Cupriavidus necator (DSM428)利用地沟油合成PHA的条件优化

聚羟基脂肪酸酯(PHA)是一种在细胞体内合成的天然高分子生物材料,由于其具有可降解性,因此可以代替传统塑料,已被广泛应用于生产生活中。选用Cupriavidus necator (DSM428)作为实验菌株,利用价格相对低廉的地沟油作为细菌生长的碳源,考察了pH、温度、培养时间、C/N(质量比)对PHA产生量的影响,同时对其结构及热学性质进行分析。通过实验发现,PHA最佳合成条件是pH值为8,温度为30℃,培养时间为84 h,C/N为20:1.5,PHA最大产量范围为7~9 g/L。     

焙烧条件对CuO/ZSM-5催化剂脱硫脱硝性能的影响

以ZSM-5分子筛为载体,通过浸渍法制备10％ CuO/ZSM-5(金属氧化物质量占载体质量)催化剂,以CH4为还原气,考察不同焙烧温度和焙烧时间对催化剂脱硫脱硝性能的影响.XRD和TPR的表征结果显示,最佳焙烧条件为550℃下焙烧4h,在此焙烧条件下,10％ CuO/ZSM-5催化剂达到的最高脱硝脱硫率分别为90.6％和98.8％.     

白腐真菌对染料脱色及降解过程机理和影响因素

许多白腐真菌对染料具有广谱的脱色和降解能力 ,其脱色及降解作用可能主要是由于其在次生代谢阶段产生的木质素过氧化酶LiPs和锰过氧化酶MnPs所致。培养条件对白腐真菌脱色及降解活性有较大的影响 ,在培养基中加入藜芦醇和二价锰等能够显著提高木质素过氧化酶的产生 ;富氮培养基会抑制LiPs的生成 ;硫脲、叠氮化物、氰化物等均能明显地抑制白腐真菌的脱色及降解活性 ;缓冲液的选择对维持稳定的 pH值和菌丝的形态有一定作用 ,从而影响其脱色效果 ;富氧环境是一切白腐真菌对染料进行脱色和降解的必要条件 ;适度的搅拌混合有利于反应时的物质之间传递 ;一般地 ,在培养时间达到 3天以后白腐真菌才能达到较高的脱色与降解活性。染料分子大小和结构及其基团的位置对脱色及降解效果有明显影响。使用特殊填料极大地提高处理系统中的生物量以克服真菌生长速度相对较慢、提高处理能力是该技术今后的研究重点。     

磷酸活化-微波热解法制备污泥吸附剂

以污泥吸附剂的碘值和其对铬的吸附去除效果为考察指标,对制备污泥吸附剂的各种影响因素进行全面考察和分析。结果表明,其最佳制备工艺条件为微波功率550 W,微波辐照时间330 s,磷酸浓度为40%及磷酸与污泥原料的液固比为2∶1,空气氛围中制备的吸附剂SAA的性能要稍优于氮气氛围中制备的吸附剂SAN,但前者的得率稍低于后者,总体来讲,两者相差不大。在实际应用中可简化制备工艺,无需通入保护气体。     

无机阴离子及有机物对过硫酸盐去除废水中苯胺的影响

突发排放废水中可能含有大量阴离子和有机物,其会淬灭自由基和限制基于过硫酸盐的高级氧化技术的应用。考察了过硫酸钠投加量、Fe²⁺投加量、pH、Cl⁻、${rm{HCO}}_3^ - $、${rm{NO}}_3^ - $和其他有机物对过硫酸盐降解苯胺的影响。结果表明：随着过硫酸盐和Fe²⁺浓度的升高,苯胺的去除率也随之增加,但过量投加反而会导致苯胺的去除率下降,活化过硫酸盐氧化去除苯胺的过程符合一级降解动力学;酸性条件有利于Fe²⁺活化过硫酸盐降解苯胺,但在不投加Fe²⁺时碱性条件可以活化过硫酸盐;${rm{HCO}}_3^ - $和硝基苯的存在会抑制苯胺的去除,而${rm{NO}}_3^ - $对苯胺的去除基本没有影响;酚的加入会促进苯胺的去除;Cl⁻的存在可以促进Fe²⁺活化过硫酸盐对苯胺的去除,但其中间产物可能会造成潜在的生态风险,后续需进一步研究。同时,在不投加Fe²⁺时,Cl⁻也可以活化过硫酸盐去除苯胺。通过对自由基的识别,发现${rm{SO}}_4^ - cdot $在降解过程中起主要作用。此外,提出了1种计算Fe²⁺/过硫酸盐体系中${rm{SO}}_4^ - cdot $和·OH稳态浓度的简单方法。该计算方法可用于估算降解过程中产生的${rm{SO}}_4^ - cdot $和·OH的量,并评价不同活化体系下${rm{SO}}_4^ - cdot $和·OH的产率,为氧化机理的研究提供参考。     

改进管式光生物反应器中雷诺数对小球藻生长的影响

微藻固碳是微藻通过光合作用将无机碳转化为有机碳,具有转化效率高,节省能源的优点,微藻固碳对于国家实现“双碳”战略目标具有潜在贡献。为了实现微藻的规模化低成本培养,设计了一种适宜大规模培养微藻的管式光生物反应器,并以该管式光生物反应器为基础,在室内开展了小球藻在不同雷诺数下的生长状况研究实验。根据实验结果得出,管式光生物反应器中小球藻比增长率、日产量均与不同雷诺数、不同藻液浓度有关。雷诺数在1.5×10⁴~2×10⁴时小球藻在实验前期生长较快,实验后期生长缓慢;雷诺数在2.5×10⁴~4×10⁴之间小球藻实验后期出现迅速生长。在藻液浓度大于1.1 g·L⁻¹时,雷诺数在3.5×10⁴左右时为管式光生物反应器中小球藻生长的最优雷诺数值。对于管式光生物反应器来说,不同管径条件下相同流速对微藻生长产生的影响是否相同是很难判定。因此,在水力学中表征水体流态的雷诺数将是一个很好的评判指标。该研究结果为实现在管式光生物反应器中低成本大规模培养微藻提供了参考。     

超声萃取法处理含油污泥

应用超声强化技术,对以汽油为萃取剂的超声萃取法处理含油污泥的工艺进行了研究,筛选了调整剂、絮凝剂、破乳剂,探讨了萃取温度、萃取时间、超声频率、超声功率等对处理效果的影响。结果表明:在调整剂为采油废水、物料配比为v(萃取剂)∶v(调整剂)∶v(油污泥)=4∶4∶1的条件下,萃取工艺为萃取温度40℃、萃取时间15 min、超声频率40kHz、超声功率150 W时,可回收含油污泥中83.7%的油品。     

Per- and polyfluorinated compounds in house dust and indoor air from northern Norway - a pilot study

Polyfluorinated compounds (PFCs) are an extremely versatile class of compounds and are used in a variety of consumer applications and products. Recent studies have suggested that PFCs in indoor air and dust could act as sources of human exposure and outdoor air contamination. This study presents method development and analysis of a wide range of PFCs in dust and air using active sampling techniques with commercially available sampling equipment (forensic nozzles with filter housings for dust collection and polyurethane foam (PUF)-XAD₂-PUF sandwich-tubes for air sampling) using both liquid and gas chromatography mass spectrometry. The developed method was validated and tested for applicability to analyze dust and air samples at both low and high concentrations (0.5 ng and 25 ng per analyte per air sample, respectively). Samples from private households and an office building were analyzed to explore differences in distribution patterns and concentrations. Perfluorooctane sulfonate, perfluorodecane sulfonate, perfluoroheptanoate, perfluorooctanoate and perfluorononanoate were observed in all samples of dust from private households, in the range from 1 to 80.1 ng g⁻¹. Fluorotelomer alcohols (FTOHs) were the predominant PFCs in indoor air samples with ∑FTOHs ranging between 4.7 and 17.9 ng m⁻³. The concentrations found in the present study are generally lower than those previously reported. This variation may be due to differences associated with geographical locations and lifestyles. However, use of different sampling techniques and strategies among studies can introduce large variations in PFC concentration found, making direct comparisons challenging.     

Indoor/outdoor connections exemplified by processes that depend on an organic compound's saturation vapor pressure

Outdoor and indoor environments are profitably viewed as parts of a whole connected through various physical and chemical interactions. This paper examines four phenomena that share a dependence on vapor pressure—the extent to which an organic compound in the gas phase sorbs on airborne particles, sorbs on surfaces, sorbs on particles collected on a filter or activates trigeminal nerve receptors. It also defines a new equilibrium coefficient for the partitioning of organic compounds between an airstream and particles collected by a filter in that airstream. Gas/particle partitioning has been studied extensively outdoors, but sparingly indoors. Gas/surface partitioning occurs primarily indoors while gas/filter partitioning occurs at the interface between outdoors and indoors. Activation of trigeminal nerve receptors occurs at the human interface. The logarithm of an organic compound's saturation vapor pressure correlates in a linear fashion with the logarithms of equilibrium coefficients characteristic of each of these four phenomena. Since, to a rough approximation, the log of an organic compound's vapor pressure scales with its molecular weight, molecular weight can be used to make first estimates of the above processes. For typical indoor conditions, only larger compounds with lower-saturation vapor pressures (e.g., tetracosane, pentacosane, or di-2-ethylhexyl phthalate) have airborne particle concentrations comparable to or larger than gas phase concentrations. Regardless of a compound's vapor pressure, the total mass sorbed on indoor airborne particles is quite small compared to the total sorbed on indoor surfaces, reflecting the large difference in surface areas between particles within a room and surfaces within a room. If the actual surface areas are considered, accounting for roughness and porosity, the surface concentration of organics sorbed on typical airborne particles appears to be comparable to the surface concentration of organics sorbed on indoor carpets, walls and other materials (based on data from several studies in the literature). Mirroring the importance of phase distributions outdoors, an organic compound's indoor lifetime, fate and even health impacts depend on its distribution between phases and among surfaces.     

石家庄市冬季一次重污染过程分析与反馈效应研究

为深入探究高ρ（PM_2.5）地区重污染过程的发展变化规律,以石家庄市一次重污染过程（2017年1月13-20日）为例,结合空气质量监测数据、PM_2.5组分测试数据、气象观测资料,从重污染发展阶段（简称\"P1阶段\"）、维持阶段（简称\"P2阶段\"）和清除阶段（简称\"P3阶段\"）分析PM_2.5及其化学组分的变化特征、气象条件和高低空天气形势演变特征,并利用WRF-Chem模型定量研究重污染过程气溶胶反馈效应对典型气象要素的影响.结果表明:①此次重污染过程属于逐步累积增长、快速清除型,在P2阶段ρ（PM_2.5）平均值为241.0 μg/m3,最大值为367.5 μg/m3.②P1和P2阶段高低空大气环流配置稳定,大气边界层高度范围为620.6~712.2 m,风速范围为1.3~2.5 m/s,相对湿度范围为60%~80%.③P2阶段SOR（硫氧化率）和NOR（氮氧化率）均为0.3,ρ（SNA）（SNA为SO₄2-、NO₃-和NH₄+的统称）为128.8 μg/m3,占ρ（PM_2.5）的56.2%;OM[有机质,ρ（OM）=ρ（POA）+ρ（SOA）,其中,POA为一次有机气溶胶,SOA为二次有机气溶胶]是除SNA以外的第二大组分,在P1和P3阶段ρ（POA）大于ρ（SOA）,而在P2阶段ρ（SOA）与ρ（POA）相等,均为28.0 μg/m3,表明在重污染过程中二次污染严重;整个污染过程ρ（NO₃-）/ρ（SO₄2-）为1.0,表明石家庄市移动源和固定源对ρ（PM_2.5）贡献相当.④WRF-Chem模型模拟结果表明,太阳辐射量、温度和大气边界层高度受气溶胶反馈效应的影响在P2阶段的下降量分别为75.1 W/m2、2.7℃和109.9 m,比P1阶段分别高33.6%、91.4%和18.6%,比P3阶段分别高147.0%、305.3%和24.1%.研究显示,此次静稳天气下的重污染过程二次污染严重,气溶胶反馈效应整体使得太阳辐射量、温度和大气边界层高度均向不利于污染扩散的趋势发展,造成石家庄市的ρ（PM_2.5）进一步增加.