比林分光光度法(4-AAP)(GB 7490-1987)测定水中挥发酚的各个环节,如样品的采集、保存、预处理、试剂纯度、反应时间控制等相关因素进行了研究,找到了影响含量准确的因素,为测定水中挥发酚的含量提供了快速、准确、重复性好的方法。对一些非国标法测定水中挥发酚的方法也进行了介绍。文章对这些方法进行了分类总结。希望能对实验人员有所帮助。     

VOC emission caps constrained by air quality targets based on response surface model: A case study in the Pearl River Delta Region, China

Because of the recent growth in ground-level ozone and increased emission of volatile organic compounds (VOCs), VOC emission control has become a major concern in China. In response, emission caps to control VOC have been stipulated in recent policies, but few of them were constrained by the co-control target of PM_2.5 and ozone, and discussed the factor that influence the emission cap formulation. Herein, we proposed a framework for quantification of VOC emission caps constrained by targets for PM_2.5 and ozone via a new response surface modeling (RSM) technique, achieving 50% computational cost savings of the quantification. In the Pearl River Delta (PRD) region, the VOC emission caps constrained by air quality targets varied greatly with the NO_x emission reduction level. If control measures in the surrounding areas of the PRD region were not considered, there could be two feasible strategies for VOC emission caps to meet air quality targets (160 µg/m³ for the maximum 8-hr-average 90th-percentile (MDA8-90%) ozone and 25 µg/m³ for the annual average of PM_2.5): a moderate VOC emission cap with <20% NOx emission reductions or a notable VOC emission cap with >60% NO_x emission reductions. If the ozone concentration target were reduced to 155 µg/m³, deep NO_x emission reductions is the only feasible ozone control measure in PRD. Optimization of seasonal VOC emission caps based on the Monte Carlo simulation could allow us to gain higher ozone benefits or greater VOC emission reductions. If VOC emissions were further reduced in autumn, MDA8-90% ozone could be lowered by 0.3-1.5 µg/m³, equaling the ozone benefits of 10% VOC emission reduction measures. The method for VOC emission cap quantification and optimization proposed in this study could provide scientific guidance for coordinated control of regional PM_2.5 and O₃ pollution in China.     

Enhanced nitrogen removal upon the addition of volatile fatty acids from activated sludge by combining calcium peroxide and low-thermal pretreatments

This study investigated a combined low-thermal and CaO₂ pretreatment to enhance the volatile fatty acid (VFA) production from waste activated sludge (WAS). The fermentative product was added to a sequencing batch reactor (SBR) as an external carbon source to enhance nitrogen removal. The results showed that the combined pretreatment improved WAS solubilization, releasing more biodegradable substrates, such as proteins and polysaccharides, from TB-EPS to LB-EPS and S-EPS. The maximum VFA production of 3529 ± 188 mg COD/L was obtained in the combined pretreatment (0.2 g CaO₂/g VS + 70 °C for 60 min), which was 2.1 and 1.4-fold of that obtained from the sole low-thermal pretreatment and the control test, respectively. Consequently, when the fermentative liquid was added as an external denitrification carbon source, the effluent total nitrogen decreased to Class A of the discharge standard for pollutants in rural wastewater treatment plants in most areas of China.     

Potential applications of porous organic polymers as adsorbent for the adsorption of volatile organic compounds

Volatile organic compounds (VOCs) with high toxicity and carcinogenicity are emitted from kinds of industries, which endanger human health and the environment. Adsorption is a promising method for the treatment of VOCs due to its low cost and high efficiency. In recent years, activated carbons, zeolites, and mesoporous materials are widely used to remove VOCs because of their high specific surface area and abundant porosity. However, the hydrophilic nature and low desorption rate of those materials limit their commercial application. Furthermore, the adsorption capacities of VOCs still need to be improved. Porous organic polymers (POPs) with extremely high porosity, structural diversity, and hydrophobic have been considered as one of the most promising candidates for VOCs adsorption. This review generalized the superiority of POPs for VOCs adsorption compared to other porous materials and summarized the studies of VOCs adsorption on different types of POPs. Moreover, the mechanism of competitive adsorption between water and VOCs on the POPs was discussed. Finally, a concise outlook for utilizing POPs for VOCs adsorption was discussed, noting areas in which further work is needed to develop the next-generation POPs for practical applications.     

New insights into different surfactants’ impacts on sludge fermentation: Focusing on the particular metabolic processes and microbial genetic traits

• The promoting effects for VFA generation follow the order of APG>SDBS>HTAB. • Surfactants improve the WAS solubilization/hydrolysis and acidification processes. • The VFA promotion is associated with surfactants’ distinctive characteristics. • Surfactants induce the enrichment of functional bacteria for VFA biosynthesis. • The vital genes for substrates delivery, metabolism, and VFA yields are upregulated. Surfactants were expected to exhibit positive effects on the waste activated sludge (WAS) disposal. However, the systematic comparison of different categories of surfactants on the WAS fermentation and the functional mechanisms, especially microbial metabolic traits, have not yet been precisely explored. This study revealed the positive effects of different surfactants on the volatile fatty acid (VFA) production, which followed the order of alkyl polysaccharides (APG)>sodium dodecylbenzene sulfonate (SDBS)>hexadecyl trimethyl ammonium bromide (HTAB). Mechanistic exploration found that the presence of different surfactants improved solubilization and hydrolysis steps, and then contributed to the subsequent acidification with different efficiencies. The functional microorganisms associated with VFA generation were enriched in surfactant-conditioned reactors. Metagenomic analysis further indicated that the key genes involved in the particular process of VFA generation were over-expressed. The simultaneous bioavailable substrate improvement, functional bacterial enrichment, and metabolic activity upregulation induced by different surfactants jointly contributed to VFA promotion during WAS fermentation. This study could provide a comprehensive realization of surfactants’ impacts on the WAS fermentation process, and more importantly, it reminded the public to discern the distinct interplaying effects induced by different chemicals in regulating the WAS disposal and resource recovery.     

酚类化合物气相色谱保留指数的定量结构相关性研究

应用偏最小二乘回归技术建立了102种酚类化合物气相色谱保留指数与分子全息结构间的相关模型,在最佳建模条件下得到非交叉验证相关系数(r2)为0.965,交叉验证相关系数(q_LOO2)为0.963. 从102种酚类化合物中随机选出68种作为训练集,其余作为测试集,来验证分子全息QSRR模型的预测能力和稳健性. 在最佳建模条件对训练集进行偏最小二乘回归分析,r2为0.967,q_LOO2为0.927. 用训练集数据所建立的QSRR模型预测测试集中酚类化合物的色谱保留指数,结果表明,基于训练集所建立的QSRR模型具有很高的预测能力和稳健性,可以对测试集酚类化合物的气相色谱保留指数进行很好的预测. 此外,利用最佳全息定量结构保留关系(HQSRR)模型的色码图,探讨酚类化合物中的不同侧链基团对其色谱保留性质的影响,及其在固定相上的色谱保留机理.      

活性炭吸附室内空气中挥发性有机化合物

活性炭吸附室内空气中挥发性有机化合物的１０％穿透时间与气相浓度及挥发性有机化合物的种类有关,通过对苯、甲苯和丙酮的实验研究,得出了由高浓度估算室内低浓度时炭床１０％穿透时间的经验公式ｔｂ,１＝ｔｂ,ｈ（Ｃ０,１／Ｃ０,ｈ）＾ａ,其中ａ值是与炭床性能及挥发性有机化合物种类有关的参数,可通过实验确定。     

络合萃取法处理工业含酚废水

设计了高效ＱＨ型络合萃取脱酚溶剂,建立了工业含酚废水络合萃取工艺,进行了不同种类含酚废水的络合萃取平衡和错流萃取的实验。结果表明,利用ＱＨ混合型络合萃取剂,通过２－３级错流接触（油水比为１：１）,废水残液中的酚类浓度小于０．５ｍｇ／Ｌ,可以达到国家规定的排放标准。初步研究表明,该法对废水中ＣＯＤ亦有较好的去除效果。     

地面水中酚类污染物的树脂吸附富集反相高压液相色谱测定

以乙腈－水－醋酸（３１：６８：１,Ｖ／Ｖ／Ｖ）为流动相的反相ＨＰＬＣ－ＵＶ法,可以方便地对水中酚类进行直接分离和分析。采用树脂吸附法为ＨＰＬＣ的预富集步骤,选用国产吸附树脂ＧＤＸ－５０２为富集剂,二氧六环为洗脱剂,可以定量测定水中μｇ／Ｌ级以下的多种酚。在实验条件下,９种一元酚的平均变异系数为２．４％,其中８种酚的富集回收率大于９０％。用本法测得的地面水的总酚含量与４－氨基安替比林法具有可比性。