胶质芽孢杆菌、黑曲霉及与沸石联合对模拟废水中Fe~（3＋）处理研究

研究沸石、胶质芽孢杆菌（Bacillus mucilaginosus）、黑曲霉（Aspergillus Niger）、胶质芽孢杆菌与沸石联合以及黑曲霉与沸石联合对模拟废水中Fe3＋的吸附等温曲线,分析它们对Fe3＋模拟废水的吸附及絮凝作用。结果表明：沸石对Fe3＋吸附作用符合Freundlich方程;胶质芽孢杆菌分泌含有—OH和COO-的胞外多糖,对Fe3＋具有较好的吸附效果;沸石与胶质芽孢杆菌联合对模拟废水中Fe3＋的处理,低浓度以沸石对Fe3＋的吸附为主,加入胶质芽孢杆菌絮凝剂使吸附了Fe3＋的沸石进行絮凝沉降,吸附等温曲线符合Langmuir吸附等温方程,高浓度两者共同作用使吸附量增加;黑曲霉对Fe3＋的吸附符合BET吸附等温方程;沸石与黑曲霉两者共同作用对Fe3＋模拟废水吸附等温曲线为直线。通过去除效果对比分析可知：胶质芽孢杆菌既有吸附又有絮凝功能;胶质芽孢杆菌絮凝剂无论是对Fe3＋的吸附还是对吸附Fe3＋沸石的絮凝都比黑曲霉对Fe3＋处理效果好;胶质芽孢杆菌和一些非金属矿物复合处理污染废水是一种无毒、低成本环保的处理方法,本研究将为它们在工程中的应用提供实践依据。     

十六烷基三甲基溴化铵改性沸石的制备及吸附废水中苯酚的性能

为高效去除废水中的苯酚,制备了十六烷基三甲基溴化铵(CTMAB)改性沸石(以下简称改性沸石),研究了改性沸石投加量、废水pH、反应时间等对废水中苯酚去除的影响,分析了改性沸石吸附废水中苯酚的动力学过程、等温线过程以及热力学特征,探讨了吸附作用机制。结果表明,CTMAB质量分数为1.2%时,改性沸石对苯酚的吸附量达到7.2mg/g,明显高于天然沸石(1.1mg/g);改性沸石投加量6g/L、反应时间40min、pH=10的条件下,废水中苯酚的去除率可达98.4%;二级动力学方程和Langmuir方程能更好地拟合改性沸石吸附废水中苯酚的过程,且吸附是自发、放热、熵增的过程。改性沸石吸附废水中苯酚的作用机制为:CTMAB中的R—N~+(R为基团)与天然沸石表面双电层中的H~+、K~+发生交换后,R—N~+与沸石表面结合,而CTMAB结构中的疏水基则向外(废水相),由此CTMAB在沸石表面形成了有机相,苯酚通过分配作用进入到沸石表面的CTMAB有机相中与R—N+缔合而得以去除。     

沸石载体催化剂研制及其催化臭氧氧化染料废水的研究

以沸石为载体负载不同金属氧化物来制备催化剂,通过试验分析该催化剂催化臭氧氧化染料废水的效果及其影响因素。结果表明:(1)沸石对染料废水的吸附作用很小,总有机碳(TOC)去除率基本维持在3.2%左右,对于后期的试验可以忽略其影响。(2)以沸石作为载体制得的MnO2、Fe2O3、ZnO、CuO负载型催化剂(分别简写为MnO2/沸石、Fe2O3/沸石、ZnO/沸石、CuO/沸石),对臭氧氧化反应均有催化作用,其催化效果依次为MnO2/沸石Fe2O3/沸石ZnO/沸石CuO/沸石。同时,MnO2/沸石的重复使用率高。(3)MnO2/沸石催化臭氧氧化效率及重复使用率均优于以活性炭为载体的MnO2负载型催化剂。(4)臭氧氧化和MnO2/沸石催化臭氧氧化对染料的脱色率基本一致。MnO2/沸石催化臭氧氧化的TOC去除率比臭氧氧化提高较多,对染料废水有很好的处理效果。(5)以沸石为载体制得的负载型催化剂催化臭氧氧化实际染料废水的处理效果较好,具有较高的实用价值。     

天然和CPB改性沸石对Hg2+的吸附特征

通过静态实验研究溴代十六烷基吡啶(CPB)改性沸石和天然沸石对废水中Hg2+的吸附特性,探讨了吸附动力学、吸附平衡和吸附热力学机制。研究表明:Langmuir方程能较好地描述2种沸石对Hg2+的吸附,CPB改性沸石对Hg2+的吸附率得到显著提高。实验条件下,改性沸石对Hg2+的吸附率从67.5%提高到98.9%,吸附容量从0.521 mg/g提高到3.07 mg/g。利用准一级动力学方程、假二级动力学方程、颗粒内扩散模型和Elovich方程分别对动力学过程进行拟合,发现2种沸石对Hg2+的吸附均满足假二级动力学方程,且离子的颗粒内扩散对整个吸附过程有影响。动力学拟合、D-R方程拟合和热力学研究综合表明:2种沸石对Hg2+的吸附既存在化学吸附又存在物理吸附,吸附吉布斯自由能变(△G0)、焓变(ΔH0)、熵变(ΔS0)均小于0,反应为自发的放热反应,低温有利于吸附的进行。     

枯草芽孢杆菌对Cu2+的吸附及菌体表面基团分析

以枯草芽孢杆菌(Bacillus subtilis)为生物吸附剂,讨论了其对Cu2+的生物吸附规律,并通过酸碱滴定这一表面分析手段,结合相关软件及傅里叶变换红外光谱(FTIR)分析了菌体表面主要的基团种类及数量.结果表明,枯草芽孢杆菌对Cu2+吸附的最佳条件是:pH为6、吸附时间为24 h,菌悬液用量和Cu2+初始浓度...     

改性沸石对低浓度氨氮废水的动态吸附

采用氯化钠溶液对甘肃白银天然沸石改性,以低浓度氨氮(NH4+-N)废水为处理对象,对比了天然沸石和改性沸石的动态吸附特性并绘制穿透曲线,利用Origin软件对实验数据分析处理,得出穿透曲线的通式。结果表明:在相同条件下,改性沸石的穿透时间和吸附饱和时间都比天然沸石的长约1.5倍;沸石经氯化钠改性后,对NH4+-N的吸附速率和饱和吸附量都明显提高,吸附性能显著改善。Origin软件对水溶液中NH4+-N的吸附穿透曲线的Logistic模型回归式具有较高的精度,该模型可以很好地反映沸石吸附剂的动态吸附过程。     

4A沸石去除水中Pb~(2+)的研究

在静态条件下,研究了4A沸石对废水中Pb2+的吸附性能,并探讨了影响吸附的因素。实验表明:当温度为30℃,废水pH为5~6,0.01 g4A沸石对100 mg/LPb2+溶液10 mL吸附20 min,Pb2+的去除率可达到99%以上。在实验研究条件下,4A沸石对Pb2+的吸附符合Langmuir和Freundlich等温吸附方程,相关系数为0.9819和0.9998。经计算,4A沸石对Pb2+的饱和吸附量为125 mg/g。4A沸石吸附水中Pb2+,达到吸附平衡的时间较短;溶液pH值的变化对吸附效果影响不显著;温度从室温略微升高,Pb2+的去除率略有增大。吸附在4 A沸石上的Pb2+可回收利用,处理后的4A沸石可以再生,且重复使用性能较好。     

金属离子对菌株JY01生长和苯酚降解性能的影响研究

金属可能通过生理和生态两方面对微生物的苯酚降解过程产生重要影响.为了提高芽孢杆菌Bacillus sp.JY01(以下称菌株JY01)的苯酚降解效率,探讨了6种金属离子(Ba2+、Cu2+、Co2+、Fe3、Zn2+、pb2+)对其生长和苯酚降解性能的影响.结果表明,在质量分数为0.001％～0.050％时,Cu2+、Zn2+、Co2、Fe3+、Ba2+、pb2+对菌株JY01的生长和苯酚降解均有抑制作用,并且抑制作用总体随金属离子浓度的升高而增强,当6种金属的质量分数分别达到0.005％时,菌株JY01对苯酚的降解能力为Ba2+ ＜Cu2+ ＜Co2+ ＜Fe3+ ＜Zn2+ ＜pb2+；金属离子通过影响菌株JY01的生长状况来影响其苯酚降解性能；很多金属离子对菌株JY01生长有明显抑制作用,因此在实际生物处理含苯酚废水时,要考虑废水中金属离子对降解菌生长状况的影响.     

4A沸石分子筛处理中低浓度氨氮废水

利用天然沸石、采用水热合成法制备4A沸石分子筛,用XRD和SEM进行了表征。通过考察吸附剂用量、pH、共存金属阳离子、吸附时间、氨氮废水初始浓度、温度对吸附性能的影响,结合动力学方程、吸附等温线、热力学函数等研究了吸附性能和机理。结果表明,当4 g/L的4A沸石分子筛在废水pH值为4~8的条件下对中低浓度氨氮吸附120min后,去除率可达88%;废水中共存单一金属阳离子(Pb2+、Cu2+、Ca2+和Mg2+)浓度大于100 mg/L时,对中低浓度的NH+4有强烈的竞争吸附;氨氮的吸附过程较好地符合准二级动力学方程、Freundlich模型,是一种混乱度增加、自发的放热过程。     

用煤矸石合成4A沸石分子筛处理氨氮废水

以煤矸石为原料,采用碱熔-水热法合成4A沸石分子筛。由于煤矸石中铝、硅主要以高岭土形式存在,其活化过程是合成4A沸石分子筛关键环节。为提高4A沸石分子筛钙离子的交换能力,增加对模拟废水氨氮的去除率,实验考察了碳酸钠与煤矸石质量比、活化温度、活化时间、晶化温度和晶化时间对4A沸石分子筛钙离子交换能力的影响,同时也考察了模拟废水的pH、4A沸石分子筛加入量及吸附时间对氨氮去除率的影响。结果表明,最佳工艺条件为,碳酸钠与煤矸石质量比为0.9、活化温度为800℃、活化时间1.5 h、晶化温度90℃和晶化时间3 h。合成4A沸石分子筛的钙离子交换能力为310 mg/g,在pH为6的100 mL模拟氨氮废水中加入6 g 4A沸石分子筛吸附40 min后,废水中氨氮的去除率达到86%。通过最佳工艺条件合成4A沸石分子筛,在处理氨氮废水方面具有一定的应用前景。     

Levels of polychlorinated biphenyls, organochlorine pesticides, mercury, cadmium, copper, selenium, arsenic, and zinc in the harbour seal, Phoca vitulina, in Norwegian waters

Residue levels of the chlorinated hydrocarbons polychlorinated biphenyls (PCBs), total DDT, alpha-, beta- and gamma-hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), and oxychlordane in blubber, and the elements mercury, cadmium, copper, selenium, arsenic, and zinc in liver, of 82 harbour seals, Phoca vitulina, were determined. The seals were found dead or dying in Norwegian waters during the disease outbreak caused by a morbilli virus in 1988. Of the chlorinated hydrocarbons, the highest concentrations were found of PCBs, which were 2-4 times higher than the total DDT concentrations. P,p'-DDE was the main contributor to the total DDT, and constituted about 80%. The PCB and total DDT concentrations ranged from 0.4-38 and 0.1-8.8 mg kg(-1), respectively. The mercury concentrations ranged from 0.1-89 mg kg(-1). Significantly higher mean levels of PCBs (13 mg kg(-1) and mercury (16 mg kg(-1)) were found in blubber and liver, respectively, of seals from the Southern coast of Norway, as compared to the corresponding mean levels in seals from the Oslofjord (8.8 and 4.1 mg kg(-1)), and at the Northwestern coast (5.8 and 7.9 mg kg(-1)), respectively. A significant positive correlation was found between the concentrations of selenium and mercury. When the seals were grouped according to sex and age, females of ageclass > 1 and pups of both sexes had significantly lower PCB and total DDT levels than males ageclass > 1. Significantly higher hepatic mercury levels were found in seals ageclass > 1 as compared to pups. Only low levels of the other organochlorines, cadmium and arsenic, were found. Copper and zinc were considered to be present at normal physiological levels. The present organochlorine and heavy metal concentrations gave no support to suggestions that organochlorines and heavy metal pollution may be directly involved in the observed seal deaths.     

Emission inventory of eight elements,Fe, Al,K, Mg,Mn, Na,Ca and Ti,in dust source region of East Asia

Based on calculation of the emission rate of the atmospheric mineral dust and the data of elemental contents in surface soils, this paper calculates the emission inventory of eight main elements of the atmospheric dust, Fe, Al, K, Mg, Mn, Na, Ca and Ti, in the dust source region of East Asia. As the dust sources in both Northern China and the Southern Mongolia are of three types and, in each of the six source type areas, surface soils are relatively uniform in soil types and soil texture, a simple method to calculate the emission of an element in one source type area is proposed by multiplying the total emission of the dust PM₁₀ and PM₅₀ in the source type area with the mean percentage content of the element in surface soils of the area. Comparison of our calculation of the total Fe emission in the source region of East Asia with the total Fe deposition to the North Pacific Ocean, measured and calculated by previous authors, shows very good agreement. This general method can also be used for the emission calculation of any other element.     

Half-lives of tetra-, penta-, hexa-, hepta-, and octachlorodibenzo-p-dioxin in rats,monkeys, and humans--a critical review

The elimination half-lives (t1/2) in Sprague-Dawley rats for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 1,2, 3,7,8-pentachlorodibenzo-p-dioxin (PeCDD), 1,2,3,4,7,8-hexachlorodibenzo-p-dioxin (HxCDD), 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin (HpCDD) and 1,2,3,4,6,7,8,9-octachlorodibenzo-p-dioxin (OCDD) were estimated in long-term studies by Schlatter, Poiger and others. Furthermore, there are some published half-lives of TCDD in adult humans. The average half-life of TCDD in adult humans is approximately 2840 days, while in Sprague-Dawley rats the average t1/2 of TCDD is 19 days. The t1/2 of TCDD in humans is about 150 times that of rats. This factor was used to calculate the t1/2 values of the other polychlorinated dibenzo-p-dioxins (PCDDs) in humans from the rat data. Furthermore, the terminal t1/2 values of PCDDs in adult humans were calculated from the regression equation: logt1/2H = 1.34 logt1/2R + 1.25 which was recently established for 50 xenobiotics (t1/2H = terminal half-lives in days for humans, t1/2R = terminal half-lives in days for rats). The following terminal half-lives in adult humans were obtained: 12.6 years for 1,2,3,7,8-PeCDD, 26-45 years for 1,2,3,4,7,8-HxCDD, 80-102 years for 1,2,3,4,6,7,8-HpCDD and ca. 112-132 years for OCDD. These half-lives of PCDDs are critically compared with measured t1/2 values of PCDDs and other persistent organic pollutants in rats, monkeys and humans.     

Phthalic acid esters in grains,vegetables, and fruits: concentration,distribution, composition,bio-accessibility,and dietary exposure

Environmental Science and Pollution Research - Grain, vegetable, and fruit samples were collected from Xi’an City in Northwest China and analyzed for the characteristics, bio-accessibility,...     

Lead,mercury, cadmium,chromium, nickel,copper, zinc,calcium, iron,manganese and chromium (VI) levels in Nigeria and United States of America cement dust

This study was aimed at investigating the relative abundance of heavy metals in cement dust from different cement dust factories in order to predict their possible roles in the severity of cement dust toxicity. The concentrations of total mercury (Hg), copper (Cu), chromium (Cr), cadmium (Cd), nickel (Ni), manganese (Mn), lead (Pb), iron (Fe) and chromium (VI) (Cr (VI)) levels in cement dust and clinker samples from Nigeria and cement dust sample from the United States of America (USA) were determined using graphite furnace atomic absorption (GFAAS), while Zn and Ca were measured by flame atomic absorption spectrophotometry (FAAS), and Cr (VI) by colorimetric method. Total Cu, Ni and Mn were significantly higher in cement dust sample from USA (p < 0.05), also, both total Cr and Cr (VI) were 5.4–26 folds higher in USA cement dust compared with Nigeria cement dust or clinker (p < 0.001). Total Cd was higher in both Nigeria cement dust and clinker (p < 0.05 and p < 0.001), respectively. Mercury was more in both Nigeria cement dust and clinker (p < 0.05), while Pb was only significantly higher in clinker from Nigeria (p < 0.001). These results show that cement dust contain mixture of metals that are known human carcinogens and also have been implicated in other debilitating health conditions. Additionally, it revealed that metal content concentrations are factory dependent. This study appears to indicate the need for additional human studies relating the toxicity of these metals and their health impacts on cement factory workers.     

Effects of elevated CO2, nitrogen supply and tropospheric ozone on spring wheat-II. Nutrients (N, P, K, S, Ca, Mg, Fe, Mn, Zn)

CO(2) enrichment is expected to alter leaf demand for nitrogen and phosphorus in plant species with C(3) carbon dioxide fixation pathway, thus possibly causing nutrient imbalances in the tissues and disturbance of distribution and redistribution patterns within the plants. To test the influence of CO(2) enrichment and elevated tropospheric ozone in combination with different nitrogen supply, spring wheat (Tritium aestivum L. cv. Minaret) was exposed to three levels of CO(2) (361, 523, and 639 microl litre(-1), 24 h mean from sowing to final harvest), two levels of ozone (28.4 and 51.3 nl litre(-1)) and two levels of nitrogen supply (150 and 270 kg ha(-1)) in a full-factorial design in open-top field chambers. Additional fertilization experiments (120, 210, and 330 kg N ha(-1)) were carried out at low and high CO(2) levels. Macronutrients (N, P, K, S, Ca, Mg) and three micronutrients (Mn, Fe, Zn) were analysed in samples obtained at three different developmental stages: beginning of shoot elongation, anthesis, and ripening. At each harvest, plant samples were separated into different organs (green and senescent leaves, stem sections, ears, grains). According to analyses of tissue concentrations at the beginning of shoot elongation, the plants were sufficiently equipped with nutrients. Elevated ozone levels neither affected tissue concentrations nor shoot uptake of the nutrients. CO(2) and nitrogen treatments affected nutrient uptake, distribution and redistribution in a complex manner. CO(2) enrichment increased nitrogen-use efficiency and caused a lower demand for nitrogen in green tissues which was reflected in a decrease of critical nitrogen concentrations, lower leaf nitrogen concentrations and lower nitrogen pools in the leaves. Since grain nitrogen uptake during grain filling depended completely on redistribution from vegetative pools in green tissues, grain nitrogen concentrations fell considerably with severe implications for grain quality. Ca, S, Mg and Zn in green tissues were influenced by CO(2) enrichment in a similar manner to nitrogen. Phosphorus concentrations in green tissues, on the other hand, were not, or only slightly, affected by elevated CO(2). In stems, 'dilution' of all nutrients except manganese was observed, caused by the huge accumulation of water soluble carbohydrates, mainly fructans, in these tissues under CO(2) enrichment. Whole shoot uptake was either remarkably increased (K, Mn, P, Mg), nearly unaffected (N, S, Fe, Zn) or decreased (Ca) under CO(2) enrichment. Thus, nutrient cycling in plant-soil systems is expected to be altered under CO(2) enrichment.